kbuild: rust: keep Rust objects out of Clang LTO with inline helpersgrafted

Under `CONFIG_LTO_CLANG` + `CONFIG_RUST_INLINE_HELPERS`, one may hit
`objtool` errors such as:

    vmlinux.o: error: objtool: _R..._3Gsp4boot+0xd6a:
    can't find jump dest instruction at .text._R..._3Gsp4boot+0x1dfd

The reason is that in such builds, the Clang invocation that compiles
the combined Rust plus helpers bitcode emits LLVM bitcode (again) --
the final code generation happens in the linker's LTO step, which the
`-mllvm` trap options passed to Clang do not reach.

This, in turn, means that unreachable traps are missing, and the
impossible paths do not merely fallthrough to the next symbol, but past
the end of their own section, since LTO builds place each function in
its own section.

Thus filter `CC_FLAGS_LTO` out of the Clang invocation, so that it always
emits machine code directly, with the traps in place.

Assisted-by: LLM
Cc: Gary Guo <gary@garyguo.net>
Cc: Boqun Feng <boqun@kernel.org>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Matthew Maurer <mmaurer@google.com>
Cc: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: stable@vger.kernel.org
Fixes: 3a2486cc1da5 ("kbuild: rust: provide an option to inline C helpers into Rust")
Acked-by: Gary Guo <gary@garyguo.net>
Link: https://patch.msgid.link/20260816133233.197500-2-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

17 files changed, 7006 insertions, 0 deletions

diff --git a/drivers/hsi/Kconfig b/drivers/hsi/Kconfig
new file mode 100644
index 000000000..42da4c235
--- /dev/null
+++ b/drivers/hsi/Kconfig
@@ -0,0 +1,21 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# HSI driver configuration
+#
+menuconfig HSI
+	tristate "HSI support"
+	help
+	  The "High speed synchronous Serial Interface" is
+	  synchronous serial interface used mainly to connect
+	  application engines and cellular modems.
+
+if HSI
+
+config HSI_BOARDINFO
+	bool
+	default y
+
+source "drivers/hsi/controllers/Kconfig"
+source "drivers/hsi/clients/Kconfig"
+
+endif # HSI
diff --git a/drivers/hsi/Makefile b/drivers/hsi/Makefile
new file mode 100644
index 000000000..53c3bcdbf
--- /dev/null
+++ b/drivers/hsi/Makefile
@@ -0,0 +1,9 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Makefile for HSI
+#
+obj-$(CONFIG_HSI)		+= hsi.o
+hsi-objs			:= hsi_core.o
+hsi-$(CONFIG_HSI_BOARDINFO)	+= hsi_boardinfo.o
+obj-y				+= controllers/
+obj-y				+= clients/
diff --git a/drivers/hsi/clients/Kconfig b/drivers/hsi/clients/Kconfig
new file mode 100644
index 000000000..80f60cb28
--- /dev/null
+++ b/drivers/hsi/clients/Kconfig
@@ -0,0 +1,41 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# HSI clients configuration
+#
+
+comment "HSI clients"
+
+config NOKIA_MODEM
+	tristate "Nokia Modem"
+	depends on HSI && SSI_PROTOCOL && CMT_SPEECH
+	help
+	Say Y here if you want to add support for the modem on Nokia
+	N900 (Nokia RX-51) hardware.
+
+	If unsure, say N.
+
+config CMT_SPEECH
+	tristate "CMT speech"
+	depends on HSI && SSI_PROTOCOL
+	help
+	If you say Y here, you will enable the CMT speech protocol used
+	by Nokia modems. If you say M the protocol will be available as
+	module named cmt_speech.
+
+	If unsure, say N.
+
+config SSI_PROTOCOL
+	tristate "SSI protocol"
+	depends on HSI && PHONET && OMAP_SSI
+	help
+	If you say Y here, you will enable the SSI protocol aka McSAAB.
+
+	If unsure, say N.
+
+config HSI_CHAR
+	tristate "HSI/SSI character driver"
+	depends on HSI
+	help
+	  If you say Y here, you will enable the HSI/SSI character driver.
+	  This driver provides a simple character device interface for
+	  serial communication with the cellular modem over HSI/SSI bus.
diff --git a/drivers/hsi/clients/Makefile b/drivers/hsi/clients/Makefile
new file mode 100644
index 000000000..8fab835fa
--- /dev/null
+++ b/drivers/hsi/clients/Makefile
@@ -0,0 +1,9 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Makefile for HSI clients
+#
+
+obj-$(CONFIG_NOKIA_MODEM)	+= nokia-modem.o
+obj-$(CONFIG_SSI_PROTOCOL)	+= ssi_protocol.o
+obj-$(CONFIG_CMT_SPEECH)	+= cmt_speech.o
+obj-$(CONFIG_HSI_CHAR)		+= hsi_char.o
diff --git a/drivers/hsi/clients/cmt_speech.c b/drivers/hsi/clients/cmt_speech.c
new file mode 100644
index 000000000..7226677eb
--- /dev/null
+++ b/drivers/hsi/clients/cmt_speech.c
@@ -0,0 +1,1448 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * cmt_speech.c - HSI CMT speech driver
+ *
+ * Copyright (C) 2008,2009,2010 Nokia Corporation. All rights reserved.
+ *
+ * Contact: Kai Vehmanen <kai.vehmanen@nokia.com>
+ * Original author: Peter Ujfalusi <peter.ujfalusi@nokia.com>
+ */
+
+#include <linux/errno.h>
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/init.h>
+#include <linux/device.h>
+#include <linux/miscdevice.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/fs.h>
+#include <linux/poll.h>
+#include <linux/sched/signal.h>
+#include <linux/ioctl.h>
+#include <linux/uaccess.h>
+#include <linux/pm_qos.h>
+#include <linux/hsi/hsi.h>
+#include <linux/hsi/ssi_protocol.h>
+#include <linux/hsi/cs-protocol.h>
+
+#define CS_MMAP_SIZE	PAGE_SIZE
+
+struct char_queue {
+	struct list_head	list;
+	u32			msg;
+};
+
+struct cs_char {
+	unsigned int		opened;
+	struct hsi_client	*cl;
+	struct cs_hsi_iface	*hi;
+	struct list_head	chardev_queue;
+	struct list_head	dataind_queue;
+	int			dataind_pending;
+	/* mmap things */
+	unsigned long		mmap_base;
+	unsigned long		mmap_size;
+	spinlock_t		lock;
+	struct fasync_struct	*async_queue;
+	wait_queue_head_t	wait;
+	/* hsi channel ids */
+	int                     channel_id_cmd;
+	int                     channel_id_data;
+};
+
+#define SSI_CHANNEL_STATE_READING	1
+#define SSI_CHANNEL_STATE_WRITING	(1 << 1)
+#define SSI_CHANNEL_STATE_POLL		(1 << 2)
+#define SSI_CHANNEL_STATE_ERROR		(1 << 3)
+
+#define TARGET_MASK			0xf000000
+#define TARGET_REMOTE			(1 << CS_DOMAIN_SHIFT)
+#define TARGET_LOCAL			0
+
+/* Number of pre-allocated commands buffers */
+#define CS_MAX_CMDS		        4
+
+/*
+ * During data transfers, transactions must be handled
+ * within 20ms (fixed value in cmtspeech HSI protocol)
+ */
+#define CS_QOS_LATENCY_FOR_DATA_USEC	20000
+
+/* Timeout to wait for pending HSI transfers to complete */
+#define CS_HSI_TRANSFER_TIMEOUT_MS      500
+
+
+#define RX_PTR_BOUNDARY_SHIFT		8
+#define RX_PTR_MAX_SHIFT		(RX_PTR_BOUNDARY_SHIFT + \
+						CS_MAX_BUFFERS_SHIFT)
+struct cs_hsi_iface {
+	struct hsi_client		*cl;
+	struct hsi_client		*master;
+
+	unsigned int			iface_state;
+	unsigned int			wakeline_state;
+	unsigned int			control_state;
+	unsigned int			data_state;
+
+	/* state exposed to application */
+	struct cs_mmap_config_block	*mmap_cfg;
+
+	unsigned long			mmap_base;
+	unsigned long			mmap_size;
+
+	unsigned int			rx_slot;
+	unsigned int			tx_slot;
+
+	/* note: for security reasons, we do not trust the contents of
+	 * mmap_cfg, but instead duplicate the variables here */
+	unsigned int			buf_size;
+	unsigned int			rx_bufs;
+	unsigned int			tx_bufs;
+	unsigned int			rx_ptr_boundary;
+	unsigned int			rx_offsets[CS_MAX_BUFFERS];
+	unsigned int			tx_offsets[CS_MAX_BUFFERS];
+
+	/* size of aligned memory blocks */
+	unsigned int			slot_size;
+	unsigned int			flags;
+
+	struct list_head		cmdqueue;
+
+	struct hsi_msg			*data_rx_msg;
+	struct hsi_msg			*data_tx_msg;
+	wait_queue_head_t		datawait;
+
+	struct pm_qos_request           pm_qos_req;
+
+	spinlock_t			lock;
+};
+
+static struct cs_char cs_char_data;
+
+static void cs_hsi_read_on_control(struct cs_hsi_iface *hi);
+static void cs_hsi_read_on_data(struct cs_hsi_iface *hi);
+
+static inline void rx_ptr_shift_too_big(void)
+{
+	BUILD_BUG_ON((1LLU << RX_PTR_MAX_SHIFT) > UINT_MAX);
+}
+
+static void cs_notify(u32 message, struct list_head *head)
+{
+	struct char_queue *entry;
+
+	spin_lock(&cs_char_data.lock);
+
+	if (!cs_char_data.opened) {
+		spin_unlock(&cs_char_data.lock);
+		goto out;
+	}
+
+	entry = kmalloc_obj(*entry, GFP_ATOMIC);
+	if (!entry) {
+		dev_err(&cs_char_data.cl->device,
+			"Can't allocate new entry for the queue.\n");
+		spin_unlock(&cs_char_data.lock);
+		goto out;
+	}
+
+	entry->msg = message;
+	list_add_tail(&entry->list, head);
+
+	spin_unlock(&cs_char_data.lock);
+
+	wake_up_interruptible(&cs_char_data.wait);
+	kill_fasync(&cs_char_data.async_queue, SIGIO, POLL_IN);
+
+out:
+	return;
+}
+
+static u32 cs_pop_entry(struct list_head *head)
+{
+	struct char_queue *entry;
+	u32 data;
+
+	entry = list_entry(head->next, struct char_queue, list);
+	data = entry->msg;
+	list_del(&entry->list);
+	kfree(entry);
+
+	return data;
+}
+
+static void cs_notify_control(u32 message)
+{
+	cs_notify(message, &cs_char_data.chardev_queue);
+}
+
+static void cs_notify_data(u32 message, int maxlength)
+{
+	cs_notify(message, &cs_char_data.dataind_queue);
+
+	spin_lock(&cs_char_data.lock);
+	cs_char_data.dataind_pending++;
+	while (cs_char_data.dataind_pending > maxlength &&
+				!list_empty(&cs_char_data.dataind_queue)) {
+		dev_dbg(&cs_char_data.cl->device, "data notification "
+		"queue overrun (%u entries)\n", cs_char_data.dataind_pending);
+
+		cs_pop_entry(&cs_char_data.dataind_queue);
+		cs_char_data.dataind_pending--;
+	}
+	spin_unlock(&cs_char_data.lock);
+}
+
+static inline void cs_set_cmd(struct hsi_msg *msg, u32 cmd)
+{
+	u32 *data = sg_virt(msg->sgt.sgl);
+	*data = cmd;
+}
+
+static inline u32 cs_get_cmd(struct hsi_msg *msg)
+{
+	u32 *data = sg_virt(msg->sgt.sgl);
+	return *data;
+}
+
+static void cs_release_cmd(struct hsi_msg *msg)
+{
+	struct cs_hsi_iface *hi = msg->context;
+
+	list_add_tail(&msg->link, &hi->cmdqueue);
+}
+
+static void cs_cmd_destructor(struct hsi_msg *msg)
+{
+	struct cs_hsi_iface *hi = msg->context;
+
+	spin_lock(&hi->lock);
+
+	dev_dbg(&cs_char_data.cl->device, "control cmd destructor\n");
+
+	if (hi->iface_state != CS_STATE_CLOSED)
+		dev_err(&hi->cl->device, "Cmd flushed while driver active\n");
+
+	if (msg->ttype == HSI_MSG_READ)
+		hi->control_state &=
+			~(SSI_CHANNEL_STATE_POLL | SSI_CHANNEL_STATE_READING);
+	else if (msg->ttype == HSI_MSG_WRITE &&
+			hi->control_state & SSI_CHANNEL_STATE_WRITING)
+		hi->control_state &= ~SSI_CHANNEL_STATE_WRITING;
+
+	cs_release_cmd(msg);
+
+	spin_unlock(&hi->lock);
+}
+
+static struct hsi_msg *cs_claim_cmd(struct cs_hsi_iface* ssi)
+{
+	struct hsi_msg *msg;
+
+	BUG_ON(list_empty(&ssi->cmdqueue));
+
+	msg = list_first_entry(&ssi->cmdqueue, struct hsi_msg, link);
+	list_del(&msg->link);
+	msg->destructor = cs_cmd_destructor;
+
+	return msg;
+}
+
+static void cs_free_cmds(struct cs_hsi_iface *ssi)
+{
+	struct hsi_msg *msg, *tmp;
+
+	list_for_each_entry_safe(msg, tmp, &ssi->cmdqueue, link) {
+		list_del(&msg->link);
+		msg->destructor = NULL;
+		kfree(sg_virt(msg->sgt.sgl));
+		hsi_free_msg(msg);
+	}
+}
+
+static int cs_alloc_cmds(struct cs_hsi_iface *hi)
+{
+	struct hsi_msg *msg;
+	u32 *buf;
+	unsigned int i;
+
+	INIT_LIST_HEAD(&hi->cmdqueue);
+
+	for (i = 0; i < CS_MAX_CMDS; i++) {
+		msg = hsi_alloc_msg(1, GFP_KERNEL);
+		if (!msg)
+			goto out;
+		buf = kmalloc_obj(*buf);
+		if (!buf) {
+			hsi_free_msg(msg);
+			goto out;
+		}
+		sg_init_one(msg->sgt.sgl, buf, sizeof(*buf));
+		msg->channel = cs_char_data.channel_id_cmd;
+		msg->context = hi;
+		list_add_tail(&msg->link, &hi->cmdqueue);
+	}
+
+	return 0;
+
+out:
+	cs_free_cmds(hi);
+	return -ENOMEM;
+}
+
+static void cs_hsi_data_destructor(struct hsi_msg *msg)
+{
+	struct cs_hsi_iface *hi = msg->context;
+	const char *dir = (msg->ttype == HSI_MSG_READ) ? "TX" : "RX";
+
+	dev_dbg(&cs_char_data.cl->device, "Freeing data %s message\n", dir);
+
+	spin_lock(&hi->lock);
+	if (hi->iface_state != CS_STATE_CLOSED)
+		dev_err(&cs_char_data.cl->device,
+				"Data %s flush while device active\n", dir);
+	if (msg->ttype == HSI_MSG_READ)
+		hi->data_state &=
+			~(SSI_CHANNEL_STATE_POLL | SSI_CHANNEL_STATE_READING);
+	else
+		hi->data_state &= ~SSI_CHANNEL_STATE_WRITING;
+
+	msg->status = HSI_STATUS_COMPLETED;
+	if (unlikely(waitqueue_active(&hi->datawait)))
+		wake_up_interruptible(&hi->datawait);
+
+	spin_unlock(&hi->lock);
+}
+
+static int cs_hsi_alloc_data(struct cs_hsi_iface *hi)
+{
+	struct hsi_msg *txmsg, *rxmsg;
+	int res = 0;
+
+	rxmsg = hsi_alloc_msg(1, GFP_KERNEL);
+	if (!rxmsg) {
+		res = -ENOMEM;
+		goto out1;
+	}
+	rxmsg->channel = cs_char_data.channel_id_data;
+	rxmsg->destructor = cs_hsi_data_destructor;
+	rxmsg->context = hi;
+
+	txmsg = hsi_alloc_msg(1, GFP_KERNEL);
+	if (!txmsg) {
+		res = -ENOMEM;
+		goto out2;
+	}
+	txmsg->channel = cs_char_data.channel_id_data;
+	txmsg->destructor = cs_hsi_data_destructor;
+	txmsg->context = hi;
+
+	hi->data_rx_msg = rxmsg;
+	hi->data_tx_msg = txmsg;
+
+	return 0;
+
+out2:
+	hsi_free_msg(rxmsg);
+out1:
+	return res;
+}
+
+static void cs_hsi_free_data_msg(struct hsi_msg *msg)
+{
+	WARN_ON(msg->status != HSI_STATUS_COMPLETED &&
+					msg->status != HSI_STATUS_ERROR);
+	hsi_free_msg(msg);
+}
+
+static void cs_hsi_free_data(struct cs_hsi_iface *hi)
+{
+	cs_hsi_free_data_msg(hi->data_rx_msg);
+	cs_hsi_free_data_msg(hi->data_tx_msg);
+}
+
+static inline void __cs_hsi_error_pre(struct cs_hsi_iface *hi,
+					struct hsi_msg *msg, const char *info,
+					unsigned int *state)
+{
+	spin_lock(&hi->lock);
+	dev_err(&hi->cl->device, "HSI %s error, msg %d, state %u\n",
+		info, msg->status, *state);
+}
+
+static inline void __cs_hsi_error_post(struct cs_hsi_iface *hi)
+{
+	spin_unlock(&hi->lock);
+}
+
+static inline void __cs_hsi_error_read_bits(unsigned int *state)
+{
+	*state |= SSI_CHANNEL_STATE_ERROR;
+	*state &= ~(SSI_CHANNEL_STATE_READING | SSI_CHANNEL_STATE_POLL);
+}
+
+static inline void __cs_hsi_error_write_bits(unsigned int *state)
+{
+	*state |= SSI_CHANNEL_STATE_ERROR;
+	*state &= ~SSI_CHANNEL_STATE_WRITING;
+}
+
+static void cs_hsi_control_read_error(struct cs_hsi_iface *hi,
+							struct hsi_msg *msg)
+{
+	__cs_hsi_error_pre(hi, msg, "control read", &hi->control_state);
+	cs_release_cmd(msg);
+	__cs_hsi_error_read_bits(&hi->control_state);
+	__cs_hsi_error_post(hi);
+}
+
+static void cs_hsi_control_write_error(struct cs_hsi_iface *hi,
+							struct hsi_msg *msg)
+{
+	__cs_hsi_error_pre(hi, msg, "control write", &hi->control_state);
+	cs_release_cmd(msg);
+	__cs_hsi_error_write_bits(&hi->control_state);
+	__cs_hsi_error_post(hi);
+
+}
+
+static void cs_hsi_data_read_error(struct cs_hsi_iface *hi, struct hsi_msg *msg)
+{
+	__cs_hsi_error_pre(hi, msg, "data read", &hi->data_state);
+	__cs_hsi_error_read_bits(&hi->data_state);
+	__cs_hsi_error_post(hi);
+}
+
+static void cs_hsi_data_write_error(struct cs_hsi_iface *hi,
+							struct hsi_msg *msg)
+{
+	__cs_hsi_error_pre(hi, msg, "data write", &hi->data_state);
+	__cs_hsi_error_write_bits(&hi->data_state);
+	__cs_hsi_error_post(hi);
+}
+
+static void cs_hsi_read_on_control_complete(struct hsi_msg *msg)
+{
+	u32 cmd = cs_get_cmd(msg);
+	struct cs_hsi_iface *hi = msg->context;
+
+	spin_lock(&hi->lock);
+	hi->control_state &= ~SSI_CHANNEL_STATE_READING;
+	if (msg->status == HSI_STATUS_ERROR) {
+		dev_err(&hi->cl->device, "Control RX error detected\n");
+		spin_unlock(&hi->lock);
+		cs_hsi_control_read_error(hi, msg);
+		goto out;
+	}
+	dev_dbg(&hi->cl->device, "Read on control: %08X\n", cmd);
+	cs_release_cmd(msg);
+	if (hi->flags & CS_FEAT_TSTAMP_RX_CTRL) {
+		struct timespec64 tspec;
+		struct cs_timestamp *tstamp =
+			&hi->mmap_cfg->tstamp_rx_ctrl;
+
+		ktime_get_ts64(&tspec);
+
+		tstamp->tv_sec = (__u32) tspec.tv_sec;
+		tstamp->tv_nsec = (__u32) tspec.tv_nsec;
+	}
+	spin_unlock(&hi->lock);
+
+	cs_notify_control(cmd);
+
+out:
+	cs_hsi_read_on_control(hi);
+}
+
+static void cs_hsi_peek_on_control_complete(struct hsi_msg *msg)
+{
+	struct cs_hsi_iface *hi = msg->context;
+	int ret;
+
+	if (msg->status == HSI_STATUS_ERROR) {
+		dev_err(&hi->cl->device, "Control peek RX error detected\n");
+		cs_hsi_control_read_error(hi, msg);
+		return;
+	}
+
+	WARN_ON(!(hi->control_state & SSI_CHANNEL_STATE_READING));
+
+	dev_dbg(&hi->cl->device, "Peek on control complete, reading\n");
+	msg->sgt.nents = 1;
+	msg->complete = cs_hsi_read_on_control_complete;
+	ret = hsi_async_read(hi->cl, msg);
+	if (ret)
+		cs_hsi_control_read_error(hi, msg);
+}
+
+static void cs_hsi_read_on_control(struct cs_hsi_iface *hi)
+{
+	struct hsi_msg *msg;
+	int ret;
+
+	spin_lock(&hi->lock);
+	if (hi->control_state & SSI_CHANNEL_STATE_READING) {
+		dev_err(&hi->cl->device, "Control read already pending (%d)\n",
+			hi->control_state);
+		spin_unlock(&hi->lock);
+		return;
+	}
+	if (hi->control_state & SSI_CHANNEL_STATE_ERROR) {
+		dev_err(&hi->cl->device, "Control read error (%d)\n",
+			hi->control_state);
+		spin_unlock(&hi->lock);
+		return;
+	}
+	hi->control_state |= SSI_CHANNEL_STATE_READING;
+	dev_dbg(&hi->cl->device, "Issuing RX on control\n");
+	msg = cs_claim_cmd(hi);
+	spin_unlock(&hi->lock);
+
+	msg->sgt.nents = 0;
+	msg->complete = cs_hsi_peek_on_control_complete;
+	ret = hsi_async_read(hi->cl, msg);
+	if (ret)
+		cs_hsi_control_read_error(hi, msg);
+}
+
+static void cs_hsi_write_on_control_complete(struct hsi_msg *msg)
+{
+	struct cs_hsi_iface *hi = msg->context;
+	if (msg->status == HSI_STATUS_COMPLETED) {
+		spin_lock(&hi->lock);
+		hi->control_state &= ~SSI_CHANNEL_STATE_WRITING;
+		cs_release_cmd(msg);
+		spin_unlock(&hi->lock);
+	} else if (msg->status == HSI_STATUS_ERROR) {
+		cs_hsi_control_write_error(hi, msg);
+	} else {
+		dev_err(&hi->cl->device,
+			"unexpected status in control write callback %d\n",
+			msg->status);
+	}
+}
+
+static int cs_hsi_write_on_control(struct cs_hsi_iface *hi, u32 message)
+{
+	struct hsi_msg *msg;
+	int ret;
+
+	spin_lock(&hi->lock);
+	if (hi->control_state & SSI_CHANNEL_STATE_ERROR) {
+		spin_unlock(&hi->lock);
+		return -EIO;
+	}
+	if (hi->control_state & SSI_CHANNEL_STATE_WRITING) {
+		dev_err(&hi->cl->device,
+			"Write still pending on control channel.\n");
+		spin_unlock(&hi->lock);
+		return -EBUSY;
+	}
+	hi->control_state |= SSI_CHANNEL_STATE_WRITING;
+	msg = cs_claim_cmd(hi);
+	spin_unlock(&hi->lock);
+
+	cs_set_cmd(msg, message);
+	msg->sgt.nents = 1;
+	msg->complete = cs_hsi_write_on_control_complete;
+	dev_dbg(&hi->cl->device,
+		"Sending control message %08X\n", message);
+	ret = hsi_async_write(hi->cl, msg);
+	if (ret) {
+		dev_err(&hi->cl->device,
+			"async_write failed with %d\n", ret);
+		cs_hsi_control_write_error(hi, msg);
+	}
+
+	/*
+	 * Make sure control read is always pending when issuing
+	 * new control writes. This is needed as the controller
+	 * may flush our messages if e.g. the peer device reboots
+	 * unexpectedly (and we cannot directly resubmit a new read from
+	 * the message destructor; see cs_cmd_destructor()).
+	 */
+	if (!(hi->control_state & SSI_CHANNEL_STATE_READING)) {
+		dev_err(&hi->cl->device, "Restarting control reads\n");
+		cs_hsi_read_on_control(hi);
+	}
+
+	return 0;
+}
+
+static void cs_hsi_read_on_data_complete(struct hsi_msg *msg)
+{
+	struct cs_hsi_iface *hi = msg->context;
+	u32 payload;
+
+	if (unlikely(msg->status == HSI_STATUS_ERROR)) {
+		cs_hsi_data_read_error(hi, msg);
+		return;
+	}
+
+	spin_lock(&hi->lock);
+	WARN_ON(!(hi->data_state & SSI_CHANNEL_STATE_READING));
+	hi->data_state &= ~SSI_CHANNEL_STATE_READING;
+	payload = CS_RX_DATA_RECEIVED;
+	payload |= hi->rx_slot;
+	hi->rx_slot++;
+	hi->rx_slot %= hi->rx_ptr_boundary;
+	/* expose current rx ptr in mmap area */
+	hi->mmap_cfg->rx_ptr = hi->rx_slot;
+	if (unlikely(waitqueue_active(&hi->datawait)))
+		wake_up_interruptible(&hi->datawait);
+	spin_unlock(&hi->lock);
+
+	cs_notify_data(payload, hi->rx_bufs);
+	cs_hsi_read_on_data(hi);
+}
+
+static void cs_hsi_peek_on_data_complete(struct hsi_msg *msg)
+{
+	struct cs_hsi_iface *hi = msg->context;
+	u32 *address;
+	int ret;
+
+	if (unlikely(msg->status == HSI_STATUS_ERROR)) {
+		cs_hsi_data_read_error(hi, msg);
+		return;
+	}
+	if (unlikely(hi->iface_state != CS_STATE_CONFIGURED)) {
+		dev_err(&hi->cl->device, "Data received in invalid state\n");
+		cs_hsi_data_read_error(hi, msg);
+		return;
+	}
+
+	spin_lock(&hi->lock);
+	WARN_ON(!(hi->data_state & SSI_CHANNEL_STATE_POLL));
+	hi->data_state &= ~SSI_CHANNEL_STATE_POLL;
+	hi->data_state |= SSI_CHANNEL_STATE_READING;
+	spin_unlock(&hi->lock);
+
+	address = (u32 *)(hi->mmap_base +
+				hi->rx_offsets[hi->rx_slot % hi->rx_bufs]);
+	sg_init_one(msg->sgt.sgl, address, hi->buf_size);
+	msg->sgt.nents = 1;
+	msg->complete = cs_hsi_read_on_data_complete;
+	ret = hsi_async_read(hi->cl, msg);
+	if (ret)
+		cs_hsi_data_read_error(hi, msg);
+}
+
+/*
+ * Read/write transaction is ongoing. Returns false if in
+ * SSI_CHANNEL_STATE_POLL state.
+ */
+static inline int cs_state_xfer_active(unsigned int state)
+{
+	return (state & SSI_CHANNEL_STATE_WRITING) ||
+		(state & SSI_CHANNEL_STATE_READING);
+}
+
+/*
+ * No pending read/writes
+ */
+static inline int cs_state_idle(unsigned int state)
+{
+	return !(state & ~SSI_CHANNEL_STATE_ERROR);
+}
+
+static void cs_hsi_read_on_data(struct cs_hsi_iface *hi)
+{
+	struct hsi_msg *rxmsg;
+	int ret;
+
+	spin_lock(&hi->lock);
+	if (hi->data_state &
+		(SSI_CHANNEL_STATE_READING | SSI_CHANNEL_STATE_POLL)) {
+		dev_dbg(&hi->cl->device, "Data read already pending (%u)\n",
+			hi->data_state);
+		spin_unlock(&hi->lock);
+		return;
+	}
+	hi->data_state |= SSI_CHANNEL_STATE_POLL;
+	spin_unlock(&hi->lock);
+
+	rxmsg = hi->data_rx_msg;
+	sg_init_one(rxmsg->sgt.sgl, (void *)hi->mmap_base, 0);
+	rxmsg->sgt.nents = 0;
+	rxmsg->complete = cs_hsi_peek_on_data_complete;
+
+	ret = hsi_async_read(hi->cl, rxmsg);
+	if (ret)
+		cs_hsi_data_read_error(hi, rxmsg);
+}
+
+static void cs_hsi_write_on_data_complete(struct hsi_msg *msg)
+{
+	struct cs_hsi_iface *hi = msg->context;
+
+	if (msg->status == HSI_STATUS_COMPLETED) {
+		spin_lock(&hi->lock);
+		hi->data_state &= ~SSI_CHANNEL_STATE_WRITING;
+		if (unlikely(waitqueue_active(&hi->datawait)))
+			wake_up_interruptible(&hi->datawait);
+		spin_unlock(&hi->lock);
+	} else {
+		cs_hsi_data_write_error(hi, msg);
+	}
+}
+
+static int cs_hsi_write_on_data(struct cs_hsi_iface *hi, unsigned int slot)
+{
+	u32 *address;
+	struct hsi_msg *txmsg;
+	int ret;
+
+	spin_lock(&hi->lock);
+	if (hi->iface_state != CS_STATE_CONFIGURED) {
+		dev_err(&hi->cl->device, "Not configured, aborting\n");
+		ret = -EINVAL;
+		goto error;
+	}
+	if (hi->data_state & SSI_CHANNEL_STATE_ERROR) {
+		dev_err(&hi->cl->device, "HSI error, aborting\n");
+		ret = -EIO;
+		goto error;
+	}
+	if (hi->data_state & SSI_CHANNEL_STATE_WRITING) {
+		dev_err(&hi->cl->device, "Write pending on data channel.\n");
+		ret = -EBUSY;
+		goto error;
+	}
+	hi->data_state |= SSI_CHANNEL_STATE_WRITING;
+	spin_unlock(&hi->lock);
+
+	hi->tx_slot = slot;
+	address = (u32 *)(hi->mmap_base + hi->tx_offsets[hi->tx_slot]);
+	txmsg = hi->data_tx_msg;
+	sg_init_one(txmsg->sgt.sgl, address, hi->buf_size);
+	txmsg->complete = cs_hsi_write_on_data_complete;
+	ret = hsi_async_write(hi->cl, txmsg);
+	if (ret)
+		cs_hsi_data_write_error(hi, txmsg);
+
+	return ret;
+
+error:
+	spin_unlock(&hi->lock);
+	if (ret == -EIO)
+		cs_hsi_data_write_error(hi, hi->data_tx_msg);
+
+	return ret;
+}
+
+static unsigned int cs_hsi_get_state(struct cs_hsi_iface *hi)
+{
+	return hi->iface_state;
+}
+
+static int cs_hsi_command(struct cs_hsi_iface *hi, u32 cmd)
+{
+	int ret = 0;
+
+	local_bh_disable();
+	switch (cmd & TARGET_MASK) {
+	case TARGET_REMOTE:
+		ret = cs_hsi_write_on_control(hi, cmd);
+		break;
+	case TARGET_LOCAL:
+		if ((cmd & CS_CMD_MASK) == CS_TX_DATA_READY)
+			ret = cs_hsi_write_on_data(hi, cmd & CS_PARAM_MASK);
+		else
+			ret = -EINVAL;
+		break;
+	default:
+		ret = -EINVAL;
+		break;
+	}
+	local_bh_enable();
+
+	return ret;
+}
+
+static void cs_hsi_set_wakeline(struct cs_hsi_iface *hi, bool new_state)
+{
+	int change = 0;
+
+	spin_lock_bh(&hi->lock);
+	if (hi->wakeline_state != new_state) {
+		hi->wakeline_state = new_state;
+		change = 1;
+		dev_dbg(&hi->cl->device, "setting wake line to %d (%p)\n",
+			new_state, hi->cl);
+	}
+	spin_unlock_bh(&hi->lock);
+
+	if (change) {
+		if (new_state)
+			ssip_slave_start_tx(hi->master);
+		else
+			ssip_slave_stop_tx(hi->master);
+	}
+
+	dev_dbg(&hi->cl->device, "wake line set to %d (%p)\n",
+		new_state, hi->cl);
+}
+
+static void set_buffer_sizes(struct cs_hsi_iface *hi, int rx_bufs, int tx_bufs)
+{
+	hi->rx_bufs = rx_bufs;
+	hi->tx_bufs = tx_bufs;
+	hi->mmap_cfg->rx_bufs = rx_bufs;
+	hi->mmap_cfg->tx_bufs = tx_bufs;
+
+	if (hi->flags & CS_FEAT_ROLLING_RX_COUNTER) {
+		/*
+		 * For more robust overrun detection, let the rx
+		 * pointer run in range 0..'boundary-1'. Boundary
+		 * is a multiple of rx_bufs, and limited in max size
+		 * by RX_PTR_MAX_SHIFT to allow for fast ptr-diff
+		 * calculation.
