st_core.c

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/*
 *  Shared Transport Line discipline driver Core
 *  This hooks up ST KIM driver and ST LL driver
 *  Copyright (C) 2009-2010 Texas Instruments
 *  Author: Pavan Savoy <[email protected]>
 *
 *  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
 *
 */

#define pr_fmt(fmt) "(stc): " fmt
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/tty.h>

#include <linux/seq_file.h>
#include <linux/skbuff.h>

#include <linux/ti_wilink_st.h>

extern void st_kim_recv(void *, const unsigned char *, long);
void st_int_recv(void *, const unsigned char *, long);
/* function pointer pointing to either,
 * st_kim_recv during registration to receive fw download responses
 * st_int_recv after registration to receive proto stack responses
 */
static void (*st_recv) (void *, const unsigned char *, long);

/********************************************************************/
static void add_channel_to_table(struct st_data_s *st_gdata,
        struct st_proto_s *new_proto)
{
    pr_info("%s: id %d\n", __func__, new_proto->chnl_id);
    /* list now has the channel id as index itself */
    st_gdata->list[new_proto->chnl_id] = new_proto;
    st_gdata->is_registered[new_proto->chnl_id] = true;
}

static void remove_channel_from_table(struct st_data_s *st_gdata,
        struct st_proto_s *proto)
{
    pr_info("%s: id %d\n", __func__, proto->chnl_id);
/*  st_gdata->list[proto->chnl_id] = NULL; */
    st_gdata->is_registered[proto->chnl_id] = false;
}

/*
 * called from KIM during firmware download.
 *
 * This is a wrapper function to tty->ops->write_room.
 * It returns number of free space available in
 * uart tx buffer.
 */
int st_get_uart_wr_room(struct st_data_s *st_gdata)
{
    struct tty_struct *tty;
    if (unlikely(st_gdata == NULL || st_gdata->tty == NULL)) {
        pr_err("tty unavailable to perform write");
        return -1;
    }
    tty = st_gdata->tty;
    return tty->ops->write_room(tty);
}

/* can be called in from
 * -- KIM (during fw download)
 * -- ST Core (during st_write)
 *
 *  This is the internal write function - a wrapper
 *  to tty->ops->write
 */
int st_int_write(struct st_data_s *st_gdata,
    const unsigned char *data, int count)
{
    struct tty_struct *tty;
    if (unlikely(st_gdata == NULL || st_gdata->tty == NULL)) {
        pr_err("tty unavailable to perform write");
        return -EINVAL;
    }
    tty = st_gdata->tty;
#ifdef VERBOSE
    print_hex_dump(KERN_DEBUG, "<out<", DUMP_PREFIX_NONE,
        16, 1, data, count, 0);
#endif
    return tty->ops->write(tty, data, count);

}

/*
 * push the skb received to relevant
 * protocol stacks
 */
static void st_send_frame(unsigned char chnl_id, struct st_data_s *st_gdata)
{
    pr_debug(" %s(prot:%d) ", __func__, chnl_id);

    if (unlikely
        (st_gdata == NULL || st_gdata->rx_skb == NULL
         || st_gdata->is_registered[chnl_id] == false)) {
        pr_err("chnl_id %d not registered, no data to send?",
               chnl_id);
        kfree_skb(st_gdata->rx_skb);
        return;
    }
    /* this cannot fail
     * this shouldn't take long
     * - should be just skb_queue_tail for the
     *   protocol stack driver
     */
    if (likely(st_gdata->list[chnl_id]->recv != NULL)) {
        if (unlikely
            (st_gdata->list[chnl_id]->recv
            (st_gdata->list[chnl_id]->priv_data, st_gdata->rx_skb)
                 != 0)) {
            pr_err(" proto stack %d's ->recv failed", chnl_id);
            kfree_skb(st_gdata->rx_skb);
            return;
        }
    } else {
        pr_err(" proto stack %d's ->recv null", chnl_id);
        kfree_skb(st_gdata->rx_skb);
    }
    return;
}

