Date:   Fri, 20 Jul 2018 13:12:29 +0800
From:   <sean.wang@...iatek.com>
To:     <robh+dt@...nel.org>, <mark.rutland@....com>,
        <marcel@...tmann.org>, <johan.hedberg@...il.com>
CC:     <devicetree@...r.kernel.org>, <linux-bluetooth@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-mediatek@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, Sean Wang <sean.wang@...iatek.com>
Subject: [PATCH v6 3/4] Bluetooth: mediatek: Add protocol support for MediaTek serial devices

From: Sean Wang <sean.wang@...iatek.com>

This adds a driver to run on the top of btuart 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@...iatek.com>
---
 drivers/bluetooth/Kconfig     |  11 +
 drivers/bluetooth/Makefile    |   2 +
 drivers/bluetooth/btmtkuart.c | 552 ++++++++++++++++++++++++++++++++++++++++++
 drivers/bluetooth/btmtkuart.h |  83 +++++++
 4 files changed, 648 insertions(+)
 create mode 100644 drivers/bluetooth/btmtkuart.c
 create mode 100644 drivers/bluetooth/btmtkuart.h

diff --git a/drivers/bluetooth/Kconfig b/drivers/bluetooth/Kconfig
index a164ac4..074737c 100644
--- a/drivers/bluetooth/Kconfig
+++ b/drivers/bluetooth/Kconfig
@@ -74,6 +74,17 @@ config BT_HCIBTSDIO
 	  Say Y here to compile support for Bluetooth SDIO devices into the
 	  kernel or say M to compile it as module (btsdio).
 
+config BT_HCIBTUART_MTK
+	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_HCIUART
 	tristate "HCI UART driver"
 	depends on SERIAL_DEV_BUS || !SERIAL_DEV_BUS
diff --git a/drivers/bluetooth/Makefile b/drivers/bluetooth/Makefile
index 2fb6268..2aea62e 100644
--- a/drivers/bluetooth/Makefile
+++ b/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-$(CONFIG_BT_HCIBTUART_MTK)	+= btmtkuart.o
+
 obj-$(CONFIG_BT_HCIUART_NOKIA)	+= hci_nokia.o
 
 btmrvl-y			:= btmrvl_main.o
diff --git a/drivers/bluetooth/btmtkuart.c b/drivers/bluetooth/btmtkuart.c
new file mode 100644
index 0000000..dd800ac
--- /dev/null
+++ b/drivers/bluetooth/btmtkuart.c
@@ -0,0 +1,552 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2018 MediaTek Inc.
+
+/*
+ * Bluetooth support for MediaTek serial devices
+ *
+ * Author: Sean Wang <sean.wang@...iatek.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 "btmtkuart.h"
+#include "h4_recv.h"
+
+static void mtk_stp_reset(struct mtk_stp_splitter *sp)
+{
+	sp->cursor = 2;
+	sp->dlen = 0;
+}
+
+static const unsigned char *
+mtk_stp_split(struct mtk_btuart_dev *bdev, struct mtk_stp_splitter *sp,
+	      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 (!sp->dlen && sp->cursor >= 6)
+		sp->cursor = 0;
+
+	/* Filling pad until all STP info is obtained. */
+	while (sp->cursor < 6 && count > 0) {
+		sp->pad[sp->cursor] = *data;
+		sp->cursor++;
+		data++;
