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/*

 *      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.

 *

 *  20020530 Joel Becker <joel.becker@oracle.com>

 *      Added Matt Domsch's nowayout module option.

 */

#include <linux/module.h>

#include <linux/config.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/smp_lock.h>

#include <linux/init.h>

#include <asm/uaccess.h>

#define TIMER_MARGIN    60              /* (secs) Default is 1 minute */

static int expect_close = 0;

static int soft_margin = TIMER_MARGIN;  /* in seconds */

#ifdef ONLY_TESTING

static int soft_noboot = 1;

#else

static int soft_noboot = 0;

#endif  /* ONLY_TESTING */

MODULE_PARM(soft_margin,"i");

MODULE_PARM(soft_noboot,"i");

MODULE_LICENSE("GPL");

#ifdef CONFIG_WATCHDOG_NOWAYOUT

static int nowayout = 1;

#else

static int nowayout = 0;

#endif

MODULE_PARM(nowayout,"i");

MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=CONFIG_WATCHDOG_NOWAYOUT)");

/*

 *      Our timer

 */

static void watchdog_fire(unsigned long);

static struct timer_list watchdog_ticktock = {

        function:       watchdog_fire,

};

static unsigned long timer_alive;

/*

 *      If the timer expires..

 */

static void watchdog_fire(unsigned long data)

{

        if (soft_noboot)

                printk(KERN_CRIT "SOFTDOG: Triggered - Reboot ignored.\n");

        else

        {

                printk(KERN_CRIT "SOFTDOG: Initiating system reboot.\n");

                machine_restart(NULL);

                printk("SOFTDOG: Reboot didn't ?????\n");

        }

}

/*

 *      Allow only one person to hold it open

 */

static int softdog_open(struct inode *inode, struct file *file)

{

        if(test_and_set_bit(0, &timer_alive))

                return -EBUSY;

        if (nowayout) {

                MOD_INC_USE_COUNT;

        }

        /*

         *      Activate timer

         */

        mod_timer(&watchdog_ticktock, jiffies+(soft_margin*HZ));

        return 0;

}

static int softdog_release(struct inode *inode, struct file *file)

{

        /*

         *      Shut off the timer.

         *      Lock it in if it's a module and we set nowayout

         */

        if (expect_close || nowayout == 0) {

                del_timer(&watchdog_ticktock);

        } else {

                printk(KERN_CRIT "SOFTDOG: WDT device closed unexpectedly.  WDT will not stop!\n");

        }

        clear_bit(0, &timer_alive);

        return 0;

}

static ssize_t softdog_write(struct file *file, const char *data, size_t len, loff_t *ppos)

{

        /*  Can't seek (pwrite) on this device  */

        if (ppos != &file->f_pos)

                return -ESPIPE;

        /*

         *      Refresh the timer.

         */

        if(len) {

                if (!nowayout) {

                        size_t i;

                        /* In case it was set long ago */

                        expect_close = 0;

                        for (i = 0; i != len; i++) {

                                char c;

                                if (get_user(c, data + i))

                                        return -EFAULT;

                                if (c == 'V')

                                        expect_close = 1;

                        }

                }

                mod_timer(&watchdog_ticktock, jiffies+(soft_margin*HZ));

                return 1;

        }

        return 0;

}

static int softdog_ioctl(struct inode *inode, struct file *file,

        unsigned int cmd, unsigned long arg)

{

        int new_margin;

        static struct watchdog_info ident = {

                WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,

                0,

                "Software Watchdog"

        };

        switch (cmd) {

                default:

                        return -ENOTTY;

                case WDIOC_GETSUPPORT:

                        if(copy_to_user((struct watchdog_info *)arg, &ident, sizeof(ident)))

                                return -EFAULT;

                        return 0;

                case WDIOC_GETSTATUS:

                case WDIOC_GETBOOTSTATUS:

                        return put_user(0,(int *)arg);

                case WDIOC_KEEPALIVE:

                        mod_timer(&watchdog_ticktock, jiffies+(soft_margin*HZ));

                        return 0;

                case WDIOC_SETTIMEOUT:

                        if (get_user(new_margin, (int *)arg))

                                return -EFAULT;

                        if (new_margin < 1)

                                return -EINVAL;

                        soft_margin = new_margin;

                        mod_timer(&watchdog_ticktock, jiffies+(soft_margin*HZ));

                        /* Fall */

                case WDIOC_GETTIMEOUT:

                        return put_user(soft_margin, (int *)arg);

        }

}

static struct file_operations softdog_fops = {

        owner:          THIS_MODULE,

        write:          softdog_write,

        ioctl:          softdog_ioctl,

        open:           softdog_open,

        release:        softdog_release,

};

static struct miscdevice softdog_miscdev = {

        minor:          WATCHDOG_MINOR,

        name:           "watchdog",

        fops:           &softdog_fops,

};

static char banner[] __initdata = KERN_INFO "Software Watchdog Timer: 0.05, timer margin: %d sec\n";

static int __init watchdog_init(void)

{

        int ret;

        ret = misc_register(&softdog_miscdev);

        if (ret)

                return ret;

        printk(banner, soft_margin);

        return 0;

}

static void __exit watchdog_exit(void)

{

        misc_deregister(&softdog_miscdev);

}

module_init(watchdog_init);

module_exit(watchdog_exit);