1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * W83877F Computer Watchdog Timer driver
4 *
5 * Based on acquirewdt.c by Alan Cox,
6 * and sbc60xxwdt.c by Jakob Oestergaard <jakob@unthought.net>
7 *
8 * The authors do NOT admit liability nor provide warranty for
9 * any of this software. This material is provided "AS-IS" in
10 * the hope that it may be useful for others.
11 *
12 * (c) Copyright 2001 Scott Jennings <linuxdrivers@oro.net>
13 *
14 * 4/19 - 2001 [Initial revision]
15 * 9/27 - 2001 Added spinlocking
16 * 4/12 - 2002 [rob@osinvestor.com] Eliminate extra comments
17 * Eliminate fop_read
18 * Eliminate extra spin_unlock
19 * Added KERN_* tags to printks
20 * add CONFIG_WATCHDOG_NOWAYOUT support
21 * fix possible wdt_is_open race
22 * changed watchdog_info to correctly reflect what
23 * the driver offers
24 * added WDIOC_GETSTATUS, WDIOC_GETBOOTSTATUS,
25 * WDIOC_SETTIMEOUT,
26 * WDIOC_GETTIMEOUT, and WDIOC_SETOPTIONS ioctls
27 * 09/8 - 2003 [wim@iguana.be] cleanup of trailing spaces
28 * added extra printk's for startup problems
29 * use module_param
30 * made timeout (the emulated heartbeat) a
31 * module_param
32 * made the keepalive ping an internal subroutine
33 *
34 * This WDT driver is different from most other Linux WDT
35 * drivers in that the driver will ping the watchdog by itself,
36 * because this particular WDT has a very short timeout (1.6
37 * seconds) and it would be insane to count on any userspace
38 * daemon always getting scheduled within that time frame.
39 */
40
41 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
42
43 #include <linux/module.h>
44 #include <linux/moduleparam.h>
45 #include <linux/types.h>
46 #include <linux/timer.h>
47 #include <linux/jiffies.h>
48 #include <linux/miscdevice.h>
49 #include <linux/watchdog.h>
50 #include <linux/fs.h>
51 #include <linux/ioport.h>
52 #include <linux/notifier.h>
53 #include <linux/reboot.h>
54 #include <linux/init.h>
55 #include <linux/io.h>
56 #include <linux/uaccess.h>
57
58 #define OUR_NAME "w83877f_wdt"
59
60 #define ENABLE_W83877F_PORT 0x3F0
61 #define ENABLE_W83877F 0x87
62 #define DISABLE_W83877F 0xAA
63 #define WDT_PING 0x443
64 #define WDT_REGISTER 0x14
65 #define WDT_ENABLE 0x9C
66 #define WDT_DISABLE 0x8C
67
68 /*
69 * The W83877F seems to be fixed at 1.6s timeout (at least on the
70 * EMACS PC-104 board I'm using). If we reset the watchdog every
71 * ~250ms we should be safe. */
72
73 #define WDT_INTERVAL (HZ/4+1)
74
75 /*
76 * We must not require too good response from the userspace daemon.
77 * Here we require the userspace daemon to send us a heartbeat
78 * char to /dev/watchdog every 30 seconds.
79 */
80
81 #define WATCHDOG_TIMEOUT 30 /* 30 sec default timeout */
82 /* in seconds, will be multiplied by HZ to get seconds to wait for a ping */
83 static int timeout = WATCHDOG_TIMEOUT;
84 module_param(timeout, int, 0);
85 MODULE_PARM_DESC(timeout,
86 "Watchdog timeout in seconds. (1<=timeout<=3600, default="
87 __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
88
89
90 static bool nowayout = WATCHDOG_NOWAYOUT;
91 module_param(nowayout, bool, 0);
92 MODULE_PARM_DESC(nowayout,
93 "Watchdog cannot be stopped once started (default="
94 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
95
96 static void wdt_timer_ping(struct timer_list *);
97 static DEFINE_TIMER(timer, wdt_timer_ping);
98 static unsigned long next_heartbeat;
99 static unsigned long wdt_is_open;
100 static char wdt_expect_close;
101 static DEFINE_SPINLOCK(wdt_spinlock);
102
103 /*
104 * Whack the dog
105 */
106
wdt_timer_ping(struct timer_list * unused)107 static void wdt_timer_ping(struct timer_list *unused)
108 {
109 /* If we got a heartbeat pulse within the WDT_US_INTERVAL