static void st_reg_complete(struct st_data_s *st_gdata, char err)
{
    unsigned char i = 0;
    pr_info(" %s ", __func__);
    for (i = 0; i < ST_MAX_CHANNELS; i++) {
        if (likely(st_gdata != NULL &&
            st_gdata->is_registered[i] == true &&
                st_gdata->list[i]->reg_complete_cb != NULL)) {
            st_gdata->list[i]->reg_complete_cb
                (st_gdata->list[i]->priv_data, err);
            pr_info("protocol %d's cb sent %d\n", i, err);
            if (err) { /* cleanup registered protocol */
                st_gdata->protos_registered--;
                st_gdata->is_registered[i] = false;
            }
        }
    }
}

static inline int st_check_data_len(struct st_data_s *st_gdata,
    unsigned char chnl_id, int len)
{
    int room = skb_tailroom(st_gdata->rx_skb);

    pr_debug("len %d room %d", len, room);

    if (!len) {
        /* Received packet has only packet header and
         * has zero length payload. So, ask ST CORE to
         * forward the packet to protocol driver (BT/FM/GPS)
         */
        st_send_frame(chnl_id, st_gdata);

    } else if (len > room) {
        /* Received packet's payload length is larger.
         * We can't accommodate it in created skb.
         */
        pr_err("Data length is too large len %d room %d", len,
               room);
        kfree_skb(st_gdata->rx_skb);
    } else {
        /* Packet header has non-zero payload length and
         * we have enough space in created skb. Lets read
         * payload data */
        st_gdata->rx_state = ST_W4_DATA;
        st_gdata->rx_count = len;
        return len;
    }

    /* Change ST state to continue to process next
     * packet */
    st_gdata->rx_state = ST_W4_PACKET_TYPE;
    st_gdata->rx_skb = NULL;
    st_gdata->rx_count = 0;
    st_gdata->rx_chnl = 0;

    return 0;
}

static inline void st_wakeup_ack(struct st_data_s *st_gdata,
    unsigned char cmd)
{
    struct sk_buff *waiting_skb;
    unsigned long flags = 0;

    spin_lock_irqsave(&st_gdata->lock, flags);
    /* de-Q from waitQ and Q in txQ now that the
     * chip is awake
     */
    while ((waiting_skb = skb_dequeue(&st_gdata->tx_waitq)))
        skb_queue_tail(&st_gdata->txq, waiting_skb);

    /* state forwarded to ST LL */
    st_ll_sleep_state(st_gdata, (unsigned long)cmd);
    spin_unlock_irqrestore(&st_gdata->lock, flags);

    /* wake up to send the recently copied skbs from waitQ */
    st_tx_wakeup(st_gdata);
}

void st_int_recv(void *disc_data,
    const unsigned char *data, long count)
{
    char *ptr;
    struct st_proto_s *proto;
    unsigned short payload_len = 0;
    int len = 0, type = 0;
    unsigned char *plen;
    struct st_data_s *st_gdata = (struct st_data_s *)disc_data;
    unsigned long flags;

    ptr = (char *)data;
    /* tty_receive sent null ? */
    if (unlikely(ptr == NULL) || (st_gdata == NULL)) {
        pr_err(" received null from TTY ");
        return;
    }

    pr_debug("count %ld rx_state %ld"
           "rx_count %ld", count, st_gdata->rx_state,
           st_gdata->rx_count);

    spin_lock_irqsave(&st_gdata->lock, flags);
    /* Decode received bytes here */
    while (count) {
        if (st_gdata->rx_count) {
            len = min_t(unsigned int, st_gdata->rx_count, count);
            memcpy(skb_put(st_gdata->rx_skb, len), ptr, len);
            st_gdata->rx_count -= len;
            count -= len;
            ptr += len;

            if (st_gdata->rx_count)
                continue;

