*: convert stream-like files from nonseekable_open -> stream_open
[sfrench/cifs-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
62 #define OUR_NAME "w83877f_wdt"
63
64 #define ENABLE_W83877F_PORT 0x3F0
65 #define ENABLE_W83877F 0x87
66 #define DISABLE_W83877F 0xAA
67 #define WDT_PING 0x443
68 #define WDT_REGISTER 0x14
69 #define WDT_ENABLE 0x9C
70 #define WDT_DISABLE 0x8C
71
72 /*
73  * The W83877F seems to be fixed at 1.6s timeout (at least on the
74  * EMACS PC-104 board I'm using). If we reset the watchdog every
75  * ~250ms we should be safe.  */
76
77 #define WDT_INTERVAL (HZ/4+1)
78
79 /*
80  * We must not require too good response from the userspace daemon.
81  * Here we require the userspace daemon to send us a heartbeat
82  * char to /dev/watchdog every 30 seconds.
83  */
84
85 #define WATCHDOG_TIMEOUT 30            /* 30 sec default timeout */
86 /* in seconds, will be multiplied by HZ to get seconds to wait for a ping */
87 static int timeout = WATCHDOG_TIMEOUT;
88 module_param(timeout, int, 0);
89 MODULE_PARM_DESC(timeout,
90         "Watchdog timeout in seconds. (1<=timeout<=3600, default="
91                                 __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
92
93
94 static bool nowayout = WATCHDOG_NOWAYOUT;
95 module_param(nowayout, bool, 0);
96 MODULE_PARM_DESC(nowayout,
97                 "Watchdog cannot be stopped once started (default="
98                                 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
99
100 static void wdt_timer_ping(struct timer_list *);
101 static DEFINE_TIMER(timer, wdt_timer_ping);
102 static unsigned long next_heartbeat;
103 static unsigned long wdt_is_open;
104 static char wdt_expect_close;
105 static DEFINE_SPINLOCK(wdt_spinlock);
106
107 /*
108  *      Whack the dog
109  */
110
111 static void wdt_timer_ping(struct timer_list *unused)
112 {
113         /* If we got a heartbeat pulse within the WDT_US_INTERVAL
114          * we agree to ping the WDT
115          */
116         if (time_before(jiffies, next_heartbeat)) {
117                 /* Ping the WDT */
118                 spin_lock(&wdt_spinlock);
119
120                 /* Ping the WDT by reading from WDT_PING */
121                 inb_p(WDT_PING);
122
123                 /* Re-set the timer interval */
124                 mod_timer(&timer, jiffies + WDT_INTERVAL);
125
126                 spin_unlock(&wdt_spinlock);
127
128         } else
129                 pr_warn("Heartbeat lost! Will not ping the watchdog\n");
130 }
131
132 /*
133  * Utility routines
134  */
135
136 static void wdt_change(int writeval)
137 {
138         unsigned long flags;
139         spin_lock_irqsave(&wdt_spinlock, flags);
140
141         /* buy some time */
142         inb_p(WDT_PING);
143
144         /* make W83877F available */
145         outb_p(ENABLE_W83877F,  ENABLE_W83877F_PORT);
146         outb_p(ENABLE_W83877F,  ENABLE_W83877F_PORT);
147
148         /* enable watchdog */
149         outb_p(WDT_REGISTER,    ENABLE_W83877F_PORT);
150         outb_p(writeval,        ENABLE_W83877F_PORT+1);
151
152         /* lock the W8387FF away */
153         outb_p(DISABLE_W83877F, ENABLE_W83877F_PORT);
154
155         spin_unlock_irqrestore(&wdt_spinlock, flags);
156 }
157
158 static void wdt_startup(void)
159 {
160         next_heartbeat = jiffies + (timeout * HZ);
161
162         /* Start the timer */
163         mod_timer(&timer, jiffies + WDT_INTERVAL);
164
165         wdt_change(WDT_ENABLE);
166
167         pr_info("Watchdog timer is now enabled\n");
168 }
169
170 static void wdt_turnoff(void)
171 {
172         /* Stop the timer */
173         del_timer(&timer);
174
175         wdt_change(WDT_DISABLE);
176
177         pr_info("Watchdog timer is now disabled...\n");
178 }
179
180 static void wdt_keepalive(void)
181 {
182         /* user land ping */
183         next_heartbeat = jiffies + (timeout * HZ);
184 }
185
186 /*
187  * /dev/watchdog handling
188  */
189
190 static ssize_t fop_write(struct file *file, const char __user *buf,
191                                                 size_t count, loff_t *ppos)
192 {
193         /* See if we got the magic character 'V' and reload the timer */
194         if (count) {
195                 if (!nowayout) {
196                         size_t ofs;
197
198                         /* note: just in case someone wrote the magic
199                            character five months ago... */
200                         wdt_expect_close = 0;
201
202                         /* scan to see whether or not we got the
203                            magic character */
204                         for (ofs = 0; ofs != count; ofs++) {
205                                 char c;
206                                 if (get_user(c, buf + ofs))
207                                         return -EFAULT;
208                                 if (c == 'V')
209                                         wdt_expect_close = 42;
210                         }
211                 }
212
213                 /* someone wrote to us, we should restart timer */
214                 wdt_keepalive();
215         }
216         return count;
217 }
218
219 static int fop_open(struct inode *inode, struct file *file)
220 {
221         /* Just in case we're already talking to someone... */
222         if (test_and_set_bit(0, &wdt_is_open))
223                 return -EBUSY;
224
225         /* Good, fire up the show */
226         wdt_startup();
227         return stream_open(inode, file);
228 }
229
230 static int fop_close(struct inode *inode, struct file *file)
231 {
232         if (wdt_expect_close == 42)
