Merge tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Don't destroy user event fields when removal fails

   User event fields are destroyed before the event is removed from
   visibility. But that can fail leaving the still visible event with no
   fields. Move the destroying of the fields to after the event is
   successfully removed from visibility.

 - Initialize function graph state is fork before calling
   copy_exec_state()

   For non-CLONE_VM forks, copy_exec_state() allocates a new
   task_exec_state. If that allocation fails, ftrace_graph_exit_task()
   will free the tasks ret_stack pointer. Since that pointer is still
   using the parent's ret_stack, it mistakenly frees the parent's
   pointer too.

   Call ftrace_graph_init() on the task first which will NULL out the
   new tasks's ret_stack and if the copy fails, it will not free
   anything.

 - Remove FGRAPH_MAX_INDEX

   The macro FGRAPH_MAX_INDEX was added but never used. Remove it.

 - Save ent_size in function graph printing of nested functions

   The function graph tracer needs to look at the next event to see if
   the next event is the return of the current function entry. If it is,
   it prints a single line:

	ktime_get();

   Otherwise it prints it like a nested function:

	tick_nohz_irq_exit() {
	    ktime_get();
	    kcpustat_irq_exit();
	}

   In order to look at the next event, it must save the current event so
   that it has the information to print from it. It saves the event in
   the iterator descriptor called "ent". What it doesn't save is the
   ent_size of the event which is now used to know if the function graph
   arguments are to be printed. The peek doesn't save the size so the
   size used happens to be that of the size of the last event that was
   seen.

   Save the entry event size in the iterator descriptor so that the
   correct size is used.

 - Fix several errors with freeing data in the histogram code

   The histogram code had a lot of leaked or or incorrect accounting
   when failures happen. Correct them.

 - Fix histogram regression of .percent and .graph modifiers

   Up until 6.3 histogram values could have "percent" or "graph"
   modifiers that changed how they were printed. But a change that added
   restricting histograms values from being strings, stack traces and
   other modifiers inadvertently prevented them from using the percent
   and graph modifiers, which were legal use cases for values.

   Put back the percent and graph modifiers.

 - Fix various typos in the comments

 - Set the trace_clock before initializing a histogram with clock
   argument

   The histogram API allows the user to specific which trace clock to
   use via a "clock=" string. The histogram is set up first before the
   clock is checked. If the passed in clock is not valid, it exits
   without fully fixing up the histogram leaving it on the list and a
   use-after-free can trigger.

   Update the clock argument first and if it fails then exit gracefully
   before the histogram trigger is placed on any lists.

 - Restore :mod: trailer after parsing in ftrace_set_clr_event

   The function ftrace_set_clr_event() modifies the parse string and
   needs to put it back to what was passed in. It searches for ":mod:"
   via a strsep() but fails to put back the first ':' in the string.

   Add back the ':' in the passed in string.

 - Take trace_array reference when opening a tracer options file

   The options files are dynamically created and some tracers add their
   own options. When a tracer adds their own list of options, the
   trace_array holding them has an array to hold the list of options for
   each tracer. This array increases in size via a krealloc(), and the
   new entry gets a newly allocated array to hold the options of the new
   tracer being added.

   The element in each entry of the tracer's option array holds a
   pointer back to the trace_array, a pointer to the tracer it is
   associated to, a pointer to the flags of the option.

   The issue is that these arrays are freed when the trace_array is
   freed when its instance it represents is removed from the instances
   directory. There's a race that an open of one of these options files
   can happen when the instance is being removed.

   Add a new helper function to be called by the open function of the
   options file to iterate all existing trace_arrays under a lock and
   find the one that has the given option element in one of it's tracer
   arrays. If found, then update the associated trace_array's reference
   counter to keep it from being freed. If not found, have the open call
   return -ENODEV.

 - Disable interrupts when acquiring the lock in rb_wake_up_waiters()

   The function rb_wake_up_waiters() assumes it will be called in
   interrupt context and does not disable irqs when taking
   cpu_buffer->reader_lock, which can be called in hard interrupt
   context. The issue is in PREEMPT_RT, this function is called in
   thread context leaving this lock open to a deadlock.

   Take the lock with interrupts disabled.

 - Use rcu_assign_pointer() for tmp_ops filter hash

   The tmp_ops used in update_ftrace_direct_mod() assigns its
   filter_hash field directly, but that field is annotated as __rcu and
   sparse complains. Assign it with rcu_assign_pointer()

 - Fix use-after-free in enable_trigger_private_data_free()

   The trace_event_call is accessed through the event_trigger_data's
   trace_event_file pointer to put the trace_event_call on freeing. The
   issue is that the trace_event_file data may have been freed already
   causing a use-after-free. Add a field to the event_trigger_data that
   points directly to the trace_event_call so that it can decrement its
   reference directly without needing to go through the
   trace_event_file.

 - Fix accounting of buffer data remote headers

   trace_buffer_desc_size() and trace_remote_alloc_buffer() undercount
   the number of pages is needed for the asked for size as it doesn't
   take into account the meta data on each page. Add a helper function
   to do the calculation properly and use that in these functions.

 - Catch nr_page_va overflow in ring_buffer_desc sizing

   The number of pages per remote ring buffer is capped by
   ring_buffer_desc::nr_page_va (32 bits). A buffer_size large enough to
   overflow that field would silently allocate a descriptor smaller than
   what was asked for.

