watchdog: nowayout is bool
[linux-2.6.git] / drivers / watchdog / w83877f_wdt.c
1 /*
2  *      W83877F Computer Watchdog Timer driver
3  *
4  *      Based on acquirewdt.c by Alan Cox,
5  *           and sbc60xxwdt.c by Jakob Oestergaard <jakob@unthought.net>
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  *      The authors do NOT admit liability nor provide warranty for
13  *      any of this software. This material is provided "AS-IS" in
14  *      the hope that it may be useful for others.
15  *
16  *      (c) Copyright 2001    Scott Jennings <linuxdrivers@oro.net>
17  *
18  *           4/19 - 2001      [Initial revision]
19  *           9/27 - 2001      Added spinlocking
20  *           4/12 - 2002      [rob@osinvestor.com] Eliminate extra comments
21  *                            Eliminate fop_read
22  *                            Eliminate extra spin_unlock
23  *                            Added KERN_* tags to printks
24  *                            add CONFIG_WATCHDOG_NOWAYOUT support
25  *                            fix possible wdt_is_open race
26  *                            changed watchdog_info to correctly reflect what
27  *                            the driver offers
28  *                            added WDIOC_GETSTATUS, WDIOC_GETBOOTSTATUS,
29  *                            WDIOC_SETTIMEOUT,
30  *                            WDIOC_GETTIMEOUT, and WDIOC_SETOPTIONS ioctls
31  *           09/8 - 2003      [wim@iguana.be] cleanup of trailing spaces
32  *                            added extra printk's for startup problems
33  *                            use module_param
34  *                            made timeout (the emulated heartbeat) a
35  *                            module_param
36  *                            made the keepalive ping an internal subroutine
37  *
38  *  This WDT driver is different from most other Linux WDT
39  *  drivers in that the driver will ping the watchdog by itself,
40  *  because this particular WDT has a very short timeout (1.6
41  *  seconds) and it would be insane to count on any userspace
42  *  daemon always getting scheduled within that time frame.
43  */
44
45 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
46
47 #include <linux/module.h>
48 #include <linux/moduleparam.h>
49 #include <linux/types.h>
50 #include <linux/timer.h>
51 #include <linux/jiffies.h>
52 #include <linux/miscdevice.h>
53 #include <linux/watchdog.h>
54 #include <linux/fs.h>
55 #include <linux/ioport.h>
56 #include <linux/notifier.h>
57 #include <linux/reboot.h>
58 #include <linux/init.h>
59 #include <linux/io.h>
60 #include <linux/uaccess.h>
61 #include <asm/system.h>
62
63 #define OUR_NAME "w83877f_wdt"
64
65 #define ENABLE_W83877F_PORT 0x3F0
66 #define ENABLE_W83877F 0x87
67 #define DISABLE_W83877F 0xAA
68 #define WDT_PING 0x443
69 #define WDT_REGISTER 0x14
70 #define WDT_ENABLE 0x9C
71 #define WDT_DISABLE 0x8C
72
73 /*
74  * The W83877F seems to be fixed at 1.6s timeout (at least on the
75  * EMACS PC-104 board I'm using). If we reset the watchdog every
76  * ~250ms we should be safe.  */
77
78 #define WDT_INTERVAL (HZ/4+1)
79
80 /*
81  * We must not require too good response from the userspace daemon.
82  * Here we require the userspace daemon to send us a heartbeat
83  * char to /dev/watchdog every 30 seconds.
