Bluetooth: mediatek: Add protocol support for MediaTek serial devices

This adds a driver based on serdev driver for the MediaTek serial protocol
based on running H:4, which can enable the built-in Bluetooth device inside
MT7622 SoC.

Signed-off-by: Sean Wang <sean.wang@mediatek.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

3 files changed, 641 insertions, 0 deletions

diff --git a/drivers/bluetooth/Kconfig b/drivers/bluetooth/Kconfig
index 5f953ca8ac5b..c3736103c2ac 100644
--- a/drivers/bluetooth/Kconfig
+++ b/drivers/bluetooth/Kconfig
@@ -365,6 +365,17 @@ config BT_WILINK
 	  Say Y here to compile support for Texas Instrument's WiLink7 driver
 	  into the kernel or say M to compile it as module (btwilink).
 
+config BT_MTKUART
+	tristate "MediaTek HCI UART driver"
+	depends on SERIAL_DEV_BUS
+	help
+	  MediaTek Bluetooth HCI UART driver.
+	  This driver is required if you want to use MediaTek Bluetooth
+	  with serial interface.
+
+	  Say Y here to compile support for MediaTek Bluetooth UART devices
+	  into the kernel or say M to compile it as module (btmtkuart).
+
 config BT_QCOMSMD
 	tristate "Qualcomm SMD based HCI support"
 	depends on RPMSG || (COMPILE_TEST && RPMSG=n)
diff --git a/drivers/bluetooth/Makefile b/drivers/bluetooth/Makefile
index ec16c55eb6e9..b7e393cfc1e3 100644
--- a/drivers/bluetooth/Makefile
+++ b/drivers/bluetooth/Makefile
@@ -20,6 +20,7 @@ obj-$(CONFIG_BT_ATH3K)		+= ath3k.o
 obj-$(CONFIG_BT_MRVL)		+= btmrvl.o
 obj-$(CONFIG_BT_MRVL_SDIO)	+= btmrvl_sdio.o
 obj-$(CONFIG_BT_WILINK)		+= btwilink.o
+obj-$(CONFIG_BT_MTKUART)	+= btmtkuart.o
 obj-$(CONFIG_BT_QCOMSMD)	+= btqcomsmd.o
 obj-$(CONFIG_BT_BCM)		+= btbcm.o
 obj-$(CONFIG_BT_RTL)		+= btrtl.o
diff --git a/drivers/bluetooth/btmtkuart.c b/drivers/bluetooth/btmtkuart.c
new file mode 100644
index 000000000000..e0571fe04d00
--- /dev/null
+++ b/drivers/bluetooth/btmtkuart.c
@@ -0,0 +1,629 @@
+// 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 <asm/unaligned.h>
+#include <linux/atomic.h>
+#include <linux/clk.h>
+#include <linux/firmware.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 <net/bluetooth/bluetooth.h>
+#include <net/bluetooth/hci_core.h>
+
+#include "h4_recv.h"
+
+#define VERSION "0.1"
+
+#define FIRMWARE_MT7622		"mediatek/mt7622pr2h.bin"
+
+#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
+
+enum {
+	MTK_WMT_PATCH_DWNLD = 0x1,
+	MTK_WMT_FUNC_CTRL = 0x6,
+	MTK_WMT_RST = 0x7
+};
+
+struct mtk_stp_hdr {
+	u8	prefix;
+	__be16	dlen;
+	u8	cs;
+} __packed;
+
+struct mtk_wmt_hdr {
+	u8	dir;
+	u8	op;
+	__le16	dlen;
+	u8	flag;
+} __packed;
+
+struct mtk_hci_wmt_cmd {
+	struct mtk_wmt_hdr hdr;
+	u8 data[256];
+} __packed;
+
+struct btmtkuart_dev {
+	struct hci_dev *hdev;
+	struct serdev_device *serdev;
+	struct clk *clk;
+
+	struct work_struct tx_work;
+	unsigned long tx_state;
+	struct sk_buff_head txq;
+
+	struct sk_buff *rx_skb;
+
+	u8	stp_pad[6];
+	u8	stp_cursor;
+	u16	stp_dlen;
+};
+
+static int mtk_hci_wmt_sync(struct hci_dev *hdev, u8 op, u8 flag, u16 plen,
+			    const void *param)
+{
+	struct btmtkuart_dev *bdev = hci_get_drvdata(hdev);
+	struct mtk_hci_wmt_cmd wc;
+	struct mtk_wmt_hdr *hdr;
+	u32 hlen;
+	int err;
+
+	hlen = sizeof(*hdr) + plen;
+	if (hlen > 255)
+		return -EINVAL;
+
+	hdr = (struct mtk_wmt_hdr *)&wc;
+	hdr->dir = 1;
+	hdr->op = op;
+	hdr->dlen = cpu_to_le16(plen + 1);
+	hdr->flag = flag;
+	memcpy(wc.data, param, plen);
+
+	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);
+		return err;
+	}
+
+	/* 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 speicfic 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");
+		return err;
+	}
+
+	if (err) {
+		bt_dev_err(hdev, "Execution of wmt command timed out");
+		return -ETIMEDOUT;
+	}
+
+	return 0;
+}
+
+static int mtk_setup_fw(struct hci_dev *hdev)
+{
+	const struct firmware *fw;
+	const u8 *fw_ptr;
+	size_t fw_size;
+	int err, dlen;
+	u8 flag;
+
+	err = request_firmware(&fw, FIRMWARE_MT7622, &hdev->dev);
+	if (err < 0) {
+		bt_dev_err(hdev, "Failed to load firmware file (%d)", err);
+		return err;
+	}
+
+	fw_ptr = fw->data;
+	fw_size = fw->size;
+
+	/* The size of patch header is 30 bytes, should be skip */