 - Do not resize the subbuf order if any per_cpu buffer is disabled

   The mmapping of ring buffers disables resizing the subbuffers, but it
   is done per-cpu whereas the subbuf size change is done for all the
   per_cpu buffers under the buffer->mutex. It could change the size of
   some while the mapping is happening on others. Have the resize of the
   subbuf order check all the per_cpu buffers under the lock to see if
   any of them is disabled before starting and causing an inconsistency
   between buffers that are being mapped.

* tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (25 commits)
  ring-buffer: Check resize_disabled before publishing the new subbuf order
  tracing/remotes: Catch nr_page_va overflow in ring_buffer_desc sizing
  tracing/remotes: Account for ring buffer page header in size calculation
  tracing: Don't dereference trace_event_file in deferred trigger free
  ftrace: Use rcu_assign_pointer() for tmp_ops filter hash
  ring-buffer: Acquire the lock with irqsave in rb_wake_up_waiters()
  tracing: Take trace_array reference when opening a tracer options file
  tracing: Fix ring_buffer_read_page_size() kernel-doc
  tracing: Restore :mod: trailer after parsing in ftrace_set_clr_event()
  tracing: Fix memory corruption from a "STACKTRACE" histogram key
  tracing: Fix memory corruption from the histogram stacktrace modifier
  tracing: Undo the registration when enabling the histogram trigger fails
  tracing: Take the reference before publishing the named histogram trigger
  tracing: Set the trace clock before registering the histogram trigger
  tracing: Fix typo "preceeded" in comment
  tracing: Fix typo "availabe" in comment
  tracing: Let histogram values keep the percent and graph modifiers
  tracing: Keep the entry count when the histogram stats allocation fails
  tracing: Free histogram the field rejected for a bad modifier
  tracing: Free histogram the var ref when its initialization fails
  ...

