summaryrefslogtreecommitdiffstats
path: root/drivers/watchdog/wdrtas.c
blob: 184a06a74f83a225c3289a53f2d98197523718f4 (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
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * FIXME: add wdrtas_get_status and wdrtas_get_boot_status as soon as
 * RTAS calls are available
 */

/*
 * RTAS watchdog driver
 *
 * (C) Copyright IBM Corp. 2005
 * device driver to exploit watchdog RTAS functions
 *
 * Authors : Utz Bacher <utz.bacher@de.ibm.com>
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/fs.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/notifier.h>
#include <linux/reboot.h>
#include <linux/types.h>
#include <linux/watchdog.h>
#include <linux/uaccess.h>

#include <asm/rtas.h>

#define WDRTAS_MAGIC_CHAR		42
#define WDRTAS_SUPPORTED_MASK		(WDIOF_SETTIMEOUT | \
					 WDIOF_MAGICCLOSE)

MODULE_AUTHOR("Utz Bacher <utz.bacher@de.ibm.com>");
MODULE_DESCRIPTION("RTAS watchdog driver");
MODULE_LICENSE("GPL");

static bool wdrtas_nowayout = WATCHDOG_NOWAYOUT;
static atomic_t wdrtas_miscdev_open = ATOMIC_INIT(0);
static char wdrtas_expect_close;

static int wdrtas_interval;

#define WDRTAS_THERMAL_SENSOR		3
static int wdrtas_token_get_sensor_state;
#define WDRTAS_SURVEILLANCE_IND		9000
static int wdrtas_token_set_indicator;
#define WDRTAS_SP_SPI			28
static int wdrtas_token_get_sp;
static int wdrtas_token_event_scan;

#define WDRTAS_DEFAULT_INTERVAL		300

#define WDRTAS_LOGBUFFER_LEN		128
static char wdrtas_logbuffer[WDRTAS_LOGBUFFER_LEN];


/*** watchdog access functions */

/**
 * wdrtas_set_interval - sets the watchdog interval
 * @interval: new interval
 *
 * returns 0 on success, <0 on failures
 *
 * wdrtas_set_interval sets the watchdog keepalive interval by calling the
 * RTAS function set-indicator (surveillance). The unit of interval is
 * seconds.
 */

static int wdrtas_set_interval(int interval)
{
	long result;
	static int print_msg = 10;

	/* rtas uses minutes */
	interval = (interval + 59) / 60;

	result = rtas_call(wdrtas_token_set_indicator, 3, 1, NULL,
			   WDRTAS_SURVEILLANCE_IND, 0, interval);
	if (result < 0 && print_msg) {
		pr_err("setting the watchdog to %i timeout failed: %li\n",
		       interval, result);
		print_msg--;
	}

	return result;
}

#define WDRTAS_SP_SPI_LEN 4

/**
 * wdrtas_get_interval - returns the current watchdog interval
 * @fallback_value: value (in seconds) to use, if the RTAS call fails
 *
 * returns the interval
 *
 * wdrtas_get_interval returns the current watchdog keepalive interval
 * as reported by the RTAS function ibm,get-system-parameter. The unit
 * of the return value is seconds.
 */
static int wdrtas_get_interval(int fallback_value)
{
	long result;
	char value[WDRTAS_SP_SPI_LEN];

	spin_lock(&rtas_data_buf_lock);
	memset(rtas_data_buf, 0, WDRTAS_SP_SPI_LEN);
	result = rtas_call(wdrtas_token_get_sp, 3, 1, NULL,
			   WDRTAS_SP_SPI, __pa(rtas_data_buf),
			   WDRTAS_SP_SPI_LEN);

	memcpy(value, rtas_data_buf, WDRTAS_SP_SPI_LEN);
	spin_unlock(&rtas_data_buf_lock);

	if (value[0] != 0 || value[1] != 2 || value[3] != 0 || result < 0) {
		pr_warn("could not get sp_spi watchdog timeout (%li). Continuing\n",
			result);
		return fallback_value;
	}

	/* rtas uses minutes */
	return ((int)value[2]) * 60;
}

/**
 * wdrtas_timer_start - starts watchdog
 *
 * wdrtas_timer_start starts the watchdog by calling the RTAS function
 * set-interval (surveillance)
 */
static void wdrtas_timer_start(void)
{
	wdrtas_set_interval(wdrtas_interval);
}

/**
 * wdrtas_timer_stop - stops watchdog
 *
 * wdrtas_timer_stop stops the watchdog timer by calling the RTAS function
 * set-interval (surveillance)
 */
static void wdrtas_timer_stop(void)
{
	wdrtas_set_interval(0);
}

