1/*
2 *	SoftDog:	A Software Watchdog Device
3 *
4 *	(c) Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>,
5 *							All Rights Reserved.
6 *
7 *	This program is free software; you can redistribute it and/or
8 *	modify it under the terms of the GNU General Public License
9 *	as published by the Free Software Foundation; either version
10 *	2 of the License, or (at your option) any later version.
11 *
12 *	Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
13 *	warranty for any of this software. This material is provided
14 *	"AS-IS" and at no charge.
15 *
16 *	(c) Copyright 1995    Alan Cox <alan@lxorguk.ukuu.org.uk>
17 *
18 *	Software only watchdog driver. Unlike its big brother the WDT501P
19 *	driver this won't always recover a failed machine.
20 *
21 *  03/96: Angelo Haritsis <ah@doc.ic.ac.uk> :
22 *	Modularised.
23 *	Added soft_margin; use upon insmod to change the timer delay.
24 *	NB: uses same minor as wdt (WATCHDOG_MINOR); we could use separate
25 *	    minors.
26 *
27 *  19980911 Alan Cox
28 *	Made SMP safe for 2.3.x
29 *
30 *  20011127 Joel Becker (jlbec@evilplan.org>
31 *	Added soft_noboot; Allows testing the softdog trigger without
32 *	requiring a recompile.
33 *	Added WDIOC_GETTIMEOUT and WDIOC_SETTIMOUT.
34 *
35 *  20020530 Joel Becker <joel.becker@oracle.com>
36 *	Added Matt Domsch's nowayout module option.
37 */
38
39#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
40
41#include <linux/module.h>
42#include <linux/moduleparam.h>
43#include <linux/types.h>
44#include <linux/timer.h>
45#include <linux/watchdog.h>
46#include <linux/notifier.h>
47#include <linux/reboot.h>
48#include <linux/init.h>
49#include <linux/jiffies.h>
50#include <linux/kernel.h>
51
52#define TIMER_MARGIN	60		/* Default is 60 seconds */
53static unsigned int soft_margin = TIMER_MARGIN;	/* in seconds */
54module_param(soft_margin, uint, 0);
55MODULE_PARM_DESC(soft_margin,
56	"Watchdog soft_margin in seconds. (0 < soft_margin < 65536, default="
57					__MODULE_STRING(TIMER_MARGIN) ")");
58
59static bool nowayout = WATCHDOG_NOWAYOUT;
60module_param(nowayout, bool, 0);
61MODULE_PARM_DESC(nowayout,
62		"Watchdog cannot be stopped once started (default="
63				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
64
65static int soft_noboot;
66module_param(soft_noboot, int, 0);
67MODULE_PARM_DESC(soft_noboot,
68	"Softdog action, set to 1 to ignore reboots, 0 to reboot (default=0)");
69
70static int soft_panic;
71module_param(soft_panic, int, 0);
72MODULE_PARM_DESC(soft_panic,
73	"Softdog action, set to 1 to panic, 0 to reboot (default=0)");
74
75/*
76 *	Our timer
77 */
78
79static void watchdog_fire(unsigned long);
80
81static struct timer_list watchdog_ticktock =
82		TIMER_INITIALIZER(watchdog_fire, 0, 0);
83
84/*
85 *	If the timer expires..
86 */
87
88static void watchdog_fire(unsigned long data)
89{
90	if (soft_noboot)
91		pr_crit("Triggered - Reboot ignored\n");
92	else if (soft_panic) {
93		pr_crit("Initiating panic\n");
94		panic("Software Watchdog Timer expired");
95	} else {
96		pr_crit("Initiating system reboot\n");
97		emergency_restart();
98		pr_crit("Reboot didn't ?????\n");
99	}
100}
101
102/*
103 *	Softdog operations
104 */
105
106static int softdog_ping(struct watchdog_device *w)
107{
108	mod_timer(&watchdog_ticktock, jiffies+(w->timeout*HZ));
109	return 0;
110}
111
112static int softdog_stop(struct watchdog_device *w)
113{
114	del_timer(&watchdog_ticktock);
115	return 0;
116}
117
118static int softdog_set_timeout(struct watchdog_device *w, unsigned int t)
119{
120	w->timeout = t;
121	return 0;
122}
123
124/*
125 *	Notifier for system down
126 */
127
128static int softdog_notify_sys(struct notifier_block *this, unsigned long code,
129	void *unused)
130{
131	if (code == SYS_DOWN || code == SYS_HALT)
132		/* Turn the WDT off */
133		softdog_stop(NULL);
134	return NOTIFY_DONE;
135}
136
137/*
138 *	Kernel Interfaces
139 */
140
141static struct notifier_block softdog_notifier = {
142	.notifier_call	= softdog_notify_sys,
143};
144
145static struct watchdog_info softdog_info = {
146	.identity = "Software Watchdog",
147	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
148};
149
150static struct watchdog_ops softdog_ops = {
151	.owner = THIS_MODULE,
152	.start = softdog_ping,
153	.stop = softdog_stop,
154	.set_timeout = softdog_set_timeout,
155};
156
157static struct watchdog_device softdog_dev = {
158	.info = &softdog_info,
159	.ops = &softdog_ops,
160	.min_timeout = 1,
161	.max_timeout = 0xFFFF
162};
163
164static int __init watchdog_init(void)
165{
166	int ret;
167
168	/* Check that the soft_margin value is within it's range;
169	   if not reset to the default */
170	if (soft_margin < 1 || soft_margin > 65535) {
171		pr_info("soft_margin must be 0 < soft_margin < 65536, using %d\n",
172			TIMER_MARGIN);
173		return -EINVAL;
174	}
175	softdog_dev.timeout = soft_margin;
176
177	watchdog_set_nowayout(&softdog_dev, nowayout);
178
179	ret = register_reboot_notifier(&softdog_notifier);
180	if (ret) {
181		pr_err("cannot register reboot notifier (err=%d)\n", ret);
182		return ret;
183	}
184
185	ret = watchdog_register_device(&softdog_dev);
186	if (ret) {
187		unregister_reboot_notifier(&softdog_notifier);
188		return ret;
189	}
190
191	pr_info("Software Watchdog Timer: 0.08 initialized. soft_noboot=%d soft_margin=%d sec soft_panic=%d (nowayout=%d)\n",
192		soft_noboot, soft_margin, soft_panic, nowayout);
193
194	return 0;
195}
196
197static void __exit watchdog_exit(void)
198{
199	watchdog_unregister_device(&softdog_dev);
200	unregister_reboot_notifier(&softdog_notifier);
201}
202
203module_init(watchdog_init);
204module_exit(watchdog_exit);
205
206MODULE_AUTHOR("Alan Cox");
207MODULE_DESCRIPTION("Software Watchdog Device Driver");
208MODULE_LICENSE("GPL");
209