110 * we agree to ping the WDT
111 */
112 if (time_before(jiffies, next_heartbeat)) {
113 /* Ping the WDT */
114 spin_lock(&wdt_spinlock);
115
116 /* Ping the WDT by reading from WDT_PING */
117 inb_p(WDT_PING);
118
119 /* Re-set the timer interval */
120 mod_timer(&timer, jiffies + WDT_INTERVAL);
121
122 spin_unlock(&wdt_spinlock);
123
124 } else
125 pr_warn("Heartbeat lost! Will not ping the watchdog\n");
126 }
127
128 /*
129 * Utility routines
130 */
131
wdt_change(int writeval)132 static void wdt_change(int writeval)
133 {
134 unsigned long flags;
135 spin_lock_irqsave(&wdt_spinlock, flags);
136
137 /* buy some time */
138 inb_p(WDT_PING);
139
140 /* make W83877F available */
141 outb_p(ENABLE_W83877F, ENABLE_W83877F_PORT);
142 outb_p(ENABLE_W83877F, ENABLE_W83877F_PORT);
143
144 /* enable watchdog */
145 outb_p(WDT_REGISTER, ENABLE_W83877F_PORT);
146 outb_p(writeval, ENABLE_W83877F_PORT+1);
147
148 /* lock the W8387FF away */
149 outb_p(DISABLE_W83877F, ENABLE_W83877F_PORT);
150
151 spin_unlock_irqrestore(&wdt_spinlock, flags);
152 }
153
wdt_startup(void)154 static void wdt_startup(void)
155 {
156 next_heartbeat = jiffies + (timeout * HZ);
157
158 /* Start the timer */
159 mod_timer(&timer, jiffies + WDT_INTERVAL);
160
161 wdt_change(WDT_ENABLE);
162
163 pr_info("Watchdog timer is now enabled\n");
164 }
165
wdt_turnoff(void)166 static void wdt_turnoff(void)
167 {
168 /* Stop the timer */
169 del_timer_sync(&timer);
170
171 wdt_change(WDT_DISABLE);
172
173 pr_info("Watchdog timer is now disabled...\n");
174 }
175
wdt_keepalive(void)176 static void wdt_keepalive(void)
177 {
178 /* user land ping */
179 next_heartbeat = jiffies + (timeout * HZ);
180 }
181
182 /*
183 * /dev/watchdog handling
184 */
185
fop_write(struct file * file,const char __user * buf,size_t count,loff_t * ppos)186 static ssize_t fop_write(struct file *file, const char __user *buf,
187 size_t count, loff_t *ppos)
188 {
189 /* See if we got the magic character 'V' and reload the timer */
190 if (count) {
191 if (!nowayout) {
192 size_t ofs;
193
194 /* note: just in case someone wrote the magic
195 character five months ago... */
196 wdt_expect_close = 0;
197
198 /* scan to see whether or not we got the
199 magic character */
200 for (ofs = 0; ofs != count; ofs++) {
201 char c;
202 if (get_user(c, buf + ofs))
203 return -EFAULT;
204 if (c == 'V')
205 wdt_expect_close = 42;
206 }
207 }
208
209 /* someone wrote to us, we should restart timer */
210 wdt_keepalive();
211 }
212 return count;
213 }
214
fop_open(struct inode * inode,struct file * file)215 static int fop_open(struct inode *inode, struct file *file)
216 {
217 /* Just in case we're already talking to someone... */
218 if (test_and_set_bit(0, &wdt_is_open))
219 return -EBUSY;
220
221 /* Good, fire up the show */
222 wdt_startup();
223 return stream_open(inode, file);
224 }
225
fop_close(struct inode * inode,struct file * file)226 static int fop_close(struct inode *inode, struct file *file)
227 {
228 if (wdt_expect_close == 42)
229 wdt_turnoff();
230 else {
231 del_timer(&timer);
232 pr_crit("device file closed unexpectedly. Will not stop the WDT!\n");
233 }
234 clear_bit(0, &wdt_is_open);
235 wdt_expect_close = 0;
236 return 0;
237 }
238
fop_ioctl(struct file * file,unsigned int cmd,unsigned long arg)239 static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
240 {
241 void __user *argp = (void __user *)arg;
242 int __user *p = argp;
243 static const struct watchdog_info ident = {
244 .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT
245 | WDIOF_MAGICCLOSE,
246 .firmware_version = 1,
247 .identity = "W83877F",
248 };
249
250 switch (cmd) {
251 case WDIOC_GETSUPPORT:
252 return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
253 case WDIOC_GETSTATUS:
254 case WDIOC_GETBOOTSTATUS:
255 return put_user(0, p);
256 case WDIOC_SETOPTIONS:
257 {
258 int new_options, retval = -EINVAL;
259
260 if (get_user(new_options, p))
261 return -EFAULT;
262
263 if (new_options & WDIOS_DISABLECARD) {
264 wdt_turnoff();
265 retval = 0;
266 }
267
268 if (new_options & WDIOS_ENABLECARD) {
269 wdt_startup();
270 retval = 0;
271 }
272
273 return retval;
274 }
275 case WDIOC_KEEPALIVE:
276 wdt_keepalive();
277 return 0;
278 case WDIOC_SETTIMEOUT:
279 {
280 int new_timeout;
281
282 if (get_user(new_timeout, p))
283 return -EFAULT;
284
285 /* arbitrary upper limit */
286 if (new_timeout < 1 || new_timeout > 3600)
287 return -EINVAL;
288
289 timeout = new_timeout;
290 wdt_keepalive();
291 }
292 fallthrough;
293 case WDIOC_GETTIMEOUT:
294 return put_user(timeout, p);
295 default:
296 return -ENOTTY;
297 }
298 }
299
300 static const struct file_operations wdt_fops = {
301 .owner = THIS_MODULE,
302 .llseek = no_llseek,
303 .write = fop_write,
304 .open = fop_open,
305 .release = fop_close,
306 .unlocked_ioctl = fop_ioctl,
307 .compat_ioctl = compat_ptr_ioctl,
308 };
309
310 static struct miscdevice wdt_miscdev = {
311 .minor = WATCHDOG_MINOR,
312 .name = "watchdog",
313 .fops = &wdt_fops,
314 };
315
316 /*
317 * Notifier for system down
318 */
319
wdt_notify_sys(struct notifier_block * this,unsigned long code,void * unused)320 static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
321 void *unused)
322 {
323 if (code == SYS_DOWN || code == SYS_HALT)
324 wdt_turnoff();
325 return NOTIFY_DONE;
326 }
327
328 /*
329 * The WDT needs to learn about soft shutdowns in order to
330 * turn the timebomb registers off.
331 */
332
333 static struct notifier_block wdt_notifier = {
334 .notifier_call = wdt_notify_sys,
335 };
336
w83877f_wdt_unload(void)337 static void __exit w83877f_wdt_unload(void)
338 {
339 wdt_turnoff();
340
341 /* Deregister */
342 misc_deregister(&wdt_miscdev);
343
344 unregister_reboot_notifier(&wdt_notifier);
345 release_region(WDT_PING, 1);
346 release_region(ENABLE_W83877F_PORT, 2);
347 }
348
w83877f_wdt_init(void)349 static int __init w83877f_wdt_init(void)
350 {
351 int rc = -EBUSY;
352
353 if (timeout < 1 || timeout > 3600) { /* arbitrary upper limit */
354 timeout = WATCHDOG_TIMEOUT;
355 pr_info("timeout value must be 1 <= x <= 3600, using %d\n",
356 timeout);
357 }
358
359 if (!request_region(ENABLE_W83877F_PORT, 2, "W83877F WDT")) {
360 pr_err("I/O address 0x%04x already in use\n",
361 ENABLE_W83877F_PORT);
362 rc = -EIO;
363 goto err_out;
364 }
365
366 if (!request_region(WDT_PING, 1, "W8387FF WDT")) {
367 pr_err("I/O address 0x%04x already in use\n", WDT_PING);
368 rc = -EIO;
369 goto err_out_region1;
370 }
371
372 rc = register_reboot_notifier(&wdt_notifier);
373 if (rc) {
374 pr_err("cannot register reboot notifier (err=%d)\n", rc);
375 goto err_out_region2;
376 }
377
378 rc = misc_register(&wdt_miscdev);
379 if (rc) {
380 pr_err("cannot register miscdev on minor=%d (err=%d)\n",
381 wdt_miscdev.minor, rc);
382 goto err_out_reboot;
383 }
384
385 pr_info("WDT driver for W83877F initialised. timeout=%d sec (nowayout=%d)\n",
386 timeout, nowayout);
387
388 return 0;
389
390 err_out_reboot:
391 unregister_reboot_notifier(&wdt_notifier);
392 err_out_region2:
393 release_region(WDT_PING, 1);
394 err_out_region1:
395 release_region(ENABLE_W83877F_PORT, 2);
396 err_out:
397 return rc;
398 }
399
400 module_init(w83877f_wdt_init);
401 module_exit(w83877f_wdt_unload);
402
403 MODULE_AUTHOR("Scott and Bill Jennings");
404 MODULE_DESCRIPTION("Driver for watchdog timer in w83877f chip");
405 MODULE_LICENSE("GPL");
406