Message-Id: <461698FC-1403-43ED-B4D2-E9CD2EB35A8D@holtmann.org>
Date:   Sat, 14 Jul 2018 18:32:39 +0200
From:   Marcel Holtmann <marcel@...tmann.org>
To:     sean.wang@...iatek.com
Cc:     robh+dt@...nel.org, mark.rutland@....com,
        Johan Hedberg <johan.hedberg@...il.com>,
        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
Subject: Re: [PATCH v5 6/7] Bluetooth: mediatek: Add protocol support for
 MediaTek serial devices

Hi Sean,

> 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 | 352 ++++++++++++++++++++++++++++++++++++++++++
> drivers/bluetooth/btmtkuart.h | 116 ++++++++++++++
> drivers/bluetooth/btuart.c    |  18 +++
> 5 files changed, 499 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 00fdf5f..4d7d640 100644
> --- a/drivers/bluetooth/Kconfig
> +++ b/drivers/bluetooth/Kconfig
> @@ -85,6 +85,17 @@ config BT_HCIBTUART
> 	  Say Y here to compile support for Bluetooth UART devices into the
> 	  kernel or say M to compile it as module (btuart).
> 
> +config BT_HCIBTUART_MTK
> +	tristate "MediaTek HCI UART driver"
> +	depends on BT_HCIBTUART
> +	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 60a19cb..c9a8926 100644
> --- a/drivers/bluetooth/Makefile
> +++ b/drivers/bluetooth/Makefile
> @@ -26,6 +26,8 @@ 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-$(CONFIG_BT_HCIUART_NOKIA)	+= hci_nokia.o
> 
> obj-$(CONFIG_BT_HCIRSI)		+= btrsi.o
> diff --git a/drivers/bluetooth/btmtkuart.c b/drivers/bluetooth/btmtkuart.c
> new file mode 100644
> index 0000000..9eed21c
> --- /dev/null
> +++ b/drivers/bluetooth/btmtkuart.c
> @@ -0,0 +1,352 @@
> +// 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/module.h>
> +#include <linux/pm_runtime.h>
> +#include <linux/serdev.h>
> +
> +#include <net/bluetooth/bluetooth.h>
> +#include <net/bluetooth/hci_core.h>
> +
> +#include "btmtkuart.h"
> +#include "btuart.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 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 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);

you have two spaces between = and __hci..
> +
> +	if (IS_ERR(skb)) {
> +		int err = PTR_ERR(skb);
> +
> +		bt_dev_err(hdev, "Failed to send wmt cmd (%d)\n", err);

No \n here since bt_dev_err already adds it.

> +		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;
> +
> +	while (fw_size > 0) {
> +		dlen = min_t(int, 250, fw_size);
> +
> +		/* Tell deivice the position in sequence. */
> +		flag = (fw_size - dlen <= 0) ? 3 :
> +		       (fw_size < fw->size - 30) ? 2 : 1;

Use an if statement here. It is easier to read.

