x86/kprobes: Fix crash when probing CS CALL instructionsgrafted

When using eBPF to probe CS CALL instructions within a function,
a crash can be triggered.

The eBPF tool probes offset 257 of the __hrtimer_run_queues()
function:

<__hrtimer_run_queues+249>:  nopl   0x0(%rax,%rax,1)
<__hrtimer_run_queues+254>:  mov    %r14,%rdi
<__hrtimer_run_queues+257>:  cs call <__x86_indirect_thunk_r12>
<__hrtimer_run_queues+263>:  mov    %eax,%r12d
<__hrtimer_run_queues+266>:  xchg   %ax,%ax
<__hrtimer_run_queues+268>:  mov    %r13,%rdi

Which triggers this crash:

  BUG: unable to handle page fault for address: 00000000000f41c9
  #PF: supervisor write access in kernel mode
  #PF: error_code(0x0002) - not-present page
  PGD 0 P4D 0
  Oops: 0002 [#1] SMP NOPTI
  CPU: 1 PID: 0 Comm: swapper/1 Kdump: loaded Tainted: P
  RIP: 0010:__hrtimer_run_queues+0x106/0x230

Note that __hrtimer_run_queues+0x106 is __hrtimer_run_queues+262, which is
at the 6th byte of the above CS CALL instruction. Since the CS CALL
instruction occupies 6 bytes, the exception occurred in the middle of that
call instruction.

The root cause is that when using eBPF tools to probe in the middle of a
function, a kprobe with INT3 is used as the underlying implementation.

During single-step emulation of the original CALL instruction,
int3_emulate_call() assumes that the probed CALL instruction is 5 bytes
long. However, the actual CS-prefixed CALL instruction occupies 6 bytes,
so it constructs an incorrect exception return address. When the CPU
returns from the kprobe handler, the next instruction to be executed is at
the address of the last byte of that CS CALL instruction. Coincidentally,
starting from that address, the CPU fetches and decodes a completely
different instruction, which ultimately triggers a kernel crash.

Fix the issue by using the actual instruction length obtained from
the instruction decoder when constructing the exception return
address, rather than relying on the hardcoded CALL_INSN_SIZE macro.

[ mingo: Refined the changelog ]

Fixes: 6256e668b7af ("x86/kprobes: Use int3 instead of debug trap for single-step")
Suggested-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Jinke Han <jinkehan@didiglobal.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Yafang Shao <laoar.shao@gmail.com>
Acked-by: Borislav Petkov <bp@alien8.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://patch.msgid.link/20260908073742.GA10517@didi-ThinkCentre-M920t-N000

1 files changed, 826 insertions, 0 deletions

diff --git a/drivers/bluetooth/hci_nokia.c b/drivers/bluetooth/hci_nokia.c
new file mode 100644
index 000000000..be2923231
--- /dev/null
+++ b/drivers/bluetooth/hci_nokia.c
@@ -0,0 +1,826 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  Bluetooth HCI UART H4 driver with Nokia Extensions AKA Nokia H4+
+ *
