/*
 *
 *  Bluetooth HCI UART driver
 *
 *  Copyright (C) 2000-2001  Qualcomm Incorporated
 *  Copyright (C) 2002-2003  Maxim Krasnyansky <maxk@qualcomm.com>
 *  Copyright (C) 2004-2005  Marcel Holtmann <marcel@holtmann.org>
 *
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  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/module.h>

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/types.h>
#include <linux/fcntl.h>
#include <linux/interrupt.h>
#include <linux/ptrace.h>
#include <linux/poll.h>

#include <linux/slab.h>
#include <linux/tty.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/signal.h>
#include <linux/ioctl.h>
#include <linux/skbuff.h>

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

#include "hci_uart.h"

#ifndef CONFIG_BT_HCIUART_DEBUG
#undef  BT_DBG
#define BT_DBG( A... )
#endif

#define VERSION "2.2"

static int reset = 0;

static struct hci_uart_proto *hup[HCI_UART_MAX_PROTO];

int hci_uart_register_proto(struct hci_uart_proto *p)
{
        if (p->id >= HCI_UART_MAX_PROTO)
                return -EINVAL;

        if (hup[p->id])
                return -EEXIST;

        hup[p->id] = p;

        return 0;
}

int hci_uart_unregister_proto(struct hci_uart_proto *p)
{
        if (p->id >= HCI_UART_MAX_PROTO)
                return -EINVAL;

        if (!hup[p->id])
                return -EINVAL;

        hup[p->id] = NULL;

        return 0;
}

static struct hci_uart_proto *hci_uart_get_proto(unsigned int id)
{
        if (id >= HCI_UART_MAX_PROTO)
                return NULL;

        return hup[id];
}

static inline void hci_uart_tx_complete(struct hci_uart *hu, int pkt_type)
{
        struct hci_dev *hdev = hu->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.cmd_tx++;
                break;
        }
}

static inline struct sk_buff *hci_uart_dequeue(struct hci_uart *hu)
{
        struct sk_buff *skb = hu->tx_skb;

        if (!skb)
                skb = hu->proto->dequeue(hu);
        else
                hu->tx_skb = NULL;

        return skb;
}

int hci_uart_tx_wakeup(struct hci_uart *hu)
{
        struct tty_struct *tty = hu->tty;
        struct hci_dev *hdev = hu->hdev;
        struct sk_buff *skb;

        if (test_and_set_bit(HCI_UART_SENDING, &hu->tx_state)) {
                set_bit(HCI_UART_TX_WAKEUP, &hu->tx_state);
                return 0;
        }

        BT_DBG("");

restart:
        clear_bit(HCI_UART_TX_WAKEUP, &hu->tx_state);

        while ((skb = hci_uart_dequeue(hu))) {
                int len;

                set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
                len = tty->ops->write(tty, skb->data, skb->len);
                hdev->stat.byte_tx += len;

                skb_pull(skb, len);
                if (skb->len) {
                        hu->tx_skb = skb;
                        break;
                }

                hci_uart_tx_complete(hu, bt_cb(skb)->pkt_type);
                kfree_skb(skb);
        }

        if (test_bit(HCI_UART_TX_WAKEUP, &hu->tx_state))
                goto restart;

        clear_bit(HCI_UART_SENDING, &hu->tx_state);
        return 0;
}

/* ------- Interface to HCI layer ------ */
/* Initialize device */
static int hci_uart_open(struct hci_dev *hdev)
{
        BT_DBG("%s %p", hdev->name, hdev);

        /* Nothing to do for UART driver */

        set_bit(HCI_RUNNING, &hdev->flags);

        return 0;
}

/* Reset device */
static int hci_uart_flush(struct hci_dev *hdev)
{
        struct hci_uart *hu  = (struct hci_uart *) hdev->driver_data;
        struct tty_struct *tty = hu->tty;

        BT_DBG("hdev %p tty %p", hdev, tty);

        if (hu->tx_skb) {
                kfree_skb(hu->tx_skb); hu->tx_skb = NULL;
        }

        /* Flush any pending characters in the driver and discipline. */
        tty_ldisc_flush(tty);
        tty_driver_flush_buffer(tty);

        if (test_bit(HCI_UART_PROTO_SET, &hu->flags))
                hu->proto->flush(hu);

        return 0;
}

/* Close device */
static int hci_uart_close(struct hci_dev *hdev)
{
        BT_DBG("hdev %p", hdev);

        if (!test_and_clear_bit(HCI_RUNNING, &hdev->flags))
                return 0;

        hci_uart_flush(hdev);
        hdev->flush = NULL;
        return 0;
}

/* Send frames from HCI layer */
static int hci_uart_send_frame(struct sk_buff *skb)
{
        struct hci_dev* hdev = (struct hci_dev *) skb->dev;
        struct tty_struct *tty;
        struct hci_uart *hu;

        if (!hdev) {
                BT_ERR("Frame for uknown device (hdev=NULL)");
                return -ENODEV;
        }

        if (!test_bit(HCI_RUNNING, &hdev->flags))
                return -EBUSY;

        hu = (struct hci_uart *) hdev->driver_data;
        tty = hu->tty;