1 files changed, 997 insertions, 0 deletions

diff --git a/drivers/bluetooth/btmtkuart.c b/drivers/bluetooth/btmtkuart.c
new file mode 100644
index 000000000..27aa48ff3
--- /dev/null
+++ b/drivers/bluetooth/btmtkuart.c
@@ -0,0 +1,997 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2018 MediaTek Inc.
+
+/*
+ * Bluetooth support for MediaTek serial devices
+ *
+ * Author: Sean Wang <sean.wang@mediatek.com>
+ *
+ */
+
+#include <linux/unaligned.h>
+#include <linux/atomic.h>
+#include <linux/clk.h>
+#include <linux/firmware.h>
+#include <linux/gpio/consumer.h>
+#include <linux/iopoll.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/pinctrl/consumer.h>
+#include <linux/pm_runtime.h>
+#include <linux/regulator/consumer.h>
+#include <linux/serdev.h>
+#include <linux/skbuff.h>
+#include <linux/usb.h>
+
+#include <net/bluetooth/bluetooth.h>
+#include <net/bluetooth/hci_core.h>
+
+#include "hci_uart.h"
+#include "btmtk.h"
+
+#define VERSION "0.2"
+
+#define MTK_STP_TLR_SIZE	2
+
+#define BTMTKUART_TX_STATE_ACTIVE	1
+#define BTMTKUART_TX_STATE_WAKEUP	2
+#define BTMTKUART_TX_WAIT_VND_EVT	3
+#define BTMTKUART_REQUIRED_WAKEUP	4
+
+#define BTMTKUART_FLAG_STANDALONE_HW	 BIT(0)
+
+struct mtk_stp_hdr {
+	u8	prefix;
+	__be16	dlen;
+	u8	cs;
+} __packed;
+
+struct btmtkuart_data {
+	unsigned int flags;
+	const char *fwname;
+};
+
+struct btmtkuart_dev {
+	struct hci_dev *hdev;
+	struct serdev_device *serdev;
+
+	struct clk *clk;
+	struct clk *osc;
+	struct regulator *vcc;
+	struct gpio_desc *reset;
+	struct gpio_desc *boot;
+	struct pinctrl *pinctrl;
+	struct pinctrl_state *pins_runtime;
+	struct pinctrl_state *pins_boot;
+	speed_t	desired_speed;
+	speed_t	curr_speed;
+
+	struct work_struct tx_work;
+	unsigned long tx_state;
+	struct sk_buff_head txq;
+
+	struct sk_buff *rx_skb;
+	struct sk_buff *evt_skb;
+
+	u8	stp_pad[6];
+	u8	stp_cursor;
+	u16	stp_dlen;
+
+	const struct btmtkuart_data *data;
+	struct hci_uart hu;
+};
+
+#define btmtkuart_is_standalone(bdev)	\
+	((bdev)->data->flags & BTMTKUART_FLAG_STANDALONE_HW)
+#define btmtkuart_is_builtin_soc(bdev)	\
+	!((bdev)->data->flags & BTMTKUART_FLAG_STANDALONE_HW)
+
+static int mtk_hci_wmt_sync(struct hci_dev *hdev,
+			    struct btmtk_hci_wmt_params *wmt_params)
+{
+	struct btmtkuart_dev *bdev = hci_get_drvdata(hdev);
+	struct btmtk_hci_wmt_evt_funcc *wmt_evt_funcc;
+	u32 hlen, status = BTMTK_WMT_INVALID;
+	struct btmtk_hci_wmt_evt *wmt_evt;
+	struct btmtk_hci_wmt_cmd *wc;
+	struct btmtk_wmt_hdr *hdr;
+	int err;
+
+	/* Send the WMT command and wait until the WMT event returns */
+	hlen = sizeof(*hdr) + wmt_params->dlen;
+	if (hlen > 255) {
+		err = -EINVAL;
+		goto err_free_skb;
+	}
+
+	wc = kzalloc(hlen, GFP_KERNEL);
+	if (!wc) {
+		err = -ENOMEM;
+		goto err_free_skb;
+	}
+
+	hdr = &wc->hdr;
+	hdr->dir = 1;
+	hdr->op = wmt_params->op;
+	hdr->dlen = cpu_to_le16(wmt_params->dlen + 1);
+	hdr->flag = wmt_params->flag;
+	memcpy(wc->data, wmt_params->data, wmt_params->dlen);
+
+	set_bit(BTMTKUART_TX_WAIT_VND_EVT, &bdev->tx_state);
+
+	err = __hci_cmd_send(hdev, 0xfc6f, hlen, wc);
+	if (err < 0) {
+		clear_bit(BTMTKUART_TX_WAIT_VND_EVT, &bdev->tx_state);
+		goto err_free_wc;
+	}
+
+	/* The vendor specific WMT commands are all answered by a vendor
+	 * specific event and will not have the Command Status or Command
+	 * Complete as with usual HCI command flow control.
+	 *
+	 * After sending the command, wait for BTMTKUART_TX_WAIT_VND_EVT
+	 * state to be cleared. The driver specific event receive routine
+	 * will clear that state and with that indicate completion of the
+	 * WMT command.
+	 */
+	err = wait_on_bit_timeout(&bdev->tx_state, BTMTKUART_TX_WAIT_VND_EVT,
+				  TASK_INTERRUPTIBLE, HCI_INIT_TIMEOUT);
+	if (err == -EINTR) {
+		bt_dev_err(hdev, "Execution of wmt command interrupted");
+		clear_bit(BTMTKUART_TX_WAIT_VND_EVT, &bdev->tx_state);
+		goto err_free_wc;
+	}
+
+	if (err) {
+		bt_dev_err(hdev, "Execution of wmt command timed out");
+		clear_bit(BTMTKUART_TX_WAIT_VND_EVT, &bdev->tx_state);
+		err = -ETIMEDOUT;
+		goto err_free_wc;
+	}
+
+	/* Parse and handle the return WMT event */
+	wmt_evt = (struct btmtk_hci_wmt_evt *)bdev->evt_skb->data;
+	if (wmt_evt->whdr.op != hdr->op) {
+		bt_dev_err(hdev, "Wrong op received %d expected %d",
+			   wmt_evt->whdr.op, hdr->op);
