aboutsummaryrefslogtreecommitdiff
path: root/drivers/char/watchdog/w83877f_wdt.c
blob: b0e5f84d6bafdc24fb9c21742f35b3b0bcdcc965 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
/*
 *	W83877F Computer Watchdog Timer driver
 *
 *      Based on acquirewdt.c by Alan Cox,
 *           and sbc60xxwdt.c by Jakob Oestergaard <jakob@unthought.net>
 *
 *	This program is free software; you can redistribute it and/or
 *	modify it under the terms of the GNU General Public License
 *	as published by the Free Software Foundation; either version
 *	2 of the License, or (at your option) any later version.
 *
 *	The authors do NOT admit liability nor provide warranty for
 *	any of this software. This material is provided "AS-IS" in
 *      the hope that it may be useful for others.
 *
 *	(c) Copyright 2001    Scott Jennings <linuxdrivers@oro.net>
 *
 *           4/19 - 2001      [Initial revision]
 *           9/27 - 2001      Added spinlocking
 *           4/12 - 2002      [rob@osinvestor.com] Eliminate extra comments
 *                            Eliminate fop_read
 *                            Eliminate extra spin_unlock
 *                            Added KERN_* tags to printks
 *                            add CONFIG_WATCHDOG_NOWAYOUT support
 *                            fix possible wdt_is_open race
 *                            changed watchdog_info to correctly reflect what the driver offers
 *                            added WDIOC_GETSTATUS, WDIOC_GETBOOTSTATUS, WDIOC_SETTIMEOUT,
 *                            WDIOC_GETTIMEOUT, and WDIOC_SETOPTIONS ioctls
 *           09/8 - 2003      [wim@iguana.be] cleanup of trailing spaces
 *                            added extra printk's for startup problems
 *                            use module_param
 *                            made timeout (the emulated heartbeat) a module_param
 *                            made the keepalive ping an internal subroutine
 *
 *  This WDT driver is different from most other Linux WDT
 *  drivers in that the driver will ping the watchdog by itself,
 *  because this particular WDT has a very short timeout (1.6
 *  seconds) and it would be insane to count on any userspace
 *  daemon always getting scheduled within that time frame.
 */

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/types.h>
#include <linux/timer.h>
#include <linux/jiffies.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/fs.h>
#include <linux/ioport.h>
#include <linux/notifier.h>
#include <linux/reboot.h>
#include <linux/init.h>
#include <asm/io.h>
#include <asm/uaccess.h>
#include <asm/system.h>

#define OUR_NAME "w83877f_wdt"
#define PFX OUR_NAME ": "

#define ENABLE_W83877F_PORT 0x3F0
#define ENABLE_W83877F 0x87
#define DISABLE_W83877F 0xAA
#define WDT_PING 0x443
#define WDT_REGISTER 0x14
#define WDT_ENABLE 0x9C
#define WDT_DISABLE 0x8C

/*
 * The W83877F seems to be fixed at 1.6s timeout (at least on the
 * EMACS PC-104 board I'm using). If we reset the watchdog every
 * ~250ms we should be safe.  */

#define WDT_INTERVAL (HZ/4+1)

/*
 * We must not require too good response from the userspace daemon.
 * Here we require the userspace daemon to send us a heartbeat
 * char to /dev/watchdog every 30 seconds.
 */

#define WATCHDOG_TIMEOUT 30            /* 30 sec default timeout */
static int timeout = WATCHDOG_TIMEOUT; /* in seconds, will be multiplied by HZ to get seconds to wait for a ping */
module_param(timeout, int, 0);
MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds. (1<=timeout<=3600, default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ")");


static int nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, int, 0);
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=CONFIG_WATCHDOG_NOWAYOUT)");

static void wdt_timer_ping(unsigned long);
static struct timer_list timer;
static unsigned long next_heartbeat;
static unsigned long wdt_is_open;
static char wdt_expect_close;
static spinlock_t wdt_spinlock;

/*
 *	Whack the dog
 */

static void wdt_timer_ping(unsigned long data)
{
	/* If we got a heartbeat pulse within the WDT_US_INTERVAL
	 * we agree to ping the WDT
	 */
	if(time_before(jiffies, next_heartbeat))
	{
		/* Ping the WDT */
		spin_lock(&wdt_spinlock);

