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hci_ldisc.c

/*
 *
 *  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->driver->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);
      if (tty->driver && tty->driver->flush_buffer)
            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);
      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.flush_buffer)
            tty->ldisc.flush_buffer(tty);

      if (tty->driver && tty->driver->flush_buffer)
            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);

      if (test_and_clear_bit(TTY_THROTTLED, &tty->flags) &&
                              tty->driver->unthrottle)
            tty->driver->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(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 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("Maxim Krasnyansky <maxk@qualcomm.com>, Marcel Holtmann <marcel@holtmann.org>");
MODULE_DESCRIPTION("Bluetooth HCI UART driver ver " VERSION);
MODULE_VERSION(VERSION);
MODULE_LICENSE("GPL");
MODULE_ALIAS_LDISC(N_HCI);

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