+		 */
+		hi->rx_ptr_boundary = (rx_bufs << RX_PTR_BOUNDARY_SHIFT);
+		hi->mmap_cfg->rx_ptr_boundary = hi->rx_ptr_boundary;
+	} else {
+		hi->rx_ptr_boundary = hi->rx_bufs;
+	}
+}
+
+static int check_buf_params(struct cs_hsi_iface *hi,
+					const struct cs_buffer_config *buf_cfg)
+{
+	size_t buf_size_aligned = L1_CACHE_ALIGN(buf_cfg->buf_size) *
+					(buf_cfg->rx_bufs + buf_cfg->tx_bufs);
+	size_t ctrl_size_aligned = L1_CACHE_ALIGN(sizeof(*hi->mmap_cfg));
+	int r = 0;
+
+	if (buf_cfg->rx_bufs > CS_MAX_BUFFERS ||
+					buf_cfg->tx_bufs > CS_MAX_BUFFERS) {
+		r = -EINVAL;
+	} else if ((buf_size_aligned + ctrl_size_aligned) >= hi->mmap_size) {
+		dev_err(&hi->cl->device, "No space for the requested buffer "
+			"configuration\n");
+		r = -ENOBUFS;
+	}
+
+	return r;
+}
+
+/*
+ * Block until pending data transfers have completed.
+ */
+static int cs_hsi_data_sync(struct cs_hsi_iface *hi)
+{
+	int r = 0;
+
+	spin_lock_bh(&hi->lock);
+
+	if (!cs_state_xfer_active(hi->data_state)) {
+		dev_dbg(&hi->cl->device, "hsi_data_sync break, idle\n");
+		goto out;
+	}
+
+	for (;;) {
+		int s;
+		DEFINE_WAIT(wait);
+		if (!cs_state_xfer_active(hi->data_state))
+			goto out;
+		if (signal_pending(current)) {
+			r = -ERESTARTSYS;
+			goto out;
+		}
+		/*
+		 * prepare_to_wait must be called with hi->lock held
+		 * so that callbacks can check for waitqueue_active()
+		 */
+		prepare_to_wait(&hi->datawait, &wait, TASK_INTERRUPTIBLE);
+		spin_unlock_bh(&hi->lock);
+		s = schedule_timeout(
+			msecs_to_jiffies(CS_HSI_TRANSFER_TIMEOUT_MS));
+		spin_lock_bh(&hi->lock);
+		finish_wait(&hi->datawait, &wait);
+		if (!s) {
+			dev_dbg(&hi->cl->device,
+				"hsi_data_sync timeout after %d ms\n",
+				CS_HSI_TRANSFER_TIMEOUT_MS);
+			r = -EIO;
+			goto out;
+		}
+	}
+
+out:
+	spin_unlock_bh(&hi->lock);
+	dev_dbg(&hi->cl->device, "hsi_data_sync done with res %d\n", r);
+
+	return r;
+}
+
+static void cs_hsi_data_enable(struct cs_hsi_iface *hi,
+					struct cs_buffer_config *buf_cfg)
+{
+	unsigned int data_start, i;
+
+	BUG_ON(hi->buf_size == 0);
+
+	set_buffer_sizes(hi, buf_cfg->rx_bufs, buf_cfg->tx_bufs);
+
+	hi->slot_size = L1_CACHE_ALIGN(hi->buf_size);
+	dev_dbg(&hi->cl->device,
+			"setting slot size to %u, buf size %u, align %u\n",
+			hi->slot_size, hi->buf_size, L1_CACHE_BYTES);
+
+	data_start = L1_CACHE_ALIGN(sizeof(*hi->mmap_cfg));
+	dev_dbg(&hi->cl->device,
+			"setting data start at %u, cfg block %zu, align %u\n",
+			data_start, sizeof(*hi->mmap_cfg), L1_CACHE_BYTES);
+
+	for (i = 0; i < hi->mmap_cfg->rx_bufs; i++) {
+		hi->rx_offsets[i] = data_start + i * hi->slot_size;
+		hi->mmap_cfg->rx_offsets[i] = hi->rx_offsets[i];
+		dev_dbg(&hi->cl->device, "DL buf #%u at %u\n",
+					i, hi->rx_offsets[i]);
+	}
+	for (i = 0; i < hi->mmap_cfg->tx_bufs; i++) {
+		hi->tx_offsets[i] = data_start +
+			(i + hi->mmap_cfg->rx_bufs) * hi->slot_size;
+		hi->mmap_cfg->tx_offsets[i] = hi->tx_offsets[i];
+		dev_dbg(&hi->cl->device, "UL buf #%u at %u\n",
+					i, hi->rx_offsets[i]);
+	}
+
+	hi->iface_state = CS_STATE_CONFIGURED;
+}
+
+static void cs_hsi_data_disable(struct cs_hsi_iface *hi, int old_state)
+{
+	if (old_state == CS_STATE_CONFIGURED) {
+		dev_dbg(&hi->cl->device,
+			"closing data channel with slot size 0\n");
+		hi->iface_state = CS_STATE_OPENED;
+	}
+}
+
+static int cs_hsi_buf_config(struct cs_hsi_iface *hi,
+					struct cs_buffer_config *buf_cfg)
+{
+	int r = 0;
+	unsigned int old_state = hi->iface_state;
+
+	spin_lock_bh(&hi->lock);
+	/* Prevent new transactions during buffer reconfig */
+	if (old_state == CS_STATE_CONFIGURED)
+		hi->iface_state = CS_STATE_OPENED;
+	spin_unlock_bh(&hi->lock);
+
+	/*
+	 * make sure that no non-zero data reads are ongoing before
+	 * proceeding to change the buffer layout
+	 */
+	r = cs_hsi_data_sync(hi);
+	if (r < 0)
+		return r;
+
+	WARN_ON(cs_state_xfer_active(hi->data_state));
+
+	spin_lock_bh(&hi->lock);
+	r = check_buf_params(hi, buf_cfg);
+	if (r < 0)
+		goto error;
+
+	hi->buf_size = buf_cfg->buf_size;
+	hi->mmap_cfg->buf_size = hi->buf_size;
+	hi->flags = buf_cfg->flags;
+
+	hi->rx_slot = 0;
+	hi->tx_slot = 0;
+	hi->slot_size = 0;
+
+	if (hi->buf_size)
+		cs_hsi_data_enable(hi, buf_cfg);
+	else
+		cs_hsi_data_disable(hi, old_state);
+
+	spin_unlock_bh(&hi->lock);
+
+	if (old_state != hi->iface_state) {
+		if (hi->iface_state == CS_STATE_CONFIGURED) {
+			cpu_latency_qos_add_request(&hi->pm_qos_req,
+				CS_QOS_LATENCY_FOR_DATA_USEC);
+			local_bh_disable();
+			cs_hsi_read_on_data(hi);
+			local_bh_enable();
+		} else if (old_state == CS_STATE_CONFIGURED) {
+			cpu_latency_qos_remove_request(&hi->pm_qos_req);
+		}
+	}
+	return r;
+
+error:
+	spin_unlock_bh(&hi->lock);
+	return r;
+}
+
+static int cs_hsi_start(struct cs_hsi_iface **hi, struct hsi_client *cl,
+			unsigned long mmap_base, unsigned long mmap_size)
+{
+	int err = 0;
+	struct cs_hsi_iface *hsi_if = kzalloc_obj(*hsi_if);
+
+	dev_dbg(&cl->device, "cs_hsi_start\n");
+
+	if (!hsi_if) {
+		err = -ENOMEM;
+		goto leave0;
+	}
+	spin_lock_init(&hsi_if->lock);
+	hsi_if->cl = cl;
+	hsi_if->iface_state = CS_STATE_CLOSED;
+	hsi_if->mmap_cfg = (struct cs_mmap_config_block *)mmap_base;
+	hsi_if->mmap_base = mmap_base;
+	hsi_if->mmap_size = mmap_size;
+	memset(hsi_if->mmap_cfg, 0, sizeof(*hsi_if->mmap_cfg));
+	init_waitqueue_head(&hsi_if->datawait);
+	err = cs_alloc_cmds(hsi_if);
+	if (err < 0) {
+		dev_err(&cl->device, "Unable to alloc HSI messages\n");
+		goto leave1;
+	}
+	err = cs_hsi_alloc_data(hsi_if);
+	if (err < 0) {
+		dev_err(&cl->device, "Unable to alloc HSI messages for data\n");
+		goto leave2;
+	}
+	err = hsi_claim_port(cl, 1);
+	if (err < 0) {
+		dev_err(&cl->device,
+				"Could not open, HSI port already claimed\n");
+		goto leave3;
+	}
+	hsi_if->master = ssip_slave_get_master(cl);
+	if (IS_ERR(hsi_if->master)) {
+		err = PTR_ERR(hsi_if->master);
+		dev_err(&cl->device, "Could not get HSI master client\n");
+		goto leave4;
+	}
+	if (!ssip_slave_running(hsi_if->master)) {
+		err = -ENODEV;
+		dev_err(&cl->device,
+				"HSI port not initialized\n");
+		goto leave4;
+	}
+
+	hsi_if->iface_state = CS_STATE_OPENED;
+	local_bh_disable();
+	cs_hsi_read_on_control(hsi_if);
+	local_bh_enable();
+
+	dev_dbg(&cl->device, "cs_hsi_start...done\n");
+
+	BUG_ON(!hi);
+	*hi = hsi_if;
+
+	return 0;
+
+leave4:
+	hsi_release_port(cl);
+leave3:
+	cs_hsi_free_data(hsi_if);
+leave2:
+	cs_free_cmds(hsi_if);
+leave1:
+	kfree(hsi_if);
+leave0:
+	dev_dbg(&cl->device, "cs_hsi_start...done/error\n\n");
+
+	return err;
+}
+
+static void cs_hsi_stop(struct cs_hsi_iface *hi)
+{
+	dev_dbg(&hi->cl->device, "cs_hsi_stop\n");
+	cs_hsi_set_wakeline(hi, 0);
+	ssip_slave_put_master(hi->master);
+
+	/* hsi_release_port() needs to be called with CS_STATE_CLOSED */
+	hi->iface_state = CS_STATE_CLOSED;
+	hsi_release_port(hi->cl);
+
+	/*
+	 * hsi_release_port() should flush out all the pending
+	 * messages, so cs_state_idle() should be true for both
+	 * control and data channels.
+	 */
+	WARN_ON(!cs_state_idle(hi->control_state));
+	WARN_ON(!cs_state_idle(hi->data_state));
+
+	if (cpu_latency_qos_request_active(&hi->pm_qos_req))
+		cpu_latency_qos_remove_request(&hi->pm_qos_req);
+
+	spin_lock_bh(&hi->lock);
+	cs_hsi_free_data(hi);
+	cs_free_cmds(hi);
+	spin_unlock_bh(&hi->lock);
+	kfree(hi);
+}
+
+static vm_fault_t cs_char_vma_fault(struct vm_fault *vmf)
+{
+	struct cs_char *csdata = vmf->vma->vm_private_data;
+	struct page *page;
+
+	page = virt_to_page((void *)csdata->mmap_base);
+	get_page(page);
+	vmf->page = page;
+
+	return 0;
+}
+
+static const struct vm_operations_struct cs_char_vm_ops = {
+	.fault	= cs_char_vma_fault,
+};
+
+static int cs_char_fasync(int fd, struct file *file, int on)
+{
+	struct cs_char *csdata = file->private_data;
+
+	if (fasync_helper(fd, file, on, &csdata->async_queue) < 0)
+		return -EIO;
+
+	return 0;
+}
+
+static __poll_t cs_char_poll(struct file *file, poll_table *wait)
+{
+	struct cs_char *csdata = file->private_data;
+	__poll_t ret = 0;
+
+	poll_wait(file, &cs_char_data.wait, wait);
+	spin_lock_bh(&csdata->lock);
+	if (!list_empty(&csdata->chardev_queue))
+		ret = EPOLLIN | EPOLLRDNORM;
+	else if (!list_empty(&csdata->dataind_queue))
+		ret = EPOLLIN | EPOLLRDNORM;
+	spin_unlock_bh(&csdata->lock);
+
+	return ret;
+}
+
+static ssize_t cs_char_read(struct file *file, char __user *buf, size_t count,
+								loff_t *unused)
+{
+	struct cs_char *csdata = file->private_data;
+	u32 data;
+	ssize_t retval;
+
+	if (count < sizeof(data))
+		return -EINVAL;
+
+	for (;;) {
+		DEFINE_WAIT(wait);
+
+		spin_lock_bh(&csdata->lock);
+		if (!list_empty(&csdata->chardev_queue)) {
+			data = cs_pop_entry(&csdata->chardev_queue);
+		} else if (!list_empty(&csdata->dataind_queue)) {
+			data = cs_pop_entry(&csdata->dataind_queue);
+			csdata->dataind_pending--;
+		} else {
+			data = 0;
+		}
+		spin_unlock_bh(&csdata->lock);
+
+		if (data)
+			break;
+		if (file->f_flags & O_NONBLOCK) {
+			retval = -EAGAIN;
+			goto out;
+		} else if (signal_pending(current)) {
+			retval = -ERESTARTSYS;
+			goto out;
+		}
+		prepare_to_wait_exclusive(&csdata->wait, &wait,
+						TASK_INTERRUPTIBLE);
+		schedule();
+		finish_wait(&csdata->wait, &wait);
+	}
+
+	retval = put_user(data, (u32 __user *)buf);
+	if (!retval)
+		retval = sizeof(data);
+
+out:
+	return retval;
+}
+
+static ssize_t cs_char_write(struct file *file, const char __user *buf,
+						size_t count, loff_t *unused)
+{
+	struct cs_char *csdata = file->private_data;
+	u32 data;
+	int err;
+	ssize_t	retval;
+
+	if (count < sizeof(data))
+		return -EINVAL;
+
+	if (get_user(data, (u32 __user *)buf))
+		retval = -EFAULT;
+	else
+		retval = count;
+
+	err = cs_hsi_command(csdata->hi, data);
+	if (err < 0)
+		retval = err;
+
+	return retval;
+}
+
+static long cs_char_ioctl(struct file *file, unsigned int cmd,
+				unsigned long arg)
+{
+	struct cs_char *csdata = file->private_data;
+	int r = 0;
+
+	switch (cmd) {
+	case CS_GET_STATE: {
+		unsigned int state;
+
+		state = cs_hsi_get_state(csdata->hi);
+		if (copy_to_user((void __user *)arg, &state, sizeof(state)))
+			r = -EFAULT;
+
+		break;
+	}
+	case CS_SET_WAKELINE: {
+		unsigned int state;
+
+		if (copy_from_user(&state, (void __user *)arg, sizeof(state))) {
+			r = -EFAULT;
+			break;
+		}
+
+		if (state > 1) {
+			r = -EINVAL;
+			break;
+		}
+
+		cs_hsi_set_wakeline(csdata->hi, !!state);
+
+		break;
+	}
+	case CS_GET_IF_VERSION: {
+		unsigned int ifver = CS_IF_VERSION;
+
+		if (copy_to_user((void __user *)arg, &ifver, sizeof(ifver)))
+			r = -EFAULT;
+
+		break;
+	}
+	case CS_CONFIG_BUFS: {
+		struct cs_buffer_config buf_cfg;
+
+		if (copy_from_user(&buf_cfg, (void __user *)arg,
+							sizeof(buf_cfg)))
+			r = -EFAULT;
+		else
+			r = cs_hsi_buf_config(csdata->hi, &buf_cfg);
+
+		break;
+	}
+	default:
+		r = -ENOTTY;
+		break;
+	}
+
+	return r;
+}
+
+static int cs_char_mmap(struct file *file, struct vm_area_struct *vma)
+{
+	if (vma->vm_end < vma->vm_start)
+		return -EINVAL;
+
+	if (vma_pages(vma) != 1)
+		return -EINVAL;
+
+	vm_flags_set(vma, VM_IO | VM_DONTDUMP | VM_DONTEXPAND);
+	vma->vm_ops = &cs_char_vm_ops;
+	vma->vm_private_data = file->private_data;
+
+	return 0;
+}
+
+static int cs_char_open(struct inode *unused, struct file *file)
+{
+	int ret = 0;
+	unsigned long p;
+
+	spin_lock_bh(&cs_char_data.lock);
+	if (cs_char_data.opened) {
+		ret = -EBUSY;
+		spin_unlock_bh(&cs_char_data.lock);
+		goto out1;
+	}
+	cs_char_data.opened = 1;
+	cs_char_data.dataind_pending = 0;
+	spin_unlock_bh(&cs_char_data.lock);
+
+	p = get_zeroed_page(GFP_KERNEL);
+	if (!p) {
+		ret = -ENOMEM;
+		goto out2;
+	}
+
+	ret = cs_hsi_start(&cs_char_data.hi, cs_char_data.cl, p, CS_MMAP_SIZE);
+	if (ret) {
+		dev_err(&cs_char_data.cl->device, "Unable to initialize HSI\n");
+		goto out3;
+	}
+
+	/* these are only used in release so lock not needed */
+	cs_char_data.mmap_base = p;
+	cs_char_data.mmap_size = CS_MMAP_SIZE;
+
+	file->private_data = &cs_char_data;
+
+	return 0;
+
+out3:
+	free_page(p);
+out2:
+	spin_lock_bh(&cs_char_data.lock);
+	cs_char_data.opened = 0;
+	spin_unlock_bh(&cs_char_data.lock);
+out1:
+	return ret;
+}
+
+static void cs_free_char_queue(struct list_head *head)
+{
+	struct char_queue *entry;
+	struct list_head *cursor, *next;
+
+	if (!list_empty(head)) {
+		list_for_each_safe(cursor, next, head) {
+			entry = list_entry(cursor, struct char_queue, list);
+			list_del(&entry->list);
+			kfree(entry);
+		}
+	}
+
+}
+
+static int cs_char_release(struct inode *unused, struct file *file)
+{
+	struct cs_char *csdata = file->private_data;
+
+	cs_hsi_stop(csdata->hi);
+	spin_lock_bh(&csdata->lock);
+	csdata->hi = NULL;
+	free_page(csdata->mmap_base);
+	cs_free_char_queue(&csdata->chardev_queue);
+	cs_free_char_queue(&csdata->dataind_queue);
+	csdata->opened = 0;
+	spin_unlock_bh(&csdata->lock);
+
+	return 0;
+}
+
+static const struct file_operations cs_char_fops = {
+	.owner		= THIS_MODULE,
+	.read		= cs_char_read,
+	.write		= cs_char_write,
+	.poll		= cs_char_poll,
+	.unlocked_ioctl	= cs_char_ioctl,
+	.mmap		= cs_char_mmap,
+	.open		= cs_char_open,
+	.release	= cs_char_release,
+	.fasync		= cs_char_fasync,
+};
+
+static struct miscdevice cs_char_miscdev = {
+	.minor	= MISC_DYNAMIC_MINOR,
+	.name	= "cmt_speech",
+	.fops	= &cs_char_fops
+};
+
+static int cs_hsi_client_probe(struct device *dev)
+{
+	int err = 0;
+	struct hsi_client *cl = to_hsi_client(dev);
+
+	dev_dbg(dev, "hsi_client_probe\n");
+	init_waitqueue_head(&cs_char_data.wait);
+	spin_lock_init(&cs_char_data.lock);
+	cs_char_data.opened = 0;
+	cs_char_data.cl = cl;
+	cs_char_data.hi = NULL;
+	INIT_LIST_HEAD(&cs_char_data.chardev_queue);
+	INIT_LIST_HEAD(&cs_char_data.dataind_queue);
+
+	cs_char_data.channel_id_cmd = hsi_get_channel_id_by_name(cl,
+		"speech-control");
+	if (cs_char_data.channel_id_cmd < 0) {
+		err = cs_char_data.channel_id_cmd;
+		dev_err(dev, "Could not get cmd channel (%d)\n", err);
+		return err;
+	}
+
+	cs_char_data.channel_id_data = hsi_get_channel_id_by_name(cl,
+		"speech-data");
+	if (cs_char_data.channel_id_data < 0) {
+		err = cs_char_data.channel_id_data;
+		dev_err(dev, "Could not get data channel (%d)\n", err);
+		return err;
+	}
+
+	err = misc_register(&cs_char_miscdev);
+	if (err)
+		dev_err(dev, "Failed to register: %d\n", err);
+
+	return err;
+}
+
+static int cs_hsi_client_remove(struct device *dev)
+{
+	struct cs_hsi_iface *hi;
+
+	dev_dbg(dev, "hsi_client_remove\n");
+	misc_deregister(&cs_char_miscdev);
+	spin_lock_bh(&cs_char_data.lock);
+	hi = cs_char_data.hi;
+	cs_char_data.hi = NULL;
+	spin_unlock_bh(&cs_char_data.lock);
+	if (hi)
+		cs_hsi_stop(hi);
+
+	return 0;
+}
+
+static struct hsi_client_driver cs_hsi_driver = {
+	.driver = {
+		.name	= "cmt-speech",
+		.owner	= THIS_MODULE,
+		.probe	= cs_hsi_client_probe,
+		.remove	= cs_hsi_client_remove,
+	},
+};
+
+static int __init cs_char_init(void)
+{
+	pr_info("CMT speech driver added\n");
+	return hsi_register_client_driver(&cs_hsi_driver);
+}
+module_init(cs_char_init);
+
+static void __exit cs_char_exit(void)
+{
+	hsi_unregister_client_driver(&cs_hsi_driver);
+	pr_info("CMT speech driver removed\n");
+}
+module_exit(cs_char_exit);
+
+MODULE_ALIAS("hsi:cmt-speech");
+MODULE_AUTHOR("Kai Vehmanen <kai.vehmanen@nokia.com>");
+MODULE_AUTHOR("Peter Ujfalusi <peter.ujfalusi@nokia.com>");
+MODULE_DESCRIPTION("CMT speech driver");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/hsi/clients/hsi_char.c b/drivers/hsi/clients/hsi_char.c
new file mode 100644
index 000000000..a31cc1466
--- /dev/null
+++ b/drivers/hsi/clients/hsi_char.c
@@ -0,0 +1,788 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * HSI character device driver, implements the character device
+ * interface.
+ *
+ * Copyright (C) 2010 Nokia Corporation. All rights reserved.
+ *
+ * Contact: Andras Domokos <andras.domokos@nokia.com>
+ */
+
+#include <linux/errno.h>
+#include <linux/types.h>
+#include <linux/atomic.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/list.h>
+#include <linux/slab.h>
+#include <linux/kmemleak.h>
+#include <linux/ioctl.h>
+#include <linux/wait.h>
+#include <linux/fs.h>
+#include <linux/sched.h>
+#include <linux/device.h>
+#include <linux/cdev.h>
+#include <linux/uaccess.h>
+#include <linux/scatterlist.h>
+#include <linux/stat.h>
+#include <linux/hsi/hsi.h>
+#include <linux/hsi/hsi_char.h>
+
+#define HSC_DEVS		16 /* Num of channels */
+#define HSC_MSGS		4
+
+#define HSC_RXBREAK		0
+
+#define HSC_ID_BITS		6
+#define HSC_PORT_ID_BITS	4
+#define HSC_ID_MASK		3
+#define HSC_PORT_ID_MASK	3
+#define HSC_CH_MASK		0xf
+
+/*
+ * We support up to 4 controllers that can have up to 4
+ * ports, which should currently be more than enough.