+ *  Copyright (C) 2015 Marcel Holtmann <marcel@holtmann.org>
+ *  Copyright (C) 2015-2017 Sebastian Reichel <sre@kernel.org>
+ */
+
+#include <linux/clk.h>
+#include <linux/errno.h>
+#include <linux/firmware.h>
+#include <linux/gpio/consumer.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/pm_runtime.h>
+#include <linux/serdev.h>
+#include <linux/skbuff.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <linux/unaligned.h>
+#include <net/bluetooth/bluetooth.h>
+#include <net/bluetooth/hci_core.h>
+
+#include "hci_uart.h"
+#include "btbcm.h"
+
+#define VERSION "0.1"
+
+#define NOKIA_ID_BCM2048	0x04
+#define NOKIA_ID_TI1271		0x31
+
+#define FIRMWARE_BCM2048	"nokia/bcmfw.bin"
+#define FIRMWARE_TI1271		"nokia/ti1273.bin"
+
+#define HCI_NOKIA_NEG_PKT	0x06
+#define HCI_NOKIA_ALIVE_PKT	0x07
+#define HCI_NOKIA_RADIO_PKT	0x08
+
+#define HCI_NOKIA_NEG_HDR_SIZE		1
+#define HCI_NOKIA_MAX_NEG_SIZE		255
+#define HCI_NOKIA_ALIVE_HDR_SIZE	1
+#define HCI_NOKIA_MAX_ALIVE_SIZE	255
+#define HCI_NOKIA_RADIO_HDR_SIZE	2
+#define HCI_NOKIA_MAX_RADIO_SIZE	255
+
+#define NOKIA_PROTO_PKT		0x44
+#define NOKIA_PROTO_BYTE	0x4c
+
+#define NOKIA_NEG_REQ		0x00
+#define NOKIA_NEG_ACK		0x20
+#define NOKIA_NEG_NAK		0x40
+
+#define H4_TYPE_SIZE		1
+
+#define NOKIA_RECV_ALIVE \
+	.type = HCI_NOKIA_ALIVE_PKT, \
+	.hlen = HCI_NOKIA_ALIVE_HDR_SIZE, \
+	.loff = 0, \
+	.lsize = 1, \
+	.maxlen = HCI_NOKIA_MAX_ALIVE_SIZE \
+
+#define NOKIA_RECV_NEG \
+	.type = HCI_NOKIA_NEG_PKT, \
+	.hlen = HCI_NOKIA_NEG_HDR_SIZE, \
+	.loff = 0, \
+	.lsize = 1, \
+	.maxlen = HCI_NOKIA_MAX_NEG_SIZE \
+
+#define NOKIA_RECV_RADIO \
+	.type = HCI_NOKIA_RADIO_PKT, \
+	.hlen = HCI_NOKIA_RADIO_HDR_SIZE, \
+	.loff = 1, \
+	.lsize = 1, \
+	.maxlen = HCI_NOKIA_MAX_RADIO_SIZE \
+
+struct hci_nokia_neg_hdr {
+	u8	dlen;
+} __packed;
+
+struct hci_nokia_neg_cmd {
+	u8	ack;
+	u16	baud;
+	u16	unused1;
+	u8	proto;
+	u16	sys_clk;
+	u16	unused2;
+} __packed;
+
+#define NOKIA_ALIVE_REQ   0x55
+#define NOKIA_ALIVE_RESP  0xcc
+
+struct hci_nokia_alive_hdr {
+	u8	dlen;
+} __packed;
+
+struct hci_nokia_alive_pkt {
+	u8	mid;
+	u8	unused;
+} __packed;
+
+struct hci_nokia_neg_evt {
+	u8	ack;
+	u16	baud;
+	u16	unused1;
+	u8	proto;
+	u16	sys_clk;
+	u16	unused2;
+	u8	man_id;
+	u8	ver_id;
+} __packed;
+
+#define MAX_BAUD_RATE		3692300
+#define SETUP_BAUD_RATE		921600
+#define INIT_BAUD_RATE		120000
+
+struct nokia_bt_dev {
+	struct hci_uart hu;
+	struct serdev_device *serdev;
+
+	struct gpio_desc *reset;
+	struct gpio_desc *wakeup_host;
+	struct gpio_desc *wakeup_bt;
+	unsigned long sysclk_speed;
+
+	int wake_irq;
+	struct sk_buff *rx_skb;
+	struct sk_buff_head txq;
+	bdaddr_t bdaddr;
+
+	int init_error;
+	struct completion init_completion;
+
+	u8 man_id;
+	u8 ver_id;
+
+	bool initialized;
+	bool tx_enabled;
+	bool rx_enabled;
+};
+