		/* Ping the WDT by reading from WDT_PING */
		inb_p(WDT_PING);

		/* Re-set the timer interval */
		timer.expires = jiffies + WDT_INTERVAL;
		add_timer(&timer);

		spin_unlock(&wdt_spinlock);

	} else {
		printk(KERN_WARNING PFX "Heartbeat lost! Will not ping the watchdog\n");
	}
}

/*
 * Utility routines
 */

static void wdt_change(int writeval)
{
	unsigned long flags;
	spin_lock_irqsave(&wdt_spinlock, flags);

	/* buy some time */
	inb_p(WDT_PING);

	/* make W83877F available */
	outb_p(ENABLE_W83877F,  ENABLE_W83877F_PORT);
	outb_p(ENABLE_W83877F,  ENABLE_W83877F_PORT);

	/* enable watchdog */
	outb_p(WDT_REGISTER,    ENABLE_W83877F_PORT);
	outb_p(writeval,        ENABLE_W83877F_PORT+1);

	/* lock the W8387FF away */
	outb_p(DISABLE_W83877F, ENABLE_W83877F_PORT);

	spin_unlock_irqrestore(&wdt_spinlock, flags);
}

static void wdt_startup(void)
{
	next_heartbeat = jiffies + (timeout * HZ);

	/* Start the timer */
	timer.expires = jiffies + WDT_INTERVAL;
	add_timer(&timer);

	wdt_change(WDT_ENABLE);

	printk(KERN_INFO PFX "Watchdog timer is now enabled.\n");
}

static void wdt_turnoff(void)
{
	/* Stop the timer */
	del_timer(&timer);

	wdt_change(WDT_DISABLE);

	printk(KERN_INFO PFX "Watchdog timer is now disabled...\n");
}

static void wdt_keepalive(void)
{
	/* user land ping */
	next_heartbeat = jiffies + (timeout * HZ);
}

/*
 * /dev/watchdog handling
 */

static ssize_t fop_write(struct file * file, const char __user * buf, size_t count, loff_t * ppos)
{
	/* See if we got the magic character 'V' and reload the timer */
	if(count)
	{
		if (!nowayout)
		{
			size_t ofs;

			/* note: just in case someone wrote the magic character
			 * five months ago... */
			wdt_expect_close = 0;

			/* scan to see whether or not we got the magic character */
			for(ofs = 0; ofs != count; ofs++)
			{
				char c;
				if (get_user(c, buf + ofs))
					return -EFAULT;
				if (c == 'V')
					wdt_expect_close = 42;
			}
		}

		/* someone wrote to us, we should restart timer */
		wdt_keepalive();
	}
	return count;
}

static int fop_open(struct inode * inode, struct file * file)
{
	/* Just in case we're already talking to someone... */
	if(test_and_set_bit(0, &wdt_is_open))
		return -EBUSY;

	/* Good, fire up the show */
	wdt_startup();
	return nonseekable_open(inode, file);
}

static int fop_close(struct inode * inode, struct file * file)
{
	if(wdt_expect_close == 42)
		wdt_turnoff();
	else {
		del_timer(&timer);
		printk(KERN_CRIT PFX "device file closed unexpectedly. Will not stop the WDT!\n");
	}
	clear_bit(0, &wdt_is_open);
	wdt_expect_close = 0;
	return 0;
}

static int fop_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
	unsigned long arg)
{
	void __user *argp = (void __user *)arg;
	int __user *p = argp;
	static struct watchdog_info ident=
	{
		.options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
		.firmware_version = 1,
		.identity = "W83877F",
	};

	switch(cmd)
	{
		default:
			return -ENOTTY;
		case WDIOC_GETSUPPORT:
			return copy_to_user(argp, &ident, sizeof(ident))?-EFAULT:0;
		case WDIOC_GETSTATUS:
		case WDIOC_GETBOOTSTATUS:
			return put_user(0, p);
		case WDIOC_KEEPALIVE:
			wdt_keepalive();
			return 0;
		case WDIOC_SETOPTIONS:
		{
			int new_options, retval = -EINVAL;