+ */
+#define HSC_BASEMINOR(id, port_id) \
+		((((id) & HSC_ID_MASK) << HSC_ID_BITS) | \
+		(((port_id) & HSC_PORT_ID_MASK) << HSC_PORT_ID_BITS))
+
+enum {
+	HSC_CH_OPEN,
+	HSC_CH_READ,
+	HSC_CH_WRITE,
+	HSC_CH_WLINE,
+};
+
+enum {
+	HSC_RX,
+	HSC_TX,
+};
+
+struct hsc_client_data;
+/**
+ * struct hsc_channel - hsi_char internal channel data
+ * @ch: channel number
+ * @flags: Keeps state of the channel (open/close, reading, writing)
+ * @free_msgs_list: List of free HSI messages/requests
+ * @rx_msgs_queue: List of pending RX requests
+ * @tx_msgs_queue: List of pending TX requests
+ * @lock: Serialize access to the lists
+ * @cl: reference to the associated hsi_client
+ * @cl_data: reference to the client data that this channels belongs to
+ * @rx_wait: RX requests wait queue
+ * @tx_wait: TX requests wait queue
+ */
+struct hsc_channel {
+	unsigned int		ch;
+	unsigned long		flags;
+	struct list_head	free_msgs_list;
+	struct list_head	rx_msgs_queue;
+	struct list_head	tx_msgs_queue;
+	spinlock_t		lock;
+	struct hsi_client	*cl;
+	struct hsc_client_data *cl_data;
+	wait_queue_head_t	rx_wait;
+	wait_queue_head_t	tx_wait;
+};
+
+/**
+ * struct hsc_client_data - hsi_char internal client data
+ * @cdev: Characther device associated to the hsi_client
+ * @lock: Lock to serialize open/close access
+ * @flags: Keeps track of port state (rx hwbreak armed)
+ * @usecnt: Use count for claiming the HSI port (mutex protected)
+ * @cl: Referece to the HSI client
+ * @channels: Array of channels accessible by the client
+ */
+struct hsc_client_data {
+	struct cdev		cdev;
+	struct mutex		lock;
+	unsigned long		flags;
+	unsigned int		usecnt;
+	struct hsi_client	*cl;
+	struct hsc_channel	channels[HSC_DEVS];
+};
+
+/* Stores the major number dynamically allocated for hsi_char */
+static unsigned int hsc_major;
+/* Maximum buffer size that hsi_char will accept from userspace */
+static unsigned int max_data_size = 0x1000;
+module_param(max_data_size, uint, 0);
+MODULE_PARM_DESC(max_data_size, "max read/write data size [4,8..65536] (^2)");
+
+static void hsc_add_tail(struct hsc_channel *channel, struct hsi_msg *msg,
+							struct list_head *queue)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&channel->lock, flags);
+	list_add_tail(&msg->link, queue);
+	spin_unlock_irqrestore(&channel->lock, flags);
+}
+
+static struct hsi_msg *hsc_get_first_msg(struct hsc_channel *channel,
+							struct list_head *queue)
+{
+	struct hsi_msg *msg = NULL;
+	unsigned long flags;
+
+	spin_lock_irqsave(&channel->lock, flags);
+
+	if (list_empty(queue))
+		goto out;
+
+	msg = list_first_entry(queue, struct hsi_msg, link);
+	list_del(&msg->link);
+out:
+	spin_unlock_irqrestore(&channel->lock, flags);
+
+	return msg;
+}
+
+static inline void hsc_msg_free(struct hsi_msg *msg)
+{
+	kfree(sg_virt(msg->sgt.sgl));
+	hsi_free_msg(msg);
+}
+
+static void hsc_free_list(struct list_head *list)
+{
+	struct hsi_msg *msg, *tmp;
+
+	list_for_each_entry_safe(msg, tmp, list, link) {
+		list_del(&msg->link);
+		hsc_msg_free(msg);
+	}
+}
+
+static void hsc_reset_list(struct hsc_channel *channel, struct list_head *l)
+{
+	unsigned long flags;
+	LIST_HEAD(list);
+
+	spin_lock_irqsave(&channel->lock, flags);
+	list_splice_init(l, &list);
+	spin_unlock_irqrestore(&channel->lock, flags);
+
+	hsc_free_list(&list);
+}
+
+static inline struct hsi_msg *hsc_msg_alloc(unsigned int alloc_size)
+{
+	struct hsi_msg *msg;
+	void *buf;
+
+	msg = hsi_alloc_msg(1, GFP_KERNEL);
+	if (!msg)
+		goto out;
+	buf = kmalloc(alloc_size, GFP_KERNEL);
+	if (!buf) {
+		hsi_free_msg(msg);
+		goto out;
+	}
+	sg_init_one(msg->sgt.sgl, buf, alloc_size);
+	/* Ignore false positive, due to sg pointer handling */
+	kmemleak_ignore(buf);
+
+	return msg;
+out:
+	return NULL;
+}
+
+static inline int hsc_msgs_alloc(struct hsc_channel *channel)
+{
+	struct hsi_msg *msg;
+	int i;
+
+	for (i = 0; i < HSC_MSGS; i++) {
+		msg = hsc_msg_alloc(max_data_size);
+		if (!msg)
+			goto out;
+		msg->channel = channel->ch;
+		list_add_tail(&msg->link, &channel->free_msgs_list);
+	}
+
+	return 0;
+out:
+	hsc_free_list(&channel->free_msgs_list);
+
+	return -ENOMEM;
+}
+
+static inline unsigned int hsc_msg_len_get(struct hsi_msg *msg)
+{
+	return msg->sgt.sgl->length;
+}
+
+static inline void hsc_msg_len_set(struct hsi_msg *msg, unsigned int len)
+{
+	msg->sgt.sgl->length = len;
+}
+
+static void hsc_rx_completed(struct hsi_msg *msg)
+{
+	struct hsc_client_data *cl_data = hsi_client_drvdata(msg->cl);
+	struct hsc_channel *channel = cl_data->channels + msg->channel;
+
+	if (test_bit(HSC_CH_READ, &channel->flags)) {
+		hsc_add_tail(channel, msg, &channel->rx_msgs_queue);
+		wake_up(&channel->rx_wait);
+	} else {
+		hsc_add_tail(channel, msg, &channel->free_msgs_list);
+	}
+}
+
+static void hsc_rx_msg_destructor(struct hsi_msg *msg)
+{
+	msg->status = HSI_STATUS_ERROR;
+	hsc_msg_len_set(msg, 0);
+	hsc_rx_completed(msg);
+}
+
+static void hsc_tx_completed(struct hsi_msg *msg)
+{
+	struct hsc_client_data *cl_data = hsi_client_drvdata(msg->cl);
+	struct hsc_channel *channel = cl_data->channels + msg->channel;
+
+	if (test_bit(HSC_CH_WRITE, &channel->flags)) {
+		hsc_add_tail(channel, msg, &channel->tx_msgs_queue);
+		wake_up(&channel->tx_wait);
+	} else {
+		hsc_add_tail(channel, msg, &channel->free_msgs_list);
+	}
+}
+
+static void hsc_tx_msg_destructor(struct hsi_msg *msg)
+{
+	msg->status = HSI_STATUS_ERROR;
+	hsc_msg_len_set(msg, 0);
+	hsc_tx_completed(msg);
+}
+
+static void hsc_break_req_destructor(struct hsi_msg *msg)
+{
+	struct hsc_client_data *cl_data = hsi_client_drvdata(msg->cl);
+
+	hsi_free_msg(msg);
+	clear_bit(HSC_RXBREAK, &cl_data->flags);
+}
+
+static void hsc_break_received(struct hsi_msg *msg)
+{
+	struct hsc_client_data *cl_data = hsi_client_drvdata(msg->cl);
+	struct hsc_channel *channel = cl_data->channels;
+	int i, ret;
+
+	/* Broadcast HWBREAK on all channels */
+	for (i = 0; i < HSC_DEVS; i++, channel++) {
+		struct hsi_msg *msg2;
+
+		if (!test_bit(HSC_CH_READ, &channel->flags))
+			continue;
+		msg2 = hsc_get_first_msg(channel, &channel->free_msgs_list);
+		if (!msg2)
+			continue;
+		clear_bit(HSC_CH_READ, &channel->flags);
+		hsc_msg_len_set(msg2, 0);
+		msg2->status = HSI_STATUS_COMPLETED;
+		hsc_add_tail(channel, msg2, &channel->rx_msgs_queue);
+		wake_up(&channel->rx_wait);
+	}
+	hsi_flush(msg->cl);
+	ret = hsi_async_read(msg->cl, msg);
+	if (ret < 0)
+		hsc_break_req_destructor(msg);
+}
+
+static int hsc_break_request(struct hsi_client *cl)
+{
+	struct hsc_client_data *cl_data = hsi_client_drvdata(cl);
+	struct hsi_msg *msg;
+	int ret;
+
+	if (test_and_set_bit(HSC_RXBREAK, &cl_data->flags))
+		return -EBUSY;
+
+	msg = hsi_alloc_msg(0, GFP_KERNEL);
+	if (!msg) {
+		clear_bit(HSC_RXBREAK, &cl_data->flags);
+		return -ENOMEM;
+	}
+	msg->break_frame = 1;
+	msg->complete = hsc_break_received;
+	msg->destructor = hsc_break_req_destructor;
+	ret = hsi_async_read(cl, msg);
+	if (ret < 0)
+		hsc_break_req_destructor(msg);
+
+	return ret;
+}
+
+static int hsc_break_send(struct hsi_client *cl)
+{
+	struct hsi_msg *msg;
+	int ret;
+
+	msg = hsi_alloc_msg(0, GFP_ATOMIC);
+	if (!msg)
+		return -ENOMEM;
+	msg->break_frame = 1;
+	msg->complete = hsi_free_msg;
+	msg->destructor = hsi_free_msg;
+	ret = hsi_async_write(cl, msg);
+	if (ret < 0)
+		hsi_free_msg(msg);
+
+	return ret;
+}
+
+static int hsc_rx_set(struct hsi_client *cl, struct hsc_rx_config *rxc)
+{
+	struct hsi_config tmp;
+	int ret;
+
+	if ((rxc->mode != HSI_MODE_STREAM) && (rxc->mode != HSI_MODE_FRAME))
+		return -EINVAL;
+	if ((rxc->channels == 0) || (rxc->channels > HSC_DEVS))
+		return -EINVAL;
+	if (rxc->channels & (rxc->channels - 1))
+		return -EINVAL;
+	if ((rxc->flow != HSI_FLOW_SYNC) && (rxc->flow != HSI_FLOW_PIPE))
+		return -EINVAL;
+	tmp = cl->rx_cfg;
+	cl->rx_cfg.mode = rxc->mode;
+	cl->rx_cfg.num_hw_channels = rxc->channels;
+	cl->rx_cfg.flow = rxc->flow;
+	ret = hsi_setup(cl);
+	if (ret < 0) {
+		cl->rx_cfg = tmp;
+		return ret;
+	}
+	if (rxc->mode == HSI_MODE_FRAME)
+		hsc_break_request(cl);
+
+	return ret;
+}
+
+static inline void hsc_rx_get(struct hsi_client *cl, struct hsc_rx_config *rxc)
+{
+	rxc->mode = cl->rx_cfg.mode;
+	rxc->channels = cl->rx_cfg.num_hw_channels;
+	rxc->flow = cl->rx_cfg.flow;
+}
+
+static int hsc_tx_set(struct hsi_client *cl, struct hsc_tx_config *txc)
+{
+	struct hsi_config tmp;
+	int ret;
+
+	if ((txc->mode != HSI_MODE_STREAM) && (txc->mode != HSI_MODE_FRAME))
+		return -EINVAL;
+	if ((txc->channels == 0) || (txc->channels > HSC_DEVS))
+		return -EINVAL;
+	if (txc->channels & (txc->channels - 1))
+		return -EINVAL;
+	if ((txc->arb_mode != HSI_ARB_RR) && (txc->arb_mode != HSI_ARB_PRIO))
+		return -EINVAL;
+	tmp = cl->tx_cfg;
+	cl->tx_cfg.mode = txc->mode;
+	cl->tx_cfg.num_hw_channels = txc->channels;
+	cl->tx_cfg.speed = txc->speed;
+	cl->tx_cfg.arb_mode = txc->arb_mode;
+	ret = hsi_setup(cl);
+	if (ret < 0) {
+		cl->tx_cfg = tmp;
+		return ret;
+	}
+
+	return ret;
+}
+
+static inline void hsc_tx_get(struct hsi_client *cl, struct hsc_tx_config *txc)
+{
+	txc->mode = cl->tx_cfg.mode;
+	txc->channels = cl->tx_cfg.num_hw_channels;
+	txc->speed = cl->tx_cfg.speed;
+	txc->arb_mode = cl->tx_cfg.arb_mode;
+}
+
+static ssize_t hsc_read(struct file *file, char __user *buf, size_t len,
+						loff_t *ppos __maybe_unused)
+{
+	struct hsc_channel *channel = file->private_data;
+	struct hsi_msg *msg;
+	ssize_t ret;
+
+	if (len == 0)
+		return 0;
+	if (!IS_ALIGNED(len, sizeof(u32)))
+		return -EINVAL;
+	if (len > max_data_size)
+		len = max_data_size;
+	if (channel->ch >= channel->cl->rx_cfg.num_hw_channels)
+		return -ECHRNG;
+	if (test_and_set_bit(HSC_CH_READ, &channel->flags))
+		return -EBUSY;
+	msg = hsc_get_first_msg(channel, &channel->free_msgs_list);
+	if (!msg) {
+		ret = -ENOSPC;
+		goto out;
+	}
+	hsc_msg_len_set(msg, len);
+	msg->complete = hsc_rx_completed;
+	msg->destructor = hsc_rx_msg_destructor;
+	ret = hsi_async_read(channel->cl, msg);
+	if (ret < 0) {
+		hsc_add_tail(channel, msg, &channel->free_msgs_list);
+		goto out;
+	}
+
+	ret = wait_event_interruptible(channel->rx_wait,
+					!list_empty(&channel->rx_msgs_queue));
+	if (ret < 0) {
+		clear_bit(HSC_CH_READ, &channel->flags);
+		hsi_flush(channel->cl);
+		return -EINTR;
+	}
+
+	msg = hsc_get_first_msg(channel, &channel->rx_msgs_queue);
+	if (msg) {
+		if (msg->status != HSI_STATUS_ERROR) {
+			ret = copy_to_user((void __user *)buf,
+			sg_virt(msg->sgt.sgl), hsc_msg_len_get(msg));
+			if (ret)
+				ret = -EFAULT;
+			else
+				ret = hsc_msg_len_get(msg);
+		} else {
+			ret = -EIO;
+		}
+		hsc_add_tail(channel, msg, &channel->free_msgs_list);
+	}
+out:
+	clear_bit(HSC_CH_READ, &channel->flags);
+
+	return ret;
+}
+
+static ssize_t hsc_write(struct file *file, const char __user *buf, size_t len,
+						loff_t *ppos __maybe_unused)
+{
+	struct hsc_channel *channel = file->private_data;
+	struct hsi_msg *msg;
+	ssize_t ret;
+
+	if ((len == 0) || !IS_ALIGNED(len, sizeof(u32)))
+		return -EINVAL;
+	if (len > max_data_size)
+		len = max_data_size;
+	if (channel->ch >= channel->cl->tx_cfg.num_hw_channels)
+		return -ECHRNG;
+	if (test_and_set_bit(HSC_CH_WRITE, &channel->flags))
+		return -EBUSY;
+	msg = hsc_get_first_msg(channel, &channel->free_msgs_list);
+	if (!msg) {
+		clear_bit(HSC_CH_WRITE, &channel->flags);
+		return -ENOSPC;
+	}
+	if (copy_from_user(sg_virt(msg->sgt.sgl), (void __user *)buf, len)) {
+		ret = -EFAULT;
+		goto out;
+	}
+	hsc_msg_len_set(msg, len);
+	msg->complete = hsc_tx_completed;
+	msg->destructor = hsc_tx_msg_destructor;
+	ret = hsi_async_write(channel->cl, msg);
+	if (ret < 0)
+		goto out;
+
+	ret = wait_event_interruptible(channel->tx_wait,
+					!list_empty(&channel->tx_msgs_queue));
+	if (ret < 0) {
+		clear_bit(HSC_CH_WRITE, &channel->flags);
+		hsi_flush(channel->cl);
+		return -EINTR;
+	}
+
+	msg = hsc_get_first_msg(channel, &channel->tx_msgs_queue);
+	if (msg) {
+		if (msg->status == HSI_STATUS_ERROR)
+			ret = -EIO;
+		else
+			ret = hsc_msg_len_get(msg);
+
+		hsc_add_tail(channel, msg, &channel->free_msgs_list);
+	}
+out:
+	clear_bit(HSC_CH_WRITE, &channel->flags);
+
+	return ret;
+}
+
+static long hsc_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+	struct hsc_channel *channel = file->private_data;
+	unsigned int state;
+	struct hsc_rx_config rxc;
+	struct hsc_tx_config txc;
+	long ret = 0;
+
+	switch (cmd) {
+	case HSC_RESET:
+		hsi_flush(channel->cl);
+		break;
+	case HSC_SET_PM:
+		if (copy_from_user(&state, (void __user *)arg, sizeof(state)))
+			return -EFAULT;
+		if (state == HSC_PM_DISABLE) {
+			if (test_and_set_bit(HSC_CH_WLINE, &channel->flags))
+				return -EINVAL;
+			ret = hsi_start_tx(channel->cl);
+		} else if (state == HSC_PM_ENABLE) {
+			if (!test_and_clear_bit(HSC_CH_WLINE, &channel->flags))
+				return -EINVAL;
+			ret = hsi_stop_tx(channel->cl);
+		} else {
+			ret = -EINVAL;
+		}
+		break;
+	case HSC_SEND_BREAK:
+		return hsc_break_send(channel->cl);
+	case HSC_SET_RX:
+		if (copy_from_user(&rxc, (void __user *)arg, sizeof(rxc)))
+			return -EFAULT;
+		return hsc_rx_set(channel->cl, &rxc);
+	case HSC_GET_RX:
+		hsc_rx_get(channel->cl, &rxc);
+		if (copy_to_user((void __user *)arg, &rxc, sizeof(rxc)))
+			return -EFAULT;
+		break;
+	case HSC_SET_TX:
+		if (copy_from_user(&txc, (void __user *)arg, sizeof(txc)))
+			return -EFAULT;
+		return hsc_tx_set(channel->cl, &txc);
+	case HSC_GET_TX:
+		hsc_tx_get(channel->cl, &txc);
+		if (copy_to_user((void __user *)arg, &txc, sizeof(txc)))
+			return -EFAULT;
+		break;
+	default:
+		return -ENOIOCTLCMD;
+	}
+
+	return ret;
+}
+
+static inline void __hsc_port_release(struct hsc_client_data *cl_data)
+{
+	BUG_ON(cl_data->usecnt == 0);
+
+	if (--cl_data->usecnt == 0) {
+		hsi_flush(cl_data->cl);
+		hsi_release_port(cl_data->cl);
+	}
+}
+
+static int hsc_open(struct inode *inode, struct file *file)
+{
+	struct hsc_client_data *cl_data;
+	struct hsc_channel *channel;
+	int ret = 0;
+
+	pr_debug("open, minor = %d\n", iminor(inode));
+
+	cl_data = container_of(inode->i_cdev, struct hsc_client_data, cdev);
+	mutex_lock(&cl_data->lock);
+	channel = cl_data->channels + (iminor(inode) & HSC_CH_MASK);
+
+	if (test_and_set_bit(HSC_CH_OPEN, &channel->flags)) {
+		ret = -EBUSY;
+		goto out;
+	}
+	/*
+	 * Check if we have already claimed the port associated to the HSI
+	 * client. If not then try to claim it, else increase its refcount
+	 */
+	if (cl_data->usecnt == 0) {
+		ret = hsi_claim_port(cl_data->cl, 0);
+		if (ret < 0)
+			goto out;
+		hsi_setup(cl_data->cl);
+	}
+	cl_data->usecnt++;
+
+	ret = hsc_msgs_alloc(channel);
+	if (ret < 0) {
+		__hsc_port_release(cl_data);
+		goto out;
+	}
+
+	file->private_data = channel;
+	mutex_unlock(&cl_data->lock);
+
+	return ret;
+out:
+	mutex_unlock(&cl_data->lock);
+
+	return ret;
+}
+
+static int hsc_release(struct inode *inode __maybe_unused, struct file *file)
+{
+	struct hsc_channel *channel = file->private_data;
+	struct hsc_client_data *cl_data = channel->cl_data;
+
+	mutex_lock(&cl_data->lock);
+	file->private_data = NULL;
+	if (test_and_clear_bit(HSC_CH_WLINE, &channel->flags))
+		hsi_stop_tx(channel->cl);
+	__hsc_port_release(cl_data);
+	hsc_reset_list(channel, &channel->rx_msgs_queue);
+	hsc_reset_list(channel, &channel->tx_msgs_queue);
+	hsc_reset_list(channel, &channel->free_msgs_list);
+	clear_bit(HSC_CH_READ, &channel->flags);
+	clear_bit(HSC_CH_WRITE, &channel->flags);
+	clear_bit(HSC_CH_OPEN, &channel->flags);
+	wake_up(&channel->rx_wait);
+	wake_up(&channel->tx_wait);
+	mutex_unlock(&cl_data->lock);
+
+	return 0;
+}
+
+static const struct file_operations hsc_fops = {
+	.owner		= THIS_MODULE,
+	.read		= hsc_read,
+	.write		= hsc_write,
+	.unlocked_ioctl	= hsc_ioctl,
+	.open		= hsc_open,
+	.release	= hsc_release,
+};
+
+static void hsc_channel_init(struct hsc_channel *channel)
+{
+	init_waitqueue_head(&channel->rx_wait);
+	init_waitqueue_head(&channel->tx_wait);
+	spin_lock_init(&channel->lock);
+	INIT_LIST_HEAD(&channel->free_msgs_list);
+	INIT_LIST_HEAD(&channel->rx_msgs_queue);
+	INIT_LIST_HEAD(&channel->tx_msgs_queue);
+}
+
+static int hsc_probe(struct device *dev)
+{
+	const char devname[] = "hsi_char";
+	struct hsc_client_data *cl_data;
+	struct hsc_channel *channel;
+	struct hsi_client *cl = to_hsi_client(dev);
+	unsigned int hsc_baseminor;
+	dev_t hsc_dev;
+	int ret;
+	int i;
+
+	cl_data = kzalloc_obj(*cl_data);
+	if (!cl_data)
+		return -ENOMEM;
+
+	hsc_baseminor = HSC_BASEMINOR(hsi_id(cl), hsi_port_id(cl));
+	if (!hsc_major) {
+		ret = alloc_chrdev_region(&hsc_dev, hsc_baseminor,
+						HSC_DEVS, devname);
+		if (ret == 0)
+			hsc_major = MAJOR(hsc_dev);
+	} else {
+		hsc_dev = MKDEV(hsc_major, hsc_baseminor);
+		ret = register_chrdev_region(hsc_dev, HSC_DEVS, devname);
+	}
+	if (ret < 0) {
+		dev_err(dev, "Device %s allocation failed %d\n",
+					hsc_major ? "minor" : "major", ret);
+		goto out1;
+	}
+	mutex_init(&cl_data->lock);
+	hsi_client_set_drvdata(cl, cl_data);
+	cdev_init(&cl_data->cdev, &hsc_fops);
+	cl_data->cdev.owner = THIS_MODULE;
+	cl_data->cl = cl;
+	for (i = 0, channel = cl_data->channels; i < HSC_DEVS; i++, channel++) {
+		hsc_channel_init(channel);
+		channel->ch = i;
+		channel->cl = cl;
+		channel->cl_data = cl_data;
+	}
+
+	/* 1 hsi client -> N char devices (one for each channel) */
+	ret = cdev_add(&cl_data->cdev, hsc_dev, HSC_DEVS);
+	if (ret) {
+		dev_err(dev, "Could not add char device %d\n", ret);
+		goto out2;
+	}
+
+	return 0;
+out2:
+	unregister_chrdev_region(hsc_dev, HSC_DEVS);
+out1:
+	kfree(cl_data);
+
+	return ret;
+}
+
+static int hsc_remove(struct device *dev)
+{
+	struct hsi_client *cl = to_hsi_client(dev);
+	struct hsc_client_data *cl_data = hsi_client_drvdata(cl);
+	dev_t hsc_dev = cl_data->cdev.dev;
+
+	cdev_del(&cl_data->cdev);
+	unregister_chrdev_region(hsc_dev, HSC_DEVS);
+	hsi_client_set_drvdata(cl, NULL);
+	kfree(cl_data);
+
+	return 0;
+}
+
+static struct hsi_client_driver hsc_driver = {
+	.driver = {
+		.name	= "hsi_char",
+		.owner	= THIS_MODULE,
+		.probe	= hsc_probe,
+		.remove	= hsc_remove,
+	},
+};
+
+static int __init hsc_init(void)
+{
+	int ret;
+
+	if ((max_data_size < 4) || (max_data_size > 0x10000) ||
+		(max_data_size & (max_data_size - 1))) {
+		pr_err("Invalid max read/write data size\n");
+		return -EINVAL;
+	}
+
+	ret = hsi_register_client_driver(&hsc_driver);
+	if (ret) {
+		pr_err("Error while registering HSI/SSI driver %d\n", ret);
+		return ret;
+	}
+
+	pr_info("HSI/SSI char device loaded\n");
+
+	return 0;
+}
+module_init(hsc_init);
+
+static void __exit hsc_exit(void)
+{
+	hsi_unregister_client_driver(&hsc_driver);
+	pr_info("HSI char device removed\n");
+}
+module_exit(hsc_exit);
+
+MODULE_AUTHOR("Andras Domokos <andras.domokos@nokia.com>");
+MODULE_ALIAS("hsi:hsi_char");
+MODULE_DESCRIPTION("HSI character device");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/hsi/clients/nokia-modem.c b/drivers/hsi/clients/nokia-modem.c
new file mode 100644
index 000000000..97ba59e60
--- /dev/null
+++ b/drivers/hsi/clients/nokia-modem.c
@@ -0,0 +1,298 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * nokia-modem.c
+ *
+ * HSI client driver for Nokia N900 modem.
+ *
+ * Copyright (C) 2014 Sebastian Reichel <sre@kernel.org>
+ */
+
+#include <linux/gpio/consumer.h>
+#include <linux/hsi/hsi.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/of.h>
+#include <linux/of_irq.h>
+#include <linux/hsi/ssi_protocol.h>
+
+static unsigned int pm = 1;
+module_param(pm, int, 0400);
+MODULE_PARM_DESC(pm,
+	"Enable power management (0=disabled, 1=userland based [default])");
+
+struct nokia_modem_gpio {
+	struct gpio_desc	*gpio;
+	const char		*name;
+};
+
+struct nokia_modem_device {
+	struct tasklet_struct	nokia_modem_rst_ind_tasklet;
+	int			nokia_modem_rst_ind_irq;
+	struct device		*device;
+	struct nokia_modem_gpio	*gpios;
+	int			gpio_amount;
+	struct hsi_client	*ssi_protocol;
+	struct hsi_client	*cmt_speech;
+};
+
+static void do_nokia_modem_rst_ind_tasklet(unsigned long data)
+{
+	struct nokia_modem_device *modem = (struct nokia_modem_device *)data;
+
+	if (!modem)
+		return;
+
+	dev_info(modem->device, "CMT rst line change detected\n");
+
+	if (modem->ssi_protocol)
+		ssip_reset_event(modem->ssi_protocol);
+}
+
+static irqreturn_t nokia_modem_rst_ind_isr(int irq, void *data)
+{
+	struct nokia_modem_device *modem = (struct nokia_modem_device *)data;
+
+	tasklet_schedule(&modem->nokia_modem_rst_ind_tasklet);
+
+	return IRQ_HANDLED;
+}
+
+static void nokia_modem_gpio_unexport(struct device *dev)
+{
+	struct nokia_modem_device *modem = dev_get_drvdata(dev);
+	int i;
+
+	for (i = 0; i < modem->gpio_amount; i++) {
+		sysfs_remove_link(&dev->kobj, modem->gpios[i].name);
+		gpiod_unexport(modem->gpios[i].gpio);
+	}
+}
+
+static int nokia_modem_gpio_probe(struct device *dev)
+{
+	struct device_node *np = dev->of_node;
+	struct nokia_modem_device *modem = dev_get_drvdata(dev);
+	int gpio_count, gpio_name_count, i, err;
+
+	gpio_count = gpiod_count(dev, NULL);
+	if (gpio_count < 0) {
+		dev_err(dev, "missing gpios: %d\n", gpio_count);
+		return gpio_count;
+	}
+
+	gpio_name_count = of_property_count_strings(np, "gpio-names");
+
+	if (gpio_count != gpio_name_count) {
+		dev_err(dev, "number of gpios does not equal number of gpio names\n");
+		return -EINVAL;
+	}
+
+	modem->gpios = devm_kcalloc(dev, gpio_count, sizeof(*modem->gpios),
+				    GFP_KERNEL);
+	if (!modem->gpios)
+		return -ENOMEM;
+
+	modem->gpio_amount = gpio_count;
+
+	for (i = 0; i < gpio_count; i++) {
+		modem->gpios[i].gpio = devm_gpiod_get_index(dev, NULL, i,
+							    GPIOD_OUT_LOW);
+		if (IS_ERR(modem->gpios[i].gpio)) {
+			dev_err(dev, "Could not get gpio %d\n", i);
+			return PTR_ERR(modem->gpios[i].gpio);
+		}
+
+		err = of_property_read_string_index(np, "gpio-names", i,
+						&(modem->gpios[i].name));
+		if (err) {
+			dev_err(dev, "Could not get gpio name %d\n", i);
+			return err;
+		}
+
+		err = gpiod_export(modem->gpios[i].gpio, 0);
+		if (err)
+			return err;
+
+		err = gpiod_export_link(dev, modem->gpios[i].name,
+							modem->gpios[i].gpio);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
+static int nokia_modem_probe(struct device *dev)
+{
+	struct device_node *np;
+	struct nokia_modem_device *modem;
+	struct hsi_client *cl = to_hsi_client(dev);
+	struct hsi_port *port = hsi_get_port(cl);
+	int irq, pflags, err;
+	struct hsi_board_info ssip;
+	struct hsi_board_info cmtspeech;
+
+	np = dev->of_node;
+	if (!np) {
+		dev_err(dev, "device tree node not found\n");
+		return -ENXIO;
+	}
+
+	modem = devm_kzalloc(dev, sizeof(*modem), GFP_KERNEL);
+	if (!modem)
+		return -ENOMEM;
+
+	dev_set_drvdata(dev, modem);
+	modem->device = dev;
+
+	irq = irq_of_parse_and_map(np, 0);
+	if (!irq) {
+		dev_err(dev, "Invalid rst_ind interrupt (%d)\n", irq);
+		return -EINVAL;
+	}
+	modem->nokia_modem_rst_ind_irq = irq;
+	pflags = irq_get_trigger_type(irq);
+
+	tasklet_init(&modem->nokia_modem_rst_ind_tasklet,
+			do_nokia_modem_rst_ind_tasklet, (unsigned long)modem);
+	err = devm_request_irq(dev, irq, nokia_modem_rst_ind_isr,
+				pflags, "modem_rst_ind", modem);
+	if (err < 0) {
+		dev_err(dev, "Request rst_ind irq(%d) failed (flags %d)\n",
+								irq, pflags);
+		return err;
+	}
+	enable_irq_wake(irq);
+
+	if (pm) {
+		err = nokia_modem_gpio_probe(dev);
+		if (err < 0) {
+			dev_err(dev, "Could not probe GPIOs\n");
+			goto error1;
+		}
+	}
+
+	ssip.name = "ssi-protocol";
+	ssip.tx_cfg = cl->tx_cfg;
+	ssip.rx_cfg = cl->rx_cfg;
+	ssip.platform_data = NULL;
+	ssip.archdata = NULL;
+
+	modem->ssi_protocol = hsi_new_client(port, &ssip);
+	if (!modem->ssi_protocol) {
+		dev_err(dev, "Could not register ssi-protocol device\n");
+		err = -ENOMEM;
+		goto error2;
+	}
+
+	err = device_attach(&modem->ssi_protocol->device);
+	if (err == 0) {
+		dev_dbg(dev, "Missing ssi-protocol driver\n");
+		err = -EPROBE_DEFER;
+		goto error3;
+	} else if (err < 0) {
+		dev_err(dev, "Could not load ssi-protocol driver (%d)\n", err);
+		goto error3;
+	}
+
+	cmtspeech.name = "cmt-speech";
+	cmtspeech.tx_cfg = cl->tx_cfg;
+	cmtspeech.rx_cfg = cl->rx_cfg;
+	cmtspeech.platform_data = NULL;
+	cmtspeech.archdata = NULL;
+
+	modem->cmt_speech = hsi_new_client(port, &cmtspeech);
+	if (!modem->cmt_speech) {
+		dev_err(dev, "Could not register cmt-speech device\n");
+		err = -ENOMEM;
+		goto error3;
+	}
+
+	err = device_attach(&modem->cmt_speech->device);
+	if (err == 0) {
+		dev_dbg(dev, "Missing cmt-speech driver\n");
+		err = -EPROBE_DEFER;
+		goto error4;
+	} else if (err < 0) {
+		dev_err(dev, "Could not load cmt-speech driver (%d)\n", err);
+		goto error4;
+	}
+
+	dev_info(dev, "Registered Nokia HSI modem\n");
+
+	return 0;
+
+error4:
+	hsi_remove_client(&modem->cmt_speech->device, NULL);
+error3:
+	hsi_remove_client(&modem->ssi_protocol->device, NULL);
+error2:
+	nokia_modem_gpio_unexport(dev);
+error1:
+	disable_irq_wake(modem->nokia_modem_rst_ind_irq);
+	tasklet_kill(&modem->nokia_modem_rst_ind_tasklet);
+
+	return err;
+}
+
+static int nokia_modem_remove(struct device *dev)
+{
+	struct nokia_modem_device *modem = dev_get_drvdata(dev);
+
+	if (!modem)
+		return 0;
+
+	if (modem->cmt_speech) {
+		hsi_remove_client(&modem->cmt_speech->device, NULL);
+		modem->cmt_speech = NULL;
+	}
+
+	if (modem->ssi_protocol) {
+		hsi_remove_client(&modem->ssi_protocol->device, NULL);
+		modem->ssi_protocol = NULL;
+	}
+
+	nokia_modem_gpio_unexport(dev);
+	dev_set_drvdata(dev, NULL);
+	disable_irq_wake(modem->nokia_modem_rst_ind_irq);
+	tasklet_kill(&modem->nokia_modem_rst_ind_tasklet);
+
+	return 0;
+}
+
+#ifdef CONFIG_OF
+static const struct of_device_id nokia_modem_of_match[] = {
+	{ .compatible = "nokia,n900-modem", },
+	{ .compatible = "nokia,n950-modem", },
+	{ .compatible = "nokia,n9-modem", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, nokia_modem_of_match);
+#endif
+
+static struct hsi_client_driver nokia_modem_driver = {
+	.driver = {
+		.name	= "nokia-modem",
+		.owner	= THIS_MODULE,
+		.probe	= nokia_modem_probe,
+		.remove	= nokia_modem_remove,
+		.of_match_table = of_match_ptr(nokia_modem_of_match),
+	},
+};
+
+static int __init nokia_modem_init(void)
+{
+	return hsi_register_client_driver(&nokia_modem_driver);
+}
+module_init(nokia_modem_init);
+
+static void __exit nokia_modem_exit(void)
+{
+	hsi_unregister_client_driver(&nokia_modem_driver);
+}
+module_exit(nokia_modem_exit);
+
+MODULE_ALIAS("hsi:nokia-modem");
+MODULE_AUTHOR("Sebastian Reichel <sre@kernel.org>");
+MODULE_DESCRIPTION("HSI driver module for Nokia N900 Modem");
+MODULE_LICENSE("GPL");
diff --git a/drivers/hsi/clients/ssi_protocol.c b/drivers/hsi/clients/ssi_protocol.c
new file mode 100644
index 000000000..7c6ca8391
--- /dev/null
+++ b/drivers/hsi/clients/ssi_protocol.c
@@ -0,0 +1,1192 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * ssi_protocol.c
+ *
+ * Implementation of the SSI McSAAB improved protocol.
+ *
+ * Copyright (C) 2010 Nokia Corporation. All rights reserved.