+static int nokia_enqueue(struct hci_uart *hu, struct sk_buff *skb);
+
+static void nokia_flow_control(struct serdev_device *serdev, bool enable)
+{
+	if (enable) {
+		serdev_device_set_rts(serdev, true);
+		serdev_device_set_flow_control(serdev, true);
+	} else {
+		serdev_device_set_flow_control(serdev, false);
+		serdev_device_set_rts(serdev, false);
+	}
+}
+
+static irqreturn_t wakeup_handler(int irq, void *data)
+{
+	struct nokia_bt_dev *btdev = data;
+	struct device *dev = &btdev->serdev->dev;
+	int wake_state = gpiod_get_value(btdev->wakeup_host);
+
+	if (btdev->rx_enabled == wake_state)
+		return IRQ_HANDLED;
+
+	if (wake_state)
+		pm_runtime_get(dev);
+	else
+		pm_runtime_put(dev);
+
+	btdev->rx_enabled = wake_state;
+
+	return IRQ_HANDLED;
+}
+
+static int nokia_reset(struct hci_uart *hu)
+{
+	struct nokia_bt_dev *btdev = hu->priv;
+	struct device *dev = &btdev->serdev->dev;
+	int err;
+
+	/* reset routine */
+	gpiod_set_value_cansleep(btdev->reset, 1);
+	gpiod_set_value_cansleep(btdev->wakeup_bt, 1);
+
+	msleep(100);
+
+	/* safety check */
+	err = gpiod_get_value_cansleep(btdev->wakeup_host);
+	if (err == 1) {
+		dev_err(dev, "reset: host wakeup not low!");
+		return -EPROTO;
+	}
+
+	/* flush queue */
+	serdev_device_write_flush(btdev->serdev);
+
+	/* init uart */
+	nokia_flow_control(btdev->serdev, false);
+	serdev_device_set_baudrate(btdev->serdev, INIT_BAUD_RATE);
+
+	gpiod_set_value_cansleep(btdev->reset, 0);
+
+	/* wait for cts */
+	err = serdev_device_wait_for_cts(btdev->serdev, true, 200);
+	if (err < 0) {
+		dev_err(dev, "CTS not received: %d", err);
+		return err;
+	}
+
+	nokia_flow_control(btdev->serdev, true);
+
+	return 0;
+}
+
+static int nokia_send_alive_packet(struct hci_uart *hu)
+{
+	struct nokia_bt_dev *btdev = hu->priv;
+	struct device *dev = &btdev->serdev->dev;
+	struct hci_nokia_alive_hdr *hdr;
+	struct hci_nokia_alive_pkt *pkt;
+	struct sk_buff *skb;
+	int len;
+
+	init_completion(&btdev->init_completion);
+
+	len = H4_TYPE_SIZE + sizeof(*hdr) + sizeof(*pkt);
+	skb = bt_skb_alloc(len, GFP_KERNEL);
+	if (!skb)
+		return -ENOMEM;
+
+	hci_skb_pkt_type(skb) = HCI_NOKIA_ALIVE_PKT;
+	memset(skb->data, 0x00, len);
+
+	hdr = skb_put(skb, sizeof(*hdr));
+	hdr->dlen = sizeof(*pkt);
+	pkt = skb_put(skb, sizeof(*pkt));
+	pkt->mid = NOKIA_ALIVE_REQ;
+
+	nokia_enqueue(hu, skb);
+	hci_uart_tx_wakeup(hu);
+
+	dev_dbg(dev, "Alive sent");
+
+	if (!wait_for_completion_interruptible_timeout(&btdev->init_completion,
+		msecs_to_jiffies(1000))) {
+		return -ETIMEDOUT;
+	}
+
+	if (btdev->init_error < 0)
+		return btdev->init_error;
+
+	return 0;
+}
+
+static int nokia_send_negotiation(struct hci_uart *hu)
+{
+	struct nokia_bt_dev *btdev = hu->priv;
+	struct device *dev = &btdev->serdev->dev;
+	struct hci_nokia_neg_cmd *neg_cmd;
+	struct hci_nokia_neg_hdr *neg_hdr;
+	struct sk_buff *skb;