            /* Check ST RX state machine , where are we? */
            switch (st_gdata->rx_state) {
            /* Waiting for complete packet ? */
            case ST_W4_DATA:
                pr_debug("Complete pkt received");
                /* Ask ST CORE to forward
                 * the packet to protocol driver */
                st_send_frame(st_gdata->rx_chnl, st_gdata);

                st_gdata->rx_state = ST_W4_PACKET_TYPE;
                st_gdata->rx_skb = NULL;
                continue;
            /* parse the header to know details */
            case ST_W4_HEADER:
                proto = st_gdata->list[st_gdata->rx_chnl];
                plen =
                &st_gdata->rx_skb->data
                [proto->offset_len_in_hdr];
                pr_debug("plen pointing to %x\n", *plen);
                if (proto->len_size == 1)/* 1 byte len field */
                    payload_len = *(unsigned char *)plen;
                else if (proto->len_size == 2)
                    payload_len =
                    __le16_to_cpu(*(unsigned short *)plen);
                else
                    pr_info("%s: invalid length "
                    "for id %d\n",
                    __func__, proto->chnl_id);
                st_check_data_len(st_gdata, proto->chnl_id,
                        payload_len);
                pr_debug("off %d, pay len %d\n",
                    proto->offset_len_in_hdr, payload_len);
                continue;
            }   /* end of switch rx_state */
        }

        /* end of if rx_count */
        /* Check first byte of packet and identify module
         * owner (BT/FM/GPS) */
        switch (*ptr) {
        case LL_SLEEP_IND:
        case LL_SLEEP_ACK:
        case LL_WAKE_UP_IND:
            pr_debug("PM packet");
            /* this takes appropriate action based on
             * sleep state received --
             */
            st_ll_sleep_state(st_gdata, *ptr);
            /* if WAKEUP_IND collides copy from waitq to txq
             * and assume chip awake
             */
            spin_unlock_irqrestore(&st_gdata->lock, flags);
            if (st_ll_getstate(st_gdata) == ST_LL_AWAKE)
                st_wakeup_ack(st_gdata, LL_WAKE_UP_ACK);
            spin_lock_irqsave(&st_gdata->lock, flags);

            ptr++;
            count--;
            continue;
        case LL_WAKE_UP_ACK:
            pr_debug("PM packet");

            spin_unlock_irqrestore(&st_gdata->lock, flags);
            /* wake up ack received */
            st_wakeup_ack(st_gdata, *ptr);
            spin_lock_irqsave(&st_gdata->lock, flags);

            ptr++;
            count--;
            continue;
            /* Unknow packet? */
        default:
            type = *ptr;
            if (st_gdata->list[type] == NULL) {
                pr_err("chip/interface misbehavior dropping"
                    " frame starting with 0x%02x", type);
                goto done;

            }
            st_gdata->rx_skb = alloc_skb(
                    st_gdata->list[type]->max_frame_size,
                    GFP_ATOMIC);
            if (st_gdata->rx_skb == NULL) {
                pr_err("out of memory: dropping\n");
                goto done;
            }

            skb_reserve(st_gdata->rx_skb,
                    st_gdata->list[type]->reserve);
            /* next 2 required for BT only */
            st_gdata->rx_skb->cb[0] = type; /*pkt_type*/
            st_gdata->rx_skb->cb[1] = 0; /*incoming*/
            st_gdata->rx_chnl = *ptr;
            st_gdata->rx_state = ST_W4_HEADER;
            st_gdata->rx_count = st_gdata->list[type]->hdr_len;
            pr_debug("rx_count %ld\n", st_gdata->rx_count);
        };
        ptr++;
        count--;
    }
done:
    spin_unlock_irqrestore(&st_gdata->lock, flags);
    pr_debug("done %s", __func__);
    return;
}

static struct sk_buff *st_int_dequeue(struct st_data_s *st_gdata)
{
    struct sk_buff *returning_skb;

    pr_debug("%s", __func__);
    if (st_gdata->tx_skb != NULL) {
        returning_skb = st_gdata->tx_skb;
        st_gdata->tx_skb = NULL;
        return returning_skb;
    }
    return skb_dequeue(&st_gdata->txq);
}

static void st_int_enqueue(struct st_data_s *st_gdata, struct sk_buff *skb)
{
    unsigned long flags = 0;

    pr_debug("%s", __func__);
    spin_lock_irqsave(&st_gdata->lock, flags);