+ * Copyright (C) 2013 Sebastian Reichel <sre@kernel.org>
+ *
+ * Contact: Carlos Chinea <carlos.chinea@nokia.com>
+ */
+
+#include <linux/atomic.h>
+#include <linux/clk.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/if_ether.h>
+#include <linux/if_arp.h>
+#include <linux/if_phonet.h>
+#include <linux/init.h>
+#include <linux/irq.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/netdevice.h>
+#include <linux/notifier.h>
+#include <linux/scatterlist.h>
+#include <linux/skbuff.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/timer.h>
+#include <linux/hsi/hsi.h>
+#include <linux/hsi/ssi_protocol.h>
+
+#define SSIP_TXQUEUE_LEN	100
+#define SSIP_MAX_MTU		65535
+#define SSIP_DEFAULT_MTU	4000
+#define PN_MEDIA_SOS		21
+#define SSIP_MIN_PN_HDR		6	/* FIXME: Revisit */
+#define SSIP_WDTOUT		2000	/* FIXME: has to be 500 msecs */
+#define SSIP_KATOUT		15	/* 15 msecs */
+#define SSIP_MAX_CMDS		5 /* Number of pre-allocated commands buffers */
+#define SSIP_BYTES_TO_FRAMES(x) ((((x) - 1) >> 2) + 1)
+#define SSIP_CMT_LOADER_SYNC	0x11223344
+/*
+ * SSI protocol command definitions
+ */
+#define SSIP_COMMAND(data)	((data) >> 28)
+#define SSIP_PAYLOAD(data)	((data) & 0xfffffff)
+/* Commands */
+#define SSIP_SW_BREAK		0
+#define SSIP_BOOTINFO_REQ	1
+#define SSIP_BOOTINFO_RESP	2
+#define SSIP_WAKETEST_RESULT	3
+#define SSIP_START_TRANS	4
+#define SSIP_READY		5
+/* Payloads */
+#define SSIP_DATA_VERSION(data)	((data) & 0xff)
+#define SSIP_LOCAL_VERID	1
+#define SSIP_WAKETEST_OK	0
+#define SSIP_WAKETEST_FAILED	1
+#define SSIP_PDU_LENGTH(data)	(((data) >> 8) & 0xffff)
+#define SSIP_MSG_ID(data)	((data) & 0xff)
+/* Generic Command */
+#define SSIP_CMD(cmd, payload)	(((cmd) << 28) | ((payload) & 0xfffffff))
+/* Commands for the control channel */
+#define SSIP_BOOTINFO_REQ_CMD(ver) \
+		SSIP_CMD(SSIP_BOOTINFO_REQ, SSIP_DATA_VERSION(ver))
+#define SSIP_BOOTINFO_RESP_CMD(ver) \
+		SSIP_CMD(SSIP_BOOTINFO_RESP, SSIP_DATA_VERSION(ver))
+#define SSIP_START_TRANS_CMD(pdulen, id) \
+		SSIP_CMD(SSIP_START_TRANS, (((pdulen) << 8) | SSIP_MSG_ID(id)))
+#define SSIP_READY_CMD		SSIP_CMD(SSIP_READY, 0)
+#define SSIP_SWBREAK_CMD	SSIP_CMD(SSIP_SW_BREAK, 0)
+
+#define SSIP_WAKETEST_FLAG 0
+
+/* Main state machine states */
+enum {
+	INIT,
+	HANDSHAKE,
+	ACTIVE,
+};
+
+/* Send state machine states */
+enum {
+	SEND_IDLE,
+	WAIT4READY,
+	SEND_READY,
+	SENDING,
+	SENDING_SWBREAK,
+};
+
+/* Receive state machine states */
+enum {
+	RECV_IDLE,
+	RECV_READY,
+	RECEIVING,
+};
+
+/**
+ * struct ssi_protocol - SSI protocol (McSAAB) data
+ * @main_state: Main state machine
+ * @send_state: TX state machine
+ * @recv_state: RX state machine
+ * @flags: Flags, currently only used to follow wake line test
+ * @rxid: RX data id
+ * @txid: TX data id
+ * @txqueue_len: TX queue length
+ * @tx_wd: TX watchdog
+ * @rx_wd: RX watchdog
+ * @keep_alive: Workaround for SSI HW bug
+ * @lock: To serialize access to this struct
+ * @netdev: Phonet network device
+ * @txqueue: TX data queue
+ * @cmdqueue: Queue of free commands
+ * @work: &struct work_struct for scheduled work
+ * @cl: HSI client own reference
+ * @link: Link for ssip_list
+ * @tx_usecnt: Refcount to keep track the slaves that use the wake line
+ * @channel_id_cmd: HSI channel id for command stream
+ * @channel_id_data: HSI channel id for data stream
+ */
+struct ssi_protocol {
+	unsigned int		main_state;
+	unsigned int		send_state;
+	unsigned int		recv_state;
+	unsigned long		flags;
+	u8			rxid;
+	u8			txid;
+	unsigned int		txqueue_len;
+	struct timer_list	tx_wd;
+	struct timer_list	rx_wd;
+	struct timer_list	keep_alive; /* wake-up workaround */
+	spinlock_t		lock;
+	struct net_device	*netdev;
+	struct list_head	txqueue;
+	struct list_head	cmdqueue;
+	struct work_struct	work;
+	struct hsi_client	*cl;
+	struct list_head	link;
+	atomic_t		tx_usecnt;
+	int			channel_id_cmd;
+	int			channel_id_data;
+};
+
+/* List of ssi protocol instances */
+static LIST_HEAD(ssip_list);
+
+static void ssip_rxcmd_complete(struct hsi_msg *msg);
+
+static inline void ssip_set_cmd(struct hsi_msg *msg, u32 cmd)
+{
+	u32 *data;
+
+	data = sg_virt(msg->sgt.sgl);
+	*data = cmd;
+}
+
+static inline u32 ssip_get_cmd(struct hsi_msg *msg)
+{
+	u32 *data;
+
+	data = sg_virt(msg->sgt.sgl);
+
+	return *data;
+}
+
+static void ssip_skb_to_msg(struct sk_buff *skb, struct hsi_msg *msg)
+{
+	skb_frag_t *frag;
+	struct scatterlist *sg;
+	int i;
+
+	BUG_ON(msg->sgt.nents != (unsigned int)(skb_shinfo(skb)->nr_frags + 1));
+
+	sg = msg->sgt.sgl;
+	sg_set_buf(sg, skb->data, skb_headlen(skb));
+	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
+		sg = sg_next(sg);
+		BUG_ON(!sg);
+		frag = &skb_shinfo(skb)->frags[i];
+		sg_set_page(sg, skb_frag_page(frag), skb_frag_size(frag),
+				skb_frag_off(frag));
+	}
+}
+
+static void ssip_free_data(struct hsi_msg *msg)
+{
+	struct sk_buff *skb;
+
+	skb = msg->context;
+	pr_debug("free data: msg %p context %p skb %p\n", msg, msg->context,
+								skb);
+	msg->destructor = NULL;
+	dev_kfree_skb(skb);
+	hsi_free_msg(msg);
+}
+
+static struct hsi_msg *ssip_alloc_data(struct ssi_protocol *ssi,
+					struct sk_buff *skb, gfp_t flags)
+{
+	struct hsi_msg *msg;
+
+	msg = hsi_alloc_msg(skb_shinfo(skb)->nr_frags + 1, flags);
+	if (!msg)
+		return NULL;
+	ssip_skb_to_msg(skb, msg);
+	msg->destructor = ssip_free_data;
+	msg->channel = ssi->channel_id_data;
+	msg->context = skb;
+
+	return msg;
+}
+
+static inline void ssip_release_cmd(struct hsi_msg *msg)
+{
+	struct ssi_protocol *ssi = hsi_client_drvdata(msg->cl);
+
+	dev_dbg(&msg->cl->device, "Release cmd 0x%08x\n", ssip_get_cmd(msg));
+	spin_lock_bh(&ssi->lock);
+	list_add_tail(&msg->link, &ssi->cmdqueue);
+	spin_unlock_bh(&ssi->lock);
+}
+
+static struct hsi_msg *ssip_claim_cmd(struct ssi_protocol *ssi)
+{
+	struct hsi_msg *msg;
+
+	BUG_ON(list_empty(&ssi->cmdqueue));
+
+	spin_lock_bh(&ssi->lock);
+	msg = list_first_entry(&ssi->cmdqueue, struct hsi_msg, link);
+	list_del(&msg->link);
+	spin_unlock_bh(&ssi->lock);
+	msg->destructor = ssip_release_cmd;
+
+	return msg;
+}
+
+static void ssip_free_cmds(struct ssi_protocol *ssi)
+{
+	struct hsi_msg *msg, *tmp;
+
+	list_for_each_entry_safe(msg, tmp, &ssi->cmdqueue, link) {
+		list_del(&msg->link);
+		msg->destructor = NULL;
+		kfree(sg_virt(msg->sgt.sgl));
+		hsi_free_msg(msg);
+	}
+}
+
+static int ssip_alloc_cmds(struct ssi_protocol *ssi)
+{
+	struct hsi_msg *msg;
+	u32 *buf;
+	unsigned int i;
+
+	for (i = 0; i < SSIP_MAX_CMDS; i++) {
+		msg = hsi_alloc_msg(1, GFP_KERNEL);
+		if (!msg)
+			goto out;
+		buf = kmalloc_obj(*buf);
+		if (!buf) {
+			hsi_free_msg(msg);
+			goto out;
+		}
+		sg_init_one(msg->sgt.sgl, buf, sizeof(*buf));
+		msg->channel = ssi->channel_id_cmd;
+		list_add_tail(&msg->link, &ssi->cmdqueue);
+	}
+
+	return 0;
+out:
+	ssip_free_cmds(ssi);
+
+	return -ENOMEM;
+}
+
+static void ssip_set_rxstate(struct ssi_protocol *ssi, unsigned int state)
+{
+	ssi->recv_state = state;
+	switch (state) {
+	case RECV_IDLE:
+		timer_delete(&ssi->rx_wd);
+		if (ssi->send_state == SEND_IDLE)
+			timer_delete(&ssi->keep_alive);
+		break;
+	case RECV_READY:
+		/* CMT speech workaround */
+		if (atomic_read(&ssi->tx_usecnt))
+			break;
+		fallthrough;
+	case RECEIVING:
+		mod_timer(&ssi->keep_alive, jiffies +
+						msecs_to_jiffies(SSIP_KATOUT));
+		mod_timer(&ssi->rx_wd, jiffies + msecs_to_jiffies(SSIP_WDTOUT));
+		break;
+	default:
+		break;
+	}
+}
+
+static void ssip_set_txstate(struct ssi_protocol *ssi, unsigned int state)
+{
+	ssi->send_state = state;
+	switch (state) {
+	case SEND_IDLE:
+	case SEND_READY:
+		timer_delete(&ssi->tx_wd);
+		if (ssi->recv_state == RECV_IDLE)
+			timer_delete(&ssi->keep_alive);
+		break;
+	case WAIT4READY:
+	case SENDING:
+	case SENDING_SWBREAK:
+		mod_timer(&ssi->keep_alive,
+				jiffies + msecs_to_jiffies(SSIP_KATOUT));
+		mod_timer(&ssi->tx_wd, jiffies + msecs_to_jiffies(SSIP_WDTOUT));
+		break;
+	default:
+		break;
+	}
+}
+
+struct hsi_client *ssip_slave_get_master(struct hsi_client *slave)
+{
+	struct hsi_client *master = ERR_PTR(-ENODEV);
+	struct ssi_protocol *ssi;
+
+	list_for_each_entry(ssi, &ssip_list, link)
+		if (slave->device.parent == ssi->cl->device.parent) {
+			master = ssi->cl;
+			break;
+		}
+
+	return master;
+}
+EXPORT_SYMBOL_GPL(ssip_slave_get_master);
+
+int ssip_slave_start_tx(struct hsi_client *master)
+{
+	struct ssi_protocol *ssi = hsi_client_drvdata(master);
+
+	dev_dbg(&master->device, "start TX %d\n", atomic_read(&ssi->tx_usecnt));
+	spin_lock_bh(&ssi->lock);
+	if (ssi->send_state == SEND_IDLE) {
+		ssip_set_txstate(ssi, WAIT4READY);
+		hsi_start_tx(master);
+	}
+	spin_unlock_bh(&ssi->lock);
+	atomic_inc(&ssi->tx_usecnt);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(ssip_slave_start_tx);
+
+int ssip_slave_stop_tx(struct hsi_client *master)
+{
+	struct ssi_protocol *ssi = hsi_client_drvdata(master);
+
+	WARN_ON_ONCE(atomic_read(&ssi->tx_usecnt) == 0);
+
+	if (atomic_dec_and_test(&ssi->tx_usecnt)) {
+		spin_lock_bh(&ssi->lock);
+		if ((ssi->send_state == SEND_READY) ||
+			(ssi->send_state == WAIT4READY)) {
+			ssip_set_txstate(ssi, SEND_IDLE);
+			hsi_stop_tx(master);
+		}
+		spin_unlock_bh(&ssi->lock);
+	}
+	dev_dbg(&master->device, "stop TX %d\n", atomic_read(&ssi->tx_usecnt));
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(ssip_slave_stop_tx);
+
+int ssip_slave_running(struct hsi_client *master)
+{
+	struct ssi_protocol *ssi = hsi_client_drvdata(master);
+	return netif_running(ssi->netdev);
+}
+EXPORT_SYMBOL_GPL(ssip_slave_running);
+
+static void ssip_reset(struct hsi_client *cl)
+{
+	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
+	struct list_head *head, *tmp;
+	struct hsi_msg *msg;
+
+	if (netif_running(ssi->netdev))
+		netif_carrier_off(ssi->netdev);
+	hsi_flush(cl);
+	spin_lock_bh(&ssi->lock);
+	if (ssi->send_state != SEND_IDLE)
+		hsi_stop_tx(cl);
+	spin_unlock_bh(&ssi->lock);
+	if (test_and_clear_bit(SSIP_WAKETEST_FLAG, &ssi->flags))
+		ssi_waketest(cl, 0); /* FIXME: To be removed */
+	spin_lock_bh(&ssi->lock);
+	timer_delete(&ssi->rx_wd);
+	timer_delete(&ssi->tx_wd);
+	timer_delete(&ssi->keep_alive);
+	cancel_work_sync(&ssi->work);
+	ssi->main_state = 0;
+	ssi->send_state = 0;
+	ssi->recv_state = 0;
+	ssi->flags = 0;
+	ssi->rxid = 0;
+	ssi->txid = 0;
+	list_for_each_safe(head, tmp, &ssi->txqueue) {
+		msg = list_entry(head, struct hsi_msg, link);
+		dev_dbg(&cl->device, "Pending TX data\n");
+		list_del(head);
+		ssip_free_data(msg);
+	}
+	ssi->txqueue_len = 0;
+	spin_unlock_bh(&ssi->lock);
+}
+
+static void ssip_dump_state(struct hsi_client *cl)
+{
+	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
+	struct hsi_msg *msg;
+
+	spin_lock_bh(&ssi->lock);
+	dev_err(&cl->device, "Main state: %d\n", ssi->main_state);
+	dev_err(&cl->device, "Recv state: %d\n", ssi->recv_state);
+	dev_err(&cl->device, "Send state: %d\n", ssi->send_state);
+	dev_err(&cl->device, "CMT %s\n", (ssi->main_state == ACTIVE) ?
+							"Online" : "Offline");
+	dev_err(&cl->device, "Wake test %d\n",
+				test_bit(SSIP_WAKETEST_FLAG, &ssi->flags));
+	dev_err(&cl->device, "Data RX id: %d\n", ssi->rxid);
+	dev_err(&cl->device, "Data TX id: %d\n", ssi->txid);
+
+	list_for_each_entry(msg, &ssi->txqueue, link)
+		dev_err(&cl->device, "pending TX data (%p)\n", msg);
+	spin_unlock_bh(&ssi->lock);
+}
+
+static void ssip_error(struct hsi_client *cl)
+{
+	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
+	struct hsi_msg *msg;
+
+	ssip_dump_state(cl);
+	ssip_reset(cl);
+	msg = ssip_claim_cmd(ssi);
+	msg->complete = ssip_rxcmd_complete;
+	hsi_async_read(cl, msg);
+}
+
+static void ssip_keep_alive(struct timer_list *t)
+{
+	struct ssi_protocol *ssi = timer_container_of(ssi, t, keep_alive);
+	struct hsi_client *cl = ssi->cl;
+
+	dev_dbg(&cl->device, "Keep alive kick in: m(%d) r(%d) s(%d)\n",
+		ssi->main_state, ssi->recv_state, ssi->send_state);
+
+	spin_lock(&ssi->lock);
+	if (ssi->recv_state == RECV_IDLE)
+		switch (ssi->send_state) {
+		case SEND_READY:
+			if (atomic_read(&ssi->tx_usecnt) == 0)
+				break;
+			fallthrough;
+			/*
+			 * Workaround for cmt-speech in that case
+			 * we relay on audio timers.
+			 */
+		case SEND_IDLE:
+			spin_unlock(&ssi->lock);
+			return;
+		}
+	mod_timer(&ssi->keep_alive, jiffies + msecs_to_jiffies(SSIP_KATOUT));
+	spin_unlock(&ssi->lock);
+}
+
+static void ssip_rx_wd(struct timer_list *t)
+{
+	struct ssi_protocol *ssi = timer_container_of(ssi, t, rx_wd);
+	struct hsi_client *cl = ssi->cl;
+
+	dev_err(&cl->device, "Watchdog triggered\n");
+	ssip_error(cl);
+}
+
+static void ssip_tx_wd(struct timer_list *t)
+{
+	struct ssi_protocol *ssi = timer_container_of(ssi, t, tx_wd);
+	struct hsi_client *cl = ssi->cl;
+
+	dev_err(&cl->device, "Watchdog triggered\n");
+	ssip_error(cl);
+}
+
+static void ssip_send_bootinfo_req_cmd(struct hsi_client *cl)
+{
+	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
+	struct hsi_msg *msg;
+
+	dev_dbg(&cl->device, "Issuing BOOT INFO REQ command\n");
+	msg = ssip_claim_cmd(ssi);
+	ssip_set_cmd(msg, SSIP_BOOTINFO_REQ_CMD(SSIP_LOCAL_VERID));
+	msg->complete = ssip_release_cmd;
+	hsi_async_write(cl, msg);
+	dev_dbg(&cl->device, "Issuing RX command\n");
+	msg = ssip_claim_cmd(ssi);
+	msg->complete = ssip_rxcmd_complete;
+	hsi_async_read(cl, msg);
+}
+
+static void ssip_start_rx(struct hsi_client *cl)
+{
+	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
+	struct hsi_msg *msg;
+
+	dev_dbg(&cl->device, "RX start M(%d) R(%d)\n", ssi->main_state,
+						ssi->recv_state);
+	spin_lock_bh(&ssi->lock);
+	/*
+	 * We can have two UP events in a row due to a short low
+	 * high transition. Therefore we need to ignore the sencond UP event.
+	 */
+	if ((ssi->main_state != ACTIVE) || (ssi->recv_state == RECV_READY)) {
+		spin_unlock_bh(&ssi->lock);
+		return;
+	}
+	ssip_set_rxstate(ssi, RECV_READY);
+	spin_unlock_bh(&ssi->lock);
+
+	msg = ssip_claim_cmd(ssi);
+	ssip_set_cmd(msg, SSIP_READY_CMD);
+	msg->complete = ssip_release_cmd;
+	dev_dbg(&cl->device, "Send READY\n");
+	hsi_async_write(cl, msg);
+}
+
+static void ssip_stop_rx(struct hsi_client *cl)
+{
+	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
+
+	dev_dbg(&cl->device, "RX stop M(%d)\n", ssi->main_state);
+	spin_lock_bh(&ssi->lock);
+	if (likely(ssi->main_state == ACTIVE))
+		ssip_set_rxstate(ssi, RECV_IDLE);
+	spin_unlock_bh(&ssi->lock);
+}
+
+static void ssip_free_strans(struct hsi_msg *msg)
+{
+	ssip_free_data(msg->context);
+	ssip_release_cmd(msg);
+}
+
+static void ssip_strans_complete(struct hsi_msg *msg)
+{
+	struct hsi_client *cl = msg->cl;
+	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
+	struct hsi_msg *data;
+
+	data = msg->context;
+	ssip_release_cmd(msg);
+	spin_lock_bh(&ssi->lock);
+	ssip_set_txstate(ssi, SENDING);
+	spin_unlock_bh(&ssi->lock);
+	hsi_async_write(cl, data);
+}
+
+static int ssip_xmit(struct hsi_client *cl)
+{
+	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
+	struct hsi_msg *msg, *dmsg;
+	struct sk_buff *skb;
+
+	spin_lock_bh(&ssi->lock);
+	if (list_empty(&ssi->txqueue)) {
+		spin_unlock_bh(&ssi->lock);
+		return 0;
+	}
+	dmsg = list_first_entry(&ssi->txqueue, struct hsi_msg, link);
+	list_del(&dmsg->link);
+	ssi->txqueue_len--;
+	spin_unlock_bh(&ssi->lock);
+
+	msg = ssip_claim_cmd(ssi);
+	skb = dmsg->context;
+	msg->context = dmsg;
+	msg->complete = ssip_strans_complete;
+	msg->destructor = ssip_free_strans;
+
+	spin_lock_bh(&ssi->lock);
+	ssip_set_cmd(msg, SSIP_START_TRANS_CMD(SSIP_BYTES_TO_FRAMES(skb->len),
+								ssi->txid));
+	ssi->txid++;
+	ssip_set_txstate(ssi, SENDING);
+	spin_unlock_bh(&ssi->lock);
+
+	dev_dbg(&cl->device, "Send STRANS (%d frames)\n",
+						SSIP_BYTES_TO_FRAMES(skb->len));
+
+	return hsi_async_write(cl, msg);
+}
+
+/* In soft IRQ context */
+static void ssip_pn_rx(struct sk_buff *skb)
+{
+	struct net_device *dev = skb->dev;
+
+	if (unlikely(!netif_running(dev))) {
+		dev_dbg(&dev->dev, "Drop RX packet\n");
+		dev->stats.rx_dropped++;
+		dev_kfree_skb(skb);
+		return;
+	}
+	if (unlikely(!pskb_may_pull(skb, SSIP_MIN_PN_HDR))) {
+		dev_dbg(&dev->dev, "Error drop RX packet\n");
+		dev->stats.rx_errors++;
+		dev->stats.rx_length_errors++;
+		dev_kfree_skb(skb);
+		return;
+	}
+	dev->stats.rx_packets++;
+	dev->stats.rx_bytes += skb->len;
+
+	/* length field is exchanged in network byte order */
+	((u16 *)skb->data)[2] = ntohs(((u16 *)skb->data)[2]);
+	dev_dbg(&dev->dev, "RX length fixed (%04x -> %u)\n",
+			((u16 *)skb->data)[2], ntohs(((u16 *)skb->data)[2]));
+
+	skb->protocol = htons(ETH_P_PHONET);
+	skb_reset_mac_header(skb);
+	__skb_pull(skb, 1);
+	netif_rx(skb);
+}
+
+static void ssip_rx_data_complete(struct hsi_msg *msg)
+{
+	struct hsi_client *cl = msg->cl;
+	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
+	struct sk_buff *skb;
+
+	if (msg->status == HSI_STATUS_ERROR) {
+		dev_err(&cl->device, "RX data error\n");
+		ssip_free_data(msg);
+		ssip_error(cl);
+		return;
+	}
+	timer_delete(&ssi->rx_wd); /* FIXME: Revisit */
+	skb = msg->context;
+	ssip_pn_rx(skb);
+	hsi_free_msg(msg);
+}
+
+static void ssip_rx_bootinforeq(struct hsi_client *cl, u32 cmd)
+{
+	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
+	struct hsi_msg *msg;
+
+	/* Workaroud: Ignore CMT Loader message leftover */
+	if (cmd == SSIP_CMT_LOADER_SYNC)
+		return;
+
+	switch (ssi->main_state) {
+	case ACTIVE:
+		dev_err(&cl->device, "Boot info req on active state\n");
+		ssip_error(cl);
+		fallthrough;
+	case INIT:
+	case HANDSHAKE:
+		spin_lock_bh(&ssi->lock);
+		ssi->main_state = HANDSHAKE;
+		spin_unlock_bh(&ssi->lock);
+
+		if (!test_and_set_bit(SSIP_WAKETEST_FLAG, &ssi->flags))
+			ssi_waketest(cl, 1); /* FIXME: To be removed */
+
+		spin_lock_bh(&ssi->lock);
+		/* Start boot handshake watchdog */
+		mod_timer(&ssi->tx_wd, jiffies + msecs_to_jiffies(SSIP_WDTOUT));
+		spin_unlock_bh(&ssi->lock);
+		dev_dbg(&cl->device, "Send BOOTINFO_RESP\n");
+		if (SSIP_DATA_VERSION(cmd) != SSIP_LOCAL_VERID)
+			dev_warn(&cl->device, "boot info req verid mismatch\n");
+		msg = ssip_claim_cmd(ssi);
+		ssip_set_cmd(msg, SSIP_BOOTINFO_RESP_CMD(SSIP_LOCAL_VERID));
+		msg->complete = ssip_release_cmd;
+		hsi_async_write(cl, msg);
+		break;
+	default:
+		dev_dbg(&cl->device, "Wrong state M(%d)\n", ssi->main_state);
+		break;
+	}
+}
+
+static void ssip_rx_bootinforesp(struct hsi_client *cl, u32 cmd)
+{
+	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
+
+	if (SSIP_DATA_VERSION(cmd) != SSIP_LOCAL_VERID)
+		dev_warn(&cl->device, "boot info resp verid mismatch\n");
+
+	spin_lock_bh(&ssi->lock);
+	if (ssi->main_state != ACTIVE)
+		/* Use tx_wd as a boot watchdog in non ACTIVE state */
+		mod_timer(&ssi->tx_wd, jiffies + msecs_to_jiffies(SSIP_WDTOUT));
+	else
+		dev_dbg(&cl->device, "boot info resp ignored M(%d)\n",
+							ssi->main_state);
+	spin_unlock_bh(&ssi->lock);
+}
+
+static void ssip_rx_waketest(struct hsi_client *cl, u32 cmd)
+{
+	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
+	unsigned int wkres = SSIP_PAYLOAD(cmd);
+
+	spin_lock_bh(&ssi->lock);
+	if (ssi->main_state != HANDSHAKE) {
+		dev_dbg(&cl->device, "wake lines test ignored M(%d)\n",
+							ssi->main_state);
+		spin_unlock_bh(&ssi->lock);
+		return;
+	}
+	spin_unlock_bh(&ssi->lock);
+
+	if (test_and_clear_bit(SSIP_WAKETEST_FLAG, &ssi->flags))
+		ssi_waketest(cl, 0); /* FIXME: To be removed */
+
+	spin_lock_bh(&ssi->lock);
+	ssi->main_state = ACTIVE;
+	timer_delete(&ssi->tx_wd); /* Stop boot handshake timer */
+	spin_unlock_bh(&ssi->lock);
+
+	dev_notice(&cl->device, "WAKELINES TEST %s\n",
+				wkres & SSIP_WAKETEST_FAILED ? "FAILED" : "OK");
+	if (wkres & SSIP_WAKETEST_FAILED) {
+		ssip_error(cl);
+		return;
+	}
+	dev_dbg(&cl->device, "CMT is ONLINE\n");
+	netif_wake_queue(ssi->netdev);
+	netif_carrier_on(ssi->netdev);
+}
+
+static void ssip_rx_ready(struct hsi_client *cl)
+{
+	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
+
+	spin_lock_bh(&ssi->lock);
+	if (unlikely(ssi->main_state != ACTIVE)) {
+		dev_dbg(&cl->device, "READY on wrong state: S(%d) M(%d)\n",
+					ssi->send_state, ssi->main_state);
+		spin_unlock_bh(&ssi->lock);
+		return;
+	}
+	if (ssi->send_state != WAIT4READY) {
+		dev_dbg(&cl->device, "Ignore spurious READY command\n");
+		spin_unlock_bh(&ssi->lock);
+		return;
+	}
+	ssip_set_txstate(ssi, SEND_READY);
+	spin_unlock_bh(&ssi->lock);
+	ssip_xmit(cl);
+}
+
+static void ssip_rx_strans(struct hsi_client *cl, u32 cmd)
+{
+	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
+	struct sk_buff *skb;
+	struct hsi_msg *msg;
+	int len = SSIP_PDU_LENGTH(cmd);
+
+	dev_dbg(&cl->device, "RX strans: %d frames\n", len);
+	spin_lock_bh(&ssi->lock);
+	if (unlikely(ssi->main_state != ACTIVE)) {
+		dev_err(&cl->device, "START TRANS wrong state: S(%d) M(%d)\n",
+					ssi->send_state, ssi->main_state);
+		spin_unlock_bh(&ssi->lock);
+		return;
+	}
+	ssip_set_rxstate(ssi, RECEIVING);
+	if (unlikely(SSIP_MSG_ID(cmd) != ssi->rxid)) {
+		dev_err(&cl->device, "START TRANS id %d expected %d\n",
+					SSIP_MSG_ID(cmd), ssi->rxid);
+		spin_unlock_bh(&ssi->lock);
+		goto out1;
+	}
+	ssi->rxid++;
+	spin_unlock_bh(&ssi->lock);
+	skb = netdev_alloc_skb(ssi->netdev, len * 4);
+	if (unlikely(!skb)) {
+		dev_err(&cl->device, "No memory for rx skb\n");
+		goto out1;
+	}
+	skb_put(skb, len * 4);
+	msg = ssip_alloc_data(ssi, skb, GFP_ATOMIC);
+	if (unlikely(!msg)) {
+		dev_err(&cl->device, "No memory for RX data msg\n");
+		goto out2;
+	}
+	msg->complete = ssip_rx_data_complete;
+	hsi_async_read(cl, msg);
+
+	return;
+out2:
+	dev_kfree_skb(skb);
+out1:
+	ssip_error(cl);
+}
+
+static void ssip_rxcmd_complete(struct hsi_msg *msg)
+{
+	struct hsi_client *cl = msg->cl;
+	u32 cmd = ssip_get_cmd(msg);
+	unsigned int cmdid = SSIP_COMMAND(cmd);
+
+	if (msg->status == HSI_STATUS_ERROR) {
+		dev_err(&cl->device, "RX error detected\n");
+		ssip_release_cmd(msg);
+		ssip_error(cl);
+		return;
+	}
+	hsi_async_read(cl, msg);
+	dev_dbg(&cl->device, "RX cmd: 0x%08x\n", cmd);
+	switch (cmdid) {
+	case SSIP_SW_BREAK:
+		/* Ignored */
+		break;
+	case SSIP_BOOTINFO_REQ:
+		ssip_rx_bootinforeq(cl, cmd);
+		break;
+	case SSIP_BOOTINFO_RESP:
+		ssip_rx_bootinforesp(cl, cmd);
+		break;
+	case SSIP_WAKETEST_RESULT:
+		ssip_rx_waketest(cl, cmd);
+		break;
+	case SSIP_START_TRANS:
+		ssip_rx_strans(cl, cmd);
+		break;
+	case SSIP_READY:
+		ssip_rx_ready(cl);
+		break;
+	default:
+		dev_warn(&cl->device, "command 0x%08x not supported\n", cmd);
+		break;
+	}
+}
+
+static void ssip_swbreak_complete(struct hsi_msg *msg)
+{
+	struct hsi_client *cl = msg->cl;
+	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
+
+	ssip_release_cmd(msg);
+	spin_lock_bh(&ssi->lock);
+	if (list_empty(&ssi->txqueue)) {
+		if (atomic_read(&ssi->tx_usecnt)) {
+			ssip_set_txstate(ssi, SEND_READY);
+		} else {
+			ssip_set_txstate(ssi, SEND_IDLE);
+			hsi_stop_tx(cl);
+		}
+		spin_unlock_bh(&ssi->lock);
+	} else {
+		spin_unlock_bh(&ssi->lock);
+		ssip_xmit(cl);
+	}
+	netif_wake_queue(ssi->netdev);
+}
+
+static void ssip_tx_data_complete(struct hsi_msg *msg)
+{
+	struct hsi_client *cl = msg->cl;
+	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
+	struct hsi_msg *cmsg;
+
+	if (msg->status == HSI_STATUS_ERROR) {
+		dev_err(&cl->device, "TX data error\n");
+		ssip_error(cl);
+		goto out;
+	}
+	spin_lock_bh(&ssi->lock);
+	if (list_empty(&ssi->txqueue)) {
+		ssip_set_txstate(ssi, SENDING_SWBREAK);
+		spin_unlock_bh(&ssi->lock);
+		cmsg = ssip_claim_cmd(ssi);
+		ssip_set_cmd(cmsg, SSIP_SWBREAK_CMD);
+		cmsg->complete = ssip_swbreak_complete;
+		dev_dbg(&cl->device, "Send SWBREAK\n");
+		hsi_async_write(cl, cmsg);
+	} else {
+		spin_unlock_bh(&ssi->lock);
+		ssip_xmit(cl);
+	}
+out:
+	ssip_free_data(msg);
+}
+
+static void ssip_port_event(struct hsi_client *cl, unsigned long event)
+{
+	switch (event) {
+	case HSI_EVENT_START_RX:
+		ssip_start_rx(cl);
+		break;
+	case HSI_EVENT_STOP_RX:
+		ssip_stop_rx(cl);
+		break;
+	default:
+		return;
+	}
+}
+
+static int ssip_pn_open(struct net_device *dev)
+{
+	struct hsi_client *cl = to_hsi_client(dev->dev.parent);
+	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
+	int err;
+
+	err = hsi_claim_port(cl, 1);
+	if (err < 0) {
+		dev_err(&cl->device, "SSI port already claimed\n");
+		return err;
+	}
+	err = hsi_register_port_event(cl, ssip_port_event);
+	if (err < 0) {
+		dev_err(&cl->device, "Register HSI port event failed (%d)\n",
+			err);
+		hsi_release_port(cl);
+		return err;
+	}
+	dev_dbg(&cl->device, "Configuring SSI port\n");
+	hsi_setup(cl);
+
+	if (!test_and_set_bit(SSIP_WAKETEST_FLAG, &ssi->flags))
+		ssi_waketest(cl, 1); /* FIXME: To be removed */
+
+	spin_lock_bh(&ssi->lock);
+	ssi->main_state = HANDSHAKE;
+	spin_unlock_bh(&ssi->lock);
+
+	ssip_send_bootinfo_req_cmd(cl);
+
+	return 0;
+}
+
+static int ssip_pn_stop(struct net_device *dev)
+{
+	struct hsi_client *cl = to_hsi_client(dev->dev.parent);
+
+	ssip_reset(cl);
+	hsi_unregister_port_event(cl);
+	hsi_release_port(cl);
+
+	return 0;
+}
+
+static void ssip_xmit_work(struct work_struct *work)
+{
+	struct ssi_protocol *ssi =
+				container_of(work, struct ssi_protocol, work);
+	struct hsi_client *cl = ssi->cl;
+
+	ssip_xmit(cl);
+}
+
+static netdev_tx_t ssip_pn_xmit(struct sk_buff *skb, struct net_device *dev)
+{
+	struct hsi_client *cl = to_hsi_client(dev->dev.parent);
+	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
+	struct hsi_msg *msg;
+
+	if ((skb->protocol != htons(ETH_P_PHONET)) ||
+					(skb->len < SSIP_MIN_PN_HDR))
+		goto drop;
+	/* Pad to 32-bits - FIXME: Revisit*/
+	if ((skb->len & 3) && skb_pad(skb, 4 - (skb->len & 3)))
+		goto inc_dropped;
+
+	/*
+	 * Modem sends Phonet messages over SSI with its own endianness.
+	 * Assume that modem has the same endianness as we do.
+	 */
+	if (skb_cow_head(skb, 0))
+		goto drop;
+
+	/* length field is exchanged in network byte order */
+	((u16 *)skb->data)[2] = htons(((u16 *)skb->data)[2]);
+
+	msg = ssip_alloc_data(ssi, skb, GFP_ATOMIC);
+	if (!msg) {
+		dev_dbg(&cl->device, "Dropping tx data: No memory\n");
+		goto drop;
+	}
+	msg->complete = ssip_tx_data_complete;
+
+	spin_lock_bh(&ssi->lock);
+	if (unlikely(ssi->main_state != ACTIVE)) {
+		spin_unlock_bh(&ssi->lock);
+		dev_dbg(&cl->device, "Dropping tx data: CMT is OFFLINE\n");
+		goto drop2;
+	}
+	list_add_tail(&msg->link, &ssi->txqueue);
+	ssi->txqueue_len++;
+	if (dev->tx_queue_len < ssi->txqueue_len) {
+		dev_info(&cl->device, "TX queue full %d\n", ssi->txqueue_len);
+		netif_stop_queue(dev);
+	}
+	if (ssi->send_state == SEND_IDLE) {
+		ssip_set_txstate(ssi, WAIT4READY);
+		spin_unlock_bh(&ssi->lock);
+		dev_dbg(&cl->device, "Start TX qlen %d\n", ssi->txqueue_len);
+		hsi_start_tx(cl);
+	} else if (ssi->send_state == SEND_READY) {
+		/* Needed for cmt-speech workaround */
+		dev_dbg(&cl->device, "Start TX on SEND READY qlen %d\n",
+							ssi->txqueue_len);
+		spin_unlock_bh(&ssi->lock);
+		schedule_work(&ssi->work);
+	} else {
+		spin_unlock_bh(&ssi->lock);
+	}
+	dev->stats.tx_packets++;
+	dev->stats.tx_bytes += skb->len;
+
+	return NETDEV_TX_OK;
+drop2:
+	hsi_free_msg(msg);
+drop:
+	dev_kfree_skb(skb);
+inc_dropped:
+	dev->stats.tx_dropped++;
+
+	return NETDEV_TX_OK;
+}
+
+/* CMT reset event handler */
+void ssip_reset_event(struct hsi_client *master)
+{
+	struct ssi_protocol *ssi = hsi_client_drvdata(master);
+	dev_err(&ssi->cl->device, "CMT reset detected!\n");
+	ssip_error(ssi->cl);
+}
+EXPORT_SYMBOL_GPL(ssip_reset_event);
+
+static const struct net_device_ops ssip_pn_ops = {
+	.ndo_open	= ssip_pn_open,
+	.ndo_stop	= ssip_pn_stop,
+	.ndo_start_xmit	= ssip_pn_xmit,
+};
+
+static void ssip_pn_setup(struct net_device *dev)
+{
+	static const u8 addr = PN_MEDIA_SOS;
+
+	dev->features		= 0;
+	dev->netdev_ops		= &ssip_pn_ops;
+	dev->type		= ARPHRD_PHONET;
+	dev->flags		= IFF_POINTOPOINT | IFF_NOARP;
+	dev->mtu		= SSIP_DEFAULT_MTU;
+	dev->hard_header_len	= 1;
+	dev->addr_len		= 1;
+	dev_addr_set(dev, &addr);
+	dev->tx_queue_len	= SSIP_TXQUEUE_LEN;
+
+	dev->needs_free_netdev	= true;
+	dev->header_ops		= &phonet_header_ops;
+}
+
+static int ssi_protocol_probe(struct device *dev)
+{
+	static const char ifname[] = "phonet%d";
+	struct hsi_client *cl = to_hsi_client(dev);
+	struct ssi_protocol *ssi;
+	int err;
+
+	ssi = kzalloc_obj(*ssi);
+	if (!ssi)
+		return -ENOMEM;
+
+	spin_lock_init(&ssi->lock);
+	timer_setup(&ssi->rx_wd, ssip_rx_wd, TIMER_DEFERRABLE);
+	timer_setup(&ssi->tx_wd, ssip_tx_wd, TIMER_DEFERRABLE);
+	timer_setup(&ssi->keep_alive, ssip_keep_alive, 0);
+	INIT_LIST_HEAD(&ssi->txqueue);
+	INIT_LIST_HEAD(&ssi->cmdqueue);
+	atomic_set(&ssi->tx_usecnt, 0);
+	hsi_client_set_drvdata(cl, ssi);
+	ssi->cl = cl;
+	INIT_WORK(&ssi->work, ssip_xmit_work);
+
+	ssi->channel_id_cmd = hsi_get_channel_id_by_name(cl, "mcsaab-control");
+	if (ssi->channel_id_cmd < 0) {
+		err = ssi->channel_id_cmd;
+		dev_err(dev, "Could not get cmd channel (%d)\n", err);
+		goto out;
+	}
+
+	ssi->channel_id_data = hsi_get_channel_id_by_name(cl, "mcsaab-data");
+	if (ssi->channel_id_data < 0) {
+		err = ssi->channel_id_data;
+		dev_err(dev, "Could not get data channel (%d)\n", err);
+		goto out;
+	}
+
+	err = ssip_alloc_cmds(ssi);
+	if (err < 0) {
+		dev_err(dev, "No memory for commands\n");
+		goto out;
+	}
+
+	ssi->netdev = alloc_netdev(0, ifname, NET_NAME_UNKNOWN, ssip_pn_setup);
+	if (!ssi->netdev) {
+		dev_err(dev, "No memory for netdev\n");
+		err = -ENOMEM;
+		goto out1;
+	}
+
+	/* MTU range: 6 - 65535 */
+	ssi->netdev->min_mtu = PHONET_MIN_MTU;
+	ssi->netdev->max_mtu = SSIP_MAX_MTU;
+
+	SET_NETDEV_DEV(ssi->netdev, dev);
+	netif_carrier_off(ssi->netdev);
+	err = register_netdev(ssi->netdev);
+	if (err < 0) {
+		dev_err(dev, "Register netdev failed (%d)\n", err);
+		goto out2;
+	}
+
+	list_add(&ssi->link, &ssip_list);
+
+	dev_dbg(dev, "channel configuration: cmd=%d, data=%d\n",
+		ssi->channel_id_cmd, ssi->channel_id_data);
+
+	return 0;
+out2:
+	free_netdev(ssi->netdev);
+out1:
+	ssip_free_cmds(ssi);
+out:
+	kfree(ssi);
+
+	return err;
+}
+
+static int ssi_protocol_remove(struct device *dev)
+{
+	struct hsi_client *cl = to_hsi_client(dev);
+	struct ssi_protocol *ssi = hsi_client_drvdata(cl);
+
+	list_del(&ssi->link);
+	unregister_netdev(ssi->netdev);
+	ssip_free_cmds(ssi);
+	hsi_client_set_drvdata(cl, NULL);
+	kfree(ssi);
+
+	return 0;
+}
+
+static struct hsi_client_driver ssip_driver = {
+	.driver = {
+		.name	= "ssi-protocol",
+		.owner	= THIS_MODULE,
+		.probe	= ssi_protocol_probe,
+		.remove	= ssi_protocol_remove,
+	},
+};
+
+static int __init ssip_init(void)
+{
+	pr_info("SSI protocol aka McSAAB added\n");
+
+	return hsi_register_client_driver(&ssip_driver);
+}
+module_init(ssip_init);
+
+static void __exit ssip_exit(void)
+{
+	hsi_unregister_client_driver(&ssip_driver);
+	pr_info("SSI protocol driver removed\n");
+}
+module_exit(ssip_exit);
+
+MODULE_ALIAS("hsi:ssi-protocol");
+MODULE_AUTHOR("Carlos Chinea <carlos.chinea@nokia.com>");
+MODULE_AUTHOR("Remi Denis-Courmont <remi.denis-courmont@nokia.com>");
+MODULE_DESCRIPTION("SSI protocol improved aka McSAAB");
+MODULE_LICENSE("GPL");
diff --git a/drivers/hsi/controllers/Kconfig b/drivers/hsi/controllers/Kconfig
new file mode 100644
index 000000000..d3543197f
--- /dev/null
+++ b/drivers/hsi/controllers/Kconfig
@@ -0,0 +1,16 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# HSI controllers configuration
+#
+comment "HSI controllers"
+
+config OMAP_SSI
+	tristate "OMAP SSI hardware driver"
+	depends on HSI && OF && COMMON_CLK
+	depends on ARCH_OMAP3 || COMPILE_TEST
+	help
+	  SSI is a legacy version of HSI. It is usually used to connect
+	  an application engine with a cellular modem.