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

        hu->proto->enqueue(hu, skb);

        hci_uart_tx_wakeup(hu);

        return 0;
}

static void hci_uart_destruct(struct hci_dev *hdev)
{
        if (!hdev)
                return;

        BT_DBG("%s", hdev->name);
        kfree(hdev->driver_data);
}

/* ------ LDISC part ------ */
/* hci_uart_tty_open
 * 
 *     Called when line discipline changed to HCI_UART.
 *
 * Arguments:
 *     tty    pointer to tty info structure
 * Return Value:    
 *     0 if success, otherwise error code
 */
static int hci_uart_tty_open(struct tty_struct *tty)
{
        struct hci_uart *hu = (void *) tty->disc_data;

        BT_DBG("tty %p", tty);

        if (hu)
                return -EEXIST;

        if (!(hu = kzalloc(sizeof(struct hci_uart), GFP_KERNEL))) {
                BT_ERR("Can't allocate control structure");
                return -ENFILE;
        }

        tty->disc_data = hu;
        hu->tty = tty;
        tty->receive_room = 65536;

        spin_lock_init(&hu->rx_lock);

        /* Flush any pending characters in the driver and line discipline. */

        /* FIXME: why is this needed. Note don't use ldisc_ref here as the
           open path is before the ldisc is referencable */

        if (tty->ldisc.ops->flush_buffer)
                tty->ldisc.ops->flush_buffer(tty);
        tty_driver_flush_buffer(tty);

        return 0;
}

/* hci_uart_tty_close()
 *
 *    Called when the line discipline is changed to something
 *    else, the tty is closed, or the tty detects a hangup.
 */
static void hci_uart_tty_close(struct tty_struct *tty)
{
        struct hci_uart *hu = (void *)tty->disc_data;

        BT_DBG("tty %p", tty);

        /* Detach from the tty */
        tty->disc_data = NULL;

        if (hu) {
                struct hci_dev *hdev = hu->hdev;

                if (hdev)
                        hci_uart_close(hdev);

                if (test_and_clear_bit(HCI_UART_PROTO_SET, &hu->flags)) {
                        hu->proto->close(hu);
                        hci_unregister_dev(hdev);
                        hci_free_dev(hdev);
                }
        }
}

/* hci_uart_tty_wakeup()
 *
 *    Callback for transmit wakeup. Called when low level
 *    device driver can accept more send data.
 *
 * Arguments:        tty    pointer to associated tty instance data
 * Return Value:    None
 */
static void hci_uart_tty_wakeup(struct tty_struct *tty)
{
        struct hci_uart *hu = (void *)tty->disc_data;

        BT_DBG("");

        if (!hu)
                return;

        clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);

        if (tty != hu->tty)
                return;

        if (test_bit(HCI_UART_PROTO_SET, &hu->flags))
                hci_uart_tx_wakeup(hu);
}

/* hci_uart_tty_receive()
 * 
 *     Called by tty low level driver when receive data is
 *     available.
 *     
 * Arguments:  tty          pointer to tty isntance data
 *             data         pointer to received data
 *             flags        pointer to flags for data
 *             count        count of received data in bytes
 *     
 * Return Value:    None
 */
static void hci_uart_tty_receive(struct tty_struct *tty, const u8 *data, char *flags, int count)
{
        struct hci_uart *hu = (void *)tty->disc_data;

        if (!hu || tty != hu->tty)
                return;

        if (!test_bit(HCI_UART_PROTO_SET, &hu->flags))
                return;

        spin_lock(&hu->rx_lock);
        hu->proto->recv(hu, (void *) data, count);
        hu->hdev->stat.byte_rx += count;
        spin_unlock(&hu->rx_lock);

        tty_unthrottle(tty);
}

static int hci_uart_register_dev(struct hci_uart *hu)
{
        struct hci_dev *hdev;

        BT_DBG("");

        /* Initialize and register HCI device */
        hdev = hci_alloc_dev();
        if (!hdev) {
                BT_ERR("Can't allocate HCI device");
                return -ENOMEM;
        }

        hu->hdev = hdev;

        hdev->type = HCI_UART;
        hdev->driver_data = hu;

        hdev->open  = hci_uart_open;
        hdev->close = hci_uart_close;
        hdev->flush = hci_uart_flush;
        hdev->send  = hci_uart_send_frame;
        hdev->destruct = hci_uart_destruct;

        hdev->owner = THIS_MODULE;

        if (reset)
                set_bit(HCI_QUIRK_RESET_ON_INIT, &hdev->quirks);

        if (hci_register_dev(hdev) < 0) {
                BT_ERR("Can't register HCI device");
                hci_free_dev(hdev);
                return -ENODEV;
        }

        return 0;
}

static int hci_uart_set_proto(struct hci_uart *hu, int id)
{
        struct hci_uart_proto *p;
        int err;