84  */
85
86 #define WATCHDOG_TIMEOUT 30            /* 30 sec default timeout */
87 /* in seconds, will be multiplied by HZ to get seconds to wait for a ping */
88 static int timeout = WATCHDOG_TIMEOUT;
89 module_param(timeout, int, 0);
90 MODULE_PARM_DESC(timeout,
91         "Watchdog timeout in seconds. (1<=timeout<=3600, default="
92                                 __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
93
94
95 static bool nowayout = WATCHDOG_NOWAYOUT;
96 module_param(nowayout, bool, 0);
97 MODULE_PARM_DESC(nowayout,
98                 "Watchdog cannot be stopped once started (default="
99                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
100
101 static void wdt_timer_ping(unsigned long);
102 static DEFINE_TIMER(timer, wdt_timer_ping, 0, 0);
103 static unsigned long next_heartbeat;
104 static unsigned long wdt_is_open;
105 static char wdt_expect_close;
106 static DEFINE_SPINLOCK(wdt_spinlock);
107
108 /*
109  *      Whack the dog
110  */
111
112 static void wdt_timer_ping(unsigned long data)
113 {
114         /* If we got a heartbeat pulse within the WDT_US_INTERVAL
115          * we agree to ping the WDT
116          */
117         if (time_before(jiffies, next_heartbeat)) {
118                 /* Ping the WDT */
119                 spin_lock(&wdt_spinlock);
120
121                 /* Ping the WDT by reading from WDT_PING */
122                 inb_p(WDT_PING);
123
124                 /* Re-set the timer interval */
125                 mod_timer(&timer, jiffies + WDT_INTERVAL);
126
127                 spin_unlock(&wdt_spinlock);
128
129         } else
130                 pr_warn("Heartbeat lost! Will not ping the watchdog\n");
131 }
132
133 /*
134  * Utility routines
135  */
136
137 static void wdt_change(int writeval)
138 {
139         unsigned long flags;
140         spin_lock_irqsave(&wdt_spinlock, flags);
141
142         /* buy some time */
143         inb_p(WDT_PING);
144
145         /* make W83877F available */
146         outb_p(ENABLE_W83877F,  ENABLE_W83877F_PORT);
147         outb_p(ENABLE_W83877F,  ENABLE_W83877F_PORT);
148
149         /* enable watchdog */
150         outb_p(WDT_REGISTER,    ENABLE_W83877F_PORT);
151         outb_p(writeval,        ENABLE_W83877F_PORT+1);
152
153         /* lock the W8387FF away */
154         outb_p(DISABLE_W83877F, ENABLE_W83877F_PORT);
155
156         spin_unlock_irqrestore(&wdt_spinlock, flags);
157 }
158
159 static void wdt_startup(void)
160 {
161         next_heartbeat = jiffies + (timeout * HZ);
162
163         /* Start the timer */
164         mod_timer(&timer, jiffies + WDT_INTERVAL);
165
166         wdt_change(WDT_ENABLE);
167
168         pr_info("Watchdog timer is now enabled\n");
169 }
170
171 static void wdt_turnoff(void)
172 {
173         /* Stop the timer */
174         del_timer(&timer);
175
176         wdt_change(WDT_DISABLE);
177
178         pr_info("Watchdog timer is now disabled...\n");
179 }
180
181 static void wdt_keepalive(void)
182 {
183         /* user land ping */
184         next_heartbeat = jiffies + (timeout * HZ);
185 }
186
187 /*
188  * /dev/watchdog handling
189  */
190
191 static ssize_t fop_write(struct file *file, const char __user *buf,
192                                                 size_t count, loff_t *ppos)
193 {
194         /* See if we got the magic character 'V' and reload the timer */
195         if (count) {
196                 if (!nowayout) {
197                         size_t ofs;
198
199                         /* note: just in case someone wrote the magic
200                            character five months ago... */
201                         wdt_expect_close = 0;
202
203                         /* scan to see whether or not we got the
204                            magic character */
205                         for (ofs = 0; ofs != count; ofs++) {
206                                 char c;
207                                 if (get_user(c, buf + ofs))
208                                         return -EFAULT;
209                                 if (c == 'V')
210                                         wdt_expect_close = 42;
211                         }
212                 }
213
214                 /* someone wrote to us, we should restart timer */
215                 wdt_keepalive();
216         }
217         return count;
218 }
219
220 static int fop_open(struct inode *inode, struct file *file)
221 {
222         /* Just in case we're already talking to someone... */
223         if (test_and_set_bit(0, &wdt_is_open))
224                 return -EBUSY;
225
226         /* Good, fire up the show */
227         wdt_startup();
228         return nonseekable_open(inode, file);
229 }
230
231 static int fop_close(struct inode *inode, struct file *file)
232 {
233         if (wdt_expect_close == 42)
234                 wdt_turnoff();
235         else {
236                 del_timer(&timer);
237                 pr_crit("device file closed unexpectedly. Will not stop the WDT!\n");
238         }
239         clear_bit(0, &wdt_is_open);
240         wdt_expect_close = 0;
241         return 0;
242 }
243
244 static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
245 {
246         void __user *argp = (void __user *)arg;