+		err = -EIO;
+		goto err_free_wc;
+	}
+
+	switch (wmt_evt->whdr.op) {
+	case BTMTK_WMT_SEMAPHORE:
+		if (wmt_evt->whdr.flag == 2)
+			status = BTMTK_WMT_PATCH_UNDONE;
+		else
+			status = BTMTK_WMT_PATCH_DONE;
+		break;
+	case BTMTK_WMT_FUNC_CTRL:
+		wmt_evt_funcc = (struct btmtk_hci_wmt_evt_funcc *)wmt_evt;
+		if (be16_to_cpu(wmt_evt_funcc->status) == 0x404)
+			status = BTMTK_WMT_ON_DONE;
+		else if (be16_to_cpu(wmt_evt_funcc->status) == 0x420)
+			status = BTMTK_WMT_ON_PROGRESS;
+		else
+			status = BTMTK_WMT_ON_UNDONE;
+		break;
+	}
+
+	if (wmt_params->status)
+		*wmt_params->status = status;
+
+err_free_wc:
+	kfree(wc);
+err_free_skb:
+	kfree_skb(bdev->evt_skb);
+	bdev->evt_skb = NULL;
+
+	return err;
+}
+
+static int btmtkuart_recv_event(struct hci_dev *hdev, struct sk_buff *skb)
+{
+	struct btmtkuart_dev *bdev = hci_get_drvdata(hdev);
+	struct hci_event_hdr *hdr = (void *)skb->data;
+	int err;
+
+	/* When someone waits for the WMT event, the skb is being cloned
+	 * and being processed the events from there then.
+	 */
+	if (test_bit(BTMTKUART_TX_WAIT_VND_EVT, &bdev->tx_state)) {
+		bdev->evt_skb = skb_clone(skb, GFP_KERNEL);
+		if (!bdev->evt_skb) {
+			err = -ENOMEM;
+			goto err_out;
+		}
+	}
+
+	err = hci_recv_frame(hdev, skb);
+	if (err < 0)
+		goto err_free_skb;
+
+	if (hdr->evt == HCI_EV_WMT) {
+		if (test_and_clear_bit(BTMTKUART_TX_WAIT_VND_EVT,
+				       &bdev->tx_state)) {
+			/* Barrier to sync with other CPUs */
+			smp_mb__after_atomic();
+			wake_up_bit(&bdev->tx_state, BTMTKUART_TX_WAIT_VND_EVT);
+		}
+	}
+
+	return 0;
+
+err_free_skb:
+	kfree_skb(bdev->evt_skb);
+	bdev->evt_skb = NULL;
+
+err_out:
+	return err;
+}
+
+static const struct h4_recv_pkt mtk_recv_pkts[] = {
+	{ H4_RECV_ACL,      .recv = hci_recv_frame },
+	{ H4_RECV_SCO,      .recv = hci_recv_frame },
+	{ H4_RECV_EVENT,    .recv = btmtkuart_recv_event },
+};
+
+static void btmtkuart_tx_work(struct work_struct *work)
+{
+	struct btmtkuart_dev *bdev = container_of(work, struct btmtkuart_dev,
+						   tx_work);
+	struct serdev_device *serdev = bdev->serdev;
+	struct hci_dev *hdev = bdev->hdev;
+
+	while (1) {
+		clear_bit(BTMTKUART_TX_STATE_WAKEUP, &bdev->tx_state);
+
+		while (1) {
+			struct sk_buff *skb = skb_dequeue(&bdev->txq);
+			int len;
+
+			if (!skb)
+				break;
+
+			len = serdev_device_write_buf(serdev, skb->data,
+						      skb->len);
+			hdev->stat.byte_tx += len;
+
+			skb_pull(skb, len);
+			if (skb->len > 0) {
+				skb_queue_head(&bdev->txq, skb);
+				break;
+			}
+
+			switch (hci_skb_pkt_type(skb)) {
+			case HCI_COMMAND_PKT:
+				hdev->stat.cmd_tx++;
+				break;
+			case HCI_ACLDATA_PKT:
+				hdev->stat.acl_tx++;
+				break;
+			case HCI_SCODATA_PKT:
+				hdev->stat.sco_tx++;
+				break;
+			}
+
+			kfree_skb(skb);
+		}
+
+		if (!test_bit(BTMTKUART_TX_STATE_WAKEUP, &bdev->tx_state))
+			break;
+	}
+
+	clear_bit(BTMTKUART_TX_STATE_ACTIVE, &bdev->tx_state);
+}
+
+static void btmtkuart_tx_wakeup(struct btmtkuart_dev *bdev)
+{
+	if (test_and_set_bit(BTMTKUART_TX_STATE_ACTIVE, &bdev->tx_state))
+		set_bit(BTMTKUART_TX_STATE_WAKEUP, &bdev->tx_state);
+
+	schedule_work(&bdev->tx_work);
+}
+
+static const unsigned char *
+mtk_stp_split(struct btmtkuart_dev *bdev, const unsigned char *data, int count,
+	      int *sz_h4)
+{
+	struct mtk_stp_hdr *shdr;
+
+	/* The cursor is reset when all the data of STP is consumed out */
+	if (!bdev->stp_dlen && bdev->stp_cursor >= 6)
+		bdev->stp_cursor = 0;
+
+	/* Filling pad until all STP info is obtained */
+	while (bdev->stp_cursor < 6 && count > 0) {
+		bdev->stp_pad[bdev->stp_cursor] = *data;
+		bdev->stp_cursor++;
+		data++;
+		count--;
+	}
+
+	/* Retrieve STP info and have a sanity check */
+	if (!bdev->stp_dlen && bdev->stp_cursor >= 6) {
+		shdr = (struct mtk_stp_hdr *)&bdev->stp_pad[2];
+		bdev->stp_dlen = be16_to_cpu(shdr->dlen) & 0x0fff;
+
+		/* Resync STP when unexpected data is being read */
+		if (shdr->prefix != 0x80 || bdev->stp_dlen > 2048) {
+			bt_dev_err(bdev->hdev, "stp format unexpected (%d, %d)",
+				   shdr->prefix, bdev->stp_dlen);
+			bdev->stp_cursor = 2;
+			bdev->stp_dlen = 0;
+		}
+	}
+
+	/* Directly quit when there's no data found for H4 can process */
+	if (count <= 0)
+		return NULL;
+