    switch (st_ll_getstate(st_gdata)) {
    case ST_LL_AWAKE:
        pr_debug("ST LL is AWAKE, sending normally");
        skb_queue_tail(&st_gdata->txq, skb);
        break;
    case ST_LL_ASLEEP_TO_AWAKE:
        skb_queue_tail(&st_gdata->tx_waitq, skb);
        break;
    case ST_LL_AWAKE_TO_ASLEEP:
        pr_err("ST LL is illegal state(%ld),"
               "purging received skb.", st_ll_getstate(st_gdata));
        kfree_skb(skb);
        break;
    case ST_LL_ASLEEP:
        skb_queue_tail(&st_gdata->tx_waitq, skb);
        st_ll_wakeup(st_gdata);
        break;
    default:
        pr_err("ST LL is illegal state(%ld),"
               "purging received skb.", st_ll_getstate(st_gdata));
        kfree_skb(skb);
        break;
    }

    spin_unlock_irqrestore(&st_gdata->lock, flags);
    pr_debug("done %s", __func__);
    return;
}

/*
 * internal wakeup function
 * called from either
 * - TTY layer when write's finished
 * - st_write (in context of the protocol stack)
 */
void st_tx_wakeup(struct st_data_s *st_data)
{
    struct sk_buff *skb;
    unsigned long flags;    /* for irq save flags */
    pr_debug("%s", __func__);
    /* check for sending & set flag sending here */
    if (test_and_set_bit(ST_TX_SENDING, &st_data->tx_state)) {
        pr_debug("ST already sending");
        /* keep sending */
        set_bit(ST_TX_WAKEUP, &st_data->tx_state);
        return;
        /* TX_WAKEUP will be checked in another
         * context
         */
    }
    do {            /* come back if st_tx_wakeup is set */
        /* woke-up to write */
        clear_bit(ST_TX_WAKEUP, &st_data->tx_state);
        while ((skb = st_int_dequeue(st_data))) {
            int len;
            spin_lock_irqsave(&st_data->lock, flags);
            /* enable wake-up from TTY */
            set_bit(TTY_DO_WRITE_WAKEUP, &st_data->tty->flags);
            len = st_int_write(st_data, skb->data, skb->len);
            skb_pull(skb, len);
            /* if skb->len = len as expected, skb->len=0 */
            if (skb->len) {
                /* would be the next skb to be sent */
                st_data->tx_skb = skb;
                spin_unlock_irqrestore(&st_data->lock, flags);
                break;
            }
            kfree_skb(skb);
            spin_unlock_irqrestore(&st_data->lock, flags);
        }
        /* if wake-up is set in another context- restart sending */
    } while (test_bit(ST_TX_WAKEUP, &st_data->tx_state));

    /* clear flag sending */
    clear_bit(ST_TX_SENDING, &st_data->tx_state);
}

/********************************************************************/
/* functions called from ST KIM
*/
void kim_st_list_protocols(struct st_data_s *st_gdata, void *buf)
{
    seq_printf(buf, "[%d]\nBT=%c\nFM=%c\nGPS=%c\n",
            st_gdata->protos_registered,
            st_gdata->is_registered[0x04] == true ? 'R' : 'U',
            st_gdata->is_registered[0x08] == true ? 'R' : 'U',
            st_gdata->is_registered[0x09] == true ? 'R' : 'U');
}

/********************************************************************/
/*
 * functions called from protocol stack drivers
 * to be EXPORT-ed
 */
long st_register(struct st_proto_s *new_proto)
{
    struct st_data_s    *st_gdata;
    long err = 0;
    unsigned long flags = 0;

    st_kim_ref(&st_gdata, 0);
    pr_info("%s(%d) ", __func__, new_proto->chnl_id);
    if (st_gdata == NULL || new_proto == NULL || new_proto->recv == NULL
        || new_proto->reg_complete_cb == NULL) {
        pr_err("gdata/new_proto/recv or reg_complete_cb not ready");
        return -EINVAL;
    }

    if (new_proto->chnl_id >= ST_MAX_CHANNELS) {
        pr_err("chnl_id %d not supported", new_proto->chnl_id);
        return -EPROTONOSUPPORT;
    }

    if (st_gdata->is_registered[new_proto->chnl_id] == true) {
        pr_err("chnl_id %d already registered", new_proto->chnl_id);
        return -EALREADY;
    }