+	  If you say Y here, you will enable the OMAP SSI hardware driver.
+
+	  If unsure, say N.
diff --git a/drivers/hsi/controllers/Makefile b/drivers/hsi/controllers/Makefile
new file mode 100644
index 000000000..41aab9380
--- /dev/null
+++ b/drivers/hsi/controllers/Makefile
@@ -0,0 +1,7 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Makefile for HSI controllers drivers
+#
+
+omap_ssi-objs		+= omap_ssi_core.o omap_ssi_port.o
+obj-$(CONFIG_OMAP_SSI)	+= omap_ssi.o
diff --git a/drivers/hsi/controllers/omap_ssi.h b/drivers/hsi/controllers/omap_ssi.h
new file mode 100644
index 000000000..c72f74b5b
--- /dev/null
+++ b/drivers/hsi/controllers/omap_ssi.h
@@ -0,0 +1,164 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/* OMAP SSI internal interface.
+ *
+ * Copyright (C) 2010 Nokia Corporation. All rights reserved.
+ * Copyright (C) 2013 Sebastian Reichel
+ *
+ * Contact: Carlos Chinea <carlos.chinea@nokia.com>
+ */
+
+#ifndef __LINUX_HSI_OMAP_SSI_H__
+#define __LINUX_HSI_OMAP_SSI_H__
+
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/hsi/hsi.h>
+#include <linux/gpio/consumer.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+
+#define SSI_MAX_CHANNELS	8
+#define SSI_MAX_GDD_LCH		8
+#define SSI_BYTES_TO_FRAMES(x) ((((x) - 1) >> 2) + 1)
+
+#define SSI_WAKE_EN 0
+
+/**
+ * struct omap_ssm_ctx - OMAP synchronous serial module (TX/RX) context
+ * @mode: Bit transmission mode
+ * @channels: Number of channels
+ * @framesize: Frame size in bits
+ * @timeout: RX frame timeout
+ * @divisor: TX divider
+ * @arb_mode: Arbitration mode for TX frame (Round robin, priority)
+ */
+struct omap_ssm_ctx {
+	u32	mode;
+	u32	channels;
+	u32	frame_size;
+	union	{
+			u32	timeout; /* Rx Only */
+			struct	{
+					u32	arb_mode;
+					u32	divisor;
+			}; /* Tx only */
+	};
+};
+
+/**
+ * struct omap_ssi_port - OMAP SSI port data
+ * @dev: device associated to the port (HSI port)
+ * @pdev: platform device associated to the port
+ * @sst_dma: SSI transmitter physical base address
+ * @ssr_dma: SSI receiver physical base address
+ * @sst_base: SSI transmitter base address
+ * @ssr_base: SSI receiver base address
+ * @wk_lock: spin lock to serialize access to the wake lines
+ * @lock: Spin lock to serialize access to the SSI port
+ * @channels: Current number of channels configured (1,2,4 or 8)
+ * @txqueue: TX message queues
+ * @rxqueue: RX message queues
+ * @brkqueue: Queue of incoming HWBREAK requests (FRAME mode)
+ * @errqueue: Queue for failed messages
+ * @errqueue_work: Delayed Work for failed messages
+ * @irq: IRQ number
+ * @wake_irq: IRQ number for incoming wake line (-1 if none)
+ * @wake_gpio: GPIO number for incoming wake line (-1 if none)
+ * @flags: flags to keep track of states
+ * @wk_refcount: Reference count for output wake line
+ * @work: worker for starting TX
+ * @sys_mpu_enable: Context for the interrupt enable register for irq 0
+ * @sst: Context for the synchronous serial transmitter
+ * @ssr: Context for the synchronous serial receiver
+ */
+struct omap_ssi_port {
+	struct device		*dev;
+	struct device           *pdev;
+	dma_addr_t		sst_dma;
+	dma_addr_t		ssr_dma;
+	void __iomem		*sst_base;
+	void __iomem		*ssr_base;
+	spinlock_t		wk_lock;
+	spinlock_t		lock;
+	unsigned int		channels;
+	struct list_head	txqueue[SSI_MAX_CHANNELS];
+	struct list_head	rxqueue[SSI_MAX_CHANNELS];
+	struct list_head	brkqueue;
+	struct list_head	errqueue;
+	struct delayed_work	errqueue_work;
+	unsigned int		irq;
+	int			wake_irq;
+	struct gpio_desc	*wake_gpio;
+	bool			wktest:1; /* FIXME: HACK to be removed */
+	unsigned long		flags;
+	unsigned int		wk_refcount;
+	struct work_struct	work;
+	/* OMAP SSI port context */
+	u32			sys_mpu_enable; /* We use only one irq */
+	struct omap_ssm_ctx	sst;
+	struct omap_ssm_ctx	ssr;
+	u32			loss_count;
+	u32			port_id;
+#ifdef CONFIG_DEBUG_FS
+	struct dentry *dir;
+#endif
+};
+
+/**
+ * struct gdd_trn - GDD transaction data
+ * @msg: Pointer to the HSI message being served
+ * @sg: Pointer to the current sg entry being served
+ */
+struct gdd_trn {
+	struct hsi_msg		*msg;
+	struct scatterlist	*sg;
+};
+
+/**
+ * struct omap_ssi_controller - OMAP SSI controller data
+ * @dev: device associated to the controller (HSI controller)
+ * @sys: SSI I/O base address
+ * @gdd: GDD I/O base address
+ * @fck: SSI functional clock
+ * @gdd_irq: IRQ line for GDD
+ * @gdd_tasklet: bottom half for DMA transfers
+ * @gdd_trn: Array of GDD transaction data for ongoing GDD transfers
+ * @lock: lock to serialize access to GDD
+ * @fck_nb: DVFS notfifier block
+ * @fck_rate: clock rate
+ * @loss_count: To follow if we need to restore context or not
+ * @max_speed: Maximum TX speed (Kb/s) set by the clients.
+ * @gdd_gcr: SSI GDD saved context
+ * @get_loss: Pointer to omap_pm_get_dev_context_loss_count, if any
+ * @port: Array of pointers of the ports of the controller
+ * @dir: Debugfs SSI root directory
+ */
+struct omap_ssi_controller {
+	struct device		*dev;
+	void __iomem		*sys;
+	void __iomem		*gdd;
+	struct clk		*fck;
+	unsigned int		gdd_irq;
+	struct tasklet_struct	gdd_tasklet;
+	struct gdd_trn		gdd_trn[SSI_MAX_GDD_LCH];
+	spinlock_t		lock;
+	struct notifier_block	fck_nb;
+	unsigned long		fck_rate;
+	u32			loss_count;
+	u32			max_speed;
+	/* OMAP SSI Controller context */
+	u32			gdd_gcr;
+	int			(*get_loss)(struct device *dev);
+	struct omap_ssi_port	**port;
+#ifdef CONFIG_DEBUG_FS
+	struct dentry *dir;
+#endif
+};
+
+void omap_ssi_port_update_fclk(struct hsi_controller *ssi,
+			       struct omap_ssi_port *omap_port);
+
+extern struct platform_driver ssi_port_pdriver;
+
+#endif /* __LINUX_HSI_OMAP_SSI_H__ */
diff --git a/drivers/hsi/controllers/omap_ssi_core.c b/drivers/hsi/controllers/omap_ssi_core.c
new file mode 100644
index 000000000..eeacc427f
--- /dev/null
+++ b/drivers/hsi/controllers/omap_ssi_core.c
@@ -0,0 +1,645 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* OMAP SSI driver.
+ *
+ * Copyright (C) 2010 Nokia Corporation. All rights reserved.
+ * Copyright (C) 2014 Sebastian Reichel <sre@kernel.org>
+ *
+ * Contact: Carlos Chinea <carlos.chinea@nokia.com>
+ */
+
+#include <linux/compiler.h>
+#include <linux/err.h>
+#include <linux/ioport.h>
+#include <linux/io.h>
+#include <linux/clk.h>
+#include <linux/device.h>
+#include <linux/platform_device.h>
+#include <linux/dma-mapping.h>
+#include <linux/dmaengine.h>
+#include <linux/delay.h>
+#include <linux/hsi/ssi_protocol.h>
+#include <linux/seq_file.h>
+#include <linux/scatterlist.h>
+#include <linux/interrupt.h>
+#include <linux/spinlock.h>
+#include <linux/debugfs.h>
+#include <linux/pinctrl/consumer.h>
+#include <linux/pm_runtime.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/hsi/hsi.h>
+#include <linux/idr.h>
+
+#include "omap_ssi_regs.h"
+#include "omap_ssi.h"
+
+/* For automatically allocated device IDs */
+static DEFINE_IDA(platform_omap_ssi_ida);
+
+#ifdef CONFIG_DEBUG_FS
+static int ssi_regs_show(struct seq_file *m, void *p __maybe_unused)
+{
+	struct hsi_controller *ssi = m->private;
+	struct omap_ssi_controller *omap_ssi = hsi_controller_drvdata(ssi);
+	void __iomem *sys = omap_ssi->sys;
+
+	pm_runtime_get_sync(ssi->device.parent);
+	seq_printf(m, "REVISION\t: 0x%08x\n",  readl(sys + SSI_REVISION_REG));
+	seq_printf(m, "SYSCONFIG\t: 0x%08x\n", readl(sys + SSI_SYSCONFIG_REG));
+	seq_printf(m, "SYSSTATUS\t: 0x%08x\n", readl(sys + SSI_SYSSTATUS_REG));
+	pm_runtime_put(ssi->device.parent);
+
+	return 0;
+}
+
+static int ssi_gdd_regs_show(struct seq_file *m, void *p __maybe_unused)
+{
+	struct hsi_controller *ssi = m->private;
+	struct omap_ssi_controller *omap_ssi = hsi_controller_drvdata(ssi);
+	void __iomem *gdd = omap_ssi->gdd;
+	void __iomem *sys = omap_ssi->sys;
+	int lch;
+
+	pm_runtime_get_sync(ssi->device.parent);
+
+	seq_printf(m, "GDD_MPU_STATUS\t: 0x%08x\n",
+		readl(sys + SSI_GDD_MPU_IRQ_STATUS_REG));
+	seq_printf(m, "GDD_MPU_ENABLE\t: 0x%08x\n\n",
+		readl(sys + SSI_GDD_MPU_IRQ_ENABLE_REG));
+	seq_printf(m, "HW_ID\t\t: 0x%08x\n",
+				readl(gdd + SSI_GDD_HW_ID_REG));
+	seq_printf(m, "PPORT_ID\t: 0x%08x\n",
+				readl(gdd + SSI_GDD_PPORT_ID_REG));
+	seq_printf(m, "MPORT_ID\t: 0x%08x\n",
+				readl(gdd + SSI_GDD_MPORT_ID_REG));
+	seq_printf(m, "TEST\t\t: 0x%08x\n",
+				readl(gdd + SSI_GDD_TEST_REG));
+	seq_printf(m, "GCR\t\t: 0x%08x\n",
+				readl(gdd + SSI_GDD_GCR_REG));
+
+	for (lch = 0; lch < SSI_MAX_GDD_LCH; lch++) {
+		seq_printf(m, "\nGDD LCH %d\n=========\n", lch);
+		seq_printf(m, "CSDP\t\t: 0x%04x\n",
+				readw(gdd + SSI_GDD_CSDP_REG(lch)));
+		seq_printf(m, "CCR\t\t: 0x%04x\n",
+				readw(gdd + SSI_GDD_CCR_REG(lch)));
+		seq_printf(m, "CICR\t\t: 0x%04x\n",
+				readw(gdd + SSI_GDD_CICR_REG(lch)));
+		seq_printf(m, "CSR\t\t: 0x%04x\n",
+				readw(gdd + SSI_GDD_CSR_REG(lch)));
+		seq_printf(m, "CSSA\t\t: 0x%08x\n",
+				readl(gdd + SSI_GDD_CSSA_REG(lch)));
+		seq_printf(m, "CDSA\t\t: 0x%08x\n",
+				readl(gdd + SSI_GDD_CDSA_REG(lch)));
+		seq_printf(m, "CEN\t\t: 0x%04x\n",
+				readw(gdd + SSI_GDD_CEN_REG(lch)));
+		seq_printf(m, "CSAC\t\t: 0x%04x\n",
+				readw(gdd + SSI_GDD_CSAC_REG(lch)));
+		seq_printf(m, "CDAC\t\t: 0x%04x\n",
+				readw(gdd + SSI_GDD_CDAC_REG(lch)));
+		seq_printf(m, "CLNK_CTRL\t: 0x%04x\n",
+				readw(gdd + SSI_GDD_CLNK_CTRL_REG(lch)));
+	}
+
+	pm_runtime_put(ssi->device.parent);
+
+	return 0;
+}
+
+DEFINE_SHOW_ATTRIBUTE(ssi_regs);
+DEFINE_SHOW_ATTRIBUTE(ssi_gdd_regs);
+
+static int ssi_debug_add_ctrl(struct hsi_controller *ssi)
+{
+	struct omap_ssi_controller *omap_ssi = hsi_controller_drvdata(ssi);
+	struct dentry *dir;
+
+	/* SSI controller */
+	omap_ssi->dir = debugfs_create_dir(dev_name(&ssi->device), NULL);
+	debugfs_create_file("regs", S_IRUGO, omap_ssi->dir, ssi, &ssi_regs_fops);
+
+	/* SSI GDD (DMA) */
+	dir = debugfs_create_dir("gdd", omap_ssi->dir);
+	debugfs_create_file("regs", S_IRUGO, dir, ssi, &ssi_gdd_regs_fops);
+
+	return 0;
+}
+
+static void ssi_debug_remove_ctrl(struct hsi_controller *ssi)
+{
+	struct omap_ssi_controller *omap_ssi = hsi_controller_drvdata(ssi);
+
+	debugfs_remove_recursive(omap_ssi->dir);
+}
+#endif /* CONFIG_DEBUG_FS */
+
+/*
+ * FIXME: Horrible HACK needed until we remove the useless wakeline test
+ * in the CMT. To be removed !!!!
+ */
+void ssi_waketest(struct hsi_client *cl, unsigned int enable)
+{
+	struct hsi_port *port = hsi_get_port(cl);
+	struct omap_ssi_port *omap_port = hsi_port_drvdata(port);
+	struct hsi_controller *ssi = to_hsi_controller(port->device.parent);
+	struct omap_ssi_controller *omap_ssi = hsi_controller_drvdata(ssi);
+
+	omap_port->wktest = !!enable;
+	if (omap_port->wktest) {
+		pm_runtime_get_sync(ssi->device.parent);
+		writel_relaxed(SSI_WAKE(0),
+				omap_ssi->sys + SSI_SET_WAKE_REG(port->num));
+	} else {
+		writel_relaxed(SSI_WAKE(0),
+				omap_ssi->sys +	SSI_CLEAR_WAKE_REG(port->num));
+		pm_runtime_put(ssi->device.parent);
+	}
+}
+EXPORT_SYMBOL_GPL(ssi_waketest);
+
+static void ssi_gdd_complete(struct hsi_controller *ssi, unsigned int lch)
+{
+	struct omap_ssi_controller *omap_ssi = hsi_controller_drvdata(ssi);
+	struct hsi_msg *msg = omap_ssi->gdd_trn[lch].msg;
+	struct hsi_port *port = to_hsi_port(msg->cl->device.parent);
+	struct omap_ssi_port *omap_port = hsi_port_drvdata(port);
+	unsigned int dir;
+	u32 csr;
+	u32 val;
+
+	spin_lock(&omap_ssi->lock);
+
+	val = readl(omap_ssi->sys + SSI_GDD_MPU_IRQ_ENABLE_REG);
+	val &= ~SSI_GDD_LCH(lch);
+	writel_relaxed(val, omap_ssi->sys + SSI_GDD_MPU_IRQ_ENABLE_REG);
+
+	if (msg->ttype == HSI_MSG_READ) {
+		dir = DMA_FROM_DEVICE;
+		val = SSI_DATAAVAILABLE(msg->channel);
+		pm_runtime_put(omap_port->pdev);
+	} else {
+		dir = DMA_TO_DEVICE;
+		val = SSI_DATAACCEPT(msg->channel);
+		/* Keep clocks reference for write pio event */
+	}
+	dma_unmap_sg(&ssi->device, msg->sgt.sgl, msg->sgt.nents, dir);
+	csr = readw(omap_ssi->gdd + SSI_GDD_CSR_REG(lch));
+	omap_ssi->gdd_trn[lch].msg = NULL; /* release GDD lch */
+	dev_dbg(&port->device, "DMA completed ch %d ttype %d\n",
+				msg->channel, msg->ttype);
+	spin_unlock(&omap_ssi->lock);
+	if (csr & SSI_CSR_TOUR) { /* Timeout error */
+		msg->status = HSI_STATUS_ERROR;
+		msg->actual_len = 0;
+		spin_lock(&omap_port->lock);
+		list_del(&msg->link); /* Dequeue msg */
+		spin_unlock(&omap_port->lock);
+
+		list_add_tail(&msg->link, &omap_port->errqueue);
+		schedule_delayed_work(&omap_port->errqueue_work, 0);
+		return;
+	}
+	spin_lock(&omap_port->lock);
+	val |= readl(omap_ssi->sys + SSI_MPU_ENABLE_REG(port->num, 0));
+	writel_relaxed(val, omap_ssi->sys + SSI_MPU_ENABLE_REG(port->num, 0));
+	spin_unlock(&omap_port->lock);
+
+	msg->status = HSI_STATUS_COMPLETED;
+	msg->actual_len = sg_dma_len(msg->sgt.sgl);
+}
+
+static void ssi_gdd_tasklet(unsigned long dev)
+{
+	struct hsi_controller *ssi = (struct hsi_controller *)dev;
+	struct omap_ssi_controller *omap_ssi = hsi_controller_drvdata(ssi);
+	void __iomem *sys = omap_ssi->sys;
+	unsigned int lch;
+	u32 status_reg;
+
+	pm_runtime_get(ssi->device.parent);
+
+	if (!pm_runtime_active(ssi->device.parent)) {
+		dev_warn(ssi->device.parent, "ssi_gdd_tasklet called without runtime PM!\n");
+		pm_runtime_put(ssi->device.parent);
+		return;
+	}
+
+	status_reg = readl(sys + SSI_GDD_MPU_IRQ_STATUS_REG);
+	for (lch = 0; lch < SSI_MAX_GDD_LCH; lch++) {
+		if (status_reg & SSI_GDD_LCH(lch))
+			ssi_gdd_complete(ssi, lch);
+	}
+	writel_relaxed(status_reg, sys + SSI_GDD_MPU_IRQ_STATUS_REG);
+	status_reg = readl(sys + SSI_GDD_MPU_IRQ_STATUS_REG);
+
+	pm_runtime_put(ssi->device.parent);
+
+	if (status_reg)
+		tasklet_hi_schedule(&omap_ssi->gdd_tasklet);
+	else
+		enable_irq(omap_ssi->gdd_irq);
+
+}
+
+static irqreturn_t ssi_gdd_isr(int irq, void *ssi)
+{
+	struct omap_ssi_controller *omap_ssi = hsi_controller_drvdata(ssi);
+
+	tasklet_hi_schedule(&omap_ssi->gdd_tasklet);
+	disable_irq_nosync(irq);
+
+	return IRQ_HANDLED;
+}
+
+static unsigned long ssi_get_clk_rate(struct hsi_controller *ssi)
+{
+	struct omap_ssi_controller *omap_ssi = hsi_controller_drvdata(ssi);
+	unsigned long rate = clk_get_rate(omap_ssi->fck);
+	return rate;
+}
+
+static int ssi_clk_event(struct notifier_block *nb, unsigned long event,
+								void *data)
+{
+	struct omap_ssi_controller *omap_ssi = container_of(nb,
+					struct omap_ssi_controller, fck_nb);
+	struct hsi_controller *ssi = to_hsi_controller(omap_ssi->dev);
+	struct clk_notifier_data *clk_data = data;
+	struct omap_ssi_port *omap_port;
+	int i;
+
+	switch (event) {
+	case PRE_RATE_CHANGE:
+		dev_dbg(&ssi->device, "pre rate change\n");
+
+		for (i = 0; i < ssi->num_ports; i++) {
+			omap_port = omap_ssi->port[i];
+
+			if (!omap_port)
+				continue;
+
+			/* Workaround for SWBREAK + CAwake down race in CMT */
+			disable_irq(omap_port->wake_irq);
+
+			/* stop all ssi communication */
+			pinctrl_pm_select_idle_state(omap_port->pdev);
+			udelay(1); /* wait for racing frames */
+		}
+
+		break;
+	case ABORT_RATE_CHANGE:
+		dev_dbg(&ssi->device, "abort rate change\n");
+		fallthrough;
+	case POST_RATE_CHANGE:
+		dev_dbg(&ssi->device, "post rate change (%lu -> %lu)\n",
+			clk_data->old_rate, clk_data->new_rate);
+		omap_ssi->fck_rate = DIV_ROUND_CLOSEST(clk_data->new_rate, 1000); /* kHz */
+
+		for (i = 0; i < ssi->num_ports; i++) {
+			omap_port = omap_ssi->port[i];
+
+			if (!omap_port)
+				continue;
+
+			omap_ssi_port_update_fclk(ssi, omap_port);
+
+			/* resume ssi communication */
+			pinctrl_pm_select_default_state(omap_port->pdev);
+			enable_irq(omap_port->wake_irq);
+		}
+
+		break;
+	default:
+		break;
+	}
+
+	return NOTIFY_DONE;
+}
+
+static int ssi_get_iomem(struct platform_device *pd,
+		const char *name, void __iomem **pbase, dma_addr_t *phy)
+{
+	struct resource *mem;
+	void __iomem *base;
+	struct hsi_controller *ssi = platform_get_drvdata(pd);
+
+	mem = platform_get_resource_byname(pd, IORESOURCE_MEM, name);
+	base = devm_ioremap_resource(&ssi->device, mem);
+	if (IS_ERR(base))
+		return PTR_ERR(base);
+
+	*pbase = base;
+
+	if (phy)
+		*phy = mem->start;
+
+	return 0;
+}
+
+static int ssi_add_controller(struct hsi_controller *ssi,
+						struct platform_device *pd)
+{
+	struct omap_ssi_controller *omap_ssi;
+	int err;
+
+	omap_ssi = devm_kzalloc(&ssi->device, sizeof(*omap_ssi), GFP_KERNEL);
+	if (!omap_ssi)
+		return -ENOMEM;
+
+	err = ida_alloc(&platform_omap_ssi_ida, GFP_KERNEL);
+	if (err < 0)
+		return err;
+	ssi->id = err;
+
+	ssi->owner = THIS_MODULE;
+	ssi->device.parent = &pd->dev;
+	dev_set_name(&ssi->device, "ssi%d", ssi->id);
+	hsi_controller_set_drvdata(ssi, omap_ssi);
+	omap_ssi->dev = &ssi->device;
+	err = ssi_get_iomem(pd, "sys", &omap_ssi->sys, NULL);
+	if (err < 0)
+		goto out_err;
+	err = ssi_get_iomem(pd, "gdd", &omap_ssi->gdd, NULL);
+	if (err < 0)
+		goto out_err;
+	err = platform_get_irq_byname(pd, "gdd_mpu");
+	if (err < 0)
+		goto out_err;
+	omap_ssi->gdd_irq = err;
+	tasklet_init(&omap_ssi->gdd_tasklet, ssi_gdd_tasklet,
+							(unsigned long)ssi);
+	err = devm_request_irq(&ssi->device, omap_ssi->gdd_irq, ssi_gdd_isr,
+						0, "gdd_mpu", ssi);
+	if (err < 0) {
+		dev_err(&ssi->device, "Request GDD IRQ %d failed (%d)",
+							omap_ssi->gdd_irq, err);
+		goto out_err;
+	}
+
+	omap_ssi->port = devm_kcalloc(&ssi->device, ssi->num_ports,
+				      sizeof(*omap_ssi->port), GFP_KERNEL);
+	if (!omap_ssi->port) {
+		err = -ENOMEM;
+		goto out_err;
+	}
+
+	omap_ssi->fck = devm_clk_get(&ssi->device, "ssi_ssr_fck");
+	if (IS_ERR(omap_ssi->fck)) {
+		dev_err(&pd->dev, "Could not acquire clock \"ssi_ssr_fck\": %li\n",
+			PTR_ERR(omap_ssi->fck));
+		err = -ENODEV;
+		goto out_err;
+	}
+
+	omap_ssi->fck_nb.notifier_call = ssi_clk_event;
+	omap_ssi->fck_nb.priority = INT_MAX;
+	clk_notifier_register(omap_ssi->fck, &omap_ssi->fck_nb);
+
+	/* TODO: find register, which can be used to detect context loss */
+	omap_ssi->get_loss = NULL;
+
+	omap_ssi->max_speed = UINT_MAX;
+	spin_lock_init(&omap_ssi->lock);
+	err = hsi_register_controller(ssi);
+
+	if (err < 0)
+		goto out_err;
+
+	return 0;
+
+out_err:
+	ida_free(&platform_omap_ssi_ida, ssi->id);
+	return err;
+}
+
+static int ssi_hw_init(struct hsi_controller *ssi)
+{
+	struct omap_ssi_controller *omap_ssi = hsi_controller_drvdata(ssi);
+	int err;
+
+	err = pm_runtime_resume_and_get(ssi->device.parent);
+	if (err < 0) {
+		dev_err(&ssi->device, "runtime PM failed %d\n", err);
+		return err;
+	}
+	/* Resetting GDD */
+	writel_relaxed(SSI_SWRESET, omap_ssi->gdd + SSI_GDD_GRST_REG);
+	/* Get FCK rate in kHz */
+	omap_ssi->fck_rate = DIV_ROUND_CLOSEST(ssi_get_clk_rate(ssi), 1000);
+	dev_dbg(&ssi->device, "SSI fck rate %lu kHz\n", omap_ssi->fck_rate);
+
+	writel_relaxed(SSI_CLK_AUTOGATING_ON, omap_ssi->sys + SSI_GDD_GCR_REG);
+	omap_ssi->gdd_gcr = SSI_CLK_AUTOGATING_ON;
+	pm_runtime_put_sync(ssi->device.parent);
+
+	return 0;
+}
+
+static void ssi_remove_controller(struct hsi_controller *ssi)
+{
+	struct omap_ssi_controller *omap_ssi = hsi_controller_drvdata(ssi);
+	int id = ssi->id;
+	tasklet_kill(&omap_ssi->gdd_tasklet);
+	hsi_unregister_controller(ssi);
+	clk_notifier_unregister(omap_ssi->fck, &omap_ssi->fck_nb);
+	ida_free(&platform_omap_ssi_ida, id);
+}
+
+static inline int ssi_of_get_available_ports_count(const struct device_node *np)
+{
+	struct device_node *child;
+	int num = 0;
+
+	for_each_available_child_of_node(np, child)
+		if (of_device_is_compatible(child, "ti,omap3-ssi-port"))
+			num++;
+
+	return num;
+}
+
+static int ssi_remove_ports(struct device *dev, void *c)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+
+	if (!dev->of_node)
+		return 0;
+
+	of_node_clear_flag(dev->of_node, OF_POPULATED);
+	of_device_unregister(pdev);
+
+	return 0;
+}
+
+static int ssi_probe(struct platform_device *pd)
+{
+	struct platform_device *childpdev;
+	struct device_node *np = pd->dev.of_node;
+	struct device_node *child;
+	struct hsi_controller *ssi;
+	int err;
+	int num_ports;
+
+	if (!np) {
+		dev_err(&pd->dev, "missing device tree data\n");
+		return -EINVAL;
+	}
+
+	num_ports = ssi_of_get_available_ports_count(np);
+
+	ssi = hsi_alloc_controller(num_ports, GFP_KERNEL);
+	if (!ssi) {
+		dev_err(&pd->dev, "No memory for controller\n");
+		return -ENOMEM;
+	}
+
+	platform_set_drvdata(pd, ssi);
+
+	err = ssi_add_controller(ssi, pd);
+	if (err < 0) {
+		hsi_put_controller(ssi);
+		goto out1;
+	}
+
+	pm_runtime_enable(&pd->dev);
+
+	err = ssi_hw_init(ssi);
+	if (err < 0)
+		goto out2;
+#ifdef CONFIG_DEBUG_FS
+	err = ssi_debug_add_ctrl(ssi);
+	if (err < 0)
+		goto out2;
+#endif
+
+	for_each_available_child_of_node(np, child) {
+		if (!of_device_is_compatible(child, "ti,omap3-ssi-port"))
+			continue;
+
+		childpdev = of_platform_device_create(child, NULL, &pd->dev);
+		if (!childpdev) {
+			err = -ENODEV;
+			dev_err(&pd->dev, "failed to create ssi controller port\n");
+			of_node_put(child);
+			goto out3;
+		}
+	}
+
+	dev_info(&pd->dev, "ssi controller %d initialized (%d ports)!\n",
+		ssi->id, num_ports);
+	return err;
+out3:
+	device_for_each_child(&pd->dev, NULL, ssi_remove_ports);
+out2:
+	ssi_remove_controller(ssi);
+	pm_runtime_disable(&pd->dev);
+out1:
+	platform_set_drvdata(pd, NULL);
+
+	return err;
+}
+
+static void ssi_remove(struct platform_device *pd)
+{
+	struct hsi_controller *ssi = platform_get_drvdata(pd);
+
+	/* cleanup of of_platform_populate() call */
+	device_for_each_child(&pd->dev, NULL, ssi_remove_ports);
+
+#ifdef CONFIG_DEBUG_FS
+	ssi_debug_remove_ctrl(ssi);
+#endif
+	ssi_remove_controller(ssi);
+	platform_set_drvdata(pd, NULL);
+
+	pm_runtime_disable(&pd->dev);
+}
+
+#ifdef CONFIG_PM
+static int omap_ssi_runtime_suspend(struct device *dev)
+{
+	struct hsi_controller *ssi = dev_get_drvdata(dev);
+	struct omap_ssi_controller *omap_ssi = hsi_controller_drvdata(ssi);
+
+	dev_dbg(dev, "runtime suspend!\n");
+
+	if (omap_ssi->get_loss)
+		omap_ssi->loss_count =
+				omap_ssi->get_loss(ssi->device.parent);
+
+	return 0;
+}
+
+static int omap_ssi_runtime_resume(struct device *dev)
+{
+	struct hsi_controller *ssi = dev_get_drvdata(dev);
+	struct omap_ssi_controller *omap_ssi = hsi_controller_drvdata(ssi);
+
+	dev_dbg(dev, "runtime resume!\n");
+
+	if ((omap_ssi->get_loss) && (omap_ssi->loss_count ==
+				omap_ssi->get_loss(ssi->device.parent)))
+		return 0;
+
+	writel_relaxed(omap_ssi->gdd_gcr, omap_ssi->gdd + SSI_GDD_GCR_REG);
+
+	return 0;
+}
+
+static const struct dev_pm_ops omap_ssi_pm_ops = {
+	SET_RUNTIME_PM_OPS(omap_ssi_runtime_suspend, omap_ssi_runtime_resume,
+		NULL)
+};
+
+#define DEV_PM_OPS     (&omap_ssi_pm_ops)
+#else
+#define DEV_PM_OPS     NULL
+#endif
+
+#ifdef CONFIG_OF
+static const struct of_device_id omap_ssi_of_match[] = {
+	{ .compatible = "ti,omap3-ssi", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, omap_ssi_of_match);
+#else
+#define omap_ssi_of_match NULL
+#endif
+
+static struct platform_driver ssi_pdriver = {
+	.probe = ssi_probe,
+	.remove = ssi_remove,
+	.driver	= {
+		.name	= "omap_ssi",
+		.pm     = DEV_PM_OPS,
+		.of_match_table = omap_ssi_of_match,
+	},
+};
+
+static int __init ssi_init(void) {
+	int ret;
+
+	ret = platform_driver_register(&ssi_pdriver);
+	if (ret)
+		return ret;
+
+	ret = platform_driver_register(&ssi_port_pdriver);
+	if (ret) {
+		platform_driver_unregister(&ssi_pdriver);
+		return ret;
+	}
+
+	return 0;
+}
+module_init(ssi_init);
+
+static void __exit ssi_exit(void) {
+	platform_driver_unregister(&ssi_port_pdriver);
+	platform_driver_unregister(&ssi_pdriver);
+}
+module_exit(ssi_exit);
+
+MODULE_ALIAS("platform:omap_ssi");
+MODULE_AUTHOR("Carlos Chinea <carlos.chinea@nokia.com>");
+MODULE_AUTHOR("Sebastian Reichel <sre@kernel.org>");
+MODULE_DESCRIPTION("Synchronous Serial Interface Driver");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/hsi/controllers/omap_ssi_port.c b/drivers/hsi/controllers/omap_ssi_port.c
new file mode 100644
index 000000000..98810bfd1
--- /dev/null
+++ b/drivers/hsi/controllers/omap_ssi_port.c
@@ -0,0 +1,1379 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* OMAP SSI port driver.
