xref: /linux/drivers/watchdog/w83877f_wdt.c (revision a4eb44a6435d6d8f9e642407a4a06f65eb90ca04) 
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 
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 
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 
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 
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 
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 
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 
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 
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 
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 
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 
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 
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