/**
 * wdrtas_timer_keepalive - resets watchdog timer to keep system alive
 *
 * wdrtas_timer_keepalive restarts the watchdog timer by calling the
 * RTAS function event-scan and repeats these calls as long as there are
 * events available. All events will be dumped.
 */
static void wdrtas_timer_keepalive(void)
{
	long result;

	do {
		result = rtas_call(wdrtas_token_event_scan, 4, 1, NULL,
				   RTAS_EVENT_SCAN_ALL_EVENTS, 0,
				   (void *)__pa(wdrtas_logbuffer),
				   WDRTAS_LOGBUFFER_LEN);
		if (result < 0)
			pr_err("event-scan failed: %li\n", result);
		if (result == 0)
			print_hex_dump(KERN_INFO, "dumping event, data: ",
				DUMP_PREFIX_OFFSET, 16, 1,
				wdrtas_logbuffer, WDRTAS_LOGBUFFER_LEN, false);
	} while (result == 0);
}

/**
 * wdrtas_get_temperature - returns current temperature
 *
 * returns temperature or <0 on failures
 *
 * wdrtas_get_temperature returns the current temperature in Fahrenheit. It
 * uses the RTAS call get-sensor-state, token 3 to do so
 */
static int wdrtas_get_temperature(void)
{
	int result;
	int temperature = 0;

	result = rtas_get_sensor(WDRTAS_THERMAL_SENSOR, 0, &temperature);

	if (result < 0)
		pr_warn("reading the thermal sensor failed: %i\n", result);
	else
		temperature = ((temperature * 9) / 5) + 32; /* fahrenheit */

	return temperature;
}

/**
 * wdrtas_get_status - returns the status of the watchdog
 *
 * returns a bitmask of defines WDIOF_... as defined in
 * include/linux/watchdog.h
 */
static int wdrtas_get_status(void)
{
	return 0; /* TODO */
}

/**
 * wdrtas_get_boot_status - returns the reason for the last boot
 *
 * returns a bitmask of defines WDIOF_... as defined in
 * include/linux/watchdog.h, indicating why the watchdog rebooted the system
 */
static int wdrtas_get_boot_status(void)
{
	return 0; /* TODO */
}

/*** watchdog API and operations stuff */

/* wdrtas_write - called when watchdog device is written to
 * @file: file structure
 * @buf: user buffer with data
 * @len: amount to data written
 * @ppos: position in file
 *
 * returns the number of successfully processed characters, which is always
 * the number of bytes passed to this function
 *
 * wdrtas_write processes all the data given to it and looks for the magic
 * character 'V'. This character allows the watchdog device to be closed
 * properly.
 */
static ssize_t wdrtas_write(struct file *file, const char __user *buf,
	     size_t len, loff_t *ppos)
{
	int i;
	char c;

	if (!len)
		goto out;

	if (!wdrtas_nowayout) {
		wdrtas_expect_close = 0;
		/* look for 'V' */
		for (i = 0; i < len; i++) {
			if (get_user(c, buf + i))
				return -EFAULT;
			/* allow to close device */
			if (c == 'V')
				wdrtas_expect_close = WDRTAS_MAGIC_CHAR;
		}
	}

	wdrtas_timer_keepalive();

out:
	return len;
}

/**
 * wdrtas_ioctl - ioctl function for the watchdog device
 * @file: file structure
 * @cmd: command for ioctl
 * @arg: argument pointer
 *
 * returns 0 on success, <0 on failure
 *
 * wdrtas_ioctl implements the watchdog API ioctls
 */

static long wdrtas_ioctl(struct file *file, unsigned int cmd,
							unsigned long arg)
{
	int __user *argp = (void __user *)arg;
	int i;
	static const struct watchdog_info wdinfo = {
		.options = WDRTAS_SUPPORTED_MASK,
		.firmware_version = 0,
		.identity = "wdrtas",
	};

	switch (cmd) {
	case WDIOC_GETSUPPORT:
		if (copy_to_user(argp, &wdinfo, sizeof(wdinfo)))
			return -EFAULT;
		return 0;

	case WDIOC_GETSTATUS:
		i = wdrtas_get_status();
		return put_user(i, argp);

	case WDIOC_GETBOOTSTATUS:
		i = wdrtas_get_boot_status();
		return put_user(i, argp);

	case WDIOC_GETTEMP:
		if (wdrtas_token_get_sensor_state == RTAS_UNKNOWN_SERVICE)
			return -EOPNOTSUPP;

		i = wdrtas_get_temperature();
		return put_user(i, argp);

	case WDIOC_SETOPTIONS:
		if (get_user(i, argp))
			return -EFAULT;
		if (i & WDIOS_DISABLECARD)
			wdrtas_timer_stop();
		if (i & WDIOS_ENABLECARD) {
			wdrtas_timer_keepalive();
			wdrtas_timer_start();
		}
		/* not implemented. Done by H8
		if (i & WDIOS_TEMPPANIC) {
		} */
		return 0;

	case WDIOC_KEEPALIVE:
		wdrtas_timer_keepalive();
		return 0;

	case WDIOC_SETTIMEOUT:
		if (get_user(i, argp))
			return -EFAULT;

		if (wdrtas_set_interval(i))
			return -EINVAL;

		wdrtas_timer_keepalive();

		if (wdrtas_token_get_sp == RTAS_UNKNOWN_SERVICE)
			wdrtas_interval = i;
		else
			wdrtas_interval = wdrtas_get_interval(i);
		/* fallthrough */