+	int len, err;
+	u16 baud = DIV_ROUND_CLOSEST(btdev->sysclk_speed * 10, SETUP_BAUD_RATE);
+	int sysclk = btdev->sysclk_speed / 1000;
+
+	len = H4_TYPE_SIZE + sizeof(*neg_hdr) + sizeof(*neg_cmd);
+	skb = bt_skb_alloc(len, GFP_KERNEL);
+	if (!skb)
+		return -ENOMEM;
+
+	hci_skb_pkt_type(skb) = HCI_NOKIA_NEG_PKT;
+
+	neg_hdr = skb_put(skb, sizeof(*neg_hdr));
+	neg_hdr->dlen = sizeof(*neg_cmd);
+
+	neg_cmd = skb_put(skb, sizeof(*neg_cmd));
+	neg_cmd->ack = NOKIA_NEG_REQ;
+	neg_cmd->baud = cpu_to_le16(baud);
+	neg_cmd->unused1 = 0x0000;
+	neg_cmd->proto = NOKIA_PROTO_BYTE;
+	neg_cmd->sys_clk = cpu_to_le16(sysclk);
+	neg_cmd->unused2 = 0x0000;
+
+	btdev->init_error = 0;
+	init_completion(&btdev->init_completion);
+
+	nokia_enqueue(hu, skb);
+	hci_uart_tx_wakeup(hu);
+
+	dev_dbg(dev, "Negotiation sent");
+
+	if (!wait_for_completion_interruptible_timeout(&btdev->init_completion,
+		msecs_to_jiffies(10000))) {
+		return -ETIMEDOUT;
+	}
+
+	if (btdev->init_error < 0)
+		return btdev->init_error;
+
+	/* Change to previously negotiated speed. Flow Control
+	 * is disabled until bluetooth adapter is ready to avoid
+	 * broken bytes being received.
+	 */
+	nokia_flow_control(btdev->serdev, false);
+	serdev_device_set_baudrate(btdev->serdev, SETUP_BAUD_RATE);
+	err = serdev_device_wait_for_cts(btdev->serdev, true, 200);
+	if (err < 0) {
+		dev_err(dev, "CTS not received: %d", err);
+		return err;
+	}
+	nokia_flow_control(btdev->serdev, true);
+
+	dev_dbg(dev, "Negotiation successful");
+
+	return 0;
+}
+
+static int nokia_setup_fw(struct hci_uart *hu)
+{
+	struct nokia_bt_dev *btdev = hu->priv;
+	struct device *dev = &btdev->serdev->dev;
+	const char *fwname;
+	const struct firmware *fw;
+	const u8 *fw_ptr;
+	size_t fw_size;
+	int err;
+
+	dev_dbg(dev, "setup firmware");
+
+	if (btdev->man_id == NOKIA_ID_BCM2048) {
+		fwname = FIRMWARE_BCM2048;
+	} else if (btdev->man_id == NOKIA_ID_TI1271) {
+		fwname = FIRMWARE_TI1271;
+	} else {
+		dev_err(dev, "Unsupported bluetooth device!");
+		return -ENODEV;
+	}
+
+	err = request_firmware(&fw, fwname, dev);
+	if (err < 0) {
+		dev_err(dev, "%s: Failed to load Nokia firmware file (%d)",
+			hu->hdev->name, err);
+		return err;
+	}
+
+	fw_ptr = fw->data;
+	fw_size = fw->size;
+
+	while (fw_size >= 4) {
+		u16 pkt_size = get_unaligned_le16(fw_ptr);
+		u8 pkt_type = fw_ptr[2];
+		const struct hci_command_hdr *cmd;
+		u16 opcode;
+		struct sk_buff *skb;
+
+		if (pkt_size > fw_size - 2) {
+			err = -EINVAL;
+			dev_err(dev, "%s: Malformed firmware packet\n",
+				hu->hdev->name);
+			goto done;
+		}
+
+		switch (pkt_type) {
+		case HCI_COMMAND_PKT:
+			if (pkt_size < 1 + HCI_COMMAND_HDR_SIZE) {
+				err = -EINVAL;
+				dev_err(dev, "%s: Malformed firmware command\n",
+					hu->hdev->name);
+				goto done;
+			}
+
+			cmd = (struct hci_command_hdr *)(fw_ptr + 3);
