// 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 <linux/unaligned.h>
#include <linux/atomic.h>
#include <linux/clk.h>
#include <linux/firmware.h>
#include <linux/gpio/consumer.h>
#include <linux/iopoll.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/pinctrl/consumer.h>
#include <linux/pm_runtime.h>
#include <linux/regulator/consumer.h>
#include <linux/serdev.h>
#include <linux/skbuff.h>
#include <linux/usb.h>

#include <net/bluetooth/bluetooth.h>
#include <net/bluetooth/hci_core.h>

#include "hci_uart.h"
#include "btmtk.h"

#define VERSION "0.2"

#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
#define BTMTKUART_REQUIRED_WAKEUP       4

#define BTMTKUART_FLAG_STANDALONE_HW     BIT(0)

struct mtk_stp_hdr {
        u8      prefix;
        __be16  dlen;
        u8      cs;
} __packed;

struct btmtkuart_data {
        unsigned int flags;
        const char *fwname;
};

struct btmtkuart_dev {
        struct hci_dev *hdev;
        struct serdev_device *serdev;

        struct clk *clk;
        struct clk *osc;
        struct regulator *vcc;
        struct gpio_desc *reset;
        struct gpio_desc *boot;
        struct pinctrl *pinctrl;
        struct pinctrl_state *pins_runtime;
        struct pinctrl_state *pins_boot;
        speed_t desired_speed;
        speed_t curr_speed;

        struct work_struct tx_work;
        unsigned long tx_state;
        struct sk_buff_head txq;

        struct sk_buff *rx_skb;
        struct sk_buff *evt_skb;

        u8      stp_pad[6];
        u8      stp_cursor;
        u16     stp_dlen;

        const struct btmtkuart_data *data;
        struct hci_uart hu;
};

#define btmtkuart_is_standalone(bdev)   \
        ((bdev)->data->flags & BTMTKUART_FLAG_STANDALONE_HW)
#define btmtkuart_is_builtin_soc(bdev)  \
        !((bdev)->data->flags & BTMTKUART_FLAG_STANDALONE_HW)

static int mtk_hci_wmt_sync(struct hci_dev *hdev,
                            struct btmtk_hci_wmt_params *wmt_params)
{
        struct btmtkuart_dev *bdev = hci_get_drvdata(hdev);
        struct btmtk_hci_wmt_evt_funcc *wmt_evt_funcc;
        u32 hlen, status = BTMTK_WMT_INVALID;
        struct btmtk_hci_wmt_evt *wmt_evt;
        struct btmtk_hci_wmt_cmd *wc;
        struct btmtk_wmt_hdr *hdr;
        int err;

        /* Send the WMT command and wait until the WMT event returns */
        hlen = sizeof(*hdr) + wmt_params->dlen;
        if (hlen > 255) {
                err = -EINVAL;
                goto err_free_skb;
        }

        wc = kzalloc(hlen, GFP_KERNEL);
        if (!wc) {
                err = -ENOMEM;
                goto err_free_skb;
        }

        hdr = &wc->hdr;
        hdr->dir = 1;
        hdr->op = wmt_params->op;
        hdr->dlen = cpu_to_le16(wmt_params->dlen + 1);
        hdr->flag = wmt_params->flag;
        memcpy(wc->data, wmt_params->data, wmt_params->dlen);

        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);
                goto err_free_wc;
        }

        /* 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 specific 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");
                clear_bit(BTMTKUART_TX_WAIT_VND_EVT, &bdev->tx_state);
                goto err_free_wc;
        }

        if (err) {
                bt_dev_err(hdev, "Execution of wmt command timed out");
                clear_bit(BTMTKUART_TX_WAIT_VND_EVT, &bdev->tx_state);
                err = -ETIMEDOUT;
                goto err_free_wc;
        }

