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 <linux/jiffies.h>
52 #include <asm/uaccess.h>
54 #define PFX "SoftDog: "
56 #define TIMER_MARGIN 60 /* Default is 60 seconds */
57 static int soft_margin
= TIMER_MARGIN
; /* in seconds */
58 module_param(soft_margin
, int, 0);
59 MODULE_PARM_DESC(soft_margin
, "Watchdog soft_margin in seconds. (0<soft_margin<65536, default=" __MODULE_STRING(TIMER_MARGIN
) ")");
61 static int nowayout
= WATCHDOG_NOWAYOUT
;
62 module_param(nowayout
, int, 0);
63 MODULE_PARM_DESC(nowayout
, "Watchdog cannot be stopped once started (default=CONFIG_WATCHDOG_NOWAYOUT)");
66 static int soft_noboot
= 1;
68 static int soft_noboot
= 0;
69 #endif /* ONLY_TESTING */
71 module_param(soft_noboot
, int, 0);
72 MODULE_PARM_DESC(soft_noboot
, "Softdog action, set to 1 to ignore reboots, 0 to reboot (default depends on ONLY_TESTING)");
78 static void watchdog_fire(unsigned long);
80 static struct timer_list watchdog_ticktock
=
81 TIMER_INITIALIZER(watchdog_fire
, 0, 0);
82 static unsigned long driver_open
, orphan_timer
;
83 static char expect_close
;
87 * If the timer expires..
90 static void watchdog_fire(unsigned long data
)
92 if (test_and_clear_bit(0, &orphan_timer
))
93 module_put(THIS_MODULE
);
96 printk(KERN_CRIT PFX
"Triggered - Reboot ignored.\n");
99 printk(KERN_CRIT PFX
"Initiating system reboot.\n");
101 printk(KERN_CRIT PFX
"Reboot didn't ?????\n");
109 static int softdog_keepalive(void)
111 mod_timer(&watchdog_ticktock
, jiffies
+(soft_margin
*HZ
));
115 static int softdog_stop(void)
117 del_timer(&watchdog_ticktock
);
121 static int softdog_set_heartbeat(int t
)
123 if ((t
< 0x0001) || (t
> 0xFFFF))
131 * /dev/watchdog handling
134 static int softdog_open(struct inode
*inode
, struct file
*file
)
136 if (test_and_set_bit(0, &driver_open
))
138 if (!test_and_clear_bit(0, &orphan_timer
))
139 __module_get(THIS_MODULE
);
144 return nonseekable_open(inode
, file
);
147 static int softdog_release(struct inode
*inode
, struct file
*file
)
150 * Shut off the timer.
151 * Lock it in if it's a module and we set nowayout
153 if (expect_close
== 42) {
155 module_put(THIS_MODULE
);
157 printk(KERN_CRIT PFX
"Unexpected close, not stopping watchdog!\n");
158 set_bit(0, &orphan_timer
);
161 clear_bit(0, &driver_open
);
166 static ssize_t
softdog_write(struct file
*file
, const char __user
*data
, size_t len
, loff_t
*ppos
)
175 /* In case it was set long ago */
178 for (i
= 0; i
!= len
; i
++) {
181 if (get_user(c
, data
+ i
))
192 static int softdog_ioctl(struct inode
*inode
, struct file
*file
,
193 unsigned int cmd
, unsigned long arg
)
195 void __user
*argp
= (void __user
*)arg
;
196 int __user
*p
= argp
;
198 static struct watchdog_info ident
= {
199 .options
= WDIOF_SETTIMEOUT
|
200 WDIOF_KEEPALIVEPING
|
202 .firmware_version
= 0,
203 .identity
= "Software Watchdog",
208 case WDIOC_GETSUPPORT
:
209 return copy_to_user(argp
, &ident
,
210 sizeof(ident
)) ? -EFAULT
: 0;
211 case WDIOC_GETSTATUS
:
212 case WDIOC_GETBOOTSTATUS
:
213 return put_user(0, p
);
214 case WDIOC_KEEPALIVE
:
217 case WDIOC_SETTIMEOUT
:
218 if (get_user(new_margin
, p
))
220 if (softdog_set_heartbeat(new_margin
))
224 case WDIOC_GETTIMEOUT
:
225 return put_user(soft_margin
, p
);
230 * Notifier for system down
233 static int softdog_notify_sys(struct notifier_block
*this, unsigned long code
,
236 if(code
==SYS_DOWN
|| code
==SYS_HALT
) {
237 /* Turn the WDT off */
247 static struct file_operations softdog_fops
= {
248 .owner
= THIS_MODULE
,
250 .write
= softdog_write
,
251 .ioctl
= softdog_ioctl
,
252 .open
= softdog_open
,
253 .release
= softdog_release
,
256 static struct miscdevice softdog_miscdev
= {
257 .minor
= WATCHDOG_MINOR
,
259 .fops
= &softdog_fops
,
262 static struct notifier_block softdog_notifier
= {
263 .notifier_call
= softdog_notify_sys
,
266 static char banner
[] __initdata
= KERN_INFO
"Software Watchdog Timer: 0.07 initialized. soft_noboot=%d soft_margin=%d sec (nowayout= %d)\n";
268 static int __init
watchdog_init(void)
272 /* Check that the soft_margin value is within it's range ; if not reset to the default */
273 if (softdog_set_heartbeat(soft_margin
)) {
274 softdog_set_heartbeat(TIMER_MARGIN
);
275 printk(KERN_INFO PFX
"soft_margin value must be 0<soft_margin<65536, using %d\n",
279 ret
= register_reboot_notifier(&softdog_notifier
);
281 printk (KERN_ERR PFX
"cannot register reboot notifier (err=%d)\n",
286 ret
= misc_register(&softdog_miscdev
);
288 printk (KERN_ERR PFX
"cannot register miscdev on minor=%d (err=%d)\n",
289 WATCHDOG_MINOR
, ret
);
290 unregister_reboot_notifier(&softdog_notifier
);
294 printk(banner
, soft_noboot
, soft_margin
, nowayout
);
299 static void __exit
watchdog_exit(void)
301 misc_deregister(&softdog_miscdev
);
302 unregister_reboot_notifier(&softdog_notifier
);
305 module_init(watchdog_init
);
306 module_exit(watchdog_exit
);
308 MODULE_AUTHOR("Alan Cox");
309 MODULE_DESCRIPTION("Software Watchdog Device Driver");
310 MODULE_LICENSE("GPL");
311 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR
);