626d0e8e56c390c48bb12301208f56fec3715c15
[sfrench/cifs-2.6.git] / drivers / watchdog / sbc60xxwdt.c
1 /*
2  *      60xx Single Board Computer Watchdog Timer driver for Linux 2.2.x
3  *
4  *      Based on acquirewdt.c by Alan Cox.
5  *
6  *      This program is free software; you can redistribute it and/or
7  *      modify it under the terms of the GNU General Public License
8  *      as published by the Free Software Foundation; either version
9  *      2 of the License, or (at your option) any later version.
10  *
11  *      The author does NOT admit liability nor provide warranty for
12  *      any of this software. This material is provided "AS-IS" in
13  *      the hope that it may be useful for others.
14  *
15  *      (c) Copyright 2000    Jakob Oestergaard <jakob@unthought.net>
16  *
17  *           12/4 - 2000      [Initial revision]
18  *           25/4 - 2000      Added /dev/watchdog support
19  *           09/5 - 2001      [smj@oro.net] fixed fop_write to "return 1"
20  *                                      on success
21  *           12/4 - 2002      [rob@osinvestor.com] eliminate fop_read
22  *                            fix possible wdt_is_open race
23  *                            add CONFIG_WATCHDOG_NOWAYOUT support
24  *                            remove lock_kernel/unlock_kernel pairs
25  *                            added KERN_* to printk's
26  *                            got rid of extraneous comments
27  *                            changed watchdog_info to correctly reflect what
28  *                            the driver offers
29  *                            added WDIOC_GETSTATUS, WDIOC_GETBOOTSTATUS,
30  *                            WDIOC_SETTIMEOUT, WDIOC_GETTIMEOUT, and
31  *                            WDIOC_SETOPTIONS ioctls
32  *           09/8 - 2003      [wim@iguana.be] cleanup of trailing spaces
33  *                            use module_param
34  *                            made timeout (the emulated heartbeat) a
35  *                            module_param
36  *                            made the keepalive ping an internal subroutine
37  *                            made wdt_stop and wdt_start module params
38  *                            added extra printk's for startup problems
39  *                            added MODULE_AUTHOR and MODULE_DESCRIPTION info
40  *
41  *
42  *  This WDT driver is different from the other Linux WDT
43  *  drivers in the following ways:
44  *  *)  The driver will ping the watchdog by itself, because this
45  *      particular WDT has a very short timeout (one second) and it
46  *      would be insane to count on any userspace daemon always
47  *      getting scheduled within that time frame.
48  *
49  */
50
51 #include <linux/module.h>
52 #include <linux/moduleparam.h>
53 #include <linux/types.h>
54 #include <linux/timer.h>
55 #include <linux/jiffies.h>
56 #include <linux/miscdevice.h>
57 #include <linux/watchdog.h>
58 #include <linux/fs.h>
59 #include <linux/ioport.h>
60 #include <linux/notifier.h>
61 #include <linux/reboot.h>
62 #include <linux/init.h>
63 #include <linux/io.h>
64 #include <linux/uaccess.h>
65
66 #include <asm/system.h>
67
68 #define OUR_NAME "sbc60xxwdt"
69 #define PFX OUR_NAME ": "
70
71 /*
72  * You must set these - The driver cannot probe for the settings
73  */
74
75 static int wdt_stop = 0x45;
76 module_param(wdt_stop, int, 0);
77 MODULE_PARM_DESC(wdt_stop, "SBC60xx WDT 'stop' io port (default 0x45)");
78
79 static int wdt_start = 0x443;
80 module_param(wdt_start, int, 0);
81 MODULE_PARM_DESC(wdt_start, "SBC60xx WDT 'start' io port (default 0x443)");
82
83 /*
84  * The 60xx board can use watchdog timeout values from one second
85  * to several minutes.  The default is one second, so if we reset
86  * the watchdog every ~250ms we should be safe.
87  */
88
89 #define WDT_INTERVAL (HZ/4+1)
90
91 /*
92  * We must not require too good response from the userspace daemon.
93  * Here we require the userspace daemon to send us a heartbeat
94  * char to /dev/watchdog every 30 seconds.
95  * If the daemon pulses us every 25 seconds, we can still afford
96  * a 5 second scheduling delay on the (high priority) daemon. That
97  * should be sufficient for a box under any load.