    /* can be from process context only */
    spin_lock_irqsave(&st_gdata->lock, flags);

    if (test_bit(ST_REG_IN_PROGRESS, &st_gdata->st_state)) {
        pr_info(" ST_REG_IN_PROGRESS:%d ", new_proto->chnl_id);
        /* fw download in progress */

        add_channel_to_table(st_gdata, new_proto);
        st_gdata->protos_registered++;
        new_proto->write = st_write;

        set_bit(ST_REG_PENDING, &st_gdata->st_state);
        spin_unlock_irqrestore(&st_gdata->lock, flags);
        return -EINPROGRESS;
    } else if (st_gdata->protos_registered == ST_EMPTY) {
        pr_info(" chnl_id list empty :%d ", new_proto->chnl_id);
        set_bit(ST_REG_IN_PROGRESS, &st_gdata->st_state);
        st_recv = st_kim_recv;

        /* enable the ST LL - to set default chip state */
        st_ll_enable(st_gdata);

        /* release lock previously held - re-locked below */
        spin_unlock_irqrestore(&st_gdata->lock, flags);

        /* this may take a while to complete
         * since it involves BT fw download
         */
        err = st_kim_start(st_gdata->kim_data);
        if (err != 0) {
            clear_bit(ST_REG_IN_PROGRESS, &st_gdata->st_state);
            if ((st_gdata->protos_registered != ST_EMPTY) &&
                (test_bit(ST_REG_PENDING, &st_gdata->st_state))) {
                pr_err(" KIM failure complete callback ");
                st_reg_complete(st_gdata, err);
                clear_bit(ST_REG_PENDING, &st_gdata->st_state);
            }
            return -EINVAL;
        }

        spin_lock_irqsave(&st_gdata->lock, flags);

        clear_bit(ST_REG_IN_PROGRESS, &st_gdata->st_state);
        st_recv = st_int_recv;

        /* this is where all pending registration
         * are signalled to be complete by calling callback functions
         */
        if ((st_gdata->protos_registered != ST_EMPTY) &&
            (test_bit(ST_REG_PENDING, &st_gdata->st_state))) {
            pr_debug(" call reg complete callback ");
            st_reg_complete(st_gdata, 0);
        }
        clear_bit(ST_REG_PENDING, &st_gdata->st_state);

        /* check for already registered once more,
         * since the above check is old
         */
        if (st_gdata->is_registered[new_proto->chnl_id] == true) {
            pr_err(" proto %d already registered ",
                   new_proto->chnl_id);
            spin_unlock_irqrestore(&st_gdata->lock, flags);
            return -EALREADY;
        }

        add_channel_to_table(st_gdata, new_proto);
        st_gdata->protos_registered++;
        new_proto->write = st_write;
        spin_unlock_irqrestore(&st_gdata->lock, flags);
        return err;
    }
    /* if fw is already downloaded & new stack registers protocol */
    else {
        add_channel_to_table(st_gdata, new_proto);
        st_gdata->protos_registered++;
        new_proto->write = st_write;

        /* lock already held before entering else */
        spin_unlock_irqrestore(&st_gdata->lock, flags);
        return err;
    }
    pr_debug("done %s(%d) ", __func__, new_proto->chnl_id);
}
EXPORT_SYMBOL_GPL(st_register);

/* to unregister a protocol -
 * to be called from protocol stack driver
 */
long st_unregister(struct st_proto_s *proto)
{
    long err = 0;
    unsigned long flags = 0;
    struct st_data_s    *st_gdata;

    pr_debug("%s: %d ", __func__, proto->chnl_id);

    st_kim_ref(&st_gdata, 0);
    if (!st_gdata || proto->chnl_id >= ST_MAX_CHANNELS) {
        pr_err(" chnl_id %d not supported", proto->chnl_id);
        return -EPROTONOSUPPORT;
    }

    spin_lock_irqsave(&st_gdata->lock, flags);

    if (st_gdata->is_registered[proto->chnl_id] == false) {
        pr_err(" chnl_id %d not registered", proto->chnl_id);
        spin_unlock_irqrestore(&st_gdata->lock, flags);
        return -EPROTONOSUPPORT;
    }

    st_gdata->protos_registered--;
    remove_channel_from_table(st_gdata, proto);
    spin_unlock_irqrestore(&st_gdata->lock, flags);