247         int __user *p = argp;
248         static const struct watchdog_info ident = {
249                 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT
250                                                         | WDIOF_MAGICCLOSE,
251                 .firmware_version = 1,
252                 .identity = "W83877F",
253         };
254
255         switch (cmd) {
256         case WDIOC_GETSUPPORT:
257                 return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
258         case WDIOC_GETSTATUS:
259         case WDIOC_GETBOOTSTATUS:
260                 return put_user(0, p);
261         case WDIOC_SETOPTIONS:
262         {
263                 int new_options, retval = -EINVAL;
264
265                 if (get_user(new_options, p))
266                         return -EFAULT;
267
268                 if (new_options & WDIOS_DISABLECARD) {
269                         wdt_turnoff();
270                         retval = 0;
271                 }
272
273                 if (new_options & WDIOS_ENABLECARD) {
274                         wdt_startup();
275                         retval = 0;
276                 }
277
278                 return retval;
279         }
280         case WDIOC_KEEPALIVE:
281                 wdt_keepalive();
282                 return 0;
283         case WDIOC_SETTIMEOUT:
284         {
285                 int new_timeout;
286
287                 if (get_user(new_timeout, p))
288                         return -EFAULT;
289
290                 /* arbitrary upper limit */
291                 if (new_timeout < 1 || new_timeout > 3600)
292                         return -EINVAL;
293
294                 timeout = new_timeout;
295                 wdt_keepalive();
296                 /* Fall through */
297         }
298         case WDIOC_GETTIMEOUT:
299                 return put_user(timeout, p);
300         default:
301                 return -ENOTTY;
302         }
303 }
304
305 static const struct file_operations wdt_fops = {
306         .owner          = THIS_MODULE,
307         .llseek         = no_llseek,
308         .write          = fop_write,
309         .open           = fop_open,
310         .release        = fop_close,
311         .unlocked_ioctl = fop_ioctl,
312 };
313
314 static struct miscdevice wdt_miscdev = {
315         .minor  = WATCHDOG_MINOR,
316         .name   = "watchdog",
317         .fops   = &wdt_fops,
318 };
319
320 /*
321  *      Notifier for system down
322  */
323
324 static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
325         void *unused)
326 {
327         if (code == SYS_DOWN || code == SYS_HALT)
328                 wdt_turnoff();
329         return NOTIFY_DONE;
330 }
331
332 /*
333  *      The WDT needs to learn about soft shutdowns in order to
334  *      turn the timebomb registers off.
335  */
336
337 static struct notifier_block wdt_notifier = {
338         .notifier_call = wdt_notify_sys,
339 };
340
341 static void __exit w83877f_wdt_unload(void)
342 {
343         wdt_turnoff();
344
345         /* Deregister */
346         misc_deregister(&wdt_miscdev);
347
348         unregister_reboot_notifier(&wdt_notifier);
349         release_region(WDT_PING, 1);
350         release_region(ENABLE_W83877F_PORT, 2);
351 }
352
353 static int __init w83877f_wdt_init(void)
354 {
355         int rc = -EBUSY;
356
357         if (timeout < 1 || timeout > 3600) { /* arbitrary upper limit */
358                 timeout = WATCHDOG_TIMEOUT;
359                 pr_info("timeout value must be 1 <= x <= 3600, using %d\n",
360                         timeout);
361         }
362
363         if (!request_region(ENABLE_W83877F_PORT, 2, "W83877F WDT")) {
364                 pr_err("I/O address 0x%04x already in use\n",
365                        ENABLE_W83877F_PORT);
366                 rc = -EIO;
367                 goto err_out;
368         }
369
370         if (!request_region(WDT_PING, 1, "W8387FF WDT")) {
371                 pr_err("I/O address 0x%04x already in use\n", WDT_PING);
372                 rc = -EIO;
373                 goto err_out_region1;
374         }
375
376         rc = register_reboot_notifier(&wdt_notifier);
377         if (rc) {
378                 pr_err("cannot register reboot notifier (err=%d)\n", rc);
379                 goto err_out_region2;
380         }
381
382         rc = misc_register(&wdt_miscdev);
383         if (rc) {
384                 pr_err("cannot register miscdev on minor=%d (err=%d)\n",
385                        wdt_miscdev.minor, rc);
386                 goto err_out_reboot;
387         }
388
389         pr_info("WDT driver for W83877F initialised. timeout=%d sec (nowayout=%d)\n",
390                 timeout, nowayout);
391
392         return 0;
393
394 err_out_reboot:
395         unregister_reboot_notifier(&wdt_notifier);
396 err_out_region2:
397         release_region(WDT_PING, 1);
398 err_out_region1:
399         release_region(ENABLE_W83877F_PORT, 2);
400 err_out:
401         return rc;
402 }
403
404 module_init(w83877f_wdt_init);
405 module_exit(w83877f_wdt_unload);
406
407 MODULE_AUTHOR("Scott and Bill Jennings");
408 MODULE_DESCRIPTION("Driver for watchdog timer in w83877f chip");
409 MODULE_LICENSE("GPL");
410 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);