        p = hci_uart_get_proto(id);
        if (!p)
                return -EPROTONOSUPPORT;

        err = p->open(hu);
        if (err)
                return err;

        hu->proto = p;

        err = hci_uart_register_dev(hu);
        if (err) {
                p->close(hu);
                return err;
        }

        return 0;
}

/* hci_uart_tty_ioctl()
 *
 *    Process IOCTL system call for the tty device.
 *
 * Arguments:
 *
 *    tty        pointer to tty instance data
 *    file       pointer to open file object for device
 *    cmd        IOCTL command code
 *    arg        argument for IOCTL call (cmd dependent)
 *
 * Return Value:    Command dependent
 */
static int hci_uart_tty_ioctl(struct tty_struct *tty, struct file * file,
                                        unsigned int cmd, unsigned long arg)
{
        struct hci_uart *hu = (void *)tty->disc_data;
        int err = 0;

        BT_DBG("");

        /* Verify the status of the device */
        if (!hu)
                return -EBADF;

        switch (cmd) {
        case HCIUARTSETPROTO:
                if (!test_and_set_bit(HCI_UART_PROTO_SET, &hu->flags)) {
                        err = hci_uart_set_proto(hu, arg);
                        if (err) {
                                clear_bit(HCI_UART_PROTO_SET, &hu->flags);
                                return err;
                        }
                        tty->low_latency = 1;
                } else
                        return -EBUSY;
                break;

        case HCIUARTGETPROTO:
                if (test_bit(HCI_UART_PROTO_SET, &hu->flags))
                        return hu->proto->id;
                return -EUNATCH;

        case HCIUARTGETDEVICE:
                if (test_bit(HCI_UART_PROTO_SET, &hu->flags))
                        return hu->hdev->id;
                return -EUNATCH;

        default:
                err = n_tty_ioctl_helper(tty, file, cmd, arg);
                break;
        };

        return err;
}

/*
 * We don't provide read/write/poll interface for user space.
 */
static ssize_t hci_uart_tty_read(struct tty_struct *tty, struct file *file,
                                        unsigned char __user *buf, size_t nr)
{
        return 0;
}

static ssize_t hci_uart_tty_write(struct tty_struct *tty, struct file *file,
                                        const unsigned char *data, size_t count)
{
        return 0;
}

static unsigned int hci_uart_tty_poll(struct tty_struct *tty,
                                        struct file *filp, poll_table *wait)
{
        return 0;
}

static int __init hci_uart_init(void)
{
        static struct tty_ldisc_ops hci_uart_ldisc;
        int err;

        BT_INFO("HCI UART driver ver %s", VERSION);

        /* Register the tty discipline */

        memset(&hci_uart_ldisc, 0, sizeof (hci_uart_ldisc));
        hci_uart_ldisc.magic            = TTY_LDISC_MAGIC;
        hci_uart_ldisc.name             = "n_hci";
        hci_uart_ldisc.open             = hci_uart_tty_open;
        hci_uart_ldisc.close            = hci_uart_tty_close;
        hci_uart_ldisc.read             = hci_uart_tty_read;
        hci_uart_ldisc.write            = hci_uart_tty_write;
        hci_uart_ldisc.ioctl            = hci_uart_tty_ioctl;
        hci_uart_ldisc.poll             = hci_uart_tty_poll;
        hci_uart_ldisc.receive_buf      = hci_uart_tty_receive;
        hci_uart_ldisc.write_wakeup     = hci_uart_tty_wakeup;
        hci_uart_ldisc.owner            = THIS_MODULE;

        if ((err = tty_register_ldisc(N_HCI, &hci_uart_ldisc))) {
                BT_ERR("HCI line discipline registration failed. (%d)", err);
                return err;
        }

#ifdef CONFIG_BT_HCIUART_H4
        h4_init();
#endif
#ifdef CONFIG_BT_HCIUART_BCSP
        bcsp_init();
#endif
#ifdef CONFIG_BT_HCIUART_LL
        ll_init();
#endif

        return 0;
}

static void __exit hci_uart_exit(void)
{
        int err;

#ifdef CONFIG_BT_HCIUART_H4
        h4_deinit();
#endif
#ifdef CONFIG_BT_HCIUART_BCSP
        bcsp_deinit();
#endif
#ifdef CONFIG_BT_HCIUART_LL
        ll_deinit();
#endif

        /* Release tty registration of line discipline */
        if ((err = tty_unregister_ldisc(N_HCI)))
                BT_ERR("Can't unregister HCI line discipline (%d)", err);
}

module_init(hci_uart_init);
module_exit(hci_uart_exit);

module_param(reset, bool, 0644);
MODULE_PARM_DESC(reset, "Send HCI reset command on initialization");

MODULE_AUTHOR("Marcel Holtmann <marcel@holtmann.org>");
MODULE_DESCRIPTION("Bluetooth HCI UART driver ver " VERSION);
MODULE_VERSION(VERSION);
MODULE_LICENSE("GPL");
MODULE_ALIAS_LDISC(N_HCI);