+			if (cmd->plen > pkt_size - 1 - HCI_COMMAND_HDR_SIZE) {
+				err = -EINVAL;
+				dev_err(dev, "%s: Truncated firmware command\n",
+					hu->hdev->name);
+				goto done;
+			}
+			opcode = le16_to_cpu(cmd->opcode);
+
+			skb = __hci_cmd_sync(hu->hdev, opcode, cmd->plen,
+					     fw_ptr + 3 + HCI_COMMAND_HDR_SIZE,
+					     HCI_INIT_TIMEOUT);
+			if (IS_ERR(skb)) {
+				err = PTR_ERR(skb);
+				dev_err(dev, "%s: FW command %04x failed (%d)",
+				       hu->hdev->name, opcode, err);
+				goto done;
+			}
+			kfree_skb(skb);
+			break;
+		case HCI_NOKIA_RADIO_PKT:
+		case HCI_NOKIA_NEG_PKT:
+		case HCI_NOKIA_ALIVE_PKT:
+			break;
+		}
+
+		fw_ptr += pkt_size + 2;
+		fw_size -= pkt_size + 2;
+	}
+
+done:
+	release_firmware(fw);
+	return err;
+}
+
+static int nokia_setup(struct hci_uart *hu)
+{
+	struct nokia_bt_dev *btdev = hu->priv;
+	struct device *dev = &btdev->serdev->dev;
+	int err;
+
+	btdev->initialized = false;
+
+	nokia_flow_control(btdev->serdev, false);
+
+	pm_runtime_get_sync(dev);
+
+	if (btdev->tx_enabled) {
+		gpiod_set_value_cansleep(btdev->wakeup_bt, 0);
+		pm_runtime_put(&btdev->serdev->dev);
+		btdev->tx_enabled = false;
+	}
+
+	dev_dbg(dev, "protocol setup");
+
+	/* 0. reset connection */
+	err = nokia_reset(hu);
+	if (err < 0) {
+		dev_err(dev, "Reset failed: %d", err);
+		goto out;
+	}
+
+	/* 1. negotiate speed etc */
+	err = nokia_send_negotiation(hu);
+	if (err < 0) {
+		dev_err(dev, "Negotiation failed: %d", err);
+		goto out;
+	}
+
+	/* 2. verify correct setup using alive packet */
+	err = nokia_send_alive_packet(hu);
+	if (err < 0) {
+		dev_err(dev, "Alive check failed: %d", err);
+		goto out;
+	}
+
+	/* 3. send firmware */
+	err = nokia_setup_fw(hu);
+	if (err < 0) {
+		dev_err(dev, "Could not setup FW: %d", err);
+		goto out;
+	}
+
+	nokia_flow_control(btdev->serdev, false);
+	serdev_device_set_baudrate(btdev->serdev, MAX_BAUD_RATE);
+	nokia_flow_control(btdev->serdev, true);
+
+	if (btdev->man_id == NOKIA_ID_BCM2048) {
+		hu->hdev->set_bdaddr = btbcm_set_bdaddr;
+		hci_set_quirk(hu->hdev, HCI_QUIRK_INVALID_BDADDR);
+		dev_dbg(dev, "bcm2048 has invalid bluetooth address!");
+	}
+
+	dev_dbg(dev, "protocol setup done!");
+
+	gpiod_set_value_cansleep(btdev->wakeup_bt, 0);
+	pm_runtime_put(dev);
+	btdev->tx_enabled = false;
+	btdev->initialized = true;
+
+	return 0;
+out:
+	pm_runtime_put(dev);
+
+	return err;
+}
+
+static int nokia_open(struct hci_uart *hu)
+{
+	struct device *dev = &hu->serdev->dev;
+
+	dev_dbg(dev, "protocol open");
+
+	pm_runtime_enable(dev);
+
+	return 0;
+}
+
+static int nokia_flush(struct hci_uart *hu)
+{
+	struct nokia_bt_dev *btdev = hu->priv;
+
+	dev_dbg(&btdev->serdev->dev, "flush device");
+
+	skb_queue_purge(&btdev->txq);
+
+	return 0;
+}
+
+static int nokia_close(struct hci_uart *hu)
+{