+		count--;
+	}
+
+	/* Retrieve STP info and have a sanity check. */
+	if (!sp->dlen && sp->cursor >= 6) {
+		shdr = (struct mtk_stp_hdr *)&sp->pad[2];
+		sp->dlen = shdr->dlen1 << 8 | shdr->dlen2;
+
+		/* Resync STP when unexpected data is being read. */
+		if (shdr->prefix != 0x80 || sp->dlen > 2048) {
+			bt_dev_err(bdev->hdev, "stp format unexpect (%d, %d)",
+				   shdr->prefix, sp->dlen);
+			mtk_stp_reset(sp);
+		}
+	}
+
+	/* 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, sp->dlen);
+
+	/* Update the remaining size of STP packet. */
+	sp->dlen -= *sz_h4;
+
+	/* Data points to STP payload which can be handled by H4. */
+	return data;
+}
+
+static int mtk_stp_send(struct mtk_btuart_dev *bdev, struct sk_buff *skb)
+{
+	struct mtk_stp_hdr *shdr;
+	struct sk_buff *new_skb;
+	int dlen;
+
+	memcpy(skb_push(skb, 1), &hci_skb_pkt_type(skb), 1);
+	dlen = skb->len;
+
+	/* Make sure of STP header at least has 4-bytes free space to fill. */
+	if (unlikely(skb_headroom(skb) < sizeof(*shdr))) {
+		new_skb = skb_realloc_headroom(skb, sizeof(*shdr));
+		kfree_skb(skb);
+		skb = new_skb;
+	}
+
+	/* Build for STP packet format. */
+	shdr = skb_push(skb, sizeof(*shdr));
+	mtk_make_stp_hdr(shdr, 0, dlen);
+	skb_put_zero(skb, MTK_STP_TLR_SIZE);
+
+	skb_queue_tail(&bdev->txq, skb);
+
+	return 0;
+}
+
+static int mtk_hci_wmt_sync(struct hci_dev *hdev, u8 opcode, u8 flag,
+			    u16 plen, const void *param)
+{
+	struct mtk_hci_wmt_cmd wc;
+	struct mtk_wmt_hdr *hdr;
+	struct sk_buff *skb;
+	u32 hlen;
+
+	hlen = sizeof(*hdr) + plen;
+	if (hlen > 255)
+		return -EINVAL;
+
+	hdr = (struct mtk_wmt_hdr *)&wc;
+	mtk_make_wmt_hdr(hdr, opcode, plen, flag);
+	memcpy(wc.data, param, plen);
+
+	atomic_inc(&hdev->cmd_cnt);
+
+	skb = __hci_cmd_sync_ev(hdev, 0xfc6f, hlen, &wc, HCI_VENDOR_PKT,
+				HCI_INIT_TIMEOUT);
+
+	if (IS_ERR(skb)) {
+		int err = PTR_ERR(skb);
+
+		bt_dev_err(hdev, "Failed to send wmt cmd (%d)", err);
+		return err;
+	}
+
+	kfree_skb(skb);
+
+	return 0;
+}
+
+static int mtk_setup_fw(struct hci_dev *hdev)
+{
+	const struct firmware *fw;
+	const char *fwname;
+	const u8 *fw_ptr;
+	size_t fw_size;
+	int err, dlen;
+	u8 flag;
+
+	fwname = FIRMWARE_MT7622;
+
+	err = request_firmware(&fw, fwname, &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 deivice 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)
+			break;
+
+		fw_size -= dlen;
+		fw_ptr += dlen;
+	}
+
+	release_firmware(fw);
+
+	return err;
+}
+
+static int mtk_btuart_hci_frame(struct hci_dev *hdev, struct sk_buff *skb)
+{
+	struct hci_event_hdr *hdr = (void *)skb->data;
+
+	/* Fix up the vendor event id with HCI_VENDOR_PKT instead of
+	 * 0xe4 so that btmon can parse the kind of vendor event properly.
