/*
   *	SoftDog:	A Software Watchdog Device
   *
   *	(c) Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>,
   *							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.
   *
   *	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.
   */
  
  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  
  #include <linux/module.h>
  #include <linux/moduleparam.h>
  #include <linux/types.h>
  #include <linux/timer.h>
  #include <linux/watchdog.h>
  #include <linux/notifier.h>
  #include <linux/reboot.h>
  #include <linux/init.h>
  #include <linux/jiffies.h>
  #include <linux/kernel.h>
  
  #define TIMER_MARGIN	60		/* Default is 60 seconds */
  static unsigned int soft_margin = TIMER_MARGIN;	/* in seconds */
  module_param(soft_margin, uint, 0);
  MODULE_PARM_DESC(soft_margin,
  	"Watchdog soft_margin in seconds. (0 < soft_margin < 65536, default="
  					__MODULE_STRING(TIMER_MARGIN) ")");
  
  static bool nowayout = WATCHDOG_NOWAYOUT;
  module_param(nowayout, bool, 0);
  MODULE_PARM_DESC(nowayout,
  		"Watchdog cannot be stopped once started (default="
  				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
  
  static int soft_noboot = 0;
  module_param(soft_noboot, int, 0);
  MODULE_PARM_DESC(soft_noboot,
  	"Softdog action, set to 1 to ignore reboots, 0 to reboot (default=0)");
  
  static int soft_panic;
  module_param(soft_panic, int, 0);
  MODULE_PARM_DESC(soft_panic,
  	"Softdog action, set to 1 to panic, 0 to reboot (default=0)");
  
  /*
   *	Our timer
   */
  
  static void watchdog_fire(unsigned long);
  
  static struct timer_list watchdog_ticktock =
  		TIMER_INITIALIZER(watchdog_fire, 0, 0);
  
  /*
   *	If the timer expires..
   */
  
  static void watchdog_fire(unsigned long data)
  {
  	if (soft_noboot)
  		pr_crit("Triggered - Reboot ignored
  ");
  	else if (soft_panic) {
  		pr_crit("Initiating panic
  ");
  		panic("Software Watchdog Timer expired");
  	} else {
  		pr_crit("Initiating system reboot
  ");
  		emergency_restart();
  		pr_crit("Reboot didn't ?????
  ");
  	}
  }
  
  /*
   *	Softdog operations
   */
  
  static int softdog_ping(struct watchdog_device *w)
  {
  	mod_timer(&watchdog_ticktock, jiffies+(w->timeout*HZ));
  	return 0;
  }
  
  static int softdog_stop(struct watchdog_device *w)
  {
  	del_timer(&watchdog_ticktock);
  	return 0;
  }
  
  static int softdog_set_timeout(struct watchdog_device *w, unsigned int t)
  {
  	w->timeout = t;
  	return 0;
  }
  
  /*
   *	Notifier for system down
   */
  
  static int softdog_notify_sys(struct notifier_block *this, unsigned long code,
  	void *unused)
  {
  	if (code == SYS_DOWN || code == SYS_HALT)
  		/* Turn the WDT off */
  		softdog_stop(NULL);
  	return NOTIFY_DONE;
  }
  
  /*
   *	Kernel Interfaces
   */
  
  static struct notifier_block softdog_notifier = {
  	.notifier_call	= softdog_notify_sys,
  };
  
  static struct watchdog_info softdog_info = {
  	.identity = "Software Watchdog",
  	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
  };
  
  static struct watchdog_ops softdog_ops = {
  	.owner = THIS_MODULE,
  	.start = softdog_ping,
  	.stop = softdog_stop,
  	.set_timeout = softdog_set_timeout,
  };
  
  static struct watchdog_device softdog_dev = {
  	.info = &softdog_info,
  	.ops = &softdog_ops,
  	.min_timeout = 1,
  	.max_timeout = 0xFFFF
  };
  
  static int __init watchdog_init(void)
  {
  	int ret;
  
  	/* Check that the soft_margin value is within it's range;
  	   if not reset to the default */
  	if (soft_margin < 1 || soft_margin > 65535) {
  		pr_info("soft_margin must be 0 < soft_margin < 65536, using %d
  ",
  			TIMER_MARGIN);
  		return -EINVAL;
  	}
  	softdog_dev.timeout = soft_margin;
  
  	watchdog_set_nowayout(&softdog_dev, nowayout);
  
  	ret = register_reboot_notifier(&softdog_notifier);
  	if (ret) {
  		pr_err("cannot register reboot notifier (err=%d)
  ", ret);
  		return ret;
  	}
  
  	ret = watchdog_register_device(&softdog_dev);
  	if (ret) {
  		unregister_reboot_notifier(&softdog_notifier);
  		return ret;
  	}
  
  	pr_info("Software Watchdog Timer: 0.08 initialized. soft_noboot=%d soft_margin=%d sec soft_panic=%d (nowayout=%d)
  ",
  		soft_noboot, soft_margin, soft_panic, nowayout);
  
  	return 0;
  }
  
  static void __exit watchdog_exit(void)
  {
  	watchdog_unregister_device(&softdog_dev);
  	unregister_reboot_notifier(&softdog_notifier);
  }
  
  module_init(watchdog_init);
  module_exit(watchdog_exit);
  
  MODULE_AUTHOR("Alan Cox");
  MODULE_DESCRIPTION("Software Watchdog Device Driver");
  MODULE_LICENSE("GPL");