+	struct nokia_bt_dev *btdev = hu->priv;
+	struct device *dev = &btdev->serdev->dev;
+
+	dev_dbg(dev, "close device");
+
+	btdev->initialized = false;
+
+	skb_queue_purge(&btdev->txq);
+
+	kfree_skb(btdev->rx_skb);
+
+	/* disable module */
+	gpiod_set_value(btdev->reset, 1);
+	gpiod_set_value(btdev->wakeup_bt, 0);
+
+	pm_runtime_disable(&btdev->serdev->dev);
+
+	return 0;
+}
+
+/* Enqueue frame for transmission (padding, crc, etc) */
+static int nokia_enqueue(struct hci_uart *hu, struct sk_buff *skb)
+{
+	struct nokia_bt_dev *btdev = hu->priv;
+	int err;
+
+	/* Prepend skb with frame type */
+	memcpy(skb_push(skb, 1), &bt_cb(skb)->pkt_type, 1);
+
+	/* Packets must be word aligned */
+	if (skb->len % 2) {
+		err = skb_pad(skb, 1);
+		if (err)
+			return err;
+		skb_put(skb, 1);
+	}
+
+	skb_queue_tail(&btdev->txq, skb);
+
+	return 0;
+}
+
+static int nokia_recv_negotiation_packet(struct hci_dev *hdev,
+					 struct sk_buff *skb)
+{
+	struct hci_uart *hu = hci_get_drvdata(hdev);
+	struct nokia_bt_dev *btdev = hu->priv;
+	struct device *dev = &btdev->serdev->dev;
+	struct hci_nokia_neg_hdr *hdr;
+	struct hci_nokia_neg_evt *evt;
+	int ret = 0;
+
+	hdr = (struct hci_nokia_neg_hdr *)skb->data;
+	if (hdr->dlen != sizeof(*evt)) {
+		btdev->init_error = -EIO;
+		ret = -EIO;
+		goto finish_neg;
+	}
+
+	evt = skb_pull(skb, sizeof(*hdr));
+
+	if (evt->ack != NOKIA_NEG_ACK) {
+		dev_err(dev, "Negotiation received: wrong reply");
+		btdev->init_error = -EINVAL;
+		ret = -EINVAL;
+		goto finish_neg;
+	}
+
+	btdev->man_id = evt->man_id;
+	btdev->ver_id = evt->ver_id;
+
+	dev_dbg(dev, "Negotiation received: baud=%u:clk=%u:manu=%u:vers=%u",
+		evt->baud, evt->sys_clk, evt->man_id, evt->ver_id);
+
+finish_neg:
+	complete(&btdev->init_completion);
+	kfree_skb(skb);
+	return ret;
+}
+
+static int nokia_recv_alive_packet(struct hci_dev *hdev, struct sk_buff *skb)
+{
+	struct hci_uart *hu = hci_get_drvdata(hdev);
+	struct nokia_bt_dev *btdev = hu->priv;
+	struct device *dev = &btdev->serdev->dev;
+	struct hci_nokia_alive_hdr *hdr;
+	struct hci_nokia_alive_pkt *pkt;
+	int ret = 0;
+
+	hdr = (struct hci_nokia_alive_hdr *)skb->data;
+	if (hdr->dlen != sizeof(*pkt)) {
+		dev_err(dev, "Corrupted alive message");
+		btdev->init_error = -EIO;
+		ret = -EIO;
+		goto finish_alive;
+	}
+
+	pkt = skb_pull(skb, sizeof(*hdr));
+
+	if (pkt->mid != NOKIA_ALIVE_RESP) {
+		dev_err(dev, "Alive received: invalid response: 0x%02x!",
+			pkt->mid);
+		btdev->init_error = -EINVAL;
+		ret = -EINVAL;
+		goto finish_alive;
+	}
+
+	dev_dbg(dev, "Alive received");
+
+finish_alive:
+	complete(&btdev->init_completion);
+	kfree_skb(skb);
+	return ret;
+}
+
+static int nokia_recv_radio(struct hci_dev *hdev, struct sk_buff *skb)
+{
+	/* Packets received on the dedicated radio channel are
+	 * HCI events and so feed them back into the core.
