2 * SoftDog 0.07: A Software Watchdog Device
4 * (c) Copyright 1996 Alan Cox <alan@redhat.com>, All Rights Reserved.
5 * http://www.redhat.com
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.
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.
16 * (c) Copyright 1995 Alan Cox <alan@lxorguk.ukuu.org.uk>
18 * Software only watchdog driver. Unlike its big brother the WDT501P
19 * driver this won't always recover a failed machine.
21 * 03/96: Angelo Haritsis <ah@doc.ic.ac.uk> :
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
28 * Made SMP safe for 2.3.x
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.
35 * 20020530 Joel Becker <joel.becker@oracle.com>
36 * Added Matt Domsch's nowayout module option.
39 #include <linux/module.h>
40 #include <linux/moduleparam.h>
41 #include <linux/config.h>
42 #include <linux/types.h>
43 #include <linux/timer.h>
44 #include <linux/miscdevice.h>
45 #include <linux/watchdog.h>
47 #include <linux/notifier.h>
48 #include <linux/reboot.h>
49 #include <linux/init.h>
50 #include <asm/uaccess.h>
52 #define PFX "SoftDog: "
54 #define TIMER_MARGIN 60 /* Default is 60 seconds */
55 static int soft_margin = TIMER_MARGIN; /* in seconds */
56 module_param(soft_margin, int, 0);
57 MODULE_PARM_DESC(soft_margin, "Watchdog soft_margin in seconds. (0<soft_margin<65536, default=" __MODULE_STRING(TIMER_MARGIN) ")");
59 static int nowayout = WATCHDOG_NOWAYOUT;
60 module_param(nowayout, int, 0);
61 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=CONFIG_WATCHDOG_NOWAYOUT)");
64 static int soft_noboot = 1;
66 static int soft_noboot = 0;
67 #endif /* ONLY_TESTING */
69 module_param(soft_noboot, int, 0);
70 MODULE_PARM_DESC(soft_noboot, "Softdog action, set to 1 to ignore reboots, 0 to reboot (default depends on ONLY_TESTING)");
76 static void watchdog_fire(unsigned long);
78 static struct timer_list watchdog_ticktock =
79 TIMER_INITIALIZER(watchdog_fire, 0, 0);
80 static unsigned long timer_alive;
81 static char expect_close;
85 * If the timer expires..
88 static void watchdog_fire(unsigned long data)
91 printk(KERN_CRIT PFX "Triggered - Reboot ignored.\n");
94 printk(KERN_CRIT PFX "Initiating system reboot.\n");
96 printk(KERN_CRIT PFX "Reboot didn't ?????\n");
104 static int softdog_keepalive(void)
106 mod_timer(&watchdog_ticktock, jiffies+(soft_margin*HZ));
110 static int softdog_stop(void)
112 del_timer(&watchdog_ticktock);
116 static int softdog_set_heartbeat(int t)
118 if ((t < 0x0001) || (t > 0xFFFF))
126 * /dev/watchdog handling
129 static int softdog_open(struct inode *inode, struct file *file)
131 if(test_and_set_bit(0, &timer_alive))
134 __module_get(THIS_MODULE);
139 return nonseekable_open(inode, file);
142 static int softdog_release(struct inode *inode, struct file *file)
145 * Shut off the timer.
146 * Lock it in if it's a module and we set nowayout
148 if (expect_close == 42) {
151 printk(KERN_CRIT PFX "Unexpected close, not stopping watchdog!\n");
154 clear_bit(0, &timer_alive);
159 static ssize_t softdog_write(struct file *file, const char __user *data, size_t len, loff_t *ppos)
168 /* In case it was set long ago */
171 for (i = 0; i != len; i++) {
174 if (get_user(c, data + i))
185 static int softdog_ioctl(struct inode *inode, struct file *file,
186 unsigned int cmd, unsigned long arg)
188 void __user *argp = (void __user *)arg;
189 int __user *p = argp;
191 static struct watchdog_info ident = {
192 .options = WDIOF_SETTIMEOUT |
193 WDIOF_KEEPALIVEPING |
195 .firmware_version = 0,
196 .identity = "Software Watchdog",
201 case WDIOC_GETSUPPORT:
202 return copy_to_user(argp, &ident,
203 sizeof(ident)) ? -EFAULT : 0;
204 case WDIOC_GETSTATUS:
205 case WDIOC_GETBOOTSTATUS:
206 return put_user(0, p);
207 case WDIOC_KEEPALIVE:
210 case WDIOC_SETTIMEOUT:
211 if (get_user(new_margin, p))
213 if (softdog_set_heartbeat(new_margin))
217 case WDIOC_GETTIMEOUT:
218 return put_user(soft_margin, p);
223 * Notifier for system down
226 static int softdog_notify_sys(struct notifier_block *this, unsigned long code,
229 if(code==SYS_DOWN || code==SYS_HALT) {
230 /* Turn the WDT off */
240 static struct file_operations softdog_fops = {
241 .owner = THIS_MODULE,
243 .write = softdog_write,
244 .ioctl = softdog_ioctl,
245 .open = softdog_open,
246 .release = softdog_release,
249 static struct miscdevice softdog_miscdev = {
250 .minor = WATCHDOG_MINOR,
252 .fops = &softdog_fops,
255 static struct notifier_block softdog_notifier = {
256 .notifier_call = softdog_notify_sys,
259 static char banner[] __initdata = KERN_INFO "Software Watchdog Timer: 0.07 initialized. soft_noboot=%d soft_margin=%d sec (nowayout= %d)\n";
261 static int __init watchdog_init(void)
265 /* Check that the soft_margin value is within it's range ; if not reset to the default */
266 if (softdog_set_heartbeat(soft_margin)) {
267 softdog_set_heartbeat(TIMER_MARGIN);
268 printk(KERN_INFO PFX "soft_margin value must be 0<soft_margin<65536, using %d\n",
272 ret = register_reboot_notifier(&softdog_notifier);
274 printk (KERN_ERR PFX "cannot register reboot notifier (err=%d)\n",
279 ret = misc_register(&softdog_miscdev);
281 printk (KERN_ERR PFX "cannot register miscdev on minor=%d (err=%d)\n",
282 WATCHDOG_MINOR, ret);
283 unregister_reboot_notifier(&softdog_notifier);
287 printk(banner, soft_noboot, soft_margin, nowayout);
292 static void __exit watchdog_exit(void)
294 misc_deregister(&softdog_miscdev);
295 unregister_reboot_notifier(&softdog_notifier);
298 module_init(watchdog_init);
299 module_exit(watchdog_exit);
301 MODULE_AUTHOR("Alan Cox");
302 MODULE_DESCRIPTION("Software Watchdog Device Driver");
303 MODULE_LICENSE("GPL");
304 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);