+ *
+ * Copyright (C) 2010 Nokia Corporation. All rights reserved.
+ * Copyright (C) 2014 Sebastian Reichel <sre@kernel.org>
+ *
+ * Contact: Carlos Chinea <carlos.chinea@nokia.com>
+ */
+
+#include <linux/platform_device.h>
+#include <linux/dma-mapping.h>
+#include <linux/pm_runtime.h>
+#include <linux/delay.h>
+
+#include <linux/gpio/consumer.h>
+#include <linux/pinctrl/consumer.h>
+#include <linux/debugfs.h>
+
+#include "omap_ssi_regs.h"
+#include "omap_ssi.h"
+
+static inline int hsi_dummy_msg(struct hsi_msg *msg __maybe_unused)
+{
+	return 0;
+}
+
+static inline int hsi_dummy_cl(struct hsi_client *cl __maybe_unused)
+{
+	return 0;
+}
+
+static inline unsigned int ssi_wakein(struct hsi_port *port)
+{
+	struct omap_ssi_port *omap_port = hsi_port_drvdata(port);
+	return gpiod_get_value(omap_port->wake_gpio);
+}
+
+#ifdef CONFIG_DEBUG_FS
+static void ssi_debug_remove_port(struct hsi_port *port)
+{
+	struct omap_ssi_port *omap_port = hsi_port_drvdata(port);
+
+	debugfs_remove_recursive(omap_port->dir);
+}
+
+static int ssi_port_regs_show(struct seq_file *m, void *p __maybe_unused)
+{
+	struct hsi_port *port = m->private;
+	struct omap_ssi_port *omap_port = hsi_port_drvdata(port);
+	struct hsi_controller *ssi = to_hsi_controller(port->device.parent);
+	struct omap_ssi_controller *omap_ssi = hsi_controller_drvdata(ssi);
+	void __iomem	*base = omap_ssi->sys;
+	unsigned int ch;
+
+	pm_runtime_get_sync(omap_port->pdev);
+	if (omap_port->wake_irq > 0)
+		seq_printf(m, "CAWAKE\t\t: %d\n", ssi_wakein(port));
+	seq_printf(m, "WAKE\t\t: 0x%08x\n",
+				readl(base + SSI_WAKE_REG(port->num)));
+	seq_printf(m, "MPU_ENABLE_IRQ%d\t: 0x%08x\n", 0,
+			readl(base + SSI_MPU_ENABLE_REG(port->num, 0)));
+	seq_printf(m, "MPU_STATUS_IRQ%d\t: 0x%08x\n", 0,
+			readl(base + SSI_MPU_STATUS_REG(port->num, 0)));
+	/* SST */
+	base = omap_port->sst_base;
+	seq_puts(m, "\nSST\n===\n");
+	seq_printf(m, "ID SST\t\t: 0x%08x\n",
+				readl(base + SSI_SST_ID_REG));
+	seq_printf(m, "MODE\t\t: 0x%08x\n",
+				readl(base + SSI_SST_MODE_REG));
+	seq_printf(m, "FRAMESIZE\t: 0x%08x\n",
+				readl(base + SSI_SST_FRAMESIZE_REG));
+	seq_printf(m, "DIVISOR\t\t: 0x%08x\n",
+				readl(base + SSI_SST_DIVISOR_REG));
+	seq_printf(m, "CHANNELS\t: 0x%08x\n",
+				readl(base + SSI_SST_CHANNELS_REG));
+	seq_printf(m, "ARBMODE\t\t: 0x%08x\n",
+				readl(base + SSI_SST_ARBMODE_REG));
+	seq_printf(m, "TXSTATE\t\t: 0x%08x\n",
+				readl(base + SSI_SST_TXSTATE_REG));
+	seq_printf(m, "BUFSTATE\t: 0x%08x\n",
+				readl(base + SSI_SST_BUFSTATE_REG));
+	seq_printf(m, "BREAK\t\t: 0x%08x\n",
+				readl(base + SSI_SST_BREAK_REG));
+	for (ch = 0; ch < omap_port->channels; ch++) {
+		seq_printf(m, "BUFFER_CH%d\t: 0x%08x\n", ch,
+				readl(base + SSI_SST_BUFFER_CH_REG(ch)));
+	}
+	/* SSR */
+	base = omap_port->ssr_base;
+	seq_puts(m, "\nSSR\n===\n");
+	seq_printf(m, "ID SSR\t\t: 0x%08x\n",
+				readl(base + SSI_SSR_ID_REG));
+	seq_printf(m, "MODE\t\t: 0x%08x\n",
+				readl(base + SSI_SSR_MODE_REG));
+	seq_printf(m, "FRAMESIZE\t: 0x%08x\n",
+				readl(base + SSI_SSR_FRAMESIZE_REG));
+	seq_printf(m, "CHANNELS\t: 0x%08x\n",
+				readl(base + SSI_SSR_CHANNELS_REG));
+	seq_printf(m, "TIMEOUT\t\t: 0x%08x\n",
+				readl(base + SSI_SSR_TIMEOUT_REG));
+	seq_printf(m, "RXSTATE\t\t: 0x%08x\n",
+				readl(base + SSI_SSR_RXSTATE_REG));
+	seq_printf(m, "BUFSTATE\t: 0x%08x\n",
+				readl(base + SSI_SSR_BUFSTATE_REG));
+	seq_printf(m, "BREAK\t\t: 0x%08x\n",
+				readl(base + SSI_SSR_BREAK_REG));
+	seq_printf(m, "ERROR\t\t: 0x%08x\n",
+				readl(base + SSI_SSR_ERROR_REG));
+	seq_printf(m, "ERRORACK\t: 0x%08x\n",
+				readl(base + SSI_SSR_ERRORACK_REG));
+	for (ch = 0; ch < omap_port->channels; ch++) {
+		seq_printf(m, "BUFFER_CH%d\t: 0x%08x\n", ch,
+				readl(base + SSI_SSR_BUFFER_CH_REG(ch)));
+	}
+	pm_runtime_put_autosuspend(omap_port->pdev);
+
+	return 0;
+}
+
+DEFINE_SHOW_ATTRIBUTE(ssi_port_regs);
+
+static int ssi_div_get(void *data, u64 *val)
+{
+	struct hsi_port *port = data;
+	struct omap_ssi_port *omap_port = hsi_port_drvdata(port);
+
+	pm_runtime_get_sync(omap_port->pdev);
+	*val = readl(omap_port->sst_base + SSI_SST_DIVISOR_REG);
+	pm_runtime_put_autosuspend(omap_port->pdev);
+
+	return 0;
+}
+
+static int ssi_div_set(void *data, u64 val)
+{
+	struct hsi_port *port = data;
+	struct omap_ssi_port *omap_port = hsi_port_drvdata(port);
+
+	if (val > 127)
+		return -EINVAL;
+
+	pm_runtime_get_sync(omap_port->pdev);
+	writel(val, omap_port->sst_base + SSI_SST_DIVISOR_REG);
+	omap_port->sst.divisor = val;
+	pm_runtime_put_autosuspend(omap_port->pdev);
+
+	return 0;
+}
+
+DEFINE_DEBUGFS_ATTRIBUTE(ssi_sst_div_fops, ssi_div_get, ssi_div_set, "%llu\n");
+
+static void ssi_debug_add_port(struct omap_ssi_port *omap_port,
+				     struct dentry *dir)
+{
+	struct hsi_port *port = to_hsi_port(omap_port->dev);
+
+	dir = debugfs_create_dir(dev_name(omap_port->dev), dir);
+	omap_port->dir = dir;
+	debugfs_create_file("regs", S_IRUGO, dir, port, &ssi_port_regs_fops);
+	dir = debugfs_create_dir("sst", dir);
+	debugfs_create_file_unsafe("divisor", 0644, dir, port,
+				   &ssi_sst_div_fops);
+}
+#endif
+
+static void ssi_process_errqueue(struct work_struct *work)
+{
+	struct omap_ssi_port *omap_port;
+	struct list_head *head, *tmp;
+	struct hsi_msg *msg;
+
+	omap_port = container_of(work, struct omap_ssi_port, errqueue_work.work);
+
+	list_for_each_safe(head, tmp, &omap_port->errqueue) {
+		msg = list_entry(head, struct hsi_msg, link);
+		msg->complete(msg);
+		list_del(head);
+	}
+}
+
+static int ssi_claim_lch(struct hsi_msg *msg)
+{
+
+	struct hsi_port *port = hsi_get_port(msg->cl);
+	struct hsi_controller *ssi = to_hsi_controller(port->device.parent);
+	struct omap_ssi_controller *omap_ssi = hsi_controller_drvdata(ssi);
+	int lch;
+
+	for (lch = 0; lch < SSI_MAX_GDD_LCH; lch++)
+		if (!omap_ssi->gdd_trn[lch].msg) {
+			omap_ssi->gdd_trn[lch].msg = msg;
+			omap_ssi->gdd_trn[lch].sg = msg->sgt.sgl;
+			return lch;
+		}
+
+	return -EBUSY;
+}
+
+static int ssi_start_dma(struct hsi_msg *msg, int lch)
+{
+	struct hsi_port *port = hsi_get_port(msg->cl);
+	struct omap_ssi_port *omap_port = hsi_port_drvdata(port);
+	struct hsi_controller *ssi = to_hsi_controller(port->device.parent);
+	struct omap_ssi_controller *omap_ssi = hsi_controller_drvdata(ssi);
+	void __iomem *gdd = omap_ssi->gdd;
+	int err;
+	u16 csdp;
+	u16 ccr;
+	u32 s_addr;
+	u32 d_addr;
+	u32 tmp;
+
+	/* Hold clocks during the transfer */
+	pm_runtime_get(omap_port->pdev);
+
+	if (!pm_runtime_active(omap_port->pdev)) {
+		dev_warn(&port->device, "ssi_start_dma called without runtime PM!\n");
+		pm_runtime_put_autosuspend(omap_port->pdev);
+		return -EREMOTEIO;
+	}
+
+	if (msg->ttype == HSI_MSG_READ) {
+		err = dma_map_sg(&ssi->device, msg->sgt.sgl, msg->sgt.nents,
+							DMA_FROM_DEVICE);
+		if (!err) {
+			dev_dbg(&ssi->device, "DMA map SG failed !\n");
+			pm_runtime_put_autosuspend(omap_port->pdev);
+			return -EIO;
+		}
+		csdp = SSI_DST_BURST_4x32_BIT | SSI_DST_MEMORY_PORT |
+			SSI_SRC_SINGLE_ACCESS0 | SSI_SRC_PERIPHERAL_PORT |
+			SSI_DATA_TYPE_S32;
+		ccr = msg->channel + 0x10 + (port->num * 8); /* Sync */
+		ccr |= SSI_DST_AMODE_POSTINC | SSI_SRC_AMODE_CONST |
+			SSI_CCR_ENABLE;
+		s_addr = omap_port->ssr_dma +
+					SSI_SSR_BUFFER_CH_REG(msg->channel);
+		d_addr = sg_dma_address(msg->sgt.sgl);
+	} else {
+		err = dma_map_sg(&ssi->device, msg->sgt.sgl, msg->sgt.nents,
+							DMA_TO_DEVICE);
+		if (!err) {
+			dev_dbg(&ssi->device, "DMA map SG failed !\n");
+			pm_runtime_put_autosuspend(omap_port->pdev);
+			return -EIO;
+		}
+		csdp = SSI_SRC_BURST_4x32_BIT | SSI_SRC_MEMORY_PORT |
+			SSI_DST_SINGLE_ACCESS0 | SSI_DST_PERIPHERAL_PORT |
+			SSI_DATA_TYPE_S32;
+		ccr = (msg->channel + 1 + (port->num * 8)) & 0xf; /* Sync */
+		ccr |= SSI_SRC_AMODE_POSTINC | SSI_DST_AMODE_CONST |
+			SSI_CCR_ENABLE;
+		s_addr = sg_dma_address(msg->sgt.sgl);
+		d_addr = omap_port->sst_dma +
+					SSI_SST_BUFFER_CH_REG(msg->channel);
+	}
+	dev_dbg(&ssi->device, "lch %d cdsp %08x ccr %04x s_addr %08x d_addr %08x\n",
+		lch, csdp, ccr, s_addr, d_addr);
+
+	writew_relaxed(csdp, gdd + SSI_GDD_CSDP_REG(lch));
+	writew_relaxed(SSI_BLOCK_IE | SSI_TOUT_IE, gdd + SSI_GDD_CICR_REG(lch));
+	writel_relaxed(d_addr, gdd + SSI_GDD_CDSA_REG(lch));
+	writel_relaxed(s_addr, gdd + SSI_GDD_CSSA_REG(lch));
+	writew_relaxed(SSI_BYTES_TO_FRAMES(msg->sgt.sgl->length),
+						gdd + SSI_GDD_CEN_REG(lch));
+
+	spin_lock_bh(&omap_ssi->lock);
+	tmp = readl(omap_ssi->sys + SSI_GDD_MPU_IRQ_ENABLE_REG);
+	tmp |= SSI_GDD_LCH(lch);
+	writel_relaxed(tmp, omap_ssi->sys + SSI_GDD_MPU_IRQ_ENABLE_REG);
+	spin_unlock_bh(&omap_ssi->lock);
+	writew(ccr, gdd + SSI_GDD_CCR_REG(lch));
+	msg->status = HSI_STATUS_PROCEEDING;
+
+	return 0;
+}
+
+static int ssi_start_pio(struct hsi_msg *msg)
+{
+	struct hsi_port *port = hsi_get_port(msg->cl);
+	struct omap_ssi_port *omap_port = hsi_port_drvdata(port);
+	struct hsi_controller *ssi = to_hsi_controller(port->device.parent);
+	struct omap_ssi_controller *omap_ssi = hsi_controller_drvdata(ssi);
+	u32 val;
+
+	pm_runtime_get(omap_port->pdev);
+
+	if (!pm_runtime_active(omap_port->pdev)) {
+		dev_warn(&port->device, "ssi_start_pio called without runtime PM!\n");
+		pm_runtime_put_autosuspend(omap_port->pdev);
+		return -EREMOTEIO;
+	}
+
+	if (msg->ttype == HSI_MSG_WRITE) {
+		val = SSI_DATAACCEPT(msg->channel);
+		/* Hold clocks for pio writes */
+		pm_runtime_get(omap_port->pdev);
+	} else {
+		val = SSI_DATAAVAILABLE(msg->channel) | SSI_ERROROCCURED;
+	}
+	dev_dbg(&port->device, "Single %s transfer\n",
+						msg->ttype ? "write" : "read");
+	val |= readl(omap_ssi->sys + SSI_MPU_ENABLE_REG(port->num, 0));
+	writel(val, omap_ssi->sys + SSI_MPU_ENABLE_REG(port->num, 0));
+	pm_runtime_put_autosuspend(omap_port->pdev);
+	msg->actual_len = 0;
+	msg->status = HSI_STATUS_PROCEEDING;
+
+	return 0;
+}
+
+static int ssi_start_transfer(struct list_head *queue)
+{
+	struct hsi_msg *msg;
+	int lch = -1;
+
+	if (list_empty(queue))
+		return 0;
+	msg = list_first_entry(queue, struct hsi_msg, link);
+	if (msg->status != HSI_STATUS_QUEUED)
+		return 0;
+	if ((msg->sgt.nents) && (msg->sgt.sgl->length > sizeof(u32)))
+		lch = ssi_claim_lch(msg);
+	if (lch >= 0)
+		return ssi_start_dma(msg, lch);
+	else
+		return ssi_start_pio(msg);
+}
+
+static int ssi_async_break(struct hsi_msg *msg)
+{
+	struct hsi_port *port = hsi_get_port(msg->cl);
+	struct omap_ssi_port *omap_port = hsi_port_drvdata(port);
+	struct hsi_controller *ssi = to_hsi_controller(port->device.parent);
+	struct omap_ssi_controller *omap_ssi = hsi_controller_drvdata(ssi);
+	int err = 0;
+	u32 tmp;
+
+	pm_runtime_get_sync(omap_port->pdev);
+	if (msg->ttype == HSI_MSG_WRITE) {
+		if (omap_port->sst.mode != SSI_MODE_FRAME) {
+			err = -EINVAL;
+			goto out;
+		}
+		writel(1, omap_port->sst_base + SSI_SST_BREAK_REG);
+		msg->status = HSI_STATUS_COMPLETED;
+		msg->complete(msg);
+	} else {
+		if (omap_port->ssr.mode != SSI_MODE_FRAME) {
+			err = -EINVAL;
+			goto out;
+		}
+		spin_lock_bh(&omap_port->lock);
+		tmp = readl(omap_ssi->sys +
+					SSI_MPU_ENABLE_REG(port->num, 0));
+		writel(tmp | SSI_BREAKDETECTED,
+			omap_ssi->sys + SSI_MPU_ENABLE_REG(port->num, 0));
+		msg->status = HSI_STATUS_PROCEEDING;
+		list_add_tail(&msg->link, &omap_port->brkqueue);
+		spin_unlock_bh(&omap_port->lock);
+	}
+out:
+	pm_runtime_put_autosuspend(omap_port->pdev);
+
+	return err;
+}
+
+static int ssi_async(struct hsi_msg *msg)
+{
+	struct hsi_port *port = hsi_get_port(msg->cl);
+	struct omap_ssi_port *omap_port = hsi_port_drvdata(port);
+	struct list_head *queue;
+	int err = 0;
+
+	BUG_ON(!msg);
+
+	if (msg->sgt.nents > 1)
+		return -ENOSYS; /* TODO: Add sg support */
+
+	if (msg->break_frame)
+		return ssi_async_break(msg);
+
+	if (msg->ttype) {
+		BUG_ON(msg->channel >= omap_port->sst.channels);
+		queue = &omap_port->txqueue[msg->channel];
+	} else {
+		BUG_ON(msg->channel >= omap_port->ssr.channels);
+		queue = &omap_port->rxqueue[msg->channel];
+	}
+	msg->status = HSI_STATUS_QUEUED;
+
+	pm_runtime_get_sync(omap_port->pdev);
+	spin_lock_bh(&omap_port->lock);
+	list_add_tail(&msg->link, queue);
+	err = ssi_start_transfer(queue);
+	if (err < 0) {
+		list_del(&msg->link);
+		msg->status = HSI_STATUS_ERROR;
+	}
+	spin_unlock_bh(&omap_port->lock);
+	pm_runtime_put_autosuspend(omap_port->pdev);
+	dev_dbg(&port->device, "msg status %d ttype %d ch %d\n",
+				msg->status, msg->ttype, msg->channel);
+
+	return err;
+}
+
+static u32 ssi_calculate_div(struct hsi_controller *ssi)
+{
+	struct omap_ssi_controller *omap_ssi = hsi_controller_drvdata(ssi);
+	u32 tx_fckrate = (u32) omap_ssi->fck_rate;
+
+	/* / 2 : SSI TX clock is always half of the SSI functional clock */
+	tx_fckrate >>= 1;
+	/* Round down when tx_fckrate % omap_ssi->max_speed == 0 */
+	tx_fckrate--;
+	dev_dbg(&ssi->device, "TX div %d for fck_rate %lu Khz speed %d Kb/s\n",
+		tx_fckrate / omap_ssi->max_speed, omap_ssi->fck_rate,
+		omap_ssi->max_speed);
+
+	return tx_fckrate / omap_ssi->max_speed;
+}
+
+static void ssi_flush_queue(struct list_head *queue, struct hsi_client *cl)
+{
+	struct list_head *node, *tmp;
+	struct hsi_msg *msg;
+
+	list_for_each_safe(node, tmp, queue) {
+		msg = list_entry(node, struct hsi_msg, link);
+		if ((cl) && (cl != msg->cl))
+			continue;
+		list_del(node);
+		pr_debug("flush queue: ch %d, msg %p len %d type %d ctxt %p\n",
+			msg->channel, msg, msg->sgt.sgl->length,
+					msg->ttype, msg->context);
+		if (msg->destructor)
+			msg->destructor(msg);
+		else
+			hsi_free_msg(msg);
+	}
+}
+
+static int ssi_setup(struct hsi_client *cl)
+{
+	struct hsi_port *port = to_hsi_port(cl->device.parent);
+	struct omap_ssi_port *omap_port = hsi_port_drvdata(port);
+	struct hsi_controller *ssi = to_hsi_controller(port->device.parent);
+	struct omap_ssi_controller *omap_ssi = hsi_controller_drvdata(ssi);
+	void __iomem *sst = omap_port->sst_base;
+	void __iomem *ssr = omap_port->ssr_base;
+	u32 div;
+	int err = 0;
+
+	pm_runtime_get_sync(omap_port->pdev);
+	spin_lock_bh(&omap_port->lock);
+	if (cl->tx_cfg.speed)
+		omap_ssi->max_speed = cl->tx_cfg.speed;
+	div = ssi_calculate_div(ssi);
+	if (div > SSI_MAX_DIVISOR) {
+		dev_err(&cl->device, "Invalid TX speed %d Mb/s (div %d)\n",
+						cl->tx_cfg.speed, div);
+		err = -EINVAL;
+		goto out;
+	}
+	/* Set TX/RX module to sleep to stop TX/RX during cfg update */
+	writel_relaxed(SSI_MODE_SLEEP, sst + SSI_SST_MODE_REG);
+	writel_relaxed(SSI_MODE_SLEEP, ssr + SSI_SSR_MODE_REG);
+	/* Flush posted write */
+	readl(ssr + SSI_SSR_MODE_REG);
+	/* TX */
+	writel_relaxed(31, sst + SSI_SST_FRAMESIZE_REG);
+	writel_relaxed(div, sst + SSI_SST_DIVISOR_REG);
+	writel_relaxed(cl->tx_cfg.num_hw_channels, sst + SSI_SST_CHANNELS_REG);
+	writel_relaxed(cl->tx_cfg.arb_mode, sst + SSI_SST_ARBMODE_REG);
+	writel_relaxed(cl->tx_cfg.mode, sst + SSI_SST_MODE_REG);
+	/* RX */
+	writel_relaxed(31, ssr + SSI_SSR_FRAMESIZE_REG);
+	writel_relaxed(cl->rx_cfg.num_hw_channels, ssr + SSI_SSR_CHANNELS_REG);
+	writel_relaxed(0, ssr + SSI_SSR_TIMEOUT_REG);
+	/* Cleanup the break queue if we leave FRAME mode */
+	if ((omap_port->ssr.mode == SSI_MODE_FRAME) &&
+		(cl->rx_cfg.mode != SSI_MODE_FRAME))
+		ssi_flush_queue(&omap_port->brkqueue, cl);
+	writel_relaxed(cl->rx_cfg.mode, ssr + SSI_SSR_MODE_REG);
+	omap_port->channels = max(cl->rx_cfg.num_hw_channels,
+				  cl->tx_cfg.num_hw_channels);
+	/* Shadow registering for OFF mode */
+	/* SST */
+	omap_port->sst.divisor = div;
+	omap_port->sst.frame_size = 31;
+	omap_port->sst.channels = cl->tx_cfg.num_hw_channels;
+	omap_port->sst.arb_mode = cl->tx_cfg.arb_mode;
+	omap_port->sst.mode = cl->tx_cfg.mode;
+	/* SSR */
+	omap_port->ssr.frame_size = 31;
+	omap_port->ssr.timeout = 0;
+	omap_port->ssr.channels = cl->rx_cfg.num_hw_channels;
+	omap_port->ssr.mode = cl->rx_cfg.mode;
+out:
+	spin_unlock_bh(&omap_port->lock);
+	pm_runtime_put_autosuspend(omap_port->pdev);
+
+	return err;
+}
+
+static int ssi_flush(struct hsi_client *cl)
+{
+	struct hsi_port *port = hsi_get_port(cl);
+	struct omap_ssi_port *omap_port = hsi_port_drvdata(port);
+	struct hsi_controller *ssi = to_hsi_controller(port->device.parent);
+	struct omap_ssi_controller *omap_ssi = hsi_controller_drvdata(ssi);
+	struct hsi_msg *msg;
+	void __iomem *sst = omap_port->sst_base;
+	void __iomem *ssr = omap_port->ssr_base;
+	unsigned int i;
+	u32 err;
+
+	pm_runtime_get_sync(omap_port->pdev);
+	spin_lock_bh(&omap_port->lock);
+
+	/* stop all ssi communication */
+	pinctrl_pm_select_idle_state(omap_port->pdev);
+	udelay(1); /* wait for racing frames */
+
+	/* Stop all DMA transfers */
+	for (i = 0; i < SSI_MAX_GDD_LCH; i++) {
+		msg = omap_ssi->gdd_trn[i].msg;
+		if (!msg || (port != hsi_get_port(msg->cl)))
+			continue;
+		writew_relaxed(0, omap_ssi->gdd + SSI_GDD_CCR_REG(i));
+		if (msg->ttype == HSI_MSG_READ)
+			pm_runtime_put_autosuspend(omap_port->pdev);
+		omap_ssi->gdd_trn[i].msg = NULL;
+	}
+	/* Flush all SST buffers */
+	writel_relaxed(0, sst + SSI_SST_BUFSTATE_REG);
+	writel_relaxed(0, sst + SSI_SST_TXSTATE_REG);
+	/* Flush all SSR buffers */
+	writel_relaxed(0, ssr + SSI_SSR_RXSTATE_REG);
+	writel_relaxed(0, ssr + SSI_SSR_BUFSTATE_REG);
+	/* Flush all errors */
+	err = readl(ssr + SSI_SSR_ERROR_REG);
+	writel_relaxed(err, ssr + SSI_SSR_ERRORACK_REG);
+	/* Flush break */
+	writel_relaxed(0, ssr + SSI_SSR_BREAK_REG);
+	/* Clear interrupts */
+	writel_relaxed(0, omap_ssi->sys + SSI_MPU_ENABLE_REG(port->num, 0));
+	writel_relaxed(0xffffff00,
+			omap_ssi->sys + SSI_MPU_STATUS_REG(port->num, 0));
+	writel_relaxed(0, omap_ssi->sys + SSI_GDD_MPU_IRQ_ENABLE_REG);
+	writel(0xff, omap_ssi->sys + SSI_GDD_MPU_IRQ_STATUS_REG);
+	/* Dequeue all pending requests */
+	for (i = 0; i < omap_port->channels; i++) {
+		/* Release write clocks */
+		if (!list_empty(&omap_port->txqueue[i]))
+			pm_runtime_put_autosuspend(omap_port->pdev);
+		ssi_flush_queue(&omap_port->txqueue[i], NULL);
+		ssi_flush_queue(&omap_port->rxqueue[i], NULL);
+	}
+	ssi_flush_queue(&omap_port->brkqueue, NULL);
+
+	/* Resume SSI communication */
+	pinctrl_pm_select_default_state(omap_port->pdev);
+
+	spin_unlock_bh(&omap_port->lock);
+	pm_runtime_put_autosuspend(omap_port->pdev);
+
+	return 0;
+}
+
+static void start_tx_work(struct work_struct *work)
+{
+	struct omap_ssi_port *omap_port =
+				container_of(work, struct omap_ssi_port, work);
+	struct hsi_port *port = to_hsi_port(omap_port->dev);
+	struct hsi_controller *ssi = to_hsi_controller(port->device.parent);
+	struct omap_ssi_controller *omap_ssi = hsi_controller_drvdata(ssi);
+
+	pm_runtime_get_sync(omap_port->pdev); /* Grab clocks */
+	writel(SSI_WAKE(0), omap_ssi->sys + SSI_SET_WAKE_REG(port->num));
+}
+
+static int ssi_start_tx(struct hsi_client *cl)
+{
+	struct hsi_port *port = hsi_get_port(cl);
+	struct omap_ssi_port *omap_port = hsi_port_drvdata(port);
+
+	dev_dbg(&port->device, "Wake out high %d\n", omap_port->wk_refcount);
+
+	spin_lock_bh(&omap_port->wk_lock);
+	if (omap_port->wk_refcount++) {
+		spin_unlock_bh(&omap_port->wk_lock);
+		return 0;
+	}
+	spin_unlock_bh(&omap_port->wk_lock);
+
+	schedule_work(&omap_port->work);
+
+	return 0;
+}
+
+static int ssi_stop_tx(struct hsi_client *cl)
+{
+	struct hsi_port *port = hsi_get_port(cl);
+	struct omap_ssi_port *omap_port = hsi_port_drvdata(port);
+	struct hsi_controller *ssi = to_hsi_controller(port->device.parent);
+	struct omap_ssi_controller *omap_ssi = hsi_controller_drvdata(ssi);
+
+	dev_dbg(&port->device, "Wake out low %d\n", omap_port->wk_refcount);
+
+	spin_lock_bh(&omap_port->wk_lock);
+	BUG_ON(!omap_port->wk_refcount);
+	if (--omap_port->wk_refcount) {
+		spin_unlock_bh(&omap_port->wk_lock);
+		return 0;
+	}
+	writel(SSI_WAKE(0), omap_ssi->sys + SSI_CLEAR_WAKE_REG(port->num));
+	spin_unlock_bh(&omap_port->wk_lock);
+
+	pm_runtime_put_autosuspend(omap_port->pdev); /* Release clocks */
+
+
+	return 0;
+}
+
+static void ssi_transfer(struct omap_ssi_port *omap_port,
+							struct list_head *queue)
+{
+	struct hsi_msg *msg;
+	int err = -1;
+
+	pm_runtime_get(omap_port->pdev);
+	spin_lock_bh(&omap_port->lock);
+	while (err < 0) {
+		err = ssi_start_transfer(queue);
+		if (err < 0) {
+			msg = list_first_entry(queue, struct hsi_msg, link);
+			msg->status = HSI_STATUS_ERROR;
+			msg->actual_len = 0;
+			list_del(&msg->link);
+			spin_unlock_bh(&omap_port->lock);
+			msg->complete(msg);
+			spin_lock_bh(&omap_port->lock);
+		}
+	}
+	spin_unlock_bh(&omap_port->lock);
+	pm_runtime_put_autosuspend(omap_port->pdev);
+}
+
+static void ssi_cleanup_queues(struct hsi_client *cl)
+{
+	struct hsi_port *port = hsi_get_port(cl);
+	struct omap_ssi_port *omap_port = hsi_port_drvdata(port);
+	struct hsi_controller *ssi = to_hsi_controller(port->device.parent);
+	struct omap_ssi_controller *omap_ssi = hsi_controller_drvdata(ssi);
+	struct hsi_msg *msg;
+	unsigned int i;
+	u32 rxbufstate = 0;
+	u32 txbufstate = 0;
+	u32 status = SSI_ERROROCCURED;
+	u32 tmp;
+
+	ssi_flush_queue(&omap_port->brkqueue, cl);
+	if (list_empty(&omap_port->brkqueue))
+		status |= SSI_BREAKDETECTED;
+
+	for (i = 0; i < omap_port->channels; i++) {
+		if (list_empty(&omap_port->txqueue[i]))
+			continue;
+		msg = list_first_entry(&omap_port->txqueue[i], struct hsi_msg,
+									link);
+		if ((msg->cl == cl) && (msg->status == HSI_STATUS_PROCEEDING)) {
+			txbufstate |= (1 << i);
+			status |= SSI_DATAACCEPT(i);
+			/* Release the clocks writes, also GDD ones */
+			pm_runtime_put_autosuspend(omap_port->pdev);
+		}
+		ssi_flush_queue(&omap_port->txqueue[i], cl);
+	}
+	for (i = 0; i < omap_port->channels; i++) {
+		if (list_empty(&omap_port->rxqueue[i]))
+			continue;
+		msg = list_first_entry(&omap_port->rxqueue[i], struct hsi_msg,
+									link);
+		if ((msg->cl == cl) && (msg->status == HSI_STATUS_PROCEEDING)) {
+			rxbufstate |= (1 << i);
+			status |= SSI_DATAAVAILABLE(i);
+		}
+		ssi_flush_queue(&omap_port->rxqueue[i], cl);
+		/* Check if we keep the error detection interrupt armed */
+		if (!list_empty(&omap_port->rxqueue[i]))
+			status &= ~SSI_ERROROCCURED;
+	}
+	/* Cleanup write buffers */
+	tmp = readl(omap_port->sst_base + SSI_SST_BUFSTATE_REG);
+	tmp &= ~txbufstate;
+	writel_relaxed(tmp, omap_port->sst_base + SSI_SST_BUFSTATE_REG);
+	/* Cleanup read buffers */
+	tmp = readl(omap_port->ssr_base + SSI_SSR_BUFSTATE_REG);
+	tmp &= ~rxbufstate;
+	writel_relaxed(tmp, omap_port->ssr_base + SSI_SSR_BUFSTATE_REG);
+	/* Disarm and ack pending interrupts */
+	tmp = readl(omap_ssi->sys + SSI_MPU_ENABLE_REG(port->num, 0));
+	tmp &= ~status;
+	writel_relaxed(tmp, omap_ssi->sys + SSI_MPU_ENABLE_REG(port->num, 0));
+	writel_relaxed(status, omap_ssi->sys +
+		SSI_MPU_STATUS_REG(port->num, 0));
+}
+
+static void ssi_cleanup_gdd(struct hsi_controller *ssi, struct hsi_client *cl)
+{
+	struct omap_ssi_controller *omap_ssi = hsi_controller_drvdata(ssi);
+	struct hsi_port *port = hsi_get_port(cl);
+	struct omap_ssi_port *omap_port = hsi_port_drvdata(port);
+	struct hsi_msg *msg;
+	unsigned int i;
+	u32 val = 0;
+	u32 tmp;
+
+	for (i = 0; i < SSI_MAX_GDD_LCH; i++) {
+		msg = omap_ssi->gdd_trn[i].msg;
+		if ((!msg) || (msg->cl != cl))
+			continue;
+		writew_relaxed(0, omap_ssi->gdd + SSI_GDD_CCR_REG(i));
+		val |= (1 << i);
+		/*
+		 * Clock references for write will be handled in
+		 * ssi_cleanup_queues
+		 */
+		if (msg->ttype == HSI_MSG_READ) {
+			pm_runtime_put_autosuspend(omap_port->pdev);
+		}
+		omap_ssi->gdd_trn[i].msg = NULL;
+	}
+	tmp = readl_relaxed(omap_ssi->sys + SSI_GDD_MPU_IRQ_ENABLE_REG);
+	tmp &= ~val;
+	writel_relaxed(tmp, omap_ssi->sys + SSI_GDD_MPU_IRQ_ENABLE_REG);
+	writel(val, omap_ssi->sys + SSI_GDD_MPU_IRQ_STATUS_REG);
+}
+
+static int ssi_set_port_mode(struct omap_ssi_port *omap_port, u32 mode)
+{
+	writel(mode, omap_port->sst_base + SSI_SST_MODE_REG);
+	writel(mode, omap_port->ssr_base + SSI_SSR_MODE_REG);
+	/* OCP barrier */
+	mode = readl(omap_port->ssr_base + SSI_SSR_MODE_REG);
+
+	return 0;
+}
+
+static int ssi_release(struct hsi_client *cl)
+{
+	struct hsi_port *port = hsi_get_port(cl);
+	struct omap_ssi_port *omap_port = hsi_port_drvdata(port);
+	struct hsi_controller *ssi = to_hsi_controller(port->device.parent);
+
+	pm_runtime_get_sync(omap_port->pdev);
+	spin_lock_bh(&omap_port->lock);
+	/* Stop all the pending DMA requests for that client */
+	ssi_cleanup_gdd(ssi, cl);
+	/* Now cleanup all the queues */
+	ssi_cleanup_queues(cl);
+	/* If it is the last client of the port, do extra checks and cleanup */
+	if (port->claimed <= 1) {
+		/*
+		 * Drop the clock reference for the incoming wake line
+		 * if it is still kept high by the other side.