+	/* Translate to how much the size of data H4 can handle so far */
+	*sz_h4 = min_t(int, count, bdev->stp_dlen);
+
+	/* Update the remaining size of STP packet */
+	bdev->stp_dlen -= *sz_h4;
+
+	/* Data points to STP payload which can be handled by H4 */
+	return data;
+}
+
+static void btmtkuart_recv(struct hci_dev *hdev, const u8 *data, size_t count)
+{
+	struct btmtkuart_dev *bdev = hci_get_drvdata(hdev);
+	const unsigned char *p_left = data, *p_h4;
+	int sz_left = count, sz_h4, adv;
+	int err;
+
+	while (sz_left > 0) {
+		/*  The serial data received from MT7622 BT controller is
+		 *  at all time padded around with the STP header and tailer.
+		 *
+		 *  A full STP packet is looking like
+		 *   -----------------------------------
+		 *  | STP header  |  H:4   | STP tailer |
+		 *   -----------------------------------
+		 *  but it doesn't guarantee to contain a full H:4 packet which
+		 *  means that it's possible for multiple STP packets forms a
+		 *  full H:4 packet that means extra STP header + length doesn't
+		 *  indicate a full H:4 frame, things can fragment. Whose length
+		 *  recorded in STP header just shows up the most length the
+		 *  H:4 engine can handle currently.
+		 */
+
+		p_h4 = mtk_stp_split(bdev, p_left, sz_left, &sz_h4);
+		if (!p_h4)
+			break;
+
+		adv = p_h4 - p_left;
+		sz_left -= adv;
+		p_left += adv;
+
+		bdev->rx_skb = h4_recv_buf(&bdev->hu, bdev->rx_skb, p_h4,
+					   sz_h4, mtk_recv_pkts,
+					   ARRAY_SIZE(mtk_recv_pkts));
+		if (IS_ERR(bdev->rx_skb)) {
+			err = PTR_ERR(bdev->rx_skb);
+			bt_dev_err(bdev->hdev,
+				   "Frame reassembly failed (%d)", err);
+			bdev->rx_skb = NULL;
+			return;
+		}
+
+		sz_left -= sz_h4;
+		p_left += sz_h4;
+	}
+}
+
+static size_t btmtkuart_receive_buf(struct serdev_device *serdev,
+				    const u8 *data, size_t count)
+{
+	struct btmtkuart_dev *bdev = serdev_device_get_drvdata(serdev);
+
+	btmtkuart_recv(bdev->hdev, data, count);
+
+	bdev->hdev->stat.byte_rx += count;
+
+	return count;
+}
+
+static void btmtkuart_write_wakeup(struct serdev_device *serdev)
+{
+	struct btmtkuart_dev *bdev = serdev_device_get_drvdata(serdev);
+
+	btmtkuart_tx_wakeup(bdev);
+}
+
+static const struct serdev_device_ops btmtkuart_client_ops = {
+	.receive_buf = btmtkuart_receive_buf,
+	.write_wakeup = btmtkuart_write_wakeup,
+};
+
+static int btmtkuart_open(struct hci_dev *hdev)
+{
+	struct btmtkuart_dev *bdev = hci_get_drvdata(hdev);
+	struct device *dev;
+	int err;
+
+	err = serdev_device_open(bdev->serdev);
+	if (err) {
+		bt_dev_err(hdev, "Unable to open UART device %s",
+			   dev_name(&bdev->serdev->dev));
+		goto err_open;
+	}
+
+	if (btmtkuart_is_standalone(bdev)) {
+		if (bdev->curr_speed != bdev->desired_speed)
+			err = serdev_device_set_baudrate(bdev->serdev,
+							 115200);
+		else
+			err = serdev_device_set_baudrate(bdev->serdev,
+							 bdev->desired_speed);
+
+		if (err < 0) {
+			bt_dev_err(hdev, "Unable to set baudrate UART device %s",
+				   dev_name(&bdev->serdev->dev));
+			goto  err_serdev_close;
+		}
+
+		serdev_device_set_flow_control(bdev->serdev, false);
+	}
+
+	bdev->stp_cursor = 2;
+	bdev->stp_dlen = 0;
+
+	dev = &bdev->serdev->dev;
+
+	/* Enable the power domain and clock the device requires */
+	pm_runtime_enable(dev);
+	err = pm_runtime_resume_and_get(dev);
+	if (err < 0)
+		goto err_disable_rpm;
+
+	err = clk_prepare_enable(bdev->clk);
+	if (err < 0)
+		goto err_put_rpm;
+
+	return 0;
+
+err_put_rpm:
+	pm_runtime_put_sync(dev);
+err_disable_rpm:
+	pm_runtime_disable(dev);
+err_serdev_close:
+	serdev_device_close(bdev->serdev);
+err_open:
+	return err;
+}
+
+static int btmtkuart_close(struct hci_dev *hdev)
+{
+	struct btmtkuart_dev *bdev = hci_get_drvdata(hdev);
+	struct device *dev = &bdev->serdev->dev;
+
+	/* Shutdown the clock and power domain the device requires */
+	clk_disable_unprepare(bdev->clk);
+	pm_runtime_put_sync(dev);
+	pm_runtime_disable(dev);
+
+	serdev_device_close(bdev->serdev);
+
+	return 0;
+}
+
+static int btmtkuart_flush(struct hci_dev *hdev)
+{
+	struct btmtkuart_dev *bdev = hci_get_drvdata(hdev);
+
+	/* Flush any pending characters */
+	serdev_device_write_flush(bdev->serdev);
+	skb_queue_purge(&bdev->txq);
+
+	cancel_work_sync(&bdev->tx_work);
+
+	kfree_skb(bdev->rx_skb);
+	bdev->rx_skb = NULL;
+
+	bdev->stp_cursor = 2;