98  */
99
100 #define WATCHDOG_TIMEOUT 30             /* 30 sec default timeout */
101 static int timeout = WATCHDOG_TIMEOUT;  /* in seconds, multiplied by HZ to
102                                            get seconds to wait for a ping */
103 module_param(timeout, int, 0);
104 MODULE_PARM_DESC(timeout,
105         "Watchdog timeout in seconds. (1<=timeout<=3600, default="
106                                 __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
107
108 static int nowayout = WATCHDOG_NOWAYOUT;
109 module_param(nowayout, int, 0);
110 MODULE_PARM_DESC(nowayout,
111         "Watchdog cannot be stopped once started (default="
112                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
113
114 static void wdt_timer_ping(unsigned long);
115 static DEFINE_TIMER(timer, wdt_timer_ping, 0, 0);
116 static unsigned long next_heartbeat;
117 static unsigned long wdt_is_open;
118 static char wdt_expect_close;
119
120 /*
121  *      Whack the dog
122  */
123
124 static void wdt_timer_ping(unsigned long data)
125 {
126         /* If we got a heartbeat pulse within the WDT_US_INTERVAL
127          * we agree to ping the WDT
128          */
129         if (time_before(jiffies, next_heartbeat)) {
130                 /* Ping the WDT by reading from wdt_start */
131                 inb_p(wdt_start);
132                 /* Re-set the timer interval */
133                 mod_timer(&timer, jiffies + WDT_INTERVAL);
134         } else
135                 printk(KERN_WARNING PFX
136                         "Heartbeat lost! Will not ping the watchdog\n");
137 }
138
139 /*
140  * Utility routines
141  */
142
143 static void wdt_startup(void)
144 {
145         next_heartbeat = jiffies + (timeout * HZ);
146
147         /* Start the timer */
148         mod_timer(&timer, jiffies + WDT_INTERVAL);
149         printk(KERN_INFO PFX "Watchdog timer is now enabled.\n");
150 }
151
152 static void wdt_turnoff(void)
153 {
154         /* Stop the timer */
155         del_timer(&timer);
156         inb_p(wdt_stop);
157         printk(KERN_INFO PFX "Watchdog timer is now disabled...\n");
158 }
159
160 static void wdt_keepalive(void)
161 {
162         /* user land ping */
163         next_heartbeat = jiffies + (timeout * HZ);
164 }
165
166 /*
167  * /dev/watchdog handling
168  */
169
170 static ssize_t fop_write(struct file *file, const char __user *buf,
171                                                 size_t count, loff_t *ppos)
172 {
173         /* See if we got the magic character 'V' and reload the timer */
174         if (count) {
175                 if (!nowayout) {
176                         size_t ofs;
177
178                         /* note: just in case someone wrote the
179                            magic character five months ago... */
180                         wdt_expect_close = 0;
181
182                         /* scan to see whether or not we got the
183                            magic character */
184                         for (ofs = 0; ofs != count; ofs++) {
185                                 char c;
186                                 if (get_user(c, buf + ofs))
187                                         return -EFAULT;
188                                 if (c == 'V')
189                                         wdt_expect_close = 42;
190                         }
191                 }
192
193                 /* Well, anyhow someone wrote to us, we should
194                    return that favour */
195                 wdt_keepalive();
196         }
197         return count;
198 }
199
200 static int fop_open(struct inode *inode, struct file *file)
201 {
202         /* Just in case we're already talking to someone... */
203         if (test_and_set_bit(0, &wdt_is_open))
204                 return -EBUSY;
205
206         if (nowayout)
207                 __module_get(THIS_MODULE);
208
209         /* Good, fire up the show */
210         wdt_startup();
211         return nonseekable_open(inode, file);
212 }
213
214 static int fop_close(struct inode *inode, struct file *file)
215 {
216         if (wdt_expect_close == 42)
217                 wdt_turnoff();
218         else {
219                 del_timer(&timer);
220                 printk(KERN_CRIT PFX
221                   "device file closed unexpectedly. Will not stop the WDT!\n");
222         }
223         clear_bit(0, &wdt_is_open);
224         wdt_expect_close = 0;
225         return 0;
226 }
227
228 static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
229 {
230         void __user *argp = (void __user *)arg;
231         int __user *p = argp;
232         static const struct watchdog_info ident = {
233                 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT |
234                                                         WDIOF_MAGICCLOSE,
235                 .firmware_version = 1,
236                 .identity = "SBC60xx",
237         };
238
239         switch (cmd) {
240         case WDIOC_GETSUPPORT:
241                 return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
242         case WDIOC_GETSTATUS:
243         case WDIOC_GETBOOTSTATUS:
244                 return put_user(0, p);
245         case WDIOC_SETOPTIONS:
246         {