+		 */
+		if (test_and_clear_bit(SSI_WAKE_EN, &omap_port->flags))
+			pm_runtime_put_sync(omap_port->pdev);
+		pm_runtime_get(omap_port->pdev);
+		/* Stop any SSI TX/RX without a client */
+		ssi_set_port_mode(omap_port, SSI_MODE_SLEEP);
+		omap_port->sst.mode = SSI_MODE_SLEEP;
+		omap_port->ssr.mode = SSI_MODE_SLEEP;
+		pm_runtime_put(omap_port->pdev);
+		WARN_ON(omap_port->wk_refcount != 0);
+	}
+	spin_unlock_bh(&omap_port->lock);
+	pm_runtime_put_sync(omap_port->pdev);
+
+	return 0;
+}
+
+
+
+static void ssi_error(struct hsi_port *port)
+{
+	struct omap_ssi_port *omap_port = hsi_port_drvdata(port);
+	struct hsi_controller *ssi = to_hsi_controller(port->device.parent);
+	struct omap_ssi_controller *omap_ssi = hsi_controller_drvdata(ssi);
+	struct hsi_msg *msg;
+	unsigned int i;
+	u32 err;
+	u32 val;
+	u32 tmp;
+
+	/* ACK error */
+	err = readl(omap_port->ssr_base + SSI_SSR_ERROR_REG);
+	dev_err(&port->device, "SSI error: 0x%02x\n", err);
+	if (!err) {
+		dev_dbg(&port->device, "spurious SSI error ignored!\n");
+		return;
+	}
+	spin_lock(&omap_ssi->lock);
+	/* Cancel all GDD read transfers */
+	for (i = 0, val = 0; i < SSI_MAX_GDD_LCH; i++) {
+		msg = omap_ssi->gdd_trn[i].msg;
+		if ((msg) && (msg->ttype == HSI_MSG_READ)) {
+			writew_relaxed(0, omap_ssi->gdd + SSI_GDD_CCR_REG(i));
+			val |= (1 << i);
+			omap_ssi->gdd_trn[i].msg = NULL;
+		}
+	}
+	tmp = readl(omap_ssi->sys + SSI_GDD_MPU_IRQ_ENABLE_REG);
+	tmp &= ~val;
+	writel_relaxed(tmp, omap_ssi->sys + SSI_GDD_MPU_IRQ_ENABLE_REG);
+	spin_unlock(&omap_ssi->lock);
+	/* Cancel all PIO read transfers */
+	spin_lock(&omap_port->lock);
+	tmp = readl(omap_ssi->sys + SSI_MPU_ENABLE_REG(port->num, 0));
+	tmp &= 0xfeff00ff; /* Disable error & all dataavailable interrupts */
+	writel_relaxed(tmp, omap_ssi->sys + SSI_MPU_ENABLE_REG(port->num, 0));
+	/* ACK error */
+	writel_relaxed(err, omap_port->ssr_base + SSI_SSR_ERRORACK_REG);
+	writel_relaxed(SSI_ERROROCCURED,
+			omap_ssi->sys + SSI_MPU_STATUS_REG(port->num, 0));
+	/* Signal the error all current pending read requests */
+	for (i = 0; i < omap_port->channels; i++) {
+		if (list_empty(&omap_port->rxqueue[i]))
+			continue;
+		msg = list_first_entry(&omap_port->rxqueue[i], struct hsi_msg,
+									link);
+		list_del(&msg->link);
+		msg->status = HSI_STATUS_ERROR;
+		spin_unlock(&omap_port->lock);
+		msg->complete(msg);
+		/* Now restart queued reads if any */
+		ssi_transfer(omap_port, &omap_port->rxqueue[i]);
+		spin_lock(&omap_port->lock);
+	}
+	spin_unlock(&omap_port->lock);
+}
+
+static void ssi_break_complete(struct hsi_port *port)
+{
+	struct omap_ssi_port *omap_port = hsi_port_drvdata(port);
+	struct hsi_controller *ssi = to_hsi_controller(port->device.parent);
+	struct omap_ssi_controller *omap_ssi = hsi_controller_drvdata(ssi);
+	struct hsi_msg *msg;
+	struct hsi_msg *tmp;
+	u32 val;
+
+	dev_dbg(&port->device, "HWBREAK received\n");
+
+	spin_lock(&omap_port->lock);
+	val = readl(omap_ssi->sys + SSI_MPU_ENABLE_REG(port->num, 0));
+	val &= ~SSI_BREAKDETECTED;
+	writel_relaxed(val, omap_ssi->sys + SSI_MPU_ENABLE_REG(port->num, 0));
+	writel_relaxed(0, omap_port->ssr_base + SSI_SSR_BREAK_REG);
+	writel(SSI_BREAKDETECTED,
+			omap_ssi->sys + SSI_MPU_STATUS_REG(port->num, 0));
+	spin_unlock(&omap_port->lock);
+
+	list_for_each_entry_safe(msg, tmp, &omap_port->brkqueue, link) {
+		msg->status = HSI_STATUS_COMPLETED;
+		spin_lock(&omap_port->lock);
+		list_del(&msg->link);
+		spin_unlock(&omap_port->lock);
+		msg->complete(msg);
+	}
+
+}
+
+static void ssi_pio_complete(struct hsi_port *port, struct list_head *queue)
+{
+	struct hsi_controller *ssi = to_hsi_controller(port->device.parent);
+	struct omap_ssi_controller *omap_ssi = hsi_controller_drvdata(ssi);
+	struct omap_ssi_port *omap_port = hsi_port_drvdata(port);
+	struct hsi_msg *msg;
+	u32 *buf;
+	u32 reg;
+	u32 val;
+
+	spin_lock_bh(&omap_port->lock);
+	msg = list_first_entry(queue, struct hsi_msg, link);
+	if ((!msg->sgt.nents) || (!msg->sgt.sgl->length)) {
+		msg->actual_len = 0;
+		msg->status = HSI_STATUS_PENDING;
+	}
+	if (msg->ttype == HSI_MSG_WRITE)
+		val = SSI_DATAACCEPT(msg->channel);
+	else
+		val = SSI_DATAAVAILABLE(msg->channel);
+	if (msg->status == HSI_STATUS_PROCEEDING) {
+		buf = sg_virt(msg->sgt.sgl) + msg->actual_len;
+		if (msg->ttype == HSI_MSG_WRITE)
+			writel(*buf, omap_port->sst_base +
+					SSI_SST_BUFFER_CH_REG(msg->channel));
+		 else
+			*buf = readl(omap_port->ssr_base +
+					SSI_SSR_BUFFER_CH_REG(msg->channel));
+		dev_dbg(&port->device, "ch %d ttype %d 0x%08x\n", msg->channel,
+							msg->ttype, *buf);
+		msg->actual_len += sizeof(*buf);
+		if (msg->actual_len >= msg->sgt.sgl->length)
+			msg->status = HSI_STATUS_COMPLETED;
+		/*
+		 * Wait for the last written frame to be really sent before
+		 * we call the complete callback
+		 */
+		if ((msg->status == HSI_STATUS_PROCEEDING) ||
+				((msg->status == HSI_STATUS_COMPLETED) &&
+					(msg->ttype == HSI_MSG_WRITE))) {
+			writel(val, omap_ssi->sys +
+					SSI_MPU_STATUS_REG(port->num, 0));
+			spin_unlock_bh(&omap_port->lock);
+
+			return;
+		}
+
+	}
+	/* Transfer completed at this point */
+	reg = readl(omap_ssi->sys + SSI_MPU_ENABLE_REG(port->num, 0));
+	if (msg->ttype == HSI_MSG_WRITE) {
+		/* Release clocks for write transfer */
+		pm_runtime_put_autosuspend(omap_port->pdev);
+	}
+	reg &= ~val;
+	writel_relaxed(reg, omap_ssi->sys + SSI_MPU_ENABLE_REG(port->num, 0));
+	writel_relaxed(val, omap_ssi->sys + SSI_MPU_STATUS_REG(port->num, 0));
+	list_del(&msg->link);
+	spin_unlock_bh(&omap_port->lock);
+	msg->complete(msg);
+	ssi_transfer(omap_port, queue);
+}
+
+static irqreturn_t ssi_pio_thread(int irq, void *ssi_port)
+{
+	struct hsi_port *port = (struct hsi_port *)ssi_port;
+	struct hsi_controller *ssi = to_hsi_controller(port->device.parent);
+	struct omap_ssi_port *omap_port = hsi_port_drvdata(port);
+	struct omap_ssi_controller *omap_ssi = hsi_controller_drvdata(ssi);
+	void __iomem *sys = omap_ssi->sys;
+	unsigned int ch;
+	u32 status_reg;
+
+	pm_runtime_get_sync(omap_port->pdev);
+
+	do {
+		status_reg = readl(sys + SSI_MPU_STATUS_REG(port->num, 0));
+		status_reg &= readl(sys + SSI_MPU_ENABLE_REG(port->num, 0));
+
+		for (ch = 0; ch < omap_port->channels; ch++) {
+			if (status_reg & SSI_DATAACCEPT(ch))
+				ssi_pio_complete(port, &omap_port->txqueue[ch]);
+			if (status_reg & SSI_DATAAVAILABLE(ch))
+				ssi_pio_complete(port, &omap_port->rxqueue[ch]);
+		}
+		if (status_reg & SSI_BREAKDETECTED)
+			ssi_break_complete(port);
+		if (status_reg & SSI_ERROROCCURED)
+			ssi_error(port);
+
+		status_reg = readl(sys + SSI_MPU_STATUS_REG(port->num, 0));
+		status_reg &= readl(sys + SSI_MPU_ENABLE_REG(port->num, 0));
+
+		/* TODO: sleep if we retry? */
+	} while (status_reg);
+
+	pm_runtime_put_autosuspend(omap_port->pdev);
+
+	return IRQ_HANDLED;
+}
+
+static irqreturn_t ssi_wake_thread(int irq __maybe_unused, void *ssi_port)
+{
+	struct hsi_port *port = (struct hsi_port *)ssi_port;
+	struct hsi_controller *ssi = to_hsi_controller(port->device.parent);
+	struct omap_ssi_port *omap_port = hsi_port_drvdata(port);
+	struct omap_ssi_controller *omap_ssi = hsi_controller_drvdata(ssi);
+
+	if (ssi_wakein(port)) {
+		/**
+		 * We can have a quick High-Low-High transition in the line.
+		 * In such a case if we have long interrupt latencies,
+		 * we can miss the low event or get twice a high event.
+		 * This workaround will avoid breaking the clock reference
+		 * count when such a situation ocurrs.
+		 */
+		if (!test_and_set_bit(SSI_WAKE_EN, &omap_port->flags))
+			pm_runtime_get_sync(omap_port->pdev);
+		dev_dbg(&ssi->device, "Wake in high\n");
+		if (omap_port->wktest) { /* FIXME: HACK ! To be removed */
+			writel(SSI_WAKE(0),
+				omap_ssi->sys + SSI_SET_WAKE_REG(port->num));
+		}
+		hsi_event(port, HSI_EVENT_START_RX);
+	} else {
+		dev_dbg(&ssi->device, "Wake in low\n");
+		if (omap_port->wktest) { /* FIXME: HACK ! To be removed */
+			writel(SSI_WAKE(0),
+				omap_ssi->sys + SSI_CLEAR_WAKE_REG(port->num));
+		}
+		hsi_event(port, HSI_EVENT_STOP_RX);
+		if (test_and_clear_bit(SSI_WAKE_EN, &omap_port->flags)) {
+			pm_runtime_put_autosuspend(omap_port->pdev);
+		}
+	}
+
+	return IRQ_HANDLED;
+}
+
+static int ssi_port_irq(struct hsi_port *port, struct platform_device *pd)
+{
+	struct omap_ssi_port *omap_port = hsi_port_drvdata(port);
+	int err;
+
+	err = platform_get_irq(pd, 0);
+	if (err < 0)
+		return err;
+	omap_port->irq = err;
+	err = devm_request_threaded_irq(&port->device, omap_port->irq, NULL,
+				ssi_pio_thread, IRQF_ONESHOT, "SSI PORT", port);
+	if (err < 0)
+		dev_err(&port->device, "Request IRQ %d failed (%d)\n",
+							omap_port->irq, err);
+	return err;
+}
+
+static int ssi_wake_irq(struct hsi_port *port, struct platform_device *pd)
+{
+	struct omap_ssi_port *omap_port = hsi_port_drvdata(port);
+	int cawake_irq;
+	int err;
+
+	if (!omap_port->wake_gpio) {
+		omap_port->wake_irq = -1;
+		return 0;
+	}
+
+	cawake_irq = gpiod_to_irq(omap_port->wake_gpio);
+	omap_port->wake_irq = cawake_irq;
+
+	err = devm_request_threaded_irq(&port->device, cawake_irq, NULL,
+		ssi_wake_thread,
+		IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
+		"SSI cawake", port);
+	if (err < 0)
+		dev_err(&port->device, "Request Wake in IRQ %d failed %d\n",
+						cawake_irq, err);
+	err = enable_irq_wake(cawake_irq);
+	if (err < 0)
+		dev_err(&port->device, "Enable wake on the wakeline in irq %d failed %d\n",
+			cawake_irq, err);
+
+	return err;
+}
+
+static void ssi_queues_init(struct omap_ssi_port *omap_port)
+{
+	unsigned int ch;
+
+	for (ch = 0; ch < SSI_MAX_CHANNELS; ch++) {
+		INIT_LIST_HEAD(&omap_port->txqueue[ch]);
+		INIT_LIST_HEAD(&omap_port->rxqueue[ch]);
+	}
+	INIT_LIST_HEAD(&omap_port->brkqueue);
+}
+
+static int ssi_port_get_iomem(struct platform_device *pd,
+		const char *name, void __iomem **pbase, dma_addr_t *phy)
+{
+	struct hsi_port *port = platform_get_drvdata(pd);
+	struct resource *mem;
+	struct resource *ioarea;
+	void __iomem *base;
+
+	mem = platform_get_resource_byname(pd, IORESOURCE_MEM, name);
+	if (!mem) {
+		dev_err(&pd->dev, "IO memory region missing (%s)\n", name);
+		return -ENXIO;
+	}
+	ioarea = devm_request_mem_region(&port->device, mem->start,
+					resource_size(mem), dev_name(&pd->dev));
+	if (!ioarea) {
+		dev_err(&pd->dev, "%s IO memory region request failed\n",
+								mem->name);
+		return -ENXIO;
+	}
+	base = devm_ioremap(&port->device, mem->start, resource_size(mem));
+	if (!base) {
+		dev_err(&pd->dev, "%s IO remap failed\n", mem->name);
+		return -ENXIO;
+	}
+	*pbase = base;
+
+	if (phy)
+		*phy = mem->start;
+
+	return 0;
+}
+
+static int ssi_port_probe(struct platform_device *pd)
+{
+	struct device_node *np = pd->dev.of_node;
+	struct hsi_port *port;
+	struct omap_ssi_port *omap_port;
+	struct hsi_controller *ssi = dev_get_drvdata(pd->dev.parent);
+	struct omap_ssi_controller *omap_ssi = hsi_controller_drvdata(ssi);
+	struct gpio_desc *cawake_gpio = NULL;
+	u32 port_id;
+	int err;
+
+	dev_dbg(&pd->dev, "init ssi port...\n");
+
+	if (!omap_ssi->port) {
+		dev_err(&pd->dev, "ssi controller not initialized!\n");
+		err = -ENODEV;
+		goto error;
+	}
+
+	/* get id of first uninitialized port in controller */
+	for (port_id = 0; port_id < ssi->num_ports && omap_ssi->port[port_id];
+		port_id++)
+		;
+
+	if (port_id >= ssi->num_ports) {
+		dev_err(&pd->dev, "port id out of range!\n");
+		err = -ENODEV;
+		goto error;
+	}
+
+	port = ssi->port[port_id];
+
+	if (!np) {
+		dev_err(&pd->dev, "missing device tree data\n");
+		err = -EINVAL;
+		goto error;
+	}
+
+	cawake_gpio = devm_gpiod_get(&pd->dev, "ti,ssi-cawake", GPIOD_IN);
+	if (IS_ERR(cawake_gpio)) {
+		err = PTR_ERR(cawake_gpio);
+		dev_err(&pd->dev, "couldn't get cawake gpio (err=%d)!\n", err);
+		goto error;
+	}
+
+	omap_port = devm_kzalloc(&port->device, sizeof(*omap_port), GFP_KERNEL);
+	if (!omap_port) {
+		err = -ENOMEM;
+		goto error;
+	}
+	omap_port->wake_gpio = cawake_gpio;
+	omap_port->pdev = &pd->dev;
+	omap_port->port_id = port_id;
+
+	INIT_DEFERRABLE_WORK(&omap_port->errqueue_work, ssi_process_errqueue);
+	INIT_WORK(&omap_port->work, start_tx_work);
+
+	/* initialize HSI port */
+	port->async	= ssi_async;
+	port->setup	= ssi_setup;
+	port->flush	= ssi_flush;
+	port->start_tx	= ssi_start_tx;
+	port->stop_tx	= ssi_stop_tx;
+	port->release	= ssi_release;
+	hsi_port_set_drvdata(port, omap_port);
+	omap_ssi->port[port_id] = omap_port;
+
+	platform_set_drvdata(pd, port);
+
+	err = ssi_port_get_iomem(pd, "tx", &omap_port->sst_base,
+		&omap_port->sst_dma);
+	if (err < 0)
+		goto error;
+	err = ssi_port_get_iomem(pd, "rx", &omap_port->ssr_base,
+		&omap_port->ssr_dma);
+	if (err < 0)
+		goto error;
+
+	err = ssi_port_irq(port, pd);
+	if (err < 0)
+		goto error;
+	err = ssi_wake_irq(port, pd);
+	if (err < 0)
+		goto error;
+
+	ssi_queues_init(omap_port);
+	spin_lock_init(&omap_port->lock);
+	spin_lock_init(&omap_port->wk_lock);
+	omap_port->dev = &port->device;
+
+	pm_runtime_use_autosuspend(omap_port->pdev);
+	pm_runtime_set_autosuspend_delay(omap_port->pdev, 250);
+	pm_runtime_enable(omap_port->pdev);
+
+#ifdef CONFIG_DEBUG_FS
+	ssi_debug_add_port(omap_port, omap_ssi->dir);
+#endif
+
+	hsi_add_clients_from_dt(port, np);
+
+	dev_info(&pd->dev, "ssi port %u successfully initialized\n", port_id);
+
+	return 0;
+
+error:
+	return err;
+}
+
+static void ssi_port_remove(struct platform_device *pd)
+{
+	struct hsi_port *port = platform_get_drvdata(pd);
+	struct omap_ssi_port *omap_port = hsi_port_drvdata(port);
+	struct hsi_controller *ssi = to_hsi_controller(port->device.parent);
+	struct omap_ssi_controller *omap_ssi = hsi_controller_drvdata(ssi);
+
+#ifdef CONFIG_DEBUG_FS
+	ssi_debug_remove_port(port);
+#endif
+
+	cancel_delayed_work_sync(&omap_port->errqueue_work);
+
+	hsi_port_unregister_clients(port);
+
+	port->async	= hsi_dummy_msg;
+	port->setup	= hsi_dummy_cl;
+	port->flush	= hsi_dummy_cl;
+	port->start_tx	= hsi_dummy_cl;
+	port->stop_tx	= hsi_dummy_cl;
+	port->release	= hsi_dummy_cl;
+
+	omap_ssi->port[omap_port->port_id] = NULL;
+	platform_set_drvdata(pd, NULL);
+
+	pm_runtime_dont_use_autosuspend(&pd->dev);
+	pm_runtime_disable(&pd->dev);
+}
+
+static int ssi_restore_divisor(struct omap_ssi_port *omap_port)
+{
+	writel_relaxed(omap_port->sst.divisor,
+				omap_port->sst_base + SSI_SST_DIVISOR_REG);
+
+	return 0;
+}
+
+void omap_ssi_port_update_fclk(struct hsi_controller *ssi,
+			       struct omap_ssi_port *omap_port)
+{
+	/* update divisor */
+	u32 div = ssi_calculate_div(ssi);
+	omap_port->sst.divisor = div;
+	ssi_restore_divisor(omap_port);
+}
+
+#ifdef CONFIG_PM
+static int ssi_save_port_ctx(struct omap_ssi_port *omap_port)
+{
+	struct hsi_port *port = to_hsi_port(omap_port->dev);
+	struct hsi_controller *ssi = to_hsi_controller(port->device.parent);
+	struct omap_ssi_controller *omap_ssi = hsi_controller_drvdata(ssi);
+
+	omap_port->sys_mpu_enable = readl(omap_ssi->sys +
+					SSI_MPU_ENABLE_REG(port->num, 0));
+
+	return 0;
+}
+
+static int ssi_restore_port_ctx(struct omap_ssi_port *omap_port)
+{
+	struct hsi_port *port = to_hsi_port(omap_port->dev);
+	struct hsi_controller *ssi = to_hsi_controller(port->device.parent);
+	struct omap_ssi_controller *omap_ssi = hsi_controller_drvdata(ssi);
+	void __iomem	*base;
+
+	writel_relaxed(omap_port->sys_mpu_enable,
+			omap_ssi->sys + SSI_MPU_ENABLE_REG(port->num, 0));
+
+	/* SST context */
+	base = omap_port->sst_base;
+	writel_relaxed(omap_port->sst.frame_size, base + SSI_SST_FRAMESIZE_REG);
+	writel_relaxed(omap_port->sst.channels, base + SSI_SST_CHANNELS_REG);
+	writel_relaxed(omap_port->sst.arb_mode, base + SSI_SST_ARBMODE_REG);
+
+	/* SSR context */
+	base = omap_port->ssr_base;
+	writel_relaxed(omap_port->ssr.frame_size, base + SSI_SSR_FRAMESIZE_REG);
+	writel_relaxed(omap_port->ssr.channels, base + SSI_SSR_CHANNELS_REG);
+	writel_relaxed(omap_port->ssr.timeout, base + SSI_SSR_TIMEOUT_REG);
+
+	return 0;
+}
+
+static int ssi_restore_port_mode(struct omap_ssi_port *omap_port)
+{
+	writel_relaxed(omap_port->sst.mode,
+				omap_port->sst_base + SSI_SST_MODE_REG);
+	writel_relaxed(omap_port->ssr.mode,
+				omap_port->ssr_base + SSI_SSR_MODE_REG);
+	/* OCP barrier */
+	readl(omap_port->ssr_base + SSI_SSR_MODE_REG);
+
+	return 0;
+}
+
+static int omap_ssi_port_runtime_suspend(struct device *dev)
+{
+	struct hsi_port *port = dev_get_drvdata(dev);
+	struct omap_ssi_port *omap_port = hsi_port_drvdata(port);
+	struct hsi_controller *ssi = to_hsi_controller(port->device.parent);
+	struct omap_ssi_controller *omap_ssi = hsi_controller_drvdata(ssi);
+
+	dev_dbg(dev, "port runtime suspend!\n");
+
+	ssi_set_port_mode(omap_port, SSI_MODE_SLEEP);
+	if (omap_ssi->get_loss)
+		omap_port->loss_count =
+				omap_ssi->get_loss(ssi->device.parent);
+	ssi_save_port_ctx(omap_port);
+
+	return 0;
+}
+
+static int omap_ssi_port_runtime_resume(struct device *dev)
+{
+	struct hsi_port *port = dev_get_drvdata(dev);
+	struct omap_ssi_port *omap_port = hsi_port_drvdata(port);
+	struct hsi_controller *ssi = to_hsi_controller(port->device.parent);
+	struct omap_ssi_controller *omap_ssi = hsi_controller_drvdata(ssi);
+
+	dev_dbg(dev, "port runtime resume!\n");
+
+	if ((omap_ssi->get_loss) && (omap_port->loss_count ==
+				omap_ssi->get_loss(ssi->device.parent)))
+		goto mode; /* We always need to restore the mode & TX divisor */
+
+	ssi_restore_port_ctx(omap_port);
+
+mode:
+	ssi_restore_divisor(omap_port);
+	ssi_restore_port_mode(omap_port);
+
+	return 0;
+}
+
+static const struct dev_pm_ops omap_ssi_port_pm_ops = {
+	SET_RUNTIME_PM_OPS(omap_ssi_port_runtime_suspend,
+		omap_ssi_port_runtime_resume, NULL)
+};
+
+#define DEV_PM_OPS     (&omap_ssi_port_pm_ops)
+#else
+#define DEV_PM_OPS     NULL
+#endif
+
+
+#ifdef CONFIG_OF
+static const struct of_device_id omap_ssi_port_of_match[] = {
+	{ .compatible = "ti,omap3-ssi-port", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, omap_ssi_port_of_match);
+#else
+#define omap_ssi_port_of_match NULL
+#endif
+
+struct platform_driver ssi_port_pdriver = {
+	.probe = ssi_port_probe,
+	.remove = ssi_port_remove,
+	.driver	= {
+		.name	= "omap_ssi_port",
+		.of_match_table = omap_ssi_port_of_match,
+		.pm	= DEV_PM_OPS,
+	},
+};
diff --git a/drivers/hsi/controllers/omap_ssi_regs.h b/drivers/hsi/controllers/omap_ssi_regs.h
new file mode 100644
index 000000000..87000e7da
--- /dev/null
+++ b/drivers/hsi/controllers/omap_ssi_regs.h
@@ -0,0 +1,158 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/* Hardware definitions for SSI.
+ *
+ * Copyright (C) 2010 Nokia Corporation. All rights reserved.