+	bdev->stp_dlen = 0;
+
+	return 0;
+}
+
+static int btmtkuart_func_query(struct hci_dev *hdev)
+{
+	struct btmtk_hci_wmt_params wmt_params;
+	int status, err;
+	u8 param = 0;
+
+	/* Query whether the function is enabled */
+	wmt_params.op = BTMTK_WMT_FUNC_CTRL;
+	wmt_params.flag = 4;
+	wmt_params.dlen = sizeof(param);
+	wmt_params.data = &param;
+	wmt_params.status = &status;
+
+	err = mtk_hci_wmt_sync(hdev, &wmt_params);
+	if (err < 0) {
+		bt_dev_err(hdev, "Failed to query function status (%d)", err);
+		return err;
+	}
+
+	return status;
+}
+
+static int btmtkuart_change_baudrate(struct hci_dev *hdev)
+{
+	struct btmtkuart_dev *bdev = hci_get_drvdata(hdev);
+	struct btmtk_hci_wmt_params wmt_params;
+	__le32 baudrate;
+	u8 param;
+	int err;
+
+	/* Indicate the device to enter the probe state the host is
+	 * ready to change a new baudrate.
+	 */
+	baudrate = cpu_to_le32(bdev->desired_speed);
+	wmt_params.op = BTMTK_WMT_HIF;
+	wmt_params.flag = 1;
+	wmt_params.dlen = 4;
+	wmt_params.data = &baudrate;
+	wmt_params.status = NULL;
+
+	err = mtk_hci_wmt_sync(hdev, &wmt_params);
+	if (err < 0) {
+		bt_dev_err(hdev, "Failed to device baudrate (%d)", err);
+		return err;
+	}
+
+	err = serdev_device_set_baudrate(bdev->serdev,
+					 bdev->desired_speed);
+	if (err < 0) {
+		bt_dev_err(hdev, "Failed to set up host baudrate (%d)",
+			   err);
+		return err;
+	}
+
+	serdev_device_set_flow_control(bdev->serdev, false);
+
+	/* Send a dummy byte 0xff to activate the new baudrate */
+	param = 0xff;
+	err = serdev_device_write_buf(bdev->serdev, &param, sizeof(param));
+	if (err < 0 || err < sizeof(param))
+		return err;
+
+	serdev_device_wait_until_sent(bdev->serdev, 0);
+
+	/* Wait some time for the device changing baudrate done */
+	usleep_range(20000, 22000);
+
+	/* Test the new baudrate */
+	wmt_params.op = BTMTK_WMT_TEST;
+	wmt_params.flag = 7;
+	wmt_params.dlen = 0;
+	wmt_params.data = NULL;
+	wmt_params.status = NULL;
+
+	err = mtk_hci_wmt_sync(hdev, &wmt_params);
+	if (err < 0) {
+		bt_dev_err(hdev, "Failed to test new baudrate (%d)",
+			   err);
+		return err;
+	}
+
+	bdev->curr_speed = bdev->desired_speed;
+
+	return 0;
+}
+
+static int btmtkuart_setup(struct hci_dev *hdev)
+{
+	struct btmtkuart_dev *bdev = hci_get_drvdata(hdev);
+	struct btmtk_hci_wmt_params wmt_params;
+	ktime_t calltime, delta, rettime;
+	struct btmtk_tci_sleep tci_sleep;
+	unsigned long long duration;
+	struct sk_buff *skb;
+	int err, status;
+	u8 param = 0x1;
+
+	calltime = ktime_get();
+
+	/* Wakeup MCUSYS is required for certain devices before we start to
+	 * do any setups.
+	 */
+	if (test_bit(BTMTKUART_REQUIRED_WAKEUP, &bdev->tx_state)) {
+		wmt_params.op = BTMTK_WMT_WAKEUP;
+		wmt_params.flag = 3;
+		wmt_params.dlen = 0;
+		wmt_params.data = NULL;
+		wmt_params.status = NULL;
+
+		err = mtk_hci_wmt_sync(hdev, &wmt_params);
+		if (err < 0) {
+			bt_dev_err(hdev, "Failed to wakeup the chip (%d)", err);
+			return err;
+		}
+
+		clear_bit(BTMTKUART_REQUIRED_WAKEUP, &bdev->tx_state);
+	}
+
+	if (btmtkuart_is_standalone(bdev))
+		btmtkuart_change_baudrate(hdev);
+
+	/* Query whether the firmware is already download */
+	wmt_params.op = BTMTK_WMT_SEMAPHORE;
+	wmt_params.flag = 1;
+	wmt_params.dlen = 0;
+	wmt_params.data = NULL;
+	wmt_params.status = &status;
+
+	err = mtk_hci_wmt_sync(hdev, &wmt_params);
+	if (err < 0) {
+		bt_dev_err(hdev, "Failed to query firmware status (%d)", err);
+		return err;
+	}
+
+	if (status == BTMTK_WMT_PATCH_DONE) {
+		bt_dev_info(hdev, "Firmware already downloaded");
+		goto ignore_setup_fw;
+	}
+
+	/* Setup a firmware which the device definitely requires */
+	err = btmtk_setup_firmware(hdev, bdev->data->fwname, mtk_hci_wmt_sync);
+	if (err < 0)
+		return err;
+
+ignore_setup_fw:
+	/* Query whether the device is already enabled */
+	err = readx_poll_timeout(btmtkuart_func_query, hdev, status,
+				 status < 0 || status != BTMTK_WMT_ON_PROGRESS,
+				 2000, 5000000);
+	/* -ETIMEDOUT happens */
+	if (err < 0)
+		return err;
+
+	/* The other errors happen in btusb_mtk_func_query */
+	if (status < 0)
+		return status;
+
+	if (status == BTMTK_WMT_ON_DONE) {
+		bt_dev_info(hdev, "function already on");
+		goto ignore_func_on;
+	}
+
+	/* Enable Bluetooth protocol */
+	wmt_params.op = BTMTK_WMT_FUNC_CTRL;
