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
wdt_timer_ping(struct timer_list * unused)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
wdt_change(int writeval)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
wdt_startup(void)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
wdt_turnoff(void)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
wdt_keepalive(void)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
fop_write(struct file * file,const char __user * buf,size_t count,loff_t * ppos)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
fop_open(struct inode * inode,struct file * file)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 nonseekable_open(inode, file);
228 }
229
fop_close(struct inode * inode,struct file * file)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
fop_ioctl(struct file * file,unsigned int cmd,unsigned long arg)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 /* Fall through */
296 }
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
wdt_notify_sys(struct notifier_block * this,unsigned long code,void * unused)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
w83877f_wdt_unload(void)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
w83877f_wdt_init(void)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");
409
