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 the driver offers
27  *                            added WDIOC_GETSTATUS, WDIOC_GETBOOTSTATUS, WDIOC_SETTIMEOUT,
28  *                            WDIOC_GETTIMEOUT, and WDIOC_SETOPTIONS ioctls
29  *           09/8 - 2003      [wim@iguana.be] cleanup of trailing spaces
30  *                            added extra printk's for startup problems
31  *                            use module_param
32  *                            made timeout (the emulated heartbeat) a module_param
33  *                            made the keepalive ping an internal subroutine
34  *
35  *  This WDT driver is different from most other Linux WDT
36  *  drivers in that the driver will ping the watchdog by itself,
37  *  because this particular WDT has a very short timeout (1.6
38  *  seconds) and it would be insane to count on any userspace
39  *  daemon always getting scheduled within that time frame.
40  */
41 
42 #include <linux/module.h>
43 #include <linux/moduleparam.h>
44 #include <linux/types.h>
45 #include <linux/timer.h>
46 #include <linux/jiffies.h>
47 #include <linux/miscdevice.h>
48 #include <linux/watchdog.h>
49 #include <linux/fs.h>
50 #include <linux/ioport.h>
51 #include <linux/notifier.h>
52 #include <linux/reboot.h>
53 #include <linux/init.h>
54 #include <asm/io.h>
55 #include <asm/uaccess.h>
56 #include <asm/system.h>
57 
58 #define OUR_NAME "w83877f_wdt"
59 #define PFX OUR_NAME ": "
60 
61 #define ENABLE_W83877F_PORT 0x3F0
62 #define ENABLE_W83877F 0x87
63 #define DISABLE_W83877F 0xAA
64 #define WDT_PING 0x443
65 #define WDT_REGISTER 0x14
66 #define WDT_ENABLE 0x9C
67 #define WDT_DISABLE 0x8C
68 
69 /*
70  * The W83877F seems to be fixed at 1.6s timeout (at least on the
71  * EMACS PC-104 board I'm using). If we reset the watchdog every
72  * ~250ms we should be safe.  */
73 
74 #define WDT_INTERVAL (HZ/4+1)
75 
76 /*
77  * We must not require too good response from the userspace daemon.
78  * Here we require the userspace daemon to send us a heartbeat
79  * char to /dev/watchdog every 30 seconds.
80  */
81 
82 #define WATCHDOG_TIMEOUT 30            /* 30 sec default timeout */
83 static int timeout = WATCHDOG_TIMEOUT; /* in seconds, will be multiplied by HZ to get seconds to wait for a ping */
84 module_param(timeout, int, 0);
85 MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds. (1<=timeout<=3600, default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
86 
87 
88 static int nowayout = WATCHDOG_NOWAYOUT;
89 module_param(nowayout, int, 0);
90 MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
91 
92 static void wdt_timer_ping(unsigned long);
93 static DEFINE_TIMER(timer, wdt_timer_ping, 0, 0);
94 static unsigned long next_heartbeat;
95 static unsigned long wdt_is_open;
96 static char wdt_expect_close;
97 static DEFINE_SPINLOCK(wdt_spinlock);
98 
99 /*
100  *	Whack the dog
101  */
102 
103 static void wdt_timer_ping(unsigned long data)
104 {
105 	/* If we got a heartbeat pulse within the WDT_US_INTERVAL
106 	 * we agree to ping the WDT
107 	 */
108 	if(time_before(jiffies, next_heartbeat))
109 	{
110 		/* Ping the WDT */
111 		spin_lock(&wdt_spinlock);
112 
113 		/* Ping the WDT by reading from WDT_PING */
114 		inb_p(WDT_PING);
115 
116 		/* Re-set the timer interval */
117 		mod_timer(&timer, jiffies + WDT_INTERVAL);