+	 */
+	hci_skb_pkt_type(skb) = HCI_EVENT_PKT;
+	return hci_recv_frame(hdev, skb);
+}
+
+/* Recv data */
+static const struct h4_recv_pkt nokia_recv_pkts[] = {
+	{ H4_RECV_ACL,		.recv = hci_recv_frame },
+	{ H4_RECV_SCO,		.recv = hci_recv_frame },
+	{ H4_RECV_EVENT,	.recv = hci_recv_frame },
+	{ NOKIA_RECV_ALIVE,	.recv = nokia_recv_alive_packet },
+	{ NOKIA_RECV_NEG,	.recv = nokia_recv_negotiation_packet },
+	{ NOKIA_RECV_RADIO,	.recv = nokia_recv_radio },
+};
+
+static int nokia_recv(struct hci_uart *hu, const void *data, int count)
+{
+	struct nokia_bt_dev *btdev = hu->priv;
+	struct device *dev = &btdev->serdev->dev;
+	int err;
+
+	if (!test_bit(HCI_UART_REGISTERED, &hu->flags))
+		return -EUNATCH;
+
+	btdev->rx_skb = h4_recv_buf(hu, btdev->rx_skb, data, count,
+				    nokia_recv_pkts, ARRAY_SIZE(nokia_recv_pkts));
+	if (IS_ERR(btdev->rx_skb)) {
+		err = PTR_ERR(btdev->rx_skb);
+		dev_err(dev, "Frame reassembly failed (%d)", err);
+		btdev->rx_skb = NULL;
+		return err;
+	}
+
+	return count;
+}
+
+static struct sk_buff *nokia_dequeue(struct hci_uart *hu)
+{
+	struct nokia_bt_dev *btdev = hu->priv;
+	struct device *dev = &btdev->serdev->dev;
+	struct sk_buff *result = skb_dequeue(&btdev->txq);
+
+	if (!btdev->initialized)
+		return result;
+
+	if (btdev->tx_enabled == !!result)
+		return result;
+
+	if (result) {
+		pm_runtime_get_sync(dev);
+		gpiod_set_value_cansleep(btdev->wakeup_bt, 1);
+	} else {
+		serdev_device_wait_until_sent(btdev->serdev, 0);
+		gpiod_set_value_cansleep(btdev->wakeup_bt, 0);
+		pm_runtime_put(dev);
+	}
+
+	btdev->tx_enabled = !!result;
+
+	return result;
+}
+
+static const struct hci_uart_proto nokia_proto = {
+	.id		= HCI_UART_NOKIA,
+	.name		= "Nokia",
+	.open		= nokia_open,
+	.close		= nokia_close,
+	.recv		= nokia_recv,
+	.enqueue	= nokia_enqueue,
+	.dequeue	= nokia_dequeue,
+	.flush		= nokia_flush,
+	.setup		= nokia_setup,
+	.manufacturer	= 1,
+};
+
+static int nokia_bluetooth_serdev_probe(struct serdev_device *serdev)
+{
+	struct device *dev = &serdev->dev;
+	struct nokia_bt_dev *btdev;
+	struct clk *sysclk;
+	int err = 0;
+
+	btdev = devm_kzalloc(dev, sizeof(*btdev), GFP_KERNEL);
+	if (!btdev)
+		return -ENOMEM;
+
+	btdev->hu.serdev = btdev->serdev = serdev;
+	serdev_device_set_drvdata(serdev, btdev);
+
+	btdev->reset = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
+	if (IS_ERR(btdev->reset)) {
+		err = PTR_ERR(btdev->reset);
+		dev_err(dev, "could not get reset gpio: %d", err);
+		return err;
+	}
+
+	btdev->wakeup_host = devm_gpiod_get(dev, "host-wakeup", GPIOD_IN);
+	if (IS_ERR(btdev->wakeup_host)) {
+		err = PTR_ERR(btdev->wakeup_host);
+		dev_err(dev, "could not get host wakeup gpio: %d", err);