+	wmt_params.flag = 0;
+	wmt_params.dlen = sizeof(param);
+	wmt_params.data = &param;
+	wmt_params.status = NULL;
+
+	err = mtk_hci_wmt_sync(hdev, &wmt_params);
+	if (err < 0) {
+		bt_dev_err(hdev, "Failed to send wmt func ctrl (%d)", err);
+		return err;
+	}
+
+ignore_func_on:
+	/* Apply the low power environment setup */
+	tci_sleep.mode = 0x5;
+	tci_sleep.duration = cpu_to_le16(0x640);
+	tci_sleep.host_duration = cpu_to_le16(0x640);
+	tci_sleep.host_wakeup_pin = 0;
+	tci_sleep.time_compensation = 0;
+
+	skb = __hci_cmd_sync(hdev, 0xfc7a, sizeof(tci_sleep), &tci_sleep,
+			     HCI_INIT_TIMEOUT);
+	if (IS_ERR(skb)) {
+		err = PTR_ERR(skb);
+		bt_dev_err(hdev, "Failed to apply low power setting (%d)", err);
+		return err;
+	}
+	kfree_skb(skb);
+
+	rettime = ktime_get();
+	delta = ktime_sub(rettime, calltime);
+	duration = (unsigned long long)ktime_to_ns(delta) >> 10;
+
+	bt_dev_info(hdev, "Device setup in %llu usecs", duration);
+
+	return 0;
+}
+
+static int btmtkuart_shutdown(struct hci_dev *hdev)
+{
+	struct btmtk_hci_wmt_params wmt_params;
+	u8 param = 0x0;
+	int err;
+
+	/* Disable the device */
+	wmt_params.op = BTMTK_WMT_FUNC_CTRL;
+	wmt_params.flag = 0;
+	wmt_params.dlen = sizeof(param);
+	wmt_params.data = &param;
+	wmt_params.status = NULL;
+
+	err = mtk_hci_wmt_sync(hdev, &wmt_params);
+	if (err < 0) {
+		bt_dev_err(hdev, "Failed to send wmt func ctrl (%d)", err);
+		return err;
+	}
+
+	return 0;
+}
+
+static int btmtkuart_send_frame(struct hci_dev *hdev, struct sk_buff *skb)
+{
+	struct btmtkuart_dev *bdev = hci_get_drvdata(hdev);
+	struct mtk_stp_hdr *shdr;
+	int err, dlen, type = 0;
+
+	/* Prepend skb with frame type */
+	memcpy(skb_push(skb, 1), &hci_skb_pkt_type(skb), 1);
+
+	/* Make sure that there is enough rooms for STP header and trailer */
+	if (unlikely(skb_headroom(skb) < sizeof(*shdr)) ||
+	    (skb_tailroom(skb) < MTK_STP_TLR_SIZE)) {
+		err = pskb_expand_head(skb, sizeof(*shdr), MTK_STP_TLR_SIZE,
+				       GFP_ATOMIC);
+		if (err < 0)
+			return err;
+	}
+
+	/* Add the STP header */
+	dlen = skb->len;
+	shdr = skb_push(skb, sizeof(*shdr));
+	shdr->prefix = 0x80;
+	shdr->dlen = cpu_to_be16((dlen & 0x0fff) | (type << 12));
+	shdr->cs = 0;		/* MT7622 doesn't care about checksum value */
+
+	/* Add the STP trailer */
+	skb_put_zero(skb, MTK_STP_TLR_SIZE);
+
+	skb_queue_tail(&bdev->txq, skb);
+
+	btmtkuart_tx_wakeup(bdev);
+	return 0;
+}
+
+static int btmtkuart_parse_dt(struct serdev_device *serdev)
+{
+	struct btmtkuart_dev *bdev = serdev_device_get_drvdata(serdev);
+	struct device_node *node = serdev->dev.of_node;
+	u32 speed = 921600;
+	int err;
+
+	if (btmtkuart_is_standalone(bdev)) {
+		of_property_read_u32(node, "current-speed", &speed);
+
+		bdev->desired_speed = speed;
+
+		bdev->vcc = devm_regulator_get(&serdev->dev, "vcc");
+		if (IS_ERR(bdev->vcc)) {
+			err = PTR_ERR(bdev->vcc);
+			return err;
+		}
+
+		bdev->osc = devm_clk_get_optional(&serdev->dev, "osc");
+		if (IS_ERR(bdev->osc)) {
+			err = PTR_ERR(bdev->osc);
+			return err;
+		}
+
+		bdev->boot = devm_gpiod_get_optional(&serdev->dev, "boot",
+						     GPIOD_OUT_LOW);
+		if (IS_ERR(bdev->boot)) {
+			err = PTR_ERR(bdev->boot);
+			return err;
+		}
+
+		bdev->pinctrl = devm_pinctrl_get(&serdev->dev);
+		if (IS_ERR(bdev->pinctrl)) {
+			err = PTR_ERR(bdev->pinctrl);
+			return err;
+		}
+
+		bdev->pins_boot = pinctrl_lookup_state(bdev->pinctrl,
+						       "default");
+		if (IS_ERR(bdev->pins_boot) && !bdev->boot) {
+			err = PTR_ERR(bdev->pins_boot);
+			dev_err(&serdev->dev,
+				"Should assign RXD to LOW at boot stage\n");
+			return err;
+		}
+
+		bdev->pins_runtime = pinctrl_lookup_state(bdev->pinctrl,
+							  "runtime");
+		if (IS_ERR(bdev->pins_runtime)) {
+			err = PTR_ERR(bdev->pins_runtime);
+			return err;
+		}
+
+		bdev->reset = devm_gpiod_get_optional(&serdev->dev, "reset",
+						      GPIOD_OUT_LOW);
+		if (IS_ERR(bdev->reset)) {
+			err = PTR_ERR(bdev->reset);
+			return err;
+		}
+	} else if (btmtkuart_is_builtin_soc(bdev)) {
+		bdev->clk = devm_clk_get(&serdev->dev, "ref");
+		if (IS_ERR(bdev->clk))
+			return PTR_ERR(bdev->clk);
+	}
+
+	return 0;
+}
+
+static int btmtkuart_probe(struct serdev_device *serdev)
+{
+	struct btmtkuart_dev *bdev;
+	struct hci_dev *hdev;
+	int err;
+
