/* UML hardware watchdog, shamelessly stolen from:
 *
 *      SoftDog 0.05:   A Software Watchdog Device
 *
 *      (c) Copyright 1996 Alan Cox <alan@redhat.com>, All Rights Reserved.
 *                              http://www.redhat.com
 *
 *      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.
 *
 *      Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
 *      warranty for any of this software. This material is provided
 *      "AS-IS" and at no charge.
 *
 *      (c) Copyright 1995    Alan Cox <alan@lxorguk.ukuu.org.uk>
 *
 *      Software only watchdog driver. Unlike its big brother the WDT501P
 *      driver this won't always recover a failed machine.
 *
 *  03/96: Angelo Haritsis <ah@doc.ic.ac.uk> :
 *      Modularised.
 *      Added soft_margin; use upon insmod to change the timer delay.
 *      NB: uses same minor as wdt (WATCHDOG_MINOR); we could use separate
 *          minors.
 *
 *  19980911 Alan Cox
 *      Made SMP safe for 2.3.x
 *
 *  20011127 Joel Becker (jlbec@evilplan.org>
 *      Added soft_noboot; Allows testing the softdog trigger without
 *      requiring a recompile.
 *      Added WDIOC_GETTIMEOUT and WDIOC_SETTIMOUT.
 */

#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/reboot.h>
#include <linux/mutex.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/uaccess.h>
#include "mconsole.h"
#include "harddog.h"

MODULE_DESCRIPTION("UML hardware watchdog");
MODULE_LICENSE("GPL");

static DEFINE_MUTEX(harddog_mutex);
static DEFINE_SPINLOCK(lock);
static int timer_alive;
static int harddog_in_fd = -1;
static int harddog_out_fd = -1;

/*
 *      Allow only one person to hold it open
 */

static int harddog_open(struct inode *inode, struct file *file)
{
        int err = -EBUSY;
        char *sock = NULL;

        mutex_lock(&harddog_mutex);
        spin_lock(&lock);
        if(timer_alive)
                goto err;
#ifdef CONFIG_WATCHDOG_NOWAYOUT
        __module_get(THIS_MODULE);
#endif

#ifdef CONFIG_MCONSOLE
        sock = mconsole_notify_socket();
#endif
        err = start_watchdog(&harddog_in_fd, &harddog_out_fd, sock);
        if(err)
                goto err;

        timer_alive = 1;
        spin_unlock(&lock);
        mutex_unlock(&harddog_mutex);
        return stream_open(inode, file);
err:
        spin_unlock(&lock);
        mutex_unlock(&harddog_mutex);
        return err;
}

static int harddog_release(struct inode *inode, struct file *file)
{
        /*
         *      Shut off the timer.
         */

        spin_lock(&lock);

        stop_watchdog(harddog_in_fd, harddog_out_fd);
        harddog_in_fd = -1;
        harddog_out_fd = -1;

        timer_alive=0;
        spin_unlock(&lock);

        return 0;
}

static ssize_t harddog_write(struct file *file, const char __user *data, size_t len,
                             loff_t *ppos)
{
        /*
         *      Refresh the timer.
         */
        if(len)
                return ping_watchdog(harddog_out_fd);
        return 0;
}

static int harddog_ioctl_unlocked(struct file *file,
                                  unsigned int cmd, unsigned long arg)
{
        void __user *argp= (void __user *)arg;
        static struct watchdog_info ident = {
                WDIOC_SETTIMEOUT,
                0,
                "UML Hardware Watchdog"
        };
        switch (cmd) {
                default:
                        return -ENOTTY;
                case WDIOC_GETSUPPORT:
                        if(copy_to_user(argp, &ident, sizeof(ident)))
                                return -EFAULT;
                        return 0;
                case WDIOC_GETSTATUS:
                case WDIOC_GETBOOTSTATUS:
                        return put_user(0,(int __user *)argp);
                case WDIOC_KEEPALIVE:
                        return ping_watchdog(harddog_out_fd);
        }
}

static long harddog_ioctl(struct file *file,
                          unsigned int cmd, unsigned long arg)
{
        long ret;

        mutex_lock(&harddog_mutex);
        ret = harddog_ioctl_unlocked(file, cmd, arg);
        mutex_unlock(&harddog_mutex);

        return ret;
}

static const struct file_operations harddog_fops = {
        .owner          = THIS_MODULE,
        .write          = harddog_write,
        .unlocked_ioctl = harddog_ioctl,
        .compat_ioctl   = compat_ptr_ioctl,
        .open           = harddog_open,
        .release        = harddog_release,
};

static struct miscdevice harddog_miscdev = {
        .minor          = WATCHDOG_MINOR,
        .name           = "watchdog",
        .fops           = &harddog_fops,
};
module_misc_device(harddog_miscdev);