	case WDIOC_GETTIMEOUT:
		return put_user(wdrtas_interval, argp);

	default:
		return -ENOTTY;
	}
}

/**
 * wdrtas_open - open function of watchdog device
 * @inode: inode structure
 * @file: file structure
 *
 * returns 0 on success, -EBUSY if the file has been opened already, <0 on
 * other failures
 *
 * function called when watchdog device is opened
 */
static int wdrtas_open(struct inode *inode, struct file *file)
{
	/* only open once */
	if (atomic_inc_return(&wdrtas_miscdev_open) > 1) {
		atomic_dec(&wdrtas_miscdev_open);
		return -EBUSY;
	}

	wdrtas_timer_start();
	wdrtas_timer_keepalive();

	return stream_open(inode, file);
}

/**
 * wdrtas_close - close function of watchdog device
 * @inode: inode structure
 * @file: file structure
 *
 * returns 0 on success
 *
 * close function. Always succeeds
 */
static int wdrtas_close(struct inode *inode, struct file *file)
{
	/* only stop watchdog, if this was announced using 'V' before */
	if (wdrtas_expect_close == WDRTAS_MAGIC_CHAR)
		wdrtas_timer_stop();
	else {
		pr_warn("got unexpected close. Watchdog not stopped.\n");
		wdrtas_timer_keepalive();
	}

	wdrtas_expect_close = 0;
	atomic_dec(&wdrtas_miscdev_open);
	return 0;
}

/**
 * wdrtas_temp_read - gives back the temperature in fahrenheit
 * @file: file structure
 * @buf: user buffer
 * @count: number of bytes to be read
 * @ppos: position in file
 *
 * returns always 1 or -EFAULT in case of user space copy failures, <0 on
 * other failures
 *
 * wdrtas_temp_read gives the temperature to the users by copying this
 * value as one byte into the user space buffer. The unit is Fahrenheit...
 */
static ssize_t wdrtas_temp_read(struct file *file, char __user *buf,
		 size_t count, loff_t *ppos)
{
	int temperature = 0;

	temperature = wdrtas_get_temperature();
	if (temperature < 0)
		return temperature;

	if (copy_to_user(buf, &temperature, 1))
		return -EFAULT;

	return 1;
}

/**
 * wdrtas_temp_open - open function of temperature device
 * @inode: inode structure
 * @file: file structure
 *
 * returns 0 on success, <0 on failure
 *
 * function called when temperature device is opened
 */
static int wdrtas_temp_open(struct inode *inode, struct file *file)
{
	return stream_open(inode, file);
}

/**
 * wdrtas_temp_close - close function of temperature device
 * @inode: inode structure
 * @file: file structure
 *
 * returns 0 on success
 *
 * close function. Always succeeds
 */
static int wdrtas_temp_close(struct inode *inode, struct file *file)
{
	return 0;
}

/**
 * wdrtas_reboot - reboot notifier function
 * @nb: notifier block structure
 * @code: reboot code
 * @ptr: unused
 *
 * returns NOTIFY_DONE
 *
 * wdrtas_reboot stops the watchdog in case of a reboot
 */
static int wdrtas_reboot(struct notifier_block *this,
					unsigned long code, void *ptr)
{
	if (code == SYS_DOWN || code == SYS_HALT)
		wdrtas_timer_stop();

	return NOTIFY_DONE;
}

/*** initialization stuff */

static const struct file_operations wdrtas_fops = {
	.owner		= THIS_MODULE,
	.llseek		= no_llseek,
	.write		= wdrtas_write,
	.unlocked_ioctl	= wdrtas_ioctl,
	.compat_ioctl	= compat_ptr_ioctl,
	.open		= wdrtas_open,
	.release	= wdrtas_close,
};

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

static const struct file_operations wdrtas_temp_fops = {
	.owner		= THIS_MODULE,
	.llseek		= no_llseek,
	.read		= wdrtas_temp_read,
	.open		= wdrtas_temp_open,
	.release	= wdrtas_temp_close,
};

static struct miscdevice wdrtas_tempdev = {
	.minor =	TEMP_MINOR,
	.name =		"temperature",
	.fops =		&wdrtas_temp_fops,
};

static struct notifier_block wdrtas_notifier = {
	.notifier_call =	wdrtas_reboot,
};

/**
 * wdrtas_get_tokens - reads in RTAS tokens
 *
 * returns 0 on success, <0 on failure
 *
 * wdrtas_get_tokens reads in the tokens for the RTAS calls used in
 * this watchdog driver. It tolerates, if "get-sensor-state" and
 * "ibm,get-system-parameter" are not available.
 */
static int wdrtas_get_tokens(void)
{
	wdrtas_token_get_sensor_state = rtas_token("get-sensor-state");
	if (wdrtas_token_get_sensor_state == RTAS_UNKNOWN_SERVICE) {
		pr_warn("couldn't get token for get-sensor-state. Trying to continue without temperature support.\n");
	}