/*
 *
 *  Bluetooth HCI UART driver
 *
 *  Copyright (C) 2002-2003  Maxim Krasnyansky <maxk@qualcomm.com>
 *  Copyright (C) 2004-2005  Marcel Holtmann <marcel@holtmann.org>
 *  Copyright (c) 2000-2001, 2010-2012, The Linux Foundation. All rights reserved.
 *
 *
 *  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"

#define VERSION "2.2"

static bool reset = 0;

static struct hci_uart_proto *hup[HCI_UART_MAX_PROTO];
static void hci_uart_tty_wakeup_action(unsigned long data);

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.sco_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 hci_uart *hu;

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

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

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

	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);

	/* FIXME: This btw is bogus, nothing requires the old ldisc to clear
	   the pointer */
	if (hu)
		return -EEXIST;

	/* Error if the tty has no write op instead of leaving an exploitable
	   hole */
	if (tty->ops->write == NULL)
		return -EOPNOTSUPP;

	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);
	tasklet_init(&hu->tty_wakeup_task, hci_uart_tty_wakeup_action,
			 (unsigned long)hu);

	/* 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);

		tasklet_kill(&hu->tty_wakeup_task);

		if (test_and_clear_bit(HCI_UART_PROTO_SET, &hu->flags)) {
			hu->proto->close(hu);
			if (hdev) {
				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.
 *    This callback gets called from the isr context so
 *    schedule the send data operation to tasklet.
 *
 * 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;
	tasklet_schedule(&hu->tty_wakeup_task);
}

/* hci_uart_tty_wakeup_action()
 *
 * Scheduled action to transmit data when low level device
 * driver can accept more data.
 */
static void hci_uart_tty_wakeup_action(unsigned long data)
{
	struct hci_uart *hu = (struct hci_uart *)data;
	struct tty_struct *tty;

	BT_DBG("");

	if (!hu)
		return;

	tty = hu->tty;

	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)
{
	int ret;
	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);
	ret = hu->proto->recv(hu, (void *) data, count);
	if (ret > 0)
		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->bus = 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->parent = hu->tty->dev;

	hdev->owner = THIS_MODULE;

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

	if (test_bit(HCI_UART_RAW_DEVICE, &hu->hdev_flags))
		set_bit(HCI_QUIRK_RAW_DEVICE, &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_IN_PROGRESS,
			&hu->flags) && !test_bit(HCI_UART_PROTO_SET,
				&hu->flags)) {
			err = hci_uart_set_proto(hu, arg);
			if (err) {
				clear_bit(HCI_UART_PROTO_SET_IN_PROGRESS,
						&hu->flags);
				return err;
			} else {
				set_bit(HCI_UART_PROTO_SET, &hu->flags);
				clear_bit(HCI_UART_PROTO_SET_IN_PROGRESS,
						&hu->flags);
			}
		} 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;

	case HCIUARTSETFLAGS:
		if (test_bit(HCI_UART_PROTO_SET, &hu->flags))
			return -EBUSY;
		hu->hdev_flags = arg;
		break;

	case HCIUARTGETFLAGS:
		return hu->hdev_flags;

	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
#ifdef CONFIG_BT_HCIUART_ATH3K
	ath_init();
#endif
#ifdef CONFIG_BT_HCIUART_IBS
	ibs_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
#ifdef CONFIG_BT_HCIUART_ATH3K
	ath_deinit();
#endif
#ifdef CONFIG_BT_HCIUART_IBS
	ibs_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);