233                 wdt_turnoff();
234         else {
235                 del_timer(&timer);
236                 pr_crit("device file closed unexpectedly. Will not stop the WDT!\n");
237         }
238         clear_bit(0, &wdt_is_open);
239         wdt_expect_close = 0;
240         return 0;
241 }
242
243 static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
244 {
245         void __user *argp = (void __user *)arg;
246         int __user *p = argp;
247         static const struct watchdog_info ident = {
248                 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT
249                                                         | WDIOF_MAGICCLOSE,
250                 .firmware_version = 1,
251                 .identity = "W83877F",
252         };
253
254         switch (cmd) {
255         case WDIOC_GETSUPPORT:
256                 return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
257         case WDIOC_GETSTATUS:
258         case WDIOC_GETBOOTSTATUS:
259                 return put_user(0, p);
260         case WDIOC_SETOPTIONS:
261         {
262                 int new_options, retval = -EINVAL;
263
264                 if (get_user(new_options, p))
265                         return -EFAULT;
266
267                 if (new_options & WDIOS_DISABLECARD) {
268                         wdt_turnoff();
269                         retval = 0;
270                 }
271
272                 if (new_options & WDIOS_ENABLECARD) {
273                         wdt_startup();
274                         retval = 0;
275                 }
276
277                 return retval;
278         }
279         case WDIOC_KEEPALIVE:
280                 wdt_keepalive();
281                 return 0;
282         case WDIOC_SETTIMEOUT:
283         {
284                 int new_timeout;
285
286                 if (get_user(new_timeout, p))
287                         return -EFAULT;
288
289                 /* arbitrary upper limit */
290                 if (new_timeout < 1 || new_timeout > 3600)
291                         return -EINVAL;
292
293                 timeout = new_timeout;
294                 wdt_keepalive();
295         }
296                 /* Fall through */
297         case WDIOC_GETTIMEOUT:
298                 return put_user(timeout, p);
299         default:
300                 return -ENOTTY;
301         }
302 }
303
304 static const struct file_operations wdt_fops = {
305         .owner          = THIS_MODULE,
306         .llseek         = no_llseek,
307         .write          = fop_write,
308         .open           = fop_open,
309         .release        = fop_close,
310         .unlocked_ioctl = fop_ioctl,
311 };
312
313 static struct miscdevice wdt_miscdev = {
314         .minor  = WATCHDOG_MINOR,
315         .name   = "watchdog",
316         .fops   = &wdt_fops,
317 };
318
319 /*
320  *      Notifier for system down
321  */
322
323 static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
324         void *unused)
325 {
326         if (code == SYS_DOWN || code == SYS_HALT)
327                 wdt_turnoff();
328         return NOTIFY_DONE;
329 }
330
331 /*
332  *      The WDT needs to learn about soft shutdowns in order to
333  *      turn the timebomb registers off.
334  */
335
336 static struct notifier_block wdt_notifier = {
337         .notifier_call = wdt_notify_sys,
338 };
339
340 static void __exit w83877f_wdt_unload(void)
341 {
342         wdt_turnoff();
343
344         /* Deregister */
345         misc_deregister(&wdt_miscdev);
346
347         unregister_reboot_notifier(&wdt_notifier);
348         release_region(WDT_PING, 1);
349         release_region(ENABLE_W83877F_PORT, 2);
350 }
351
352 static int __init w83877f_wdt_init(void)
353 {
354         int rc = -EBUSY;
355
356         if (timeout < 1 || timeout > 3600) { /* arbitrary upper limit */
357                 timeout = WATCHDOG_TIMEOUT;
358                 pr_info("timeout value must be 1 <= x <= 3600, using %d\n",
359                         timeout);
360         }
361
362         if (!request_region(ENABLE_W83877F_PORT, 2, "W83877F WDT")) {
363                 pr_err("I/O address 0x%04x already in use\n",
364                        ENABLE_W83877F_PORT);
365                 rc = -EIO;
366                 goto err_out;
367         }
368
369         if (!request_region(WDT_PING, 1, "W8387FF WDT")) {
370                 pr_err("I/O address 0x%04x already in use\n", WDT_PING);
371                 rc = -EIO;
372                 goto err_out_region1;
373         }
374
375         rc = register_reboot_notifier(&wdt_notifier);
376         if (rc) {
377                 pr_err("cannot register reboot notifier (err=%d)\n", rc);
378                 goto err_out_region2;
379         }
380
381         rc = misc_register(&wdt_miscdev);
382         if (rc) {
383                 pr_err("cannot register miscdev on minor=%d (err=%d)\n",
384                        wdt_miscdev.minor, rc);
385                 goto err_out_reboot;
386         }
387
388         pr_info("WDT driver for W83877F initialised. timeout=%d sec (nowayout=%d)\n",
389                 timeout, nowayout);
390
391         return 0;
392
393 err_out_reboot:
394         unregister_reboot_notifier(&wdt_notifier);
395 err_out_region2:
396         release_region(WDT_PING, 1);
397 err_out_region1:
398         release_region(ENABLE_W83877F_PORT, 2);
399 err_out:
400         return rc;
401 }
402
403 module_init(w83877f_wdt_init);
404 module_exit(w83877f_wdt_unload);
405
406 MODULE_AUTHOR("Scott and Bill Jennings");
407 MODULE_DESCRIPTION("Driver for watchdog timer in w83877f chip");
408 MODULE_LICENSE("GPL");