118 
119 		spin_unlock(&wdt_spinlock);
120 
121 	} else {
122 		printk(KERN_WARNING PFX "Heartbeat lost! Will not ping the watchdog\n");
123 	}
124 }
125 
126 /*
127  * Utility routines
128  */
129 
130 static void wdt_change(int writeval)
131 {
132 	unsigned long flags;
133 	spin_lock_irqsave(&wdt_spinlock, flags);
134 
135 	/* buy some time */
136 	inb_p(WDT_PING);
137 
138 	/* make W83877F available */
139 	outb_p(ENABLE_W83877F,  ENABLE_W83877F_PORT);
140 	outb_p(ENABLE_W83877F,  ENABLE_W83877F_PORT);
141 
142 	/* enable watchdog */
143 	outb_p(WDT_REGISTER,    ENABLE_W83877F_PORT);
144 	outb_p(writeval,        ENABLE_W83877F_PORT+1);
145 
146 	/* lock the W8387FF away */
147 	outb_p(DISABLE_W83877F, ENABLE_W83877F_PORT);
148 
149 	spin_unlock_irqrestore(&wdt_spinlock, flags);
150 }
151 
152 static void wdt_startup(void)
153 {
154 	next_heartbeat = jiffies + (timeout * HZ);
155 
156 	/* Start the timer */
157 	mod_timer(&timer, jiffies + WDT_INTERVAL);
158 
159 	wdt_change(WDT_ENABLE);
160 
161 	printk(KERN_INFO PFX "Watchdog timer is now enabled.\n");
162 }
163 
164 static void wdt_turnoff(void)
165 {
166 	/* Stop the timer */
167 	del_timer(&timer);
168 
169 	wdt_change(WDT_DISABLE);
170 
171 	printk(KERN_INFO PFX "Watchdog timer is now disabled...\n");
172 }
173 
174 static void wdt_keepalive(void)
175 {
176 	/* user land ping */
177 	next_heartbeat = jiffies + (timeout * HZ);
178 }
179 
180 /*
181  * /dev/watchdog handling
182  */
183 
184 static ssize_t fop_write(struct file * file, const char __user * buf, size_t count, loff_t * ppos)
185 {
186 	/* See if we got the magic character 'V' and reload the timer */
187 	if(count)
188 	{
189 		if (!nowayout)
190 		{
191 			size_t ofs;
192 
193 			/* note: just in case someone wrote the magic character
194 			 * five months ago... */
195 			wdt_expect_close = 0;
196 
197 			/* scan to see whether or not we got the magic character */
198 			for(ofs = 0; ofs != count; ofs++)
199 			{
200 				char c;
201 				if (get_user(c, buf + ofs))
202 					return -EFAULT;
203 				if (c == 'V')
204 					wdt_expect_close = 42;
205 			}
206 		}
207 
208 		/* someone wrote to us, we should restart timer */
209 		wdt_keepalive();
210 	}
211 	return count;
212 }
213 
214 static int fop_open(struct inode * inode, struct file * file)
215 {
216 	/* Just in case we're already talking to someone... */
217 	if(test_and_set_bit(0, &wdt_is_open))
218 		return -EBUSY;
219 
220 	/* Good, fire up the show */
221 	wdt_startup();
222 	return nonseekable_open(inode, file);
223 }
224 
225 static int fop_close(struct inode * inode, struct file * file)
226 {
227 	if(wdt_expect_close == 42)
228 		wdt_turnoff();
229 	else {
230 		del_timer(&timer);
231 		printk(KERN_CRIT PFX "device file closed unexpectedly. Will not stop the WDT!\n");
232 	}
233 	clear_bit(0, &wdt_is_open);
234 	wdt_expect_close = 0;
235 	return 0;
236 }
237 
238 static int fop_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
239 	unsigned long arg)
240 {
241 	void __user *argp = (void __user *)arg;
242 	int __user *p = argp;
243 	static struct watchdog_info ident=
244 	{
245 		.options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
246 		.firmware_version = 1,
247 		.identity = "W83877F",
248 	};
249 
250 	switch(cmd)
251 	{
252 		default:
253 			return -ENOTTY;