+		return err;
+	}
+
+	btdev->wake_irq = gpiod_to_irq(btdev->wakeup_host);
+
+	err = devm_request_threaded_irq(dev, btdev->wake_irq, NULL,
+		wakeup_handler,
+		IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
+		"wakeup", btdev);
+	if (err) {
+		dev_err(dev, "could request wakeup irq: %d", err);
+		return err;
+	}
+
+	btdev->wakeup_bt = devm_gpiod_get(dev, "bluetooth-wakeup",
+					   GPIOD_OUT_LOW);
+	if (IS_ERR(btdev->wakeup_bt)) {
+		err = PTR_ERR(btdev->wakeup_bt);
+		dev_err(dev, "could not get BT wakeup gpio: %d", err);
+		return err;
+	}
+
+	sysclk = devm_clk_get(dev, "sysclk");
+	if (IS_ERR(sysclk)) {
+		err = PTR_ERR(sysclk);
+		dev_err(dev, "could not get sysclk: %d", err);
+		return err;
+	}
+
+	err = clk_prepare_enable(sysclk);
+	if (err) {
+		dev_err(dev, "could not enable sysclk: %d", err);
+		return err;
+	}
+	btdev->sysclk_speed = clk_get_rate(sysclk);
+	clk_disable_unprepare(sysclk);
+
+	skb_queue_head_init(&btdev->txq);
+
+	btdev->hu.priv = btdev;
+	btdev->hu.alignment = 2; /* Nokia H4+ is word aligned */
+
+	err = hci_uart_register_device(&btdev->hu, &nokia_proto);
+	if (err) {
+		dev_err(dev, "could not register bluetooth uart: %d", err);
+		return err;
+	}
+
+	return 0;
+}
+
+static void nokia_bluetooth_serdev_remove(struct serdev_device *serdev)
+{
+	struct nokia_bt_dev *btdev = serdev_device_get_drvdata(serdev);
+
+	hci_uart_unregister_device(&btdev->hu);
+}
+
+static int nokia_bluetooth_runtime_suspend(struct device *dev)
+{
+	struct serdev_device *serdev = to_serdev_device(dev);
+
+	nokia_flow_control(serdev, false);
+	return 0;
+}
+
+static int nokia_bluetooth_runtime_resume(struct device *dev)
+{
+	struct serdev_device *serdev = to_serdev_device(dev);
+
+	nokia_flow_control(serdev, true);
+	return 0;
+}
+
+static const struct dev_pm_ops nokia_bluetooth_pm_ops = {
+	SET_RUNTIME_PM_OPS(nokia_bluetooth_runtime_suspend,
+			   nokia_bluetooth_runtime_resume,
+			   NULL)
+};
+
+#ifdef CONFIG_OF
+static const struct of_device_id nokia_bluetooth_of_match[] = {
+	{ .compatible = "nokia,h4p-bluetooth", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, nokia_bluetooth_of_match);
+#endif
+
+static struct serdev_device_driver nokia_bluetooth_serdev_driver = {
+	.probe = nokia_bluetooth_serdev_probe,
+	.remove = nokia_bluetooth_serdev_remove,
+	.driver = {
+		.name = "nokia-bluetooth",
+		.pm = &nokia_bluetooth_pm_ops,
+		.of_match_table = of_match_ptr(nokia_bluetooth_of_match),
+	},
+};
+
+module_serdev_device_driver(nokia_bluetooth_serdev_driver);
+
+MODULE_AUTHOR("Sebastian Reichel <sre@kernel.org>");
+MODULE_DESCRIPTION("Bluetooth HCI UART Nokia H4+ driver ver " VERSION);
+MODULE_VERSION(VERSION);
+MODULE_LICENSE("GPL");