Re: [PATCH v7 2/3] Bluetooth: mediatek: Add protocol support for MediaTek serial devices

[Marcel Holtmann <marcel@holtmann.org>]

Hi Sean,

>>> 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.
>>> 
> 
> [ ... ]
> 
>>> +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;
>> 
>> So this is the hard one. I doubt that this is endian safe. It is also some fun way of packing it. Can you find a better variable name and just pack it into an u16 in the function. And then also label this __le16 or __be16 accordingly.
> 
> okay, I will do it. here I suppose 'u8 dlen1:4 and u8 type:4' only take up one byte. 
> 
>>> +	u8 dlen2;
>>> +	u8 cs;
>> 
>> Are you checking the checksum on receive?
>> 
> 
> it is no needs. cs always shows zeros when I dump these received packets.
> 
>>> +} __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 work_struct tx_work;
>>> +	unsigned long tx_state;
>>> +	struct sk_buff_head txq;
>>> +
>>> +	struct sk_buff *rx_skb;
>>> +
>>> +	struct mtk_stp_splitter *sp;
>> 
>> This should be a leftover and no longer be needed.
>> 
> 
> okay. it's my fault and I should have a removal in the version
> 
>>> +	struct clk *clk;
>> 
>> Move the struct clk below struct serdev_device.
>> 
> 
> okay, it is a nice arrangement
> 
>>> +
>>> +	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 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;
>>> +	hdr->dir = 1;
>>> +	hdr->op = op;
>>> +	hdr->dlen = cpu_to_le16(plen + 1);
>>> +	hdr->flag = flag;
>>> +	memcpy(wc.data, param, plen);
>>> +
>>> +	atomic_inc(&hdev->cmd_cnt);
>> 
>> Why are you doing this one. It will need a comment here if really needed. However I doubt that this is needed. You are only using it from hdev->setup and hdev->shutdown callbacks.
>> 
> 
> An increment on cmd_cnt is really needed because hci_cmd_work would check whether cmd_cnt is positive and then has a decrement on cmd_cnt before a packet is being sent out.
> 
> okay will add a comment.

but you are in ->setup callback this time. So if you need this, then all the other ->setup routines would actually fail as well. Either this is leftover from when you did things in ->probe or ->open or this is some thing we might better fix properly in the core instead of papering over it. Can you recheck if this is really needed.

>>> +
>>> +	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;
>> 
>> Scrap the fwname variable and use it directly. If you later want to support newer/older hardware with other firmware names, we deal with it then.
>> 
> 
> okay
> 
>>> +
>>> +	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 btmtkuart_recv_event(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. */
>> 
>> This comment adds really no value here. Just remove it.
>> 
> 
> okay
> 
>>> +	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 = btmtkuart_recv_event },
>>> +};
>>> +
>>> +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 = shdr->dlen1 << 8 | shdr->dlen2;
>>> +
>>> +		/* 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 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);
>>> +}
>>> +
>> 
>> Move btmtkuart_recv and mtk_stp_split above this function to keep them close where they are used.
>> 
> 
> okay
> 
>>> +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;
>>> +	}
>>> +
>>> +	dev = &bdev->serdev->dev;
>>> +
>>> +	bdev->stp_cursor = 2;
>>> +	bdev->stp_dlen = 0;
>>> +
>>> +	/* 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;
>> 
>> Add an extra empty line here.
>> 
> 
> okay
> 
>>> +	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;
>> 
>> I would assume you want to reset the stp_cursor here as well.
>> 
> 
> yes, it can be and is better
> 
>>> +
>>> +	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 funciton the firmware providing to. */
>>> +	err = mtk_hci_wmt_sync(hdev, MTK_WMT_RST, 0x4, 0, 0);
>>> +	if (err < 0)
>>> +		return err;
>>> +
>>> +	/* Enable Bluetooth protocol. */
>>> +	err = mtk_hci_wmt_sync(hdev, MTK_WMT_FUNC_CTRL, 0x0, sizeof(param),
>>> +			       &param);
>>> +	if (err < 0)
>>> +		return err;
>>> +
>>> +	set_bit(HCI_QUIRK_NON_PERSISTENT_SETUP, &hdev->quirks);
>> 
>> Since you have your own driver. Just move this after the hdev->manufacturer setting in probe(). There is no need to keep setting this over and over again.
>> 
> 
> okay
> 
>>> +
>>> +	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);
>>> +
>>> +	return err;
>>> +}
>>> +
>>> +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;
>>> +	struct sk_buff *new_skb;
>>> +	int dlen;
>>> +	u8 *p;
>>> +
>>> +	/* Prepend skb with frame type */
>>> +	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));
>>> +	p = (u8 *)shdr;
>>> +	shdr->prefix = 0x80;
>>> +	shdr->dlen1 = (dlen & 0xf00) >> 8;
>>> +	shdr->type = 0;
>>> +	shdr->dlen2 = dlen & 0xff;
>>> +	shdr->cs = p[0] + p[1] + p[2];
>> 
> 
> as above discussion about shr->cs , it can be filled with zero to have less computing 

If it has no value, then zero it out and add a comment for it.

> 
>> I would add another comment here that this added the STP trailer. And change the above to mention it adds the STP header.
>> 
> 
> sure
> 
>> And you might want to check if there is space for the trailer as well. Otherwise skb_put tends to call BUG() if I remember correctly. I know this is super unlikely since our bt_skb_alloc is pretty large.
>> 
> 
> sure, I will add the handling for that. it should be better to make sure all rooms are enough for header and trailer before adding content to them
> 
> 
>>> +	skb_put_zero(skb, MTK_STP_TLR_SIZE);
>> 
>> Extra empty line here please.
>> 
> 
> okay
> 
>>> +	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;
>>> +
>>> +	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" VERSION);
>> 
>> You are missing a “ ver “ at the end of your string here. Check with modinfo that it looks correct.
>> 
> 
> okay
> 
>>> +MODULE_VERSION(VERSION);
>>> +MODULE_LICENSE("GPL”);
>> 
>> You want to add a MODULE_FIRMWARE here as well.
>> 
> 
> okay

Regards

Marcel