+	if (fw_size < 30)
+		return -EINVAL;
+
+	fw_size -= 30;
+	fw_ptr += 30;
+	flag = 1;
+
+	while (fw_size > 0) {
+		dlen = min_t(int, 250, fw_size);
+
+		/* Tell device the position in sequence */
+		if (fw_size - dlen <= 0)
+			flag = 3;
+		else if (fw_size < fw->size - 30)
+			flag = 2;
+
+		err = mtk_hci_wmt_sync(hdev, MTK_WMT_PATCH_DWNLD, flag, dlen,
+				       fw_ptr);
+		if (err < 0) {
+			bt_dev_err(hdev, "Failed to send wmt patch dwnld (%d)",
+				   err);
+			break;
+		}
+
+		fw_size -= dlen;
+		fw_ptr += dlen;
+	}
+
+	release_firmware(fw);
+
+	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;
+
+	/* Fix up the vendor event id with 0xff for vendor specific instead
+	 * of 0xe4 so that event send via monitoring socket can be parsed
+	 * properly.
+	 */
+	if (hdr->evt == 0xe4)
+		hdr->evt = HCI_EV_VENDOR;
+
+	err = hci_recv_frame(hdev, skb);
+
+	if (hdr->evt == HCI_EV_VENDOR) {
+		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 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 unexpect (%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;
+
+	/* Tranlate 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 int 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->hdev, bdev->rx_skb, p_h4,
+					   sz_h4, mtk_recv_pkts,
+					   sizeof(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 err;
+		}
+
+		sz_left -= sz_h4;
+		p_left += sz_h4;
+	}
+
+	return 0;
+}
+
+static int btmtkuart_receive_buf(struct serdev_device *serdev, const u8 *data,
+				 size_t count)
+{
+	struct btmtkuart_dev *bdev = serdev_device_get_drvdata(serdev);
+	int err;
+
+	err = btmtkuart_recv(bdev->hdev, data, count);
+	if (err < 0)
+		return err;
+
+	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;
+	}
+
+	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_get_sync(dev);
+	if (err < 0) {
+		pm_runtime_put_noidle(dev);
+		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_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_setup(struct hci_dev *hdev)
+{
+	u8 param = 0x1;
+	int err = 0;
+
+	/* Setup a firmware which the device definitely requires */
+	err = mtk_setup_fw(hdev);
+	if (err < 0)
+		return err;
+
+	/* Activate function the firmware providing to */
+	err = mtk_hci_wmt_sync(hdev, MTK_WMT_RST, 0x4, 0, 0);
+	if (err < 0) {
+		bt_dev_err(hdev, "Failed to send wmt rst (%d)", err);
+		return err;
+	}
+
+	/* Enable Bluetooth protocol */
+	err = mtk_hci_wmt_sync(hdev, MTK_WMT_FUNC_CTRL, 0x0, sizeof(param),
+			       &param);
+	if (err < 0) {
+		bt_dev_err(hdev, "Failed to send wmt func ctrl (%d)", err);
+		return err;
+	}
+
+	return 0;
+}
+
+static int btmtkuart_shutdown(struct hci_dev *hdev)
+{
+	u8 param = 0x0;
+	int err;
+
+	/* Disable the device */
+	err = mtk_hci_wmt_sync(hdev, MTK_WMT_FUNC_CTRL, 0x0, sizeof(param),
+			       &param);
+	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_probe(struct serdev_device *serdev)
+{
+	struct btmtkuart_dev *bdev;
+	struct hci_dev *hdev;
+
+	bdev = devm_kzalloc(&serdev->dev, sizeof(*bdev), GFP_KERNEL);
+	if (!bdev)
+		return -ENOMEM;
+
+	bdev->clk = devm_clk_get(&serdev->dev, "ref");
+	if (IS_ERR(bdev->clk))
+		return PTR_ERR(bdev->clk);
+
+	bdev->serdev = serdev;
+	serdev_device_set_drvdata(serdev, bdev);
+
+	serdev_device_set_client_ops(serdev, &btmtkuart_client_ops);
+
+	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;
+
+	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;
+	SET_HCIDEV_DEV(hdev, &serdev->dev);
+
+	hdev->manufacturer = 70;
+	set_bit(HCI_QUIRK_NON_PERSISTENT_SETUP, &hdev->quirks);
+
+	if (hci_register_dev(hdev) < 0) {
+		dev_err(&serdev->dev, "Can't register HCI device\n");
+		hci_free_dev(hdev);
+		return -ENODEV;
+	}
+
+	return 0;
+}
+
+static void btmtkuart_remove(struct serdev_device *serdev)
+{
+	struct btmtkuart_dev *bdev = serdev_device_get_drvdata(serdev);
+	struct hci_dev *hdev = bdev->hdev;
+
+	hci_unregister_dev(hdev);
+	hci_free_dev(hdev);
+}
+
+#ifdef CONFIG_OF
+static const struct of_device_id mtk_of_match_table[] = {
+	{ .compatible = "mediatek,mt7622-bluetooth"},
+	{ }
+};
+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");
+MODULE_FIRMWARE(FIRMWARE_MT7622);