247                 int new_options, retval = -EINVAL;
248                 if (get_user(new_options, p))
249                         return -EFAULT;
250                 if (new_options & WDIOS_DISABLECARD) {
251                         wdt_turnoff();
252                         retval = 0;
253                 }
254                 if (new_options & WDIOS_ENABLECARD) {
255                         wdt_startup();
256                         retval = 0;
257                 }
258                 return retval;
259         }
260         case WDIOC_KEEPALIVE:
261                 wdt_keepalive();
262                 return 0;
263         case WDIOC_SETTIMEOUT:
264         {
265                 int new_timeout;
266                 if (get_user(new_timeout, p))
267                         return -EFAULT;
268                 /* arbitrary upper limit */
269                 if (new_timeout < 1 || new_timeout > 3600)
270                         return -EINVAL;
271
272                 timeout = new_timeout;
273                 wdt_keepalive();
274                 /* Fall through */
275         }
276         case WDIOC_GETTIMEOUT:
277                 return put_user(timeout, p);
278         default:
279                 return -ENOTTY;
280         }
281 }
282
283 static const struct file_operations wdt_fops = {
284         .owner          = THIS_MODULE,
285         .llseek         = no_llseek,
286         .write          = fop_write,
287         .open           = fop_open,
288         .release        = fop_close,
289         .unlocked_ioctl = fop_ioctl,
290 };
291
292 static struct miscdevice wdt_miscdev = {
293         .minor = WATCHDOG_MINOR,
294         .name = "watchdog",
295         .fops = &wdt_fops,
296 };
297
298 /*
299  *      Notifier for system down
300  */
301
302 static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
303         void *unused)
304 {
305         if (code == SYS_DOWN || code == SYS_HALT)
306                 wdt_turnoff();
307         return NOTIFY_DONE;
308 }
309
310 /*
311  *      The WDT needs to learn about soft shutdowns in order to
312  *      turn the timebomb registers off.
313  */
314
315 static struct notifier_block wdt_notifier = {
316         .notifier_call = wdt_notify_sys,
317 };
318
319 static void __exit sbc60xxwdt_unload(void)
320 {
321         wdt_turnoff();
322
323         /* Deregister */
324         misc_deregister(&wdt_miscdev);
325
326         unregister_reboot_notifier(&wdt_notifier);
327         if ((wdt_stop != 0x45) && (wdt_stop != wdt_start))
328                 release_region(wdt_stop, 1);
329         release_region(wdt_start, 1);
330 }
331
332 static int __init sbc60xxwdt_init(void)
333 {
334         int rc = -EBUSY;
335
336         if (timeout < 1 || timeout > 3600) { /* arbitrary upper limit */
337                 timeout = WATCHDOG_TIMEOUT;
338                 printk(KERN_INFO PFX
339                         "timeout value must be 1 <= x <= 3600, using %d\n",
340                                                                 timeout);
341         }
342
343         if (!request_region(wdt_start, 1, "SBC 60XX WDT")) {
344                 printk(KERN_ERR PFX "I/O address 0x%04x already in use\n",
345                         wdt_start);
346                 rc = -EIO;
347                 goto err_out;
348         }
349
350         /* We cannot reserve 0x45 - the kernel already has! */
351         if (wdt_stop != 0x45 && wdt_stop != wdt_start) {
352                 if (!request_region(wdt_stop, 1, "SBC 60XX WDT")) {
353                         printk(KERN_ERR PFX
354                                 "I/O address 0x%04x already in use\n",
355                                                         wdt_stop);
356                         rc = -EIO;
357                         goto err_out_region1;
358                 }
359         }
360
361         rc = register_reboot_notifier(&wdt_notifier);
362         if (rc) {
363                 printk(KERN_ERR PFX
364                         "cannot register reboot notifier (err=%d)\n", rc);
365                 goto err_out_region2;
366         }
367
368         rc = misc_register(&wdt_miscdev);
369         if (rc) {
370                 printk(KERN_ERR PFX
371                         "cannot register miscdev on minor=%d (err=%d)\n",
372                                                 wdt_miscdev.minor, rc);
373                 goto err_out_reboot;
374         }
375         printk(KERN_INFO PFX
376                 "WDT driver for 60XX single board computer initialised. "
377                 "timeout=%d sec (nowayout=%d)\n", timeout, nowayout);
378
379         return 0;
380
381 err_out_reboot:
382         unregister_reboot_notifier(&wdt_notifier);
383 err_out_region2:
384         if (wdt_stop != 0x45 && wdt_stop != wdt_start)
385                 release_region(wdt_stop, 1);
386 err_out_region1:
387         release_region(wdt_start, 1);
388 err_out:
389         return rc;
390 }
391
392 module_init(sbc60xxwdt_init);
393 module_exit(sbc60xxwdt_unload);
394
395 MODULE_AUTHOR("Jakob Oestergaard <jakob@unthought.net>");
396 MODULE_DESCRIPTION("60xx Single Board Computer Watchdog Timer driver");
397 MODULE_LICENSE("GPL");
398 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);