Bluetooth: add nokia driver

This adds a driver for the Nokia H4+ protocol, which is used
at least on the Nokia N9, N900 & N950.
Signed-off-by: NSebastian Reichel <sre@kernel.org>
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>

drivers/bluetooth/Kconfig

@@ -86,6 +86,18 @@ config BT_HCIUART_H4
 
 	  Say Y here to compile support for HCI UART (H4) protocol.
 
+config BT_HCIUART_NOKIA
+	tristate "UART Nokia H4+ protocol support"
+	depends on BT_HCIUART
+	depends on SERIAL_DEV_BUS
+	depends on PM
+	help
+	  Nokia H4+ is serial protocol for communication between Bluetooth
+	  device and host. This protocol is required for Bluetooth devices
+	  with UART interface in Nokia devices.
+
+	  Say Y here to compile support for Nokia's H4+ protocol.
+
 config BT_HCIUART_BCSP
 	bool "BCSP protocol support"
 	depends on BT_HCIUART

drivers/bluetooth/Makefile

@@ -25,6 +25,8 @@ obj-$(CONFIG_BT_BCM)		+= btbcm.o
 obj-$(CONFIG_BT_RTL)		+= btrtl.o
 obj-$(CONFIG_BT_QCA)		+= btqca.o
 
+obj-$(CONFIG_BT_HCIUART_NOKIA)	+= hci_nokia.o
+
 btmrvl-y			:= btmrvl_main.o
 btmrvl-$(CONFIG_DEBUG_FS)	+= btmrvl_debugfs.o
 

drivers/bluetooth/hci_nokia.c

+/*
+ *  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>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ */
+
+#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/le_struct.h>
+#include <net/bluetooth/bluetooth.h>
+#include <net/bluetooth/hci_core.h>
+
+#include "hci_uart.h"
+#include "btbcm.h"
+
+#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 hci_nokia_radio_hdr {
+	u8	evt;
+	u8	dlen;
+} __packed;
+
+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 = (struct hci_nokia_alive_hdr *)skb_put(skb, sizeof(*hdr));
+	hdr->dlen = sizeof(*pkt);
+	pkt = (struct hci_nokia_alive_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 = (struct hci_nokia_neg_hdr *)skb_put(skb, sizeof(*neg_hdr));
+	neg_hdr->dlen = sizeof(*neg_cmd);
+
+	neg_cmd = (struct hci_nokia_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;
+
+		switch (pkt_type) {
+		case HCI_COMMAND_PKT:
+			cmd = (struct hci_command_hdr *)(fw_ptr + 3);
+			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;
+		set_bit(HCI_QUIRK_INVALID_BDADDR, &hu->hdev->quirks);
+		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");
+
+	serdev_device_open(hu->serdev);
+
+	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);
+	serdev_device_close(btdev->serdev);
+
+	return 0;
+}
+
+/* Enqueue frame for transmittion (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) = 0x00;
+	}
+
+	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 = (struct hci_nokia_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 = (struct hci_nokia_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->hdev, 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;
+	}
+
+	clk_prepare_enable(sysclk);
+	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);
+	struct hci_uart *hu = &btdev->hu;
+	struct hci_dev *hdev = hu->hdev;
+
+	cancel_work_sync(&hu->write_work);
+
+	hci_unregister_dev(hdev);
+	hci_free_dev(hdev);
+	hu->proto->close(hu);
+
+	pm_runtime_disable(&btdev->serdev->dev);
+}
+
+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);