    /* paranoid check */
    if (st_gdata->protos_registered < ST_EMPTY)
        st_gdata->protos_registered = ST_EMPTY;

    if ((st_gdata->protos_registered == ST_EMPTY) &&
        (!test_bit(ST_REG_PENDING, &st_gdata->st_state))) {
        pr_info(" all chnl_ids unregistered ");

        /* stop traffic on tty */
        if (st_gdata->tty) {
            tty_ldisc_flush(st_gdata->tty);
            stop_tty(st_gdata->tty);
        }

        /* all chnl_ids now unregistered */
        st_kim_stop(st_gdata->kim_data);
        /* disable ST LL */
        st_ll_disable(st_gdata);
    }
    return err;
}

/*
 * called in protocol stack drivers
 * via the write function pointer
 */
long st_write(struct sk_buff *skb)
{
    struct st_data_s *st_gdata;
    long len;

    st_kim_ref(&st_gdata, 0);
    if (unlikely(skb == NULL || st_gdata == NULL
        || st_gdata->tty == NULL)) {
        pr_err("data/tty unavailable to perform write");
        return -EINVAL;
    }

    pr_debug("%d to be written", skb->len);
    len = skb->len;

    /* st_ll to decide where to enqueue the skb */
    st_int_enqueue(st_gdata, skb);
    /* wake up */
    st_tx_wakeup(st_gdata);

    /* return number of bytes written */
    return len;
}

/* for protocols making use of shared transport */
EXPORT_SYMBOL_GPL(st_unregister);

/********************************************************************/
/*
 * functions called from TTY layer
 */
static int st_tty_open(struct tty_struct *tty)
{
    int err = 0;
    struct st_data_s *st_gdata;
    pr_info("%s ", __func__);

    st_kim_ref(&st_gdata, 0);
    st_gdata->tty = tty;
    tty->disc_data = st_gdata;

    /* don't do an wakeup for now */
    clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);

    /* mem already allocated
     */
    tty->receive_room = 65536;
    /* Flush any pending characters in the driver and discipline. */
    tty_ldisc_flush(tty);
    tty_driver_flush_buffer(tty);
    /*
     * signal to UIM via KIM that -
     * installation of N_TI_WL ldisc is complete
     */
    st_kim_complete(st_gdata->kim_data);
    pr_debug("done %s", __func__);
    return err;
}

static void st_tty_close(struct tty_struct *tty)
{
    unsigned char i = ST_MAX_CHANNELS;
    unsigned long flags = 0;
    struct  st_data_s *st_gdata = tty->disc_data;

    pr_info("%s ", __func__);

    /* TODO:
     * if a protocol has been registered & line discipline
     * un-installed for some reason - what should be done ?
     */
    spin_lock_irqsave(&st_gdata->lock, flags);
    for (i = ST_BT; i < ST_MAX_CHANNELS; i++) {
        if (st_gdata->is_registered[i] == true)
            pr_err("%d not un-registered", i);
        st_gdata->list[i] = NULL;
        st_gdata->is_registered[i] = false;
    }
    st_gdata->protos_registered = 0;
    spin_unlock_irqrestore(&st_gdata->lock, flags);
    /*
     * signal to UIM via KIM that -
     * N_TI_WL ldisc is un-installed
     */
    st_kim_complete(st_gdata->kim_data);
    st_gdata->tty = NULL;
    /* Flush any pending characters in the driver and discipline. */
    tty_ldisc_flush(tty);
    tty_driver_flush_buffer(tty);

    spin_lock_irqsave(&st_gdata->lock, flags);
    /* empty out txq and tx_waitq */
    skb_queue_purge(&st_gdata->txq);
    skb_queue_purge(&st_gdata->tx_waitq);
    /* reset the TTY Rx states of ST */
    st_gdata->rx_count = 0;
    st_gdata->rx_state = ST_W4_PACKET_TYPE;
    kfree_skb(st_gdata->rx_skb);
    st_gdata->rx_skb = NULL;
    spin_unlock_irqrestore(&st_gdata->lock, flags);

    pr_debug("%s: done ", __func__);
}

static void st_tty_receive(struct tty_struct *tty, const unsigned char *data,
               char *tty_flags, int count)
{
#ifdef VERBOSE
    print_hex_dump(KERN_DEBUG, ">in>", DUMP_PREFIX_NONE,
        16, 1, data, count, 0);
#endif

