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

Marcel Holtmann
2018-08-02T07:38:11Z

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