/home/lenb/src/to-linus branch 'acpi-2.6.12'
[linux-2.6] / drivers / char / watchdog / softdog.c
1 /*
2  *      SoftDog 0.07:   A Software Watchdog Device
3  *
4  *      (c) Copyright 1996 Alan Cox <alan@redhat.com>, All Rights Reserved.
5  *                              http://www.redhat.com
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 #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>
46 #include <linux/fs.h>
47 #include <linux/notifier.h>
48 #include <linux/reboot.h>
49 #include <linux/init.h>
50 #include <asm/uaccess.h>
51
52 #define PFX "SoftDog: "
53
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) ")");
58
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)");
62
63 #ifdef ONLY_TESTING
64 static int soft_noboot = 1;
65 #else
66 static int soft_noboot = 0;
67 #endif  /* ONLY_TESTING */
68
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)");
71
72 /*
73  *      Our timer
74  */
75
76 static void watchdog_fire(unsigned long);
77
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;
82
83
84 /*
85  *      If the timer expires..
86  */
87
88 static void watchdog_fire(unsigned long data)
89 {
90         if (soft_noboot)
91                 printk(KERN_CRIT PFX "Triggered - Reboot ignored.\n");
92         else
93         {
94                 printk(KERN_CRIT PFX "Initiating system reboot.\n");
95                 emergency_restart();
96                 printk(KERN_CRIT PFX "Reboot didn't ?????\n");
97         }
98 }
99
100 /*
101  *      Softdog operations
102  */
103
104 static int softdog_keepalive(void)
105 {
106         mod_timer(&watchdog_ticktock, jiffies+(soft_margin*HZ));
107         return 0;
108 }
109
110 static int softdog_stop(void)
111 {
112         del_timer(&watchdog_ticktock);
113         return 0;
114 }
115
116 static int softdog_set_heartbeat(int t)
117 {
118         if ((t < 0x0001) || (t > 0xFFFF))
119                 return -EINVAL;
120
121         soft_margin = t;
122         return 0;
123 }
124
125 /*
126  *      /dev/watchdog handling
127  */
128
129 static int softdog_open(struct inode *inode, struct file *file)
130 {
131         if(test_and_set_bit(0, &timer_alive))
132                 return -EBUSY;
133         if (nowayout)
134                 __module_get(THIS_MODULE);
135         /*
136          *      Activate timer
137          */
138         softdog_keepalive();
139         return nonseekable_open(inode, file);
140 }
141
142 static int softdog_release(struct inode *inode, struct file *file)
143 {
144         /*
145          *      Shut off the timer.
146          *      Lock it in if it's a module and we set nowayout
147          */
148         if (expect_close == 42) {
149                 softdog_stop();
150         } else {
151                 printk(KERN_CRIT PFX "Unexpected close, not stopping watchdog!\n");
152                 softdog_keepalive();
153         }
154         clear_bit(0, &timer_alive);
155         expect_close = 0;
156         return 0;
157 }
158
159 static ssize_t softdog_write(struct file *file, const char __user *data, size_t len, loff_t *ppos)
160 {
161         /*
162          *      Refresh the timer.
163          */
164         if(len) {
165                 if (!nowayout) {
166                         size_t i;
167
168                         /* In case it was set long ago */
169                         expect_close = 0;
170
171                         for (i = 0; i != len; i++) {
172                                 char c;
173
174                                 if (get_user(c, data + i))
175                                         return -EFAULT;
176                                 if (c == 'V')
177                                         expect_close = 42;
178                         }
179                 }
180                 softdog_keepalive();
181         }
182         return len;
183 }
184
185 static int softdog_ioctl(struct inode *inode, struct file *file,
186         unsigned int cmd, unsigned long arg)
187 {
188         void __user *argp = (void __user *)arg;
189         int __user *p = argp;
190         int new_margin;
191         static struct watchdog_info ident = {
192                 .options =              WDIOF_SETTIMEOUT |
193                                         WDIOF_KEEPALIVEPING |
194                                         WDIOF_MAGICCLOSE,
195                 .firmware_version =     0,
196                 .identity =             "Software Watchdog",
197         };
198         switch (cmd) {
199                 default:
200                         return -ENOIOCTLCMD;
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:
208                         softdog_keepalive();
209                         return 0;
210                 case WDIOC_SETTIMEOUT:
211                         if (get_user(new_margin, p))
212                                 return -EFAULT;
213                         if (softdog_set_heartbeat(new_margin))
214                                 return -EINVAL;
215                         softdog_keepalive();
216                         /* Fall */
217                 case WDIOC_GETTIMEOUT:
218                         return put_user(soft_margin, p);
219         }
220 }
221
222 /*
223  *      Notifier for system down
224  */
225
226 static int softdog_notify_sys(struct notifier_block *this, unsigned long code,
227         void *unused)
228 {
229         if(code==SYS_DOWN || code==SYS_HALT) {
230                 /* Turn the WDT off */
231                 softdog_stop();
232         }
233         return NOTIFY_DONE;
234 }
235
236 /*
237  *      Kernel Interfaces
238  */
239
240 static struct file_operations softdog_fops = {
241         .owner          = THIS_MODULE,
242         .llseek         = no_llseek,
243         .write          = softdog_write,
244         .ioctl          = softdog_ioctl,
245         .open           = softdog_open,
246         .release        = softdog_release,
247 };
248
249 static struct miscdevice softdog_miscdev = {
250         .minor          = WATCHDOG_MINOR,
251         .name           = "watchdog",
252         .fops           = &softdog_fops,
253 };
254
255 static struct notifier_block softdog_notifier = {
256         .notifier_call  = softdog_notify_sys,
257 };
258
259 static char banner[] __initdata = KERN_INFO "Software Watchdog Timer: 0.07 initialized. soft_noboot=%d soft_margin=%d sec (nowayout= %d)\n";
260
261 static int __init watchdog_init(void)
262 {
263         int ret;
264
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",
269                         TIMER_MARGIN);
270         }
271
272         ret = register_reboot_notifier(&softdog_notifier);
273         if (ret) {
274                 printk (KERN_ERR PFX "cannot register reboot notifier (err=%d)\n",
275                         ret);
276                 return ret;
277         }
278
279         ret = misc_register(&softdog_miscdev);
280         if (ret) {
281                 printk (KERN_ERR PFX "cannot register miscdev on minor=%d (err=%d)\n",
282                         WATCHDOG_MINOR, ret);
283                 unregister_reboot_notifier(&softdog_notifier);
284                 return ret;
285         }
286
287         printk(banner, soft_noboot, soft_margin, nowayout);
288
289         return 0;
290 }
291
292 static void __exit watchdog_exit(void)
293 {
294         misc_deregister(&softdog_miscdev);
295         unregister_reboot_notifier(&softdog_notifier);
296 }
297
298 module_init(watchdog_init);
299 module_exit(watchdog_exit);
300
301 MODULE_AUTHOR("Alan Cox");
302 MODULE_DESCRIPTION("Software Watchdog Device Driver");
303 MODULE_LICENSE("GPL");
304 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);