254 		case WDIOC_GETSUPPORT:
255 			return copy_to_user(argp, &ident, sizeof(ident))?-EFAULT:0;
256 		case WDIOC_GETSTATUS:
257 		case WDIOC_GETBOOTSTATUS:
258 			return put_user(0, p);
259 		case WDIOC_KEEPALIVE:
260 			wdt_keepalive();
261 			return 0;
262 		case WDIOC_SETOPTIONS:
263 		{
264 			int new_options, retval = -EINVAL;
265 
266 			if(get_user(new_options, p))
267 				return -EFAULT;
268 
269 			if(new_options & WDIOS_DISABLECARD) {
270 				wdt_turnoff();
271 				retval = 0;
272 			}
273 
274 			if(new_options & WDIOS_ENABLECARD) {
275 				wdt_startup();
276 				retval = 0;
277 			}
278 
279 			return retval;
280 		}
281 		case WDIOC_SETTIMEOUT:
282 		{
283 			int new_timeout;
284 
285 			if(get_user(new_timeout, p))
286 				return -EFAULT;
287 
288 			if(new_timeout < 1 || new_timeout > 3600) /* arbitrary upper limit */
289 				return -EINVAL;
290 
291 			timeout = new_timeout;
292 			wdt_keepalive();
293 			/* Fall through */
294 		}
295 		case WDIOC_GETTIMEOUT:
296 			return put_user(timeout, p);
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 	.ioctl		= fop_ioctl,
307 };
308 
309 static struct miscdevice wdt_miscdev = {
310 	.minor	= WATCHDOG_MINOR,
311 	.name	= "watchdog",
312 	.fops	= &wdt_fops,
313 };
314 
315 /*
316  *	Notifier for system down
317  */
318 
319 static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
320 	void *unused)
321 {
322 	if(code==SYS_DOWN || code==SYS_HALT)
323 		wdt_turnoff();
324 	return NOTIFY_DONE;
325 }
326 
327 /*
328  *	The WDT needs to learn about soft shutdowns in order to
329  *	turn the timebomb registers off.
330  */
331 
332 static struct notifier_block wdt_notifier=
333 {
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 	{
355 		timeout = WATCHDOG_TIMEOUT;
356 		printk(KERN_INFO PFX "timeout value must be 1<=x<=3600, using %d\n",
357 			timeout);
358 	}
359 
360 	if (!request_region(ENABLE_W83877F_PORT, 2, "W83877F WDT"))
361 	{
362 		printk(KERN_ERR PFX "I/O address 0x%04x already in use\n",
363 			ENABLE_W83877F_PORT);
364 		rc = -EIO;
365 		goto err_out;
366 	}
367 
368 	if (!request_region(WDT_PING, 1, "W8387FF WDT"))
369 	{
370 		printk(KERN_ERR PFX "I/O address 0x%04x already in use\n",
371 			WDT_PING);
372 		rc = -EIO;
373 		goto err_out_region1;
374 	}
375 
376 	rc = register_reboot_notifier(&wdt_notifier);
377 	if (rc)
378 	{
379 		printk(KERN_ERR PFX "cannot register reboot notifier (err=%d)\n",
380 			rc);
381 		goto err_out_region2;
382 	}
383 
384 	rc = misc_register(&wdt_miscdev);
385 	if (rc)
386 	{
387 		printk(KERN_ERR PFX "cannot register miscdev on minor=%d (err=%d)\n",
388 			wdt_miscdev.minor, rc);
389 		goto err_out_reboot;
390 	}
391 
392 	printk(KERN_INFO PFX "WDT driver for W83877F initialised. timeout=%d sec (nowayout=%d)\n",
393 		timeout, nowayout);
394 
395 	return 0;
396 
397 err_out_reboot:
398 	unregister_reboot_notifier(&wdt_notifier);
399 err_out_region2:
400 	release_region(WDT_PING,1);
401 err_out_region1:
402 	release_region(ENABLE_W83877F_PORT,2);
403 err_out:
404 	return rc;
405 }
406 
407 module_init(w83877f_wdt_init);
408 module_exit(w83877f_wdt_unload);
409 
410 MODULE_AUTHOR("Scott and Bill Jennings");
411 MODULE_DESCRIPTION("Driver for watchdog timer in w83877f chip");
412 MODULE_LICENSE("GPL");
413 MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
414