> +
> +		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;
> +}
> +
> +void *mtk_btuart_init(struct device *dev)
> +{
> +	struct mtk_bt_dev *soc;
> +
> +	soc = devm_kzalloc(dev, sizeof(*soc), GFP_KERNEL);
> +	if (!soc)
> +		return ERR_PTR(-ENOMEM);
> +
> +	soc->sp = devm_kzalloc(dev, sizeof(*soc->sp), GFP_KERNEL);
> +	if (!soc->sp)
> +		return ERR_PTR(-ENOMEM);
> +
> +	soc->clk = devm_clk_get(dev, "ref");
> +	if (IS_ERR(soc->clk))
> +		return ERR_CAST(soc->clk);
> +
> +	return soc;
> +}
> +EXPORT_SYMBOL_GPL(mtk_btuart_init);
> +
> +int mtk_btuart_send(struct hci_dev *hdev, struct sk_buff *skb)
> +{
> +	struct btuart_dev *bdev = hci_get_drvdata(hdev);
> +
> +	return mtk_stp_send(bdev, skb);
> +}
> +EXPORT_SYMBOL_GPL(mtk_btuart_send);
> +
> +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);
> +}
> +EXPORT_SYMBOL_GPL(mtk_btuart_hci_frame);
> +
> +int mtk_btuart_recv(struct hci_dev *hdev, const u8 *data, size_t count)
> +{
> +	struct btuart_dev *bdev = hci_get_drvdata(hdev);
> +	const unsigned char *p_left = data, *p_h4;
> +	const struct btuart_vnd *vnd = bdev->vnd;
> +	struct mtk_bt_dev *soc = bdev->data;
> +	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 don'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 and whose length recorded in STP header can
> +		 *  shows up the most length the H:4 engine can handle in one
> +		 *  time.
> +		 */
> +
> +		p_h4 = mtk_stp_split(bdev, soc->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, vnd->recv_pkts,
> +					   vnd->recv_pkts_cnt);
> +		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;
> +}
> +EXPORT_SYMBOL_GPL(mtk_btuart_recv);
> +
> +int mtk_btuart_setup(struct hci_dev *hdev)
> +{
> +	struct btuart_dev *bdev = hci_get_drvdata(hdev);
> +	struct mtk_bt_dev *soc = bdev->data;
> +	struct device *dev;
> +	u8 param = 0x1;
> +	int err = 0;
> +
> +	dev = &bdev->serdev->dev;
> +
> +	mtk_stp_reset(soc->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(soc->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(soc->clk);
> +err_put_rpm:
> +	pm_runtime_put_sync(dev);
> +err_disable_rpm:
> +	pm_runtime_disable(dev);
> +
> +	return err;
> +}
> +EXPORT_SYMBOL_GPL(mtk_btuart_setup);
> +
> +int mtk_btuart_shutdown(struct hci_dev *hdev)
> +{
> +	struct btuart_dev *bdev = hci_get_drvdata(hdev);
> +	struct device *dev = &bdev->serdev->dev;
> +	struct mtk_bt_dev *soc = bdev->data;
> +	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(soc->clk);
> +	pm_runtime_put_sync(dev);
> +	pm_runtime_disable(dev);
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(mtk_btuart_shutdown);
> +
> +MODULE_AUTHOR("Sean Wang <sean.wang@...iatek.com>");
> +MODULE_DESCRIPTION("Bluetooth Support for MediaTek Serial Devices");
> +MODULE_LICENSE("GPL v2");
> diff --git a/drivers/bluetooth/btmtkuart.h b/drivers/bluetooth/btmtkuart.h
> new file mode 100644
> index 0000000..4c2c24e
> --- /dev/null
> +++ b/drivers/bluetooth/btmtkuart.h
> @@ -0,0 +1,116 @@
> +/* 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
> +
> +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_bt_dev {
> +	struct clk *clk;
> +	struct completion wmt_cmd;
> +	struct mtk_stp_splitter *sp;
> +};
> +
> +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;
> +}
> +
> +#if IS_ENABLED(CONFIG_BT_HCIBTUART_MTK)
> +
> +void *mtk_btuart_init(struct device *dev);
> +int mtk_btuart_setup(struct hci_dev *hdev);
> +int mtk_btuart_shutdown(struct hci_dev *hdev);
> +int mtk_btuart_send(struct hci_dev *hdev, struct sk_buff *skb);
> +int mtk_btuart_hci_frame(struct hci_dev *hdev, struct sk_buff *skb);
> +int mtk_btuart_recv(struct hci_dev *hdev, const u8 *data, size_t count);
> +
> +#else
> +
> +static void *mtk_btuart_init(struct device *dev)
> +{
> +	return 0;
> +}
> +
> +static inline int mtk_btuart_setup(struct hci_dev *hdev)
> +{
> +	return -EOPNOTSUPP;
> +}
> +
> +static inline int mtk_btuart_shutdown(struct hci_dev *hdev)
> +{
> +	return -EOPNOTSUPP;
> +}
> +
> +static inline int mtk_btuart_send(struct hci_dev *hdev, struct sk_buff *skb)
> +{
> +	return -EOPNOTSUPP;
> +}
> +
> +static int mtk_btuart_hci_frame(struct hci_dev *hdev, struct sk_buff *skb)
> +{
> +	return -EOPNOTSUPP;
> +}
> +
> +static inline int mtk_btuart_recv(struct hci_dev *hdev, const u8 *data,
> +				  size_t count)
> +{
> +	return -EOPNOTSUPP;
> +}
> +
> +#endif
> diff --git a/drivers/bluetooth/btuart.c b/drivers/bluetooth/btuart.c
> index 65d0086..2e715a5 100644
> --- a/drivers/bluetooth/btuart.c
> +++ b/drivers/bluetooth/btuart.c
> @@ -35,6 +35,7 @@
> #include "h4_recv.h"
> #include "btuart.h"
> #include "btbcm.h"
> +#include "btmtkuart.h"
> 
> #define VERSION "1.0"
> 
> @@ -396,6 +397,12 @@ static const struct h4_recv_pkt bcm_recv_pkts[] = {
> 	{ BCM_RECV_NULL,    .recv = hci_recv_diag  },
> };
> 
> +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 const struct btuart_vnd bcm_vnd = {
> 	.recv_pkts	= bcm_recv_pkts,
> 	.recv_pkts_cnt	= ARRAY_SIZE(bcm_recv_pkts),
> @@ -403,6 +410,16 @@ static const struct btuart_vnd bcm_vnd = {
> 	.setup		= bcm_setup,
> };
> 
> +static const struct btuart_vnd mtk_vnd = {
> +	.recv_pkts	= mtk_recv_pkts,
> +	.recv_pkts_cnt	= ARRAY_SIZE(mtk_recv_pkts),
> +	.init		= mtk_btuart_init,
> +	.setup		= mtk_btuart_setup,
> +	.shutdown	= mtk_btuart_shutdown,
> +	.send		= mtk_btuart_send,
> +	.recv		= mtk_btuart_recv,
> +};
> +
> static const struct h4_recv_pkt default_recv_pkts[] = {
> 	{ H4_RECV_ACL,      .recv = hci_recv_frame },
> 	{ H4_RECV_SCO,      .recv = hci_recv_frame },
> @@ -487,6 +504,7 @@ static void btuart_remove(struct serdev_device *serdev)
> #ifdef CONFIG_OF
> static const struct of_device_id btuart_of_match_table[] = {
> 	{ .compatible = "brcm,bcm43438-bt", .data = &bcm_vnd },
> +	{ .compatible = "mediatek,mt7622-bluetooth", .data = &mtk_vnd },
> 	{ }
> };
> MODULE_DEVICE_TABLE(of, btuart_of_match_table);

Regards

Marcel

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