+ *
+ * Contact: Carlos Chinea <carlos.chinea@nokia.com>
+ */
+
+#ifndef __OMAP_SSI_REGS_H__
+#define __OMAP_SSI_REGS_H__
+
+/*
+ * SSI SYS registers
+ */
+#define SSI_REVISION_REG    0
+#  define SSI_REV_MAJOR    0xf0
+#  define SSI_REV_MINOR    0xf
+#define SSI_SYSCONFIG_REG    0x10
+#  define SSI_AUTOIDLE    (1 << 0)
+#  define SSI_SOFTRESET    (1 << 1)
+#  define SSI_SIDLEMODE_FORCE  0
+#  define SSI_SIDLEMODE_NO    (1 << 3)
+#  define SSI_SIDLEMODE_SMART  (1 << 4)
+#  define SSI_SIDLEMODE_MASK  0x18
+#  define SSI_MIDLEMODE_FORCE  0
+#  define SSI_MIDLEMODE_NO    (1 << 12)
+#  define SSI_MIDLEMODE_SMART  (1 << 13)
+#  define SSI_MIDLEMODE_MASK  0x3000
+#define SSI_SYSSTATUS_REG    0x14
+#  define SSI_RESETDONE    1
+#define SSI_MPU_STATUS_REG(port, irq)  (0x808 + ((port) * 0x10) + ((irq) * 2))
+#define SSI_MPU_ENABLE_REG(port, irq)  (0x80c + ((port) * 0x10) + ((irq) * 8))
+#  define SSI_DATAACCEPT(channel)    (1 << (channel))
+#  define SSI_DATAAVAILABLE(channel)  (1 << ((channel) + 8))
+#  define SSI_DATAOVERRUN(channel)    (1 << ((channel) + 16))
+#  define SSI_ERROROCCURED      (1 << 24)
+#  define SSI_BREAKDETECTED    (1 << 25)
+#define SSI_GDD_MPU_IRQ_STATUS_REG  0x0800
+#define SSI_GDD_MPU_IRQ_ENABLE_REG  0x0804
+#  define SSI_GDD_LCH(channel)  (1 << (channel))
+#define SSI_WAKE_REG(port)    (0xc00 + ((port) * 0x10))
+#define SSI_CLEAR_WAKE_REG(port)  (0xc04 + ((port) * 0x10))
+#define SSI_SET_WAKE_REG(port)    (0xc08 + ((port) * 0x10))
+#  define SSI_WAKE(channel)  (1 << (channel))
+#  define SSI_WAKE_MASK    0xff
+
+/*
+ * SSI SST registers
+ */
+#define SSI_SST_ID_REG      0
+#define SSI_SST_MODE_REG    4
+#  define SSI_MODE_VAL_MASK  3
+#  define SSI_MODE_SLEEP    0
+#  define SSI_MODE_STREAM    1
+#  define SSI_MODE_FRAME    2
+#  define SSI_MODE_MULTIPOINTS  3
+#define SSI_SST_FRAMESIZE_REG    8
+#  define SSI_FRAMESIZE_DEFAULT  31
+#define SSI_SST_TXSTATE_REG    0xc
+#  define  SSI_TXSTATE_IDLE  0
+#define SSI_SST_BUFSTATE_REG    0x10
+#  define  SSI_FULL(channel)  (1 << (channel))
+#define SSI_SST_DIVISOR_REG    0x18
+#  define SSI_MAX_DIVISOR    127
+#define SSI_SST_BREAK_REG    0x20
+#define SSI_SST_CHANNELS_REG    0x24
+#  define SSI_CHANNELS_DEFAULT  4
+#define SSI_SST_ARBMODE_REG    0x28
+#  define SSI_ARBMODE_ROUNDROBIN  0
+#  define SSI_ARBMODE_PRIORITY  1
+#define SSI_SST_BUFFER_CH_REG(channel)  (0x80 + ((channel) * 4))
+#define SSI_SST_SWAPBUF_CH_REG(channel)  (0xc0 + ((channel) * 4))
+
+/*
+ * SSI SSR registers
+ */
+#define SSI_SSR_ID_REG      0
+#define SSI_SSR_MODE_REG    4
+#define SSI_SSR_FRAMESIZE_REG    8
+#define SSI_SSR_RXSTATE_REG    0xc
+#define SSI_SSR_BUFSTATE_REG    0x10
+#  define SSI_NOTEMPTY(channel)  (1 << (channel))
+#define SSI_SSR_BREAK_REG    0x1c
+#define SSI_SSR_ERROR_REG    0x20
+#define SSI_SSR_ERRORACK_REG    0x24
+#define SSI_SSR_OVERRUN_REG    0x2c
+#define SSI_SSR_OVERRUNACK_REG    0x30
+#define SSI_SSR_TIMEOUT_REG    0x34
+#  define SSI_TIMEOUT_DEFAULT  0
+#define SSI_SSR_CHANNELS_REG    0x28
+#define SSI_SSR_BUFFER_CH_REG(channel)  (0x80 + ((channel) * 4))
+#define SSI_SSR_SWAPBUF_CH_REG(channel)  (0xc0 + ((channel) * 4))
+
+/*
+ * SSI GDD registers
+ */
+#define SSI_GDD_HW_ID_REG    0
+#define SSI_GDD_PPORT_ID_REG    0x10
+#define SSI_GDD_MPORT_ID_REG    0x14
+#define SSI_GDD_PPORT_SR_REG    0x20
+#define SSI_GDD_MPORT_SR_REG    0x24
+#  define SSI_ACTIVE_LCH_NUM_MASK  0xff
+#define SSI_GDD_TEST_REG    0x40
+#  define SSI_TEST      1
+#define SSI_GDD_GCR_REG      0x100
+#  define  SSI_CLK_AUTOGATING_ON  (1 << 3)
+#  define  SSI_FREE    (1 << 2)
+#  define  SSI_SWITCH_OFF    (1 << 0)
+#define SSI_GDD_GRST_REG    0x200
+#  define SSI_SWRESET    1
+#define SSI_GDD_CSDP_REG(channel)  (0x800 + ((channel) * 0x40))
+#  define SSI_DST_BURST_EN_MASK  0xc000
+#  define SSI_DST_SINGLE_ACCESS0  0
+#  define SSI_DST_SINGLE_ACCESS  (1 << 14)
+#  define SSI_DST_BURST_4x32_BIT  (2 << 14)
+#  define SSI_DST_BURST_8x32_BIT  (3 << 14)
+#  define SSI_DST_MASK    0x1e00
+#  define SSI_DST_MEMORY_PORT  (8 << 9)
+#  define SSI_DST_PERIPHERAL_PORT  (9 << 9)
+#  define SSI_SRC_BURST_EN_MASK  0x180
+#  define SSI_SRC_SINGLE_ACCESS0  0
+#  define SSI_SRC_SINGLE_ACCESS  (1 << 7)
+#  define SSI_SRC_BURST_4x32_BIT  (2 << 7)
+#  define SSI_SRC_BURST_8x32_BIT  (3 << 7)
+#  define SSI_SRC_MASK    0x3c
+#  define SSI_SRC_MEMORY_PORT  (8 << 2)
+#  define SSI_SRC_PERIPHERAL_PORT  (9 << 2)
+#  define SSI_DATA_TYPE_MASK  3
+#  define SSI_DATA_TYPE_S32  2
+#define SSI_GDD_CCR_REG(channel)  (0x802 + ((channel) * 0x40))
+#  define SSI_DST_AMODE_MASK  (3 << 14)
+#  define SSI_DST_AMODE_CONST  0
+#  define SSI_DST_AMODE_POSTINC  (1 << 12)
+#  define SSI_SRC_AMODE_MASK  (3 << 12)
+#  define SSI_SRC_AMODE_CONST  0
+#  define SSI_SRC_AMODE_POSTINC  (1 << 12)
+#  define SSI_CCR_ENABLE    (1 << 7)
+#  define SSI_CCR_SYNC_MASK  0x1f
+#define SSI_GDD_CICR_REG(channel)  (0x804 + ((channel) * 0x40))
+#  define SSI_BLOCK_IE    (1 << 5)
+#  define SSI_HALF_IE    (1 << 2)
+#  define SSI_TOUT_IE    (1 << 0)
+#define SSI_GDD_CSR_REG(channel)  (0x806 + ((channel) * 0x40))
+#  define SSI_CSR_SYNC    (1 << 6)
+#  define SSI_CSR_BLOCK    (1 << 5)
+#  define SSI_CSR_HALF    (1 << 2)
+#  define SSI_CSR_TOUR    (1 << 0)
+#define SSI_GDD_CSSA_REG(channel)  (0x808 + ((channel) * 0x40))
+#define SSI_GDD_CDSA_REG(channel)  (0x80c + ((channel) * 0x40))
+#define SSI_GDD_CEN_REG(channel)  (0x810 + ((channel) * 0x40))
+#define SSI_GDD_CSAC_REG(channel)  (0x818 + ((channel) * 0x40))
+#define SSI_GDD_CDAC_REG(channel)  (0x81a + ((channel) * 0x40))
+#define SSI_GDD_CLNK_CTRL_REG(channel)  (0x828 + ((channel) * 0x40))
+#  define SSI_ENABLE_LNK    (1 << 15)
+#  define SSI_STOP_LNK    (1 << 14)
+#  define SSI_NEXT_CH_ID_MASK  0xf
+
+#endif /* __OMAP_SSI_REGS_H__ */
diff --git a/drivers/hsi/hsi_boardinfo.c b/drivers/hsi/hsi_boardinfo.c
new file mode 100644
index 000000000..8c79e4062
--- /dev/null
+++ b/drivers/hsi/hsi_boardinfo.c
@@ -0,0 +1,49 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * HSI clients registration interface
+ *
+ * Copyright (C) 2010 Nokia Corporation. All rights reserved.
+ *
+ * Contact: Carlos Chinea <carlos.chinea@nokia.com>
+ */
+#include <linux/hsi/hsi.h>
+#include <linux/list.h>
+#include <linux/slab.h>
+#include "hsi_core.h"
+
+/*
+ * hsi_board_list is only used internally by the HSI framework.
+ * No one else is allowed to make use of it.
+ */
+LIST_HEAD(hsi_board_list);
+EXPORT_SYMBOL_GPL(hsi_board_list);
+
+/**
+ * hsi_register_board_info - Register HSI clients information
+ * @info: Array of HSI clients on the board
+ * @len: Length of the array
+ *
+ * HSI clients are statically declared and registered on board files.
+ *
+ * HSI clients will be automatically registered to the HSI bus once the
+ * controller and the port where the clients wishes to attach are registered
+ * to it.
+ *
+ * Return -errno on failure, 0 on success.
+ */
+int __init hsi_register_board_info(struct hsi_board_info const *info,
+							unsigned int len)
+{
+	struct hsi_cl_info *cl_info;
+
+	cl_info = kzalloc_objs(*cl_info, len);
+	if (!cl_info)
+		return -ENOMEM;
+
+	for (; len; len--, info++, cl_info++) {
+		cl_info->info = *info;
+		list_add_tail(&cl_info->list, &hsi_board_list);
+	}
+
+	return 0;
+}
diff --git a/drivers/hsi/hsi_core.c b/drivers/hsi/hsi_core.c
new file mode 100644
index 000000000..754949f5e
--- /dev/null
+++ b/drivers/hsi/hsi_core.c
@@ -0,0 +1,760 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * HSI core.
+ *
+ * Copyright (C) 2010 Nokia Corporation. All rights reserved.
+ *
+ * Contact: Carlos Chinea <carlos.chinea@nokia.com>
+ */
+#include <linux/hsi/hsi.h>
+#include <linux/compiler.h>
+#include <linux/list.h>
+#include <linux/kobject.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+#include <linux/notifier.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include "hsi_core.h"
+
+static ssize_t modalias_show(struct device *dev,
+			struct device_attribute *a __maybe_unused, char *buf)
+{
+	return sprintf(buf, "hsi:%s\n", dev_name(dev));
+}
+static DEVICE_ATTR_RO(modalias);
+
+static struct attribute *hsi_bus_dev_attrs[] = {
+	&dev_attr_modalias.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(hsi_bus_dev);
+
+static int hsi_bus_uevent(const struct device *dev, struct kobj_uevent_env *env)
+{
+	add_uevent_var(env, "MODALIAS=hsi:%s", dev_name(dev));
+
+	return 0;
+}
+
+static int hsi_bus_match(struct device *dev, const struct device_driver *driver)
+{
+	if (of_driver_match_device(dev, driver))
+		return true;
+
+	if (strcmp(dev_name(dev), driver->name) == 0)
+		return true;
+
+	return false;
+}
+
+static const struct bus_type hsi_bus_type = {
+	.name		= "hsi",
+	.dev_groups	= hsi_bus_dev_groups,
+	.match		= hsi_bus_match,
+	.uevent		= hsi_bus_uevent,
+};
+
+static void hsi_client_release(struct device *dev)
+{
+	struct hsi_client *cl = to_hsi_client(dev);
+
+	kfree(cl->tx_cfg.channels);
+	kfree(cl->rx_cfg.channels);
+	kfree(cl);
+}
+
+struct hsi_client *hsi_new_client(struct hsi_port *port,
+						struct hsi_board_info *info)
+{
+	struct hsi_client *cl;
+	size_t size;
+
+	cl = kzalloc_obj(*cl);
+	if (!cl)
+		goto err;
+
+	cl->tx_cfg = info->tx_cfg;
+	if (cl->tx_cfg.channels) {
+		size = cl->tx_cfg.num_channels * sizeof(*cl->tx_cfg.channels);
+		cl->tx_cfg.channels = kmemdup(info->tx_cfg.channels, size,
+					      GFP_KERNEL);
+		if (!cl->tx_cfg.channels)
+			goto err_tx;
+	}
+
+	cl->rx_cfg = info->rx_cfg;
+	if (cl->rx_cfg.channels) {
+		size = cl->rx_cfg.num_channels * sizeof(*cl->rx_cfg.channels);
+		cl->rx_cfg.channels = kmemdup(info->rx_cfg.channels, size,
+					      GFP_KERNEL);
+		if (!cl->rx_cfg.channels)
+			goto err_rx;
+	}
+
+	cl->device.bus = &hsi_bus_type;
+	cl->device.parent = &port->device;
+	cl->device.release = hsi_client_release;
+	dev_set_name(&cl->device, "%s", info->name);
+	cl->device.platform_data = info->platform_data;
+	if (info->archdata)
+		cl->device.archdata = *info->archdata;
+	if (device_register(&cl->device) < 0) {
+		pr_err("hsi: failed to register client: %s\n", info->name);
+		put_device(&cl->device);
+		goto err;
+	}
+
+	return cl;
+err_rx:
+	kfree(cl->tx_cfg.channels);
+err_tx:
+	kfree(cl);
+err:
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(hsi_new_client);
+
+static void hsi_scan_board_info(struct hsi_controller *hsi)
+{
+	struct hsi_cl_info *cl_info;
+	struct hsi_port	*p;
+
+	list_for_each_entry(cl_info, &hsi_board_list, list)
+		if (cl_info->info.hsi_id == hsi->id) {
+			p = hsi_find_port_num(hsi, cl_info->info.port);
+			if (!p)
+				continue;
+			hsi_new_client(p, &cl_info->info);
+		}
+}
+
+#ifdef CONFIG_OF
+static struct hsi_board_info hsi_char_dev_info = {
+	.name = "hsi_char",
+};
+
+static int hsi_of_property_parse_mode(struct device_node *client, char *name,
+				      unsigned int *result)
+{
+	const char *mode;
+	int err;
+
+	err = of_property_read_string(client, name, &mode);
+	if (err < 0)
+		return err;
+
+	if (strcmp(mode, "stream") == 0)
+		*result = HSI_MODE_STREAM;
+	else if (strcmp(mode, "frame") == 0)
+		*result = HSI_MODE_FRAME;
+	else
+		return -EINVAL;
+
+	return 0;
+}
+
+static int hsi_of_property_parse_flow(struct device_node *client, char *name,
+				      unsigned int *result)
+{
+	const char *flow;
+	int err;
+
+	err = of_property_read_string(client, name, &flow);
+	if (err < 0)
+		return err;
+
+	if (strcmp(flow, "synchronized") == 0)
+		*result = HSI_FLOW_SYNC;
+	else if (strcmp(flow, "pipeline") == 0)
+		*result = HSI_FLOW_PIPE;
+	else
+		return -EINVAL;
+
+	return 0;
+}
+
+static int hsi_of_property_parse_arb_mode(struct device_node *client,
+					  char *name, unsigned int *result)
+{
+	const char *arb_mode;
+	int err;
+
+	err = of_property_read_string(client, name, &arb_mode);
+	if (err < 0)
+		return err;
+
+	if (strcmp(arb_mode, "round-robin") == 0)
+		*result = HSI_ARB_RR;
+	else if (strcmp(arb_mode, "priority") == 0)
+		*result = HSI_ARB_PRIO;
+	else
+		return -EINVAL;
+
+	return 0;
+}
+
+static void hsi_add_client_from_dt(struct hsi_port *port,
+						struct device_node *client)
+{
+	struct hsi_client *cl;
+	struct hsi_channel channel;
+	struct property *prop;
+	char name[32];
+	int length, cells, err, i, max_chan, mode;
+
+	cl = kzalloc_obj(*cl);
+	if (!cl)
+		return;
+
+	err = of_alias_from_compatible(client, name, sizeof(name));
+	if (err)
+		goto err;
+
+	err = hsi_of_property_parse_mode(client, "hsi-mode", &mode);
+	if (err) {
+		err = hsi_of_property_parse_mode(client, "hsi-rx-mode",
+						 &cl->rx_cfg.mode);
+		if (err)
+			goto err;
+
+		err = hsi_of_property_parse_mode(client, "hsi-tx-mode",
+						 &cl->tx_cfg.mode);
+		if (err)
+			goto err;
+	} else {
+		cl->rx_cfg.mode = mode;
+		cl->tx_cfg.mode = mode;
+	}
+
+	err = of_property_read_u32(client, "hsi-speed-kbps",
+				   &cl->tx_cfg.speed);
+	if (err)
+		goto err;
+	cl->rx_cfg.speed = cl->tx_cfg.speed;
+
+	err = hsi_of_property_parse_flow(client, "hsi-flow",
+					 &cl->rx_cfg.flow);
+	if (err)
+		goto err;
+
+	err = hsi_of_property_parse_arb_mode(client, "hsi-arb-mode",
+					     &cl->rx_cfg.arb_mode);
+	if (err)
+		goto err;
+
+	prop = of_find_property(client, "hsi-channel-ids", &length);
+	if (!prop) {
+		err = -EINVAL;
+		goto err;
+	}
+
+	cells = length / sizeof(u32);
+
+	cl->rx_cfg.num_channels = cells;
+	cl->tx_cfg.num_channels = cells;
+	cl->rx_cfg.channels = kzalloc_objs(channel, cells);
+	if (!cl->rx_cfg.channels) {
+		err = -ENOMEM;
+		goto err;
+	}
+
+	cl->tx_cfg.channels = kzalloc_objs(channel, cells);
+	if (!cl->tx_cfg.channels) {
+		err = -ENOMEM;
+		goto err2;
+	}
+
+	max_chan = 0;
+	for (i = 0; i < cells; i++) {
+		err = of_property_read_u32_index(client, "hsi-channel-ids", i,
+						 &channel.id);
+		if (err)
+			goto err3;
+
+		err = of_property_read_string_index(client, "hsi-channel-names",
+						    i, &channel.name);
+		if (err)
+			channel.name = NULL;
+
+		if (channel.id > max_chan)
+			max_chan = channel.id;
+
+		cl->rx_cfg.channels[i] = channel;
+		cl->tx_cfg.channels[i] = channel;
+	}
+
+	cl->rx_cfg.num_hw_channels = max_chan + 1;
+	cl->tx_cfg.num_hw_channels = max_chan + 1;
+
+	cl->device.bus = &hsi_bus_type;
+	cl->device.parent = &port->device;
+	cl->device.release = hsi_client_release;
+	cl->device.of_node = client;
+
+	dev_set_name(&cl->device, "%s", name);
+	if (device_register(&cl->device) < 0) {
+		pr_err("hsi: failed to register client: %s\n", name);
+		put_device(&cl->device);
+	}
+
+	return;
+
+err3:
+	kfree(cl->tx_cfg.channels);
+err2:
+	kfree(cl->rx_cfg.channels);
+err:
+	kfree(cl);
+	pr_err("hsi client: missing or incorrect of property: err=%d\n", err);
+}
+
+void hsi_add_clients_from_dt(struct hsi_port *port, struct device_node *clients)
+{
+	struct device_node *child;
+
+	/* register hsi-char device */
+	hsi_new_client(port, &hsi_char_dev_info);
+
+	for_each_available_child_of_node(clients, child)
+		hsi_add_client_from_dt(port, child);
+}
+EXPORT_SYMBOL_GPL(hsi_add_clients_from_dt);
+#endif
+
+int hsi_remove_client(struct device *dev, void *data __maybe_unused)
+{
+	device_unregister(dev);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(hsi_remove_client);
+
+static int hsi_remove_port(struct device *dev, void *data __maybe_unused)
+{
+	device_for_each_child(dev, NULL, hsi_remove_client);
+	device_unregister(dev);
+
+	return 0;
+}
+
+static void hsi_controller_release(struct device *dev)
+{
+	struct hsi_controller *hsi = to_hsi_controller(dev);
+
+	kfree(hsi);
+}
+
+static void hsi_port_release(struct device *dev)
+{
+	kfree(to_hsi_port(dev));
+}
+
+/**
+ * hsi_port_unregister_clients - Unregister an HSI port
+ * @port: The HSI port to unregister
+ */
+void hsi_port_unregister_clients(struct hsi_port *port)
+{
+	device_for_each_child(&port->device, NULL, hsi_remove_client);
+}
+EXPORT_SYMBOL_GPL(hsi_port_unregister_clients);
+
+/**
+ * hsi_unregister_controller - Unregister an HSI controller
+ * @hsi: The HSI controller to register
+ */
+void hsi_unregister_controller(struct hsi_controller *hsi)
+{
+	device_for_each_child(&hsi->device, NULL, hsi_remove_port);
+	device_unregister(&hsi->device);
+}
+EXPORT_SYMBOL_GPL(hsi_unregister_controller);
+
+/**
+ * hsi_register_controller - Register an HSI controller and its ports
+ * @hsi: The HSI controller to register
+ *
+ * Returns -errno on failure, 0 on success.
+ */
+int hsi_register_controller(struct hsi_controller *hsi)
+{
+	unsigned int i;
+	int err;
+
+	err = device_add(&hsi->device);
+	if (err < 0)
+		return err;
+	for (i = 0; i < hsi->num_ports; i++) {
+		hsi->port[i]->device.parent = &hsi->device;
+		err = device_add(&hsi->port[i]->device);
+		if (err < 0)
+			goto out;
+	}
+	/* Populate HSI bus with HSI clients */
+	hsi_scan_board_info(hsi);
+
+	return 0;
+out:
+	while (i-- > 0)
+		device_del(&hsi->port[i]->device);
+	device_del(&hsi->device);
+
+	return err;
+}
+EXPORT_SYMBOL_GPL(hsi_register_controller);
+
+/**
+ * hsi_register_client_driver - Register an HSI client to the HSI bus
+ * @drv: HSI client driver to register
+ *
+ * Returns -errno on failure, 0 on success.
+ */
+int hsi_register_client_driver(struct hsi_client_driver *drv)
+{
+	drv->driver.bus = &hsi_bus_type;
+
+	return driver_register(&drv->driver);
+}
+EXPORT_SYMBOL_GPL(hsi_register_client_driver);
+
+static inline int hsi_dummy_msg(struct hsi_msg *msg __maybe_unused)
+{
+	return 0;
+}
+
+static inline int hsi_dummy_cl(struct hsi_client *cl __maybe_unused)
+{
+	return 0;
+}
+
+/**
+ * hsi_put_controller - Free an HSI controller
+ *
+ * @hsi: Pointer to the HSI controller to freed
+ *
+ * HSI controller drivers should only use this function if they need
+ * to free their allocated hsi_controller structures before a successful
+ * call to hsi_register_controller. Other use is not allowed.
+ */
+void hsi_put_controller(struct hsi_controller *hsi)
+{
+	unsigned int i;
+
+	if (!hsi)
+		return;
+
+	for (i = 0; i < hsi->num_ports; i++)
+		if (hsi->port[i])
+			put_device(&hsi->port[i]->device);
+	put_device(&hsi->device);
+}
+EXPORT_SYMBOL_GPL(hsi_put_controller);
+
+/**
+ * hsi_alloc_controller - Allocate an HSI controller and its ports
+ * @n_ports: Number of ports on the HSI controller
+ * @flags: Kernel allocation flags
+ *
+ * Return NULL on failure or a pointer to an hsi_controller on success.
+ */
+struct hsi_controller *hsi_alloc_controller(unsigned int n_ports, gfp_t flags)
+{
+	struct hsi_controller	*hsi;
+	unsigned int		i;
+
+	if (!n_ports)
+		return NULL;
+
+	hsi = kzalloc_flex(*hsi, port, n_ports, flags);
+	if (!hsi)
+		return NULL;
+
+	hsi->num_ports = n_ports;
+	hsi->device.release = hsi_controller_release;
+	device_initialize(&hsi->device);
+
+	for (i = 0; i < n_ports; i++) {
+		hsi->port[i] = kzalloc_obj(**hsi->port, flags);
+		if (hsi->port[i] == NULL)
+			goto out;
+		hsi->port[i]->num = i;
+		hsi->port[i]->async = hsi_dummy_msg;
+		hsi->port[i]->setup = hsi_dummy_cl;
+		hsi->port[i]->flush = hsi_dummy_cl;
+		hsi->port[i]->start_tx = hsi_dummy_cl;
+		hsi->port[i]->stop_tx = hsi_dummy_cl;
+		hsi->port[i]->release = hsi_dummy_cl;
+		mutex_init(&hsi->port[i]->lock);
+		BLOCKING_INIT_NOTIFIER_HEAD(&hsi->port[i]->n_head);
+		dev_set_name(&hsi->port[i]->device, "port%d", i);
+		hsi->port[i]->device.release = hsi_port_release;
+		device_initialize(&hsi->port[i]->device);
+	}
+
+	return hsi;
+out:
+	hsi_put_controller(hsi);
+
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(hsi_alloc_controller);
+
+/**
+ * hsi_free_msg - Free an HSI message
+ * @msg: Pointer to the HSI message
+ *
+ * Client is responsible to free the buffers pointed by the scatterlists.
+ */
+void hsi_free_msg(struct hsi_msg *msg)
+{
+	if (!msg)
+		return;
+	sg_free_table(&msg->sgt);
+	kfree(msg);
+}
+EXPORT_SYMBOL_GPL(hsi_free_msg);
+
+/**
+ * hsi_alloc_msg - Allocate an HSI message
+ * @nents: Number of memory entries
+ * @flags: Kernel allocation flags
+ *
+ * nents can be 0. This mainly makes sense for read transfer.
+ * In that case, HSI drivers will call the complete callback when
+ * there is data to be read without consuming it.
+ *
+ * Return NULL on failure or a pointer to an hsi_msg on success.
+ */
+struct hsi_msg *hsi_alloc_msg(unsigned int nents, gfp_t flags)
+{
+	struct hsi_msg *msg;
+	int err;
+
+	msg = kzalloc_obj(*msg, flags);
+	if (!msg)
+		return NULL;
+
+	if (!nents)
+		return msg;
+
+	err = sg_alloc_table(&msg->sgt, nents, flags);
+	if (unlikely(err)) {
+		kfree(msg);
+		msg = NULL;
+	}
+
+	return msg;
+}
+EXPORT_SYMBOL_GPL(hsi_alloc_msg);
+
+/**
+ * hsi_async - Submit an HSI transfer to the controller
+ * @cl: HSI client sending the transfer
+ * @msg: The HSI transfer passed to controller
+ *
+ * The HSI message must have the channel, ttype, complete and destructor
+ * fields set beforehand. If nents > 0 then the client has to initialize
+ * also the scatterlists to point to the buffers to write to or read from.
+ *
+ * HSI controllers relay on pre-allocated buffers from their clients and they
+ * do not allocate buffers on their own.
+ *
+ * Once the HSI message transfer finishes, the HSI controller calls the
+ * complete callback with the status and actual_len fields of the HSI message
+ * updated. The complete callback can be called before returning from
+ * hsi_async.
+ *
+ * Returns -errno on failure or 0 on success
+ */
+int hsi_async(struct hsi_client *cl, struct hsi_msg *msg)
+{
+	struct hsi_port *port = hsi_get_port(cl);
+
+	if (!hsi_port_claimed(cl))
+		return -EACCES;
+
+	WARN_ON_ONCE(!msg->destructor || !msg->complete);
+	msg->cl = cl;
+
+	return port->async(msg);
+}
+EXPORT_SYMBOL_GPL(hsi_async);
+
+/**
+ * hsi_claim_port - Claim the HSI client's port
+ * @cl: HSI client that wants to claim its port
+ * @share: Flag to indicate if the client wants to share the port or not.
+ *
+ * Returns -errno on failure, 0 on success.
+ */
+int hsi_claim_port(struct hsi_client *cl, unsigned int share)
+{
+	struct hsi_port *port = hsi_get_port(cl);
+	int err = 0;
+
+	mutex_lock(&port->lock);
+	if ((port->claimed) && (!port->shared || !share)) {
+		err = -EBUSY;
+		goto out;
+	}
+	if (!try_module_get(to_hsi_controller(port->device.parent)->owner)) {
+		err = -ENODEV;
+		goto out;
+	}
+	port->claimed++;
+	port->shared = !!share;
+	cl->pclaimed = 1;
+out:
+	mutex_unlock(&port->lock);
+
+	return err;
+}
+EXPORT_SYMBOL_GPL(hsi_claim_port);
+
+/**
+ * hsi_release_port - Release the HSI client's port
+ * @cl: HSI client which previously claimed its port
+ */
+void hsi_release_port(struct hsi_client *cl)
+{
+	struct hsi_port *port = hsi_get_port(cl);
+
+	mutex_lock(&port->lock);
+	/* Allow HW driver to do some cleanup */
+	port->release(cl);
+	if (cl->pclaimed)
+		port->claimed--;
+	BUG_ON(port->claimed < 0);
+	cl->pclaimed = 0;
+	if (!port->claimed)
+		port->shared = 0;
+	module_put(to_hsi_controller(port->device.parent)->owner);
+	mutex_unlock(&port->lock);
+}
+EXPORT_SYMBOL_GPL(hsi_release_port);
+
+static int hsi_event_notifier_call(struct notifier_block *nb,
+				unsigned long event, void *data __maybe_unused)
+{
+	struct hsi_client *cl = container_of(nb, struct hsi_client, nb);
+
+	(*cl->ehandler)(cl, event);
+
+	return 0;
+}
+
+/**
+ * hsi_register_port_event - Register a client to receive port events
+ * @cl: HSI client that wants to receive port events
+ * @handler: Event handler callback
+ *
+ * Clients should register a callback to be able to receive
+ * events from the ports. Registration should happen after
+ * claiming the port.
+ * The handler can be called in interrupt context.
+ *
+ * Returns -errno on error, or 0 on success.
+ */
+int hsi_register_port_event(struct hsi_client *cl,
+			void (*handler)(struct hsi_client *, unsigned long))
+{
+	struct hsi_port *port = hsi_get_port(cl);
+
+	if (!handler || cl->ehandler)
+		return -EINVAL;
+	if (!hsi_port_claimed(cl))
+		return -EACCES;
+	cl->ehandler = handler;
+	cl->nb.notifier_call = hsi_event_notifier_call;
+
+	return blocking_notifier_chain_register(&port->n_head, &cl->nb);
+}
+EXPORT_SYMBOL_GPL(hsi_register_port_event);
+
+/**
+ * hsi_unregister_port_event - Stop receiving port events for a client
+ * @cl: HSI client that wants to stop receiving port events
+ *
+ * Clients should call this function before releasing their associated
+ * port.
+ *
+ * Returns -errno on error, or 0 on success.
+ */
+int hsi_unregister_port_event(struct hsi_client *cl)
+{
+	struct hsi_port *port = hsi_get_port(cl);
+	int err;
+
+	WARN_ON(!hsi_port_claimed(cl));
+
+	err = blocking_notifier_chain_unregister(&port->n_head, &cl->nb);
+	if (!err)
+		cl->ehandler = NULL;
+
+	return err;
+}
+EXPORT_SYMBOL_GPL(hsi_unregister_port_event);
+
+/**
+ * hsi_event - Notifies clients about port events
+ * @port: Port where the event occurred
+ * @event: The event type
+ *
+ * Clients should not be concerned about wake line behavior. However, due
+ * to a race condition in HSI HW protocol, clients need to be notified
+ * about wake line changes, so they can implement a workaround for it.
+ *
+ * Events:
+ * HSI_EVENT_START_RX - Incoming wake line high
+ * HSI_EVENT_STOP_RX - Incoming wake line down
+ *
+ * Returns -errno on error, or 0 on success.
+ */
+int hsi_event(struct hsi_port *port, unsigned long event)
+{
+	return blocking_notifier_call_chain(&port->n_head, event, NULL);
+}
+EXPORT_SYMBOL_GPL(hsi_event);
+
+/**
+ * hsi_get_channel_id_by_name - acquire channel id by channel name
+ * @cl: HSI client, which uses the channel
+ * @name: name the channel is known under
+ *
+ * Clients can call this function to get the hsi channel ids similar to
+ * requesting IRQs or GPIOs by name. This function assumes the same
+ * channel configuration is used for RX and TX.
+ *
+ * Returns -errno on error or channel id on success.
+ */
+int hsi_get_channel_id_by_name(struct hsi_client *cl, char *name)
+{
+	int i;
+
+	if (!cl->rx_cfg.channels)
+		return -ENOENT;
+
+	for (i = 0; i < cl->rx_cfg.num_channels; i++)
+		if (!strcmp(cl->rx_cfg.channels[i].name, name))
+			return cl->rx_cfg.channels[i].id;
+
+	return -ENXIO;
+}
+EXPORT_SYMBOL_GPL(hsi_get_channel_id_by_name);
+
+static int __init hsi_init(void)
+{
+	return bus_register(&hsi_bus_type);
+}
+postcore_initcall(hsi_init);
+
+static void __exit hsi_exit(void)
+{
+	bus_unregister(&hsi_bus_type);
+}
+module_exit(hsi_exit);
+
+MODULE_AUTHOR("Carlos Chinea <carlos.chinea@nokia.com>");
+MODULE_DESCRIPTION("High-speed Synchronous Serial Interface (HSI) framework");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/hsi/hsi_core.h b/drivers/hsi/hsi_core.h
new file mode 100644
index 000000000..bdb06ca09
--- /dev/null
+++ b/drivers/hsi/hsi_core.h
@@ -0,0 +1,22 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * HSI framework internal interfaces,
+ *
+ * Copyright (C) 2010 Nokia Corporation. All rights reserved.
+ *
+ * Contact: Carlos Chinea <carlos.chinea@nokia.com>
+ */
+
+#ifndef __LINUX_HSI_CORE_H__
+#define __LINUX_HSI_CORE_H__
+
+#include <linux/hsi/hsi.h>
+
+struct hsi_cl_info {
+	struct list_head	list;
+	struct hsi_board_info	info;
+};
+
+extern struct list_head hsi_board_list;
+
+#endif /* __LINUX_HSI_CORE_H__ */