+	 */
+	if (hdr->evt == 0xe4)
+		hdr->evt = HCI_VENDOR_PKT;
+
+	/* Each HCI event would go through the core. */
+	return hci_recv_frame(hdev, skb);
+}
+
+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 = mtk_btuart_hci_frame },
+};
+
+static int mtk_btuart_recv(struct hci_dev *hdev, const u8 *data, size_t count)
+{
+	struct mtk_btuart_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, bdev->sp, 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 void mtk_btuart_tx_work(struct work_struct *work)
+{
+	struct mtk_btuart_dev *bdev = container_of(work, struct mtk_btuart_dev,
+						   tx_work);
+	struct serdev_device *serdev = bdev->serdev;
+	struct hci_dev *hdev = bdev->hdev;
+
+	while (1) {
+		clear_bit(BTUART_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(BTUART_TX_STATE_WAKEUP, &bdev->tx_state))
+			break;
+	}
+
+	clear_bit(BTUART_TX_STATE_ACTIVE, &bdev->tx_state);
+}
+
+static int mtk_btuart_tx_wakeup(struct mtk_btuart_dev *bdev)
+{
+	if (test_and_set_bit(BTUART_TX_STATE_ACTIVE, &bdev->tx_state)) {
+		set_bit(BTUART_TX_STATE_WAKEUP, &bdev->tx_state);
+		return 0;
+	}
+
+	schedule_work(&bdev->tx_work);
+
+	return 0;
+}
+
+static int mtk_btuart_receive_buf(struct serdev_device *serdev, const u8 *data,
+				  size_t count)
+{
+	struct mtk_btuart_dev *bdev = serdev_device_get_drvdata(serdev);
+	int err;
+
+	err = mtk_btuart_recv(bdev->hdev, data, count);
+	if (err < 0)
+		return err;
+
+	bdev->hdev->stat.byte_rx += count;
+
+	return count;
+}
+
+static void mtk_btuart_write_wakeup(struct serdev_device *serdev)
+{
+	struct mtk_btuart_dev *bdev = serdev_device_get_drvdata(serdev);
+
+	mtk_btuart_tx_wakeup(bdev);
+}
+
+static const struct serdev_device_ops mtk_btuart_client_ops = {
+	.receive_buf = mtk_btuart_receive_buf,
+	.write_wakeup = mtk_btuart_write_wakeup,
+};
+
+static int mtk_btuart_open(struct hci_dev *hdev)
+{
+	struct mtk_btuart_dev *bdev = hci_get_drvdata(hdev);
+	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));
+
+	return err;
+}
+
+static int mtk_btuart_close(struct hci_dev *hdev)
+{
+	struct mtk_btuart_dev *bdev = hci_get_drvdata(hdev);
+
+	serdev_device_close(bdev->serdev);
+
+	return 0;
+}
+
+static int mtk_btuart_flush(struct hci_dev *hdev)
+{
+	struct mtk_btuart_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;
+
+	return 0;
+}
+
+static int mtk_btuart_setup(struct hci_dev *hdev)
+{
+	struct mtk_btuart_dev *bdev = hci_get_drvdata(hdev);
+	struct device *dev;
+	u8 param = 0x1;
+	int err = 0;
+
+	dev = &bdev->serdev->dev;
+
+	mtk_stp_reset(bdev->sp);
+
+	/* 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;
+
+	/* Setup a firmware which the device definitely requires. */
+	err = mtk_setup_fw(hdev);
+	if (err < 0)
+		goto err_clk;
+
+	/* Activate funciton the firmware providing to. */
+	err = mtk_hci_wmt_sync(hdev, MTK_WMT_RST, 0x4, 0, 0);
+	if (err < 0)
+		goto err_clk;
+
+	/* Enable Bluetooth protocol. */
+	err = mtk_hci_wmt_sync(hdev, MTK_WMT_FUNC_CTRL, 0x0, sizeof(param),
+			       &param);
+	if (err < 0)
+		goto err_clk;
+
+	set_bit(HCI_QUIRK_NON_PERSISTENT_SETUP, &hdev->quirks);
+
+	return 0;
+err_clk:
+	clk_disable_unprepare(bdev->clk);
+err_put_rpm:
+	pm_runtime_put_sync(dev);
+err_disable_rpm:
+	pm_runtime_disable(dev);
+
+	return err;
+}
+
+static int mtk_btuart_shutdown(struct hci_dev *hdev)
+{
+	struct mtk_btuart_dev *bdev = hci_get_drvdata(hdev);
+	struct device *dev = &bdev->serdev->dev;
+	u8 param = 0x0;
+