+	bdev = devm_kzalloc(&serdev->dev, sizeof(*bdev), GFP_KERNEL);
+	if (!bdev)
+		return -ENOMEM;
+
+	bdev->data = of_device_get_match_data(&serdev->dev);
+	if (!bdev->data)
+		return -ENODEV;
+
+	bdev->serdev = serdev;
+	serdev_device_set_drvdata(serdev, bdev);
+
+	serdev_device_set_client_ops(serdev, &btmtkuart_client_ops);
+
+	err = btmtkuart_parse_dt(serdev);
+	if (err < 0)
+		return err;
+
+	INIT_WORK(&bdev->tx_work, btmtkuart_tx_work);
+	skb_queue_head_init(&bdev->txq);
+
+	/* Initialize and register HCI device */
+	hdev = hci_alloc_dev();
+	if (!hdev) {
+		dev_err(&serdev->dev, "Can't allocate HCI device\n");
+		return -ENOMEM;
+	}
+
+	bdev->hdev = hdev;
+	bdev->hu.hdev = hdev;
+
+	hdev->bus = HCI_UART;
+	hci_set_drvdata(hdev, bdev);
+
+	hdev->open     = btmtkuart_open;
+	hdev->close    = btmtkuart_close;
+	hdev->flush    = btmtkuart_flush;
+	hdev->setup    = btmtkuart_setup;
+	hdev->shutdown = btmtkuart_shutdown;
+	hdev->send     = btmtkuart_send_frame;
+	hdev->set_bdaddr = btmtk_set_bdaddr;
+	SET_HCIDEV_DEV(hdev, &serdev->dev);
+
+	hdev->manufacturer = 70;
+	hci_set_quirk(hdev, HCI_QUIRK_NON_PERSISTENT_SETUP);
+
+	if (btmtkuart_is_standalone(bdev)) {
+		err = clk_prepare_enable(bdev->osc);
+		if (err < 0)
+			goto err_hci_free_dev;
+
+		if (bdev->boot) {
+			gpiod_set_value_cansleep(bdev->boot, 1);
+		} else {
+			/* Switch to the specific pin state for the booting
+			 * requires.
+			 */
+			pinctrl_select_state(bdev->pinctrl, bdev->pins_boot);
+		}
+
+		/* Power on */
+		err = regulator_enable(bdev->vcc);
+		if (err < 0)
+			goto err_clk_disable_unprepare;
+
+		/* Reset if the reset-gpios is available otherwise the board
+		 * -level design should be guaranteed.
+		 */
+		if (bdev->reset) {
+			gpiod_set_value_cansleep(bdev->reset, 1);
+			usleep_range(1000, 2000);
+			gpiod_set_value_cansleep(bdev->reset, 0);
+		}
+
+		/* Wait some time until device got ready and switch to the pin
+		 * mode the device requires for UART transfers.
+		 */
+		msleep(50);
+
+		if (bdev->boot)
+			devm_gpiod_put(&serdev->dev, bdev->boot);
+
+		pinctrl_select_state(bdev->pinctrl, bdev->pins_runtime);
+
+		/* A standalone device doesn't depends on power domain on SoC,
+		 * so mark it as no callbacks.
+		 */
+		pm_runtime_no_callbacks(&serdev->dev);
+
+		set_bit(BTMTKUART_REQUIRED_WAKEUP, &bdev->tx_state);
+	}
+
+	err = hci_register_dev(hdev);
+	if (err < 0) {
+		dev_err(&serdev->dev, "Can't register HCI device\n");
+		goto err_regulator_disable;
+	}
+
+	return 0;
+
+err_regulator_disable:
+	if (btmtkuart_is_standalone(bdev))
+		regulator_disable(bdev->vcc);
+err_clk_disable_unprepare:
+	if (btmtkuart_is_standalone(bdev))
+		clk_disable_unprepare(bdev->osc);
+err_hci_free_dev:
+	hci_free_dev(hdev);
+
+	return err;
+}
+
+static void btmtkuart_remove(struct serdev_device *serdev)
+{
+	struct btmtkuart_dev *bdev = serdev_device_get_drvdata(serdev);
+	struct hci_dev *hdev = bdev->hdev;
+
+	if (btmtkuart_is_standalone(bdev)) {
+		regulator_disable(bdev->vcc);
+		clk_disable_unprepare(bdev->osc);
+	}
+
+	hci_unregister_dev(hdev);
+	hci_free_dev(hdev);
+}
+
+static const struct btmtkuart_data mt7622_data __maybe_unused = {
+	.fwname = FIRMWARE_MT7622,
+};
+
+static const struct btmtkuart_data mt7663_data __maybe_unused = {
+	.flags = BTMTKUART_FLAG_STANDALONE_HW,
+	.fwname = FIRMWARE_MT7663,
+};
+
+static const struct btmtkuart_data mt7668_data __maybe_unused = {
+	.flags = BTMTKUART_FLAG_STANDALONE_HW,
+	.fwname = FIRMWARE_MT7668,
+};
+
+#ifdef CONFIG_OF
+static const struct of_device_id mtk_of_match_table[] = {
+	{ .compatible = "mediatek,mt7622-bluetooth", .data = &mt7622_data},
+	{ .compatible = "mediatek,mt7663u-bluetooth", .data = &mt7663_data},
+	{ .compatible = "mediatek,mt7668u-bluetooth", .data = &mt7668_data},
+	{ }
+};
+MODULE_DEVICE_TABLE(of, mtk_of_match_table);
+#endif
+
+static struct serdev_device_driver btmtkuart_driver = {
+	.probe = btmtkuart_probe,
+	.remove = btmtkuart_remove,
+	.driver = {
+		.name = "btmtkuart",
+		.of_match_table = of_match_ptr(mtk_of_match_table),
+	},
+};
+
+module_serdev_device_driver(btmtkuart_driver);
+
+MODULE_AUTHOR("Sean Wang <sean.wang@mediatek.com>");
+MODULE_DESCRIPTION("MediaTek Bluetooth Serial driver ver " VERSION);
+MODULE_VERSION(VERSION);
+MODULE_LICENSE("GPL");