        /* Parse and handle the return WMT event */
        wmt_evt = (struct btmtk_hci_wmt_evt *)bdev->evt_skb->data;
        if (wmt_evt->whdr.op != hdr->op) {
                bt_dev_err(hdev, "Wrong op received %d expected %d",
                           wmt_evt->whdr.op, hdr->op);
                err = -EIO;
                goto err_free_wc;
        }

        switch (wmt_evt->whdr.op) {
        case BTMTK_WMT_SEMAPHORE:
                if (wmt_evt->whdr.flag == 2)
                        status = BTMTK_WMT_PATCH_UNDONE;
                else
                        status = BTMTK_WMT_PATCH_DONE;
                break;
        case BTMTK_WMT_FUNC_CTRL:
                wmt_evt_funcc = (struct btmtk_hci_wmt_evt_funcc *)wmt_evt;
                if (be16_to_cpu(wmt_evt_funcc->status) == 0x404)
                        status = BTMTK_WMT_ON_DONE;
                else if (be16_to_cpu(wmt_evt_funcc->status) == 0x420)
                        status = BTMTK_WMT_ON_PROGRESS;
                else
                        status = BTMTK_WMT_ON_UNDONE;
                break;
        }

        if (wmt_params->status)
                *wmt_params->status = status;

err_free_wc:
        kfree(wc);
err_free_skb:
        kfree_skb(bdev->evt_skb);
        bdev->evt_skb = NULL;

        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;

        /* When someone waits for the WMT event, the skb is being cloned
         * and being processed the events from there then.
         */
        if (test_bit(BTMTKUART_TX_WAIT_VND_EVT, &bdev->tx_state)) {
                bdev->evt_skb = skb_clone(skb, GFP_KERNEL);
                if (!bdev->evt_skb) {
                        err = -ENOMEM;
                        goto err_out;
                }
        }

        err = hci_recv_frame(hdev, skb);
        if (err < 0)
                goto err_free_skb;

        if (hdr->evt == HCI_EV_WMT) {
                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 0;

err_free_skb:
        kfree_skb(bdev->evt_skb);
        bdev->evt_skb = NULL;

err_out:
        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 unexpected (%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;

        /* Translate 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 void 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->hu, bdev->rx_skb, p_h4,
                                           sz_h4, mtk_recv_pkts,
                                           ARRAY_SIZE(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;
                }

                sz_left -= sz_h4;
                p_left += sz_h4;
        }
}

static size_t btmtkuart_receive_buf(struct serdev_device *serdev,
                                    const u8 *data, size_t count)
{
        struct btmtkuart_dev *bdev = serdev_device_get_drvdata(serdev);

        btmtkuart_recv(bdev->hdev, data, count);

        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;
        }

        if (btmtkuart_is_standalone(bdev)) {
                if (bdev->curr_speed != bdev->desired_speed)
                        err = serdev_device_set_baudrate(bdev->serdev,
                                                         115200);
                else
                        err = serdev_device_set_baudrate(bdev->serdev,
                                                         bdev->desired_speed);

                if (err < 0) {
                        bt_dev_err(hdev, "Unable to set baudrate UART device %s",
                                   dev_name(&bdev->serdev->dev));
                        goto  err_serdev_close;
                }

                serdev_device_set_flow_control(bdev->serdev, false);
        }

        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_resume_and_get(dev);
        if (err < 0)
                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_serdev_close:
        serdev_device_close(bdev->serdev);
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_func_query(struct hci_dev *hdev)
{
        struct btmtk_hci_wmt_params wmt_params;
        int status, err;
        u8 param = 0;

        /* Query whether the function is enabled */
        wmt_params.op = BTMTK_WMT_FUNC_CTRL;
        wmt_params.flag = 4;
        wmt_params.dlen = sizeof(param);
        wmt_params.data = &param;
        wmt_params.status = &status;

        err = mtk_hci_wmt_sync(hdev, &wmt_params);
        if (err < 0) {
                bt_dev_err(hdev, "Failed to query function status (%d)", err);
                return err;
        }

        return status;
}

static int btmtkuart_change_baudrate(struct hci_dev *hdev)
{
        struct btmtkuart_dev *bdev = hci_get_drvdata(hdev);
        struct btmtk_hci_wmt_params wmt_params;
        __le32 baudrate;
        u8 param;
        int err;

        /* Indicate the device to enter the probe state the host is
         * ready to change a new baudrate.
         */
        baudrate = cpu_to_le32(bdev->desired_speed);
        wmt_params.op = BTMTK_WMT_HIF;
        wmt_params.flag = 1;
        wmt_params.dlen = 4;
        wmt_params.data = &baudrate;
        wmt_params.status = NULL;

        err = mtk_hci_wmt_sync(hdev, &wmt_params);
        if (err < 0) {
                bt_dev_err(hdev, "Failed to device baudrate (%d)", err);
                return err;
        }

        err = serdev_device_set_baudrate(bdev->serdev,
                                         bdev->desired_speed);
        if (err < 0) {
                bt_dev_err(hdev, "Failed to set up host baudrate (%d)",
                           err);
                return err;
        }

        serdev_device_set_flow_control(bdev->serdev, false);

        /* Send a dummy byte 0xff to activate the new baudrate */
        param = 0xff;
        err = serdev_device_write_buf(bdev->serdev, &param, sizeof(param));
        if (err < 0 || err < sizeof(param))
                return err;

        serdev_device_wait_until_sent(bdev->serdev, 0);

        /* Wait some time for the device changing baudrate done */
        usleep_range(20000, 22000);

        /* Test the new baudrate */
        wmt_params.op = BTMTK_WMT_TEST;
        wmt_params.flag = 7;
        wmt_params.dlen = 0;
        wmt_params.data = NULL;
        wmt_params.status = NULL;

        err = mtk_hci_wmt_sync(hdev, &wmt_params);
        if (err < 0) {
                bt_dev_err(hdev, "Failed to test new baudrate (%d)",
                           err);
                return err;
        }

        bdev->curr_speed = bdev->desired_speed;

        return 0;
}

static int btmtkuart_setup(struct hci_dev *hdev)
{
        struct btmtkuart_dev *bdev = hci_get_drvdata(hdev);
        struct btmtk_hci_wmt_params wmt_params;
        ktime_t calltime, delta, rettime;
        struct btmtk_tci_sleep tci_sleep;
        unsigned long long duration;
        struct sk_buff *skb;
        int err, status;
        u8 param = 0x1;

        calltime = ktime_get();

        /* Wakeup MCUSYS is required for certain devices before we start to
         * do any setups.
         */
        if (test_bit(BTMTKUART_REQUIRED_WAKEUP, &bdev->tx_state)) {
                wmt_params.op = BTMTK_WMT_WAKEUP;
                wmt_params.flag = 3;
                wmt_params.dlen = 0;
                wmt_params.data = NULL;
                wmt_params.status = NULL;

                err = mtk_hci_wmt_sync(hdev, &wmt_params);
                if (err < 0) {
                        bt_dev_err(hdev, "Failed to wakeup the chip (%d)", err);
                        return err;
                }

                clear_bit(BTMTKUART_REQUIRED_WAKEUP, &bdev->tx_state);
        }

        if (btmtkuart_is_standalone(bdev))
                btmtkuart_change_baudrate(hdev);

        /* Query whether the firmware is already download */
        wmt_params.op = BTMTK_WMT_SEMAPHORE;
        wmt_params.flag = 1;
        wmt_params.dlen = 0;
        wmt_params.data = NULL;
        wmt_params.status = &status;

        err = mtk_hci_wmt_sync(hdev, &wmt_params);
        if (err < 0) {
                bt_dev_err(hdev, "Failed to query firmware status (%d)", err);
                return err;
        }

        if (status == BTMTK_WMT_PATCH_DONE) {
                bt_dev_info(hdev, "Firmware already downloaded");
                goto ignore_setup_fw;
        }

        /* Setup a firmware which the device definitely requires */
        err = btmtk_setup_firmware(hdev, bdev->data->fwname, mtk_hci_wmt_sync);
        if (err < 0)
                return err;

ignore_setup_fw:
        /* Query whether the device is already enabled */
        err = readx_poll_timeout(btmtkuart_func_query, hdev, status,
                                 status < 0 || status != BTMTK_WMT_ON_PROGRESS,
                                 2000, 5000000);
        /* -ETIMEDOUT happens */
        if (err < 0)
                return err;

        /* The other errors happen in btusb_mtk_func_query */
        if (status < 0)
                return status;

        if (status == BTMTK_WMT_ON_DONE) {
                bt_dev_info(hdev, "function already on");
                goto ignore_func_on;
        }

        /* Enable Bluetooth protocol */
        wmt_params.op = BTMTK_WMT_FUNC_CTRL;
        wmt_params.flag = 0;
        wmt_params.dlen = sizeof(param);
        wmt_params.data = &param;
        wmt_params.status = NULL;

        err = mtk_hci_wmt_sync(hdev, &wmt_params);
        if (err < 0) {
                bt_dev_err(hdev, "Failed to send wmt func ctrl (%d)", err);
                return err;
        }

ignore_func_on:
        /* Apply the low power environment setup */
        tci_sleep.mode = 0x5;
        tci_sleep.duration = cpu_to_le16(0x640);
        tci_sleep.host_duration = cpu_to_le16(0x640);
        tci_sleep.host_wakeup_pin = 0;
        tci_sleep.time_compensation = 0;

        skb = __hci_cmd_sync(hdev, 0xfc7a, sizeof(tci_sleep), &tci_sleep,
                             HCI_INIT_TIMEOUT);
        if (IS_ERR(skb)) {
                err = PTR_ERR(skb);
                bt_dev_err(hdev, "Failed to apply low power setting (%d)", err);
                return err;
        }
        kfree_skb(skb);

        rettime = ktime_get();
        delta = ktime_sub(rettime, calltime);
        duration = (unsigned long long)ktime_to_ns(delta) >> 10;

        bt_dev_info(hdev, "Device setup in %llu usecs", duration);

        return 0;
}

static int btmtkuart_shutdown(struct hci_dev *hdev)
{
        struct btmtk_hci_wmt_params wmt_params;
        u8 param = 0x0;
        int err;

        /* Disable the device */
        wmt_params.op = BTMTK_WMT_FUNC_CTRL;
        wmt_params.flag = 0;
        wmt_params.dlen = sizeof(param);
        wmt_params.data = &param;
        wmt_params.status = NULL;

        err = mtk_hci_wmt_sync(hdev, &wmt_params);
        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_parse_dt(struct serdev_device *serdev)
{
        struct btmtkuart_dev *bdev = serdev_device_get_drvdata(serdev);
        struct device_node *node = serdev->dev.of_node;
        u32 speed = 921600;
        int err;

        if (btmtkuart_is_standalone(bdev)) {
                of_property_read_u32(node, "current-speed", &speed);

                bdev->desired_speed = speed;

                bdev->vcc = devm_regulator_get(&serdev->dev, "vcc");
                if (IS_ERR(bdev->vcc)) {
                        err = PTR_ERR(bdev->vcc);
                        return err;
                }

                bdev->osc = devm_clk_get_optional(&serdev->dev, "osc");
                if (IS_ERR(bdev->osc)) {
                        err = PTR_ERR(bdev->osc);
                        return err;
                }

                bdev->boot = devm_gpiod_get_optional(&serdev->dev, "boot",
                                                     GPIOD_OUT_LOW);
                if (IS_ERR(bdev->boot)) {
                        err = PTR_ERR(bdev->boot);
                        return err;
                }

                bdev->pinctrl = devm_pinctrl_get(&serdev->dev);
                if (IS_ERR(bdev->pinctrl)) {
                        err = PTR_ERR(bdev->pinctrl);
                        return err;
                }

                bdev->pins_boot = pinctrl_lookup_state(bdev->pinctrl,
                                                       "default");
                if (IS_ERR(bdev->pins_boot) && !bdev->boot) {
                        err = PTR_ERR(bdev->pins_boot);
                        dev_err(&serdev->dev,
                                "Should assign RXD to LOW at boot stage\n");
                        return err;
                }

                bdev->pins_runtime = pinctrl_lookup_state(bdev->pinctrl,
                                                          "runtime");
                if (IS_ERR(bdev->pins_runtime)) {
                        err = PTR_ERR(bdev->pins_runtime);
                        return err;
                }

                bdev->reset = devm_gpiod_get_optional(&serdev->dev, "reset",
                                                      GPIOD_OUT_LOW);
                if (IS_ERR(bdev->reset)) {
                        err = PTR_ERR(bdev->reset);
                        return err;
                }
        } else if (btmtkuart_is_builtin_soc(bdev)) {
                bdev->clk = devm_clk_get(&serdev->dev, "ref");
                if (IS_ERR(bdev->clk))
                        return PTR_ERR(bdev->clk);
        }

        return 0;
}

static int btmtkuart_probe(struct serdev_device *serdev)
{
        struct btmtkuart_dev *bdev;
        struct hci_dev *hdev;
        int err;

        bdev = devm_kzalloc(&serdev->dev, sizeof(*bdev), GFP_KERNEL);
        if (!bdev)
                return -ENOMEM;

        bdev->data = of_device_get_match_data(&serdev->dev);
        if (!bdev->data)
                return -ENODEV;

        bdev->serdev = serdev;
        serdev_device_set_drvdata(serdev, bdev);

        serdev_device_set_client_ops(serdev, &btmtkuart_client_ops);

        err = btmtkuart_parse_dt(serdev);
        if (err < 0)
                return err;