+	/* Disable the device. */
+	mtk_hci_wmt_sync(hdev, MTK_WMT_FUNC_CTRL, 0x0, sizeof(param), &param);
+
+	/* Shutdown the clock and power domain the device requires. */
+	clk_disable_unprepare(bdev->clk);
+	pm_runtime_put_sync(dev);
+	pm_runtime_disable(dev);
+
+	return 0;
+}
+
+static int mtk_btuart_send(struct hci_dev *hdev, struct sk_buff *skb)
+{
+	struct mtk_btuart_dev *bdev = hci_get_drvdata(hdev);
+	int err;
+
+	err = mtk_stp_send(bdev, skb);
+	if (err < 0)
+		return err;
+
+	err = mtk_btuart_tx_wakeup(bdev);
+
+	return err;
+}
+
+static int mtk_btuart_probe(struct serdev_device *serdev)
+{
+	struct mtk_btuart_dev *bdev;
+	struct hci_dev *hdev;
+
+	bdev = devm_kzalloc(&serdev->dev, sizeof(*bdev), GFP_KERNEL);
+	if (!bdev)
+		return -ENOMEM;
+
+	bdev->sp = devm_kzalloc(&serdev->dev, sizeof(*bdev->sp), GFP_KERNEL);
+	if (!bdev->sp)
+		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, &mtk_btuart_client_ops);
+
+	INIT_WORK(&bdev->tx_work, mtk_btuart_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;
+	hdev->manufacturer = 70;
+	hci_set_drvdata(hdev, bdev);
+
+	hdev->open  = mtk_btuart_open;
+	hdev->close = mtk_btuart_close;
+	hdev->flush = mtk_btuart_flush;
+	hdev->setup = mtk_btuart_setup;
+	hdev->shutdown = mtk_btuart_shutdown;
+	hdev->send  = mtk_btuart_send;
+	SET_HCIDEV_DEV(hdev, &serdev->dev);
+
+	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 mtk_btuart_remove(struct serdev_device *serdev)
+{
+	struct mtk_btuart_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 mtk_btuart_driver = {
+	.probe = mtk_btuart_probe,
+	.remove = mtk_btuart_remove,
+	.driver = {
+		.name = "btmtkuart",
+		.of_match_table = of_match_ptr(mtk_of_match_table),
+	},
+};
+
+module_serdev_device_driver(mtk_btuart_driver);
+
+MODULE_AUTHOR("Sean Wang <sean.wang@...iatek.com>");
+MODULE_DESCRIPTION("MediaTek Bluetooth Serial driver");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/bluetooth/btmtkuart.h b/drivers/bluetooth/btmtkuart.h
new file mode 100644
index 0000000..b77d175
--- /dev/null
+++ b/drivers/bluetooth/btmtkuart.h
@@ -0,0 +1,83 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2018 MediaTek Inc.
+ *
+ * Bluetooth support for MediaTek serial devices
+ *
+ * Author: Sean Wang <sean.wang@...iatek.com>
+ *
+ */
+
+#define FIRMWARE_MT7622		"mediatek/mt7622pr2h.bin"
+
+#define MTK_STP_TLR_SIZE	2
+
+#define BTUART_TX_STATE_ACTIVE	1
+#define BTUART_TX_STATE_WAKEUP	2
+
+enum {
+	MTK_WMT_PATCH_DWNLD = 0x1,
+	MTK_WMT_FUNC_CTRL = 0x6,
+	MTK_WMT_RST = 0x7
+};
+
+struct mtk_stp_hdr {
+	u8 prefix;
+	u8 dlen1:4;
+	u8 type:4;
+	u8 dlen2;
+	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 mtk_stp_splitter {
+	u8	pad[6];
+	u8	cursor;
+	u16	dlen;
+};
+
+struct mtk_btuart_dev {
+	struct hci_dev *hdev;
+	struct serdev_device *serdev;
+
+	struct work_struct tx_work;
+	unsigned long tx_state;
+	struct sk_buff_head txq;
+
+	struct sk_buff *rx_skb;
+
+	struct mtk_stp_splitter *sp;
+	struct clk *clk;
+};
+
+static inline void
+mtk_make_stp_hdr(struct mtk_stp_hdr *hdr, u8 type, u32 dlen)
+{
+	u8 *p = (u8 *)hdr;
+
+	hdr->prefix = 0x80;
+	hdr->dlen1 = (dlen & 0xf00) >> 8;
+	hdr->type = type;
+	hdr->dlen2 = dlen & 0xff;
+	hdr->cs = p[0] + p[1] + p[2];
+}
+
+static inline void
+mtk_make_wmt_hdr(struct mtk_wmt_hdr *hdr, u8 op, u16 plen, u8 flag)
+{
+	hdr->dir = 1;
+	hdr->op = op;
+	hdr->dlen = cpu_to_le16(plen + 1);
+	hdr->flag = flag;
+}
-- 
2.7.4

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