    /*
     * if fw download is in progress then route incoming data
     * to KIM for validation
     */
    st_recv(tty->disc_data, data, count);
    pr_debug("done %s", __func__);
}

/* wake-up function called in from the TTY layer
 * inside the internal wakeup function will be called
 */
static void st_tty_wakeup(struct tty_struct *tty)
{
    struct  st_data_s *st_gdata = tty->disc_data;
    pr_debug("%s ", __func__);
    /* don't do an wakeup for now */
    clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);

    /* call our internal wakeup */
    st_tx_wakeup((void *)st_gdata);
}

static void st_tty_flush_buffer(struct tty_struct *tty)
{
    struct  st_data_s *st_gdata = tty->disc_data;
    pr_debug("%s ", __func__);

    kfree_skb(st_gdata->tx_skb);
    st_gdata->tx_skb = NULL;

    tty->ops->flush_buffer(tty);
    return;
}

static struct tty_ldisc_ops st_ldisc_ops = {
    .magic = TTY_LDISC_MAGIC,
    .name = "n_st",
    .open = st_tty_open,
    .close = st_tty_close,
    .receive_buf = st_tty_receive,
    .write_wakeup = st_tty_wakeup,
    .flush_buffer = st_tty_flush_buffer,
    .owner = THIS_MODULE
};

/********************************************************************/
int st_core_init(struct st_data_s **core_data)
{
    struct st_data_s *st_gdata;
    long err;

    err = tty_register_ldisc(N_TI_WL, &st_ldisc_ops);
    if (err) {
        pr_err("error registering %d line discipline %ld",
               N_TI_WL, err);
        return err;
    }
    pr_debug("registered n_shared line discipline");

    st_gdata = kzalloc(sizeof(struct st_data_s), GFP_KERNEL);
    if (!st_gdata) {
        pr_err("memory allocation failed");
        err = tty_unregister_ldisc(N_TI_WL);
        if (err)
            pr_err("unable to un-register ldisc %ld", err);
        err = -ENOMEM;
        return err;
    }

    /* Initialize ST TxQ and Tx waitQ queue head. All BT/FM/GPS module skb's
     * will be pushed in this queue for actual transmission.
     */
    skb_queue_head_init(&st_gdata->txq);
    skb_queue_head_init(&st_gdata->tx_waitq);

    /* Locking used in st_int_enqueue() to avoid multiple execution */
    spin_lock_init(&st_gdata->lock);

    err = st_ll_init(st_gdata);
    if (err) {
        pr_err("error during st_ll initialization(%ld)", err);
        kfree(st_gdata);
        err = tty_unregister_ldisc(N_TI_WL);
        if (err)
            pr_err("unable to un-register ldisc");
        return err;
    }
    *core_data = st_gdata;
    return 0;
}

void st_core_exit(struct st_data_s *st_gdata)
{
    long err;
    /* internal module cleanup */
    err = st_ll_deinit(st_gdata);
    if (err)
        pr_err("error during deinit of ST LL %ld", err);

    if (st_gdata != NULL) {
        /* Free ST Tx Qs and skbs */
        skb_queue_purge(&st_gdata->txq);
        skb_queue_purge(&st_gdata->tx_waitq);
        kfree_skb(st_gdata->rx_skb);
        kfree_skb(st_gdata->tx_skb);
        /* TTY ldisc cleanup */
        err = tty_unregister_ldisc(N_TI_WL);
        if (err)
            pr_err("unable to un-register ldisc %ld", err);
        /* free the global data pointer */
        kfree(st_gdata);
    }
}