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 nonseekable_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 		/* 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 
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");
409