			if(get_user(new_options, p))
				return -EFAULT;

			if(new_options & WDIOS_DISABLECARD) {
				wdt_turnoff();
				retval = 0;
			}

			if(new_options & WDIOS_ENABLECARD) {
				wdt_startup();
				retval = 0;
			}

			return retval;
		}
		case WDIOC_SETTIMEOUT:
		{
			int new_timeout;

			if(get_user(new_timeout, p))
				return -EFAULT;

			if(new_timeout < 1 || new_timeout > 3600) /* arbitrary upper limit */
				return -EINVAL;

			timeout = new_timeout;
			wdt_keepalive();
			/* Fall through */
		}
		case WDIOC_GETTIMEOUT:
			return put_user(timeout, p);
	}
}

static const struct file_operations wdt_fops = {
	.owner		= THIS_MODULE,
	.llseek		= no_llseek,
	.write		= fop_write,
	.open		= fop_open,
	.release	= fop_close,
	.ioctl		= fop_ioctl,
};

static struct miscdevice wdt_miscdev = {
	.minor	= WATCHDOG_MINOR,
	.name	= "watchdog",
	.fops	= &wdt_fops,
};

/*
 *	Notifier for system down
 */

static int wdt_notify_sys(struct notifier_block *this, unsigned long code,
	void *unused)
{
	if(code==SYS_DOWN || code==SYS_HALT)
		wdt_turnoff();
	return NOTIFY_DONE;
}

/*
 *	The WDT needs to learn about soft shutdowns in order to
 *	turn the timebomb registers off.
 */

static struct notifier_block wdt_notifier=
{
	.notifier_call = wdt_notify_sys,
};

static void __exit w83877f_wdt_unload(void)
{
	wdt_turnoff();

	/* Deregister */
	misc_deregister(&wdt_miscdev);

	unregister_reboot_notifier(&wdt_notifier);
	release_region(WDT_PING,1);
	release_region(ENABLE_W83877F_PORT,2);
}

static int __init w83877f_wdt_init(void)
{
	int rc = -EBUSY;

	spin_lock_init(&wdt_spinlock);

	if(timeout < 1 || timeout > 3600) /* arbitrary upper limit */
	{
		timeout = WATCHDOG_TIMEOUT;
		printk(KERN_INFO PFX "timeout value must be 1<=x<=3600, using %d\n",
			timeout);
	}

	if (!request_region(ENABLE_W83877F_PORT, 2, "W83877F WDT"))
	{
		printk(KERN_ERR PFX "I/O address 0x%04x already in use\n",
			ENABLE_W83877F_PORT);
		rc = -EIO;
		goto err_out;
	}

	if (!request_region(WDT_PING, 1, "W8387FF WDT"))
	{
		printk(KERN_ERR PFX "I/O address 0x%04x already in use\n",
			WDT_PING);
		rc = -EIO;
		goto err_out_region1;
	}

	init_timer(&timer);
	timer.function = wdt_timer_ping;
	timer.data = 0;

	rc = misc_register(&wdt_miscdev);
	if (rc)
	{
		printk(KERN_ERR PFX "cannot register miscdev on minor=%d (err=%d)\n",
			wdt_miscdev.minor, rc);
		goto err_out_region2;
	}

	rc = register_reboot_notifier(&wdt_notifier);
	if (rc)
	{
		printk(KERN_ERR PFX "cannot register reboot notifier (err=%d)\n",
			rc);
		goto err_out_miscdev;
	}

	printk(KERN_INFO PFX "WDT driver for W83877F initialised. timeout=%d sec (nowayout=%d)\n",
		timeout, nowayout);

	return 0;

err_out_miscdev:
	misc_deregister(&wdt_miscdev);
err_out_region2:
	release_region(WDT_PING,1);
err_out_region1:
	release_region(ENABLE_W83877F_PORT,2);
err_out:
	return rc;
}

module_init(w83877f_wdt_init);
module_exit(w83877f_wdt_unload);

MODULE_AUTHOR("Scott and Bill Jennings");
MODULE_DESCRIPTION("Driver for watchdog timer in w83877f chip");
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);