        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;
        bdev->hu.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;
        hdev->set_bdaddr = btmtk_set_bdaddr;
        SET_HCIDEV_DEV(hdev, &serdev->dev);

        hdev->manufacturer = 70;
        hci_set_quirk(hdev, HCI_QUIRK_NON_PERSISTENT_SETUP);

        if (btmtkuart_is_standalone(bdev)) {
                err = clk_prepare_enable(bdev->osc);
                if (err < 0)
                        goto err_hci_free_dev;

                if (bdev->boot) {
                        gpiod_set_value_cansleep(bdev->boot, 1);
                } else {
                        /* Switch to the specific pin state for the booting
                         * requires.
                         */
                        pinctrl_select_state(bdev->pinctrl, bdev->pins_boot);
                }

                /* Power on */
                err = regulator_enable(bdev->vcc);
                if (err < 0)
                        goto err_clk_disable_unprepare;

                /* Reset if the reset-gpios is available otherwise the board
                 * -level design should be guaranteed.
                 */
                if (bdev->reset) {
                        gpiod_set_value_cansleep(bdev->reset, 1);
                        usleep_range(1000, 2000);
                        gpiod_set_value_cansleep(bdev->reset, 0);
                }

                /* Wait some time until device got ready and switch to the pin
                 * mode the device requires for UART transfers.
                 */
                msleep(50);

                if (bdev->boot)
                        devm_gpiod_put(&serdev->dev, bdev->boot);

                pinctrl_select_state(bdev->pinctrl, bdev->pins_runtime);

                /* A standalone device doesn't depends on power domain on SoC,
                 * so mark it as no callbacks.
                 */
                pm_runtime_no_callbacks(&serdev->dev);

                set_bit(BTMTKUART_REQUIRED_WAKEUP, &bdev->tx_state);
        }

        err = hci_register_dev(hdev);
        if (err < 0) {
                dev_err(&serdev->dev, "Can't register HCI device\n");
                goto err_regulator_disable;
        }

        return 0;

err_regulator_disable:
        if (btmtkuart_is_standalone(bdev))
                regulator_disable(bdev->vcc);
err_clk_disable_unprepare:
        if (btmtkuart_is_standalone(bdev))
                clk_disable_unprepare(bdev->osc);
err_hci_free_dev:
        hci_free_dev(hdev);

        return err;
}

static void btmtkuart_remove(struct serdev_device *serdev)
{
        struct btmtkuart_dev *bdev = serdev_device_get_drvdata(serdev);
        struct hci_dev *hdev = bdev->hdev;

        if (btmtkuart_is_standalone(bdev)) {
                regulator_disable(bdev->vcc);
                clk_disable_unprepare(bdev->osc);
        }

        hci_unregister_dev(hdev);
        hci_free_dev(hdev);
}

static const struct btmtkuart_data mt7622_data __maybe_unused = {
        .fwname = FIRMWARE_MT7622,
};

static const struct btmtkuart_data mt7663_data __maybe_unused = {
        .flags = BTMTKUART_FLAG_STANDALONE_HW,
        .fwname = FIRMWARE_MT7663,
};

static const struct btmtkuart_data mt7668_data __maybe_unused = {
        .flags = BTMTKUART_FLAG_STANDALONE_HW,
        .fwname = FIRMWARE_MT7668,
};

#ifdef CONFIG_OF
static const struct of_device_id mtk_of_match_table[] = {
        { .compatible = "mediatek,mt7622-bluetooth", .data = &mt7622_data},
        { .compatible = "mediatek,mt7663u-bluetooth", .data = &mt7663_data},
        { .compatible = "mediatek,mt7668u-bluetooth", .data = &mt7668_data},
        { }
};
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");