/*
 *  Texas Instrument's Bluetooth Driver For Shared Transport.
 *
 *  Bluetooth Driver acts as interface between HCI core and
 *  TI Shared Transport Layer.
 *
 *  Copyright (C) 2009-2010 Texas Instruments
 *  Author: Raja Mani <raja_mani@ti.com>
 *      Pavan Savoy <pavan_savoy@ti.com>
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License version 2 as
 *  published by the Free Software Foundation.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 */

#include <linux/platform_device.h>
#include <net/bluetooth/bluetooth.h>
#include <net/bluetooth/hci_core.h>
#include <net/bluetooth/hci.h>

#include <linux/ti_wilink_st.h>
#include <linux/module.h>

/* Bluetooth Driver Version */
#define VERSION               "1.0"
#define MAX_BT_CHNL_IDS         3

/* Number of seconds to wait for registration completion
 * when ST returns PENDING status.
 */
#define BT_REGISTER_TIMEOUT   6000      /* 6 sec */

/**
 * struct ti_st - driver operation structure
 * @hdev: hci device pointer which binds to bt driver
 * @reg_status: ST registration callback status
 * @st_write: write function provided by the ST driver
 *      to be used by the driver during send_frame.
 * @wait_reg_completion - completion sync between ti_st_open
 *      and st_reg_completion_cb.
 */
struct ti_st {
        struct hci_dev *hdev;
        char reg_status;
        long (*st_write) (struct sk_buff *);
        struct completion wait_reg_completion;
};

/* Increments HCI counters based on pocket ID (cmd,acl,sco) */
static inline void ti_st_tx_complete(struct ti_st *hst, int pkt_type)
{
        struct hci_dev *hdev = hst->hdev;

        /* Update HCI stat counters */
        switch (pkt_type) {
        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;
        }
}

/* ------- Interfaces to Shared Transport ------ */

/* Called by ST layer to indicate protocol registration completion
 * status.ti_st_open() function will wait for signal from this
 * API when st_register() function returns ST_PENDING.
 */
static void st_reg_completion_cb(void *priv_data, char data)
{
        struct ti_st *lhst = priv_data;

        /* Save registration status for use in ti_st_open() */
        lhst->reg_status = data;
        /* complete the wait in ti_st_open() */
        complete(&lhst->wait_reg_completion);
}

/* Called by Shared Transport layer when receive data is
 * available */
static long st_receive(void *priv_data, struct sk_buff *skb)
{
        struct ti_st *lhst = priv_data;
        int err;

        if (!skb)
                return -EFAULT;

        if (!lhst) {
                kfree_skb(skb);
                return -EFAULT;
        }

        /* Forward skb to HCI core layer */
        err = hci_recv_frame(lhst->hdev, skb);
        if (err < 0) {
                BT_ERR("Unable to push skb to HCI core(%d)", err);
                return err;
        }

        lhst->hdev->stat.byte_rx += skb->len;

        return 0;
}

/* ------- Interfaces to HCI layer ------ */
/* protocol structure registered with shared transport */
static struct st_proto_s ti_st_proto[MAX_BT_CHNL_IDS] = {
        {
                .chnl_id = HCI_EVENT_PKT, /* HCI Events */
                .hdr_len = sizeof(struct hci_event_hdr),
                .offset_len_in_hdr = offsetof(struct hci_event_hdr, plen),
                .len_size = 1, /* sizeof(plen) in struct hci_event_hdr */
                .reserve = 8,
        },
        {
                .chnl_id = HCI_ACLDATA_PKT, /* ACL */
                .hdr_len = sizeof(struct hci_acl_hdr),
                .offset_len_in_hdr = offsetof(struct hci_acl_hdr, dlen),
                .len_size = 2,  /* sizeof(dlen) in struct hci_acl_hdr */
                .reserve = 8,
        },
        {
                .chnl_id = HCI_SCODATA_PKT, /* SCO */
                .hdr_len = sizeof(struct hci_sco_hdr),
                .offset_len_in_hdr = offsetof(struct hci_sco_hdr, dlen),
                .len_size = 1, /* sizeof(dlen) in struct hci_sco_hdr */
                .reserve = 8,
        },
};

/* Called from HCI core to initialize the device */
static int ti_st_open(struct hci_dev *hdev)
{
        unsigned long timeleft;
        struct ti_st *hst;
        int err, i;

        BT_DBG("%s %p", hdev->name, hdev);

        /* provide contexts for callbacks from ST */
        hst = hci_get_drvdata(hdev);

        for (i = 0; i < MAX_BT_CHNL_IDS; i++) {
                ti_st_proto[i].priv_data = hst;
                ti_st_proto[i].max_frame_size = HCI_MAX_FRAME_SIZE;
                ti_st_proto[i].recv = st_receive;
                ti_st_proto[i].reg_complete_cb = st_reg_completion_cb;

                /* Prepare wait-for-completion handler */
                init_completion(&hst->wait_reg_completion);
                /* Reset ST registration callback status flag,
                 * this value will be updated in
                 * st_reg_completion_cb()
                 * function whenever it called from ST driver.
                 */
                hst->reg_status = -EINPROGRESS;

                err = st_register(&ti_st_proto[i]);
                if (!err)
                        goto done;

                if (err != -EINPROGRESS) {
                        BT_ERR("st_register failed %d", err);
                        return err;
                }

                /* ST is busy with either protocol
                 * registration or firmware download.
                 */
                BT_DBG("waiting for registration "
                                "completion signal from ST");
                timeleft = wait_for_completion_timeout
                        (&hst->wait_reg_completion,
                         msecs_to_jiffies(BT_REGISTER_TIMEOUT));
                if (!timeleft) {
                        BT_ERR("Timeout(%d sec),didn't get reg "
                                        "completion signal from ST",
                                        BT_REGISTER_TIMEOUT / 1000);
                        return -ETIMEDOUT;
                }

                /* Is ST registration callback
                 * called with ERROR status? */
                if (hst->reg_status != 0) {
                        BT_ERR("ST registration completed with invalid "
                                        "status %d", hst->reg_status);
                        return -EAGAIN;
                }

done:
                hst->st_write = ti_st_proto[i].write;
                if (!hst->st_write) {
                        BT_ERR("undefined ST write function");
                        for (i = 0; i < MAX_BT_CHNL_IDS; i++) {
                                /* Undo registration with ST */
                                err = st_unregister(&ti_st_proto[i]);
                                if (err)
                                        BT_ERR("st_unregister() failed with "
                                                        "error %d", err);
                                hst->st_write = NULL;
                        }
                        return -EIO;
                }
        }
        return 0;
}

/* Close device */
static int ti_st_close(struct hci_dev *hdev)
{
        int err, i;
        struct ti_st *hst = hci_get_drvdata(hdev);

        for (i = MAX_BT_CHNL_IDS-1; i >= 0; i--) {
                err = st_unregister(&ti_st_proto[i]);
                if (err)
                        BT_ERR("st_unregister(%d) failed with error %d",
                                        ti_st_proto[i].chnl_id, err);
        }

        hst->st_write = NULL;

        return err;
}

static int ti_st_send_frame(struct hci_dev *hdev, struct sk_buff *skb)
{
        struct ti_st *hst;
        long len;

        hst = hci_get_drvdata(hdev);

        /* Prepend skb with frame type */
        memcpy(skb_push(skb, 1), &hci_skb_pkt_type(skb), 1);

        BT_DBG("%s: type %d len %d", hdev->name, hci_skb_pkt_type(skb),
               skb->len);

        /* Insert skb to shared transport layer's transmit queue.
         * Freeing skb memory is taken care in shared transport layer,
         * so don't free skb memory here.
         */
        len = hst->st_write(skb);
        if (len < 0) {
                kfree_skb(skb);
                BT_ERR("ST write failed (%ld)", len);
                /* Try Again, would only fail if UART has gone bad */
                return -EAGAIN;
        }

        /* ST accepted our skb. So, Go ahead and do rest */
        hdev->stat.byte_tx += len;
        ti_st_tx_complete(hst, hci_skb_pkt_type(skb));

        return 0;
}

static int bt_ti_probe(struct platform_device *pdev)
{
        static struct ti_st *hst;
        struct hci_dev *hdev;
        int err;

        hst = devm_kzalloc(&pdev->dev, sizeof(struct ti_st), GFP_KERNEL);
        if (!hst)
                return -ENOMEM;

        /* Expose "hciX" device to user space */
        hdev = hci_alloc_dev();
        if (!hdev)
                return -ENOMEM;

        BT_DBG("hdev %p", hdev);

        hst->hdev = hdev;
        hdev->bus = HCI_UART;
        hci_set_drvdata(hdev, hst);
        hdev->open = ti_st_open;
        hdev->close = ti_st_close;
        hdev->flush = NULL;
        hdev->send = ti_st_send_frame;

        err = hci_register_dev(hdev);
        if (err < 0) {
                BT_ERR("Can't register HCI device error %d", err);
                hci_free_dev(hdev);
                return err;
        }

        BT_DBG("HCI device registered (hdev %p)", hdev);

        dev_set_drvdata(&pdev->dev, hst);
        return err;
}

static int bt_ti_remove(struct platform_device *pdev)
{
        struct hci_dev *hdev;
        struct ti_st *hst = dev_get_drvdata(&pdev->dev);

        if (!hst)
                return -EFAULT;

        BT_DBG("%s", hst->hdev->name);

        hdev = hst->hdev;
        ti_st_close(hdev);
        hci_unregister_dev(hdev);

        hci_free_dev(hdev);

        dev_set_drvdata(&pdev->dev, NULL);
        return 0;
}

static struct platform_driver btwilink_driver = {
        .probe = bt_ti_probe,
        .remove = bt_ti_remove,
        .driver = {
                .name = "btwilink",
        },
};

module_platform_driver(btwilink_driver);

/* ------ Module Info ------ */

MODULE_AUTHOR("Raja Mani <raja_mani@ti.com>");
MODULE_DESCRIPTION("Bluetooth Driver for TI Shared Transport" VERSION);
MODULE_VERSION(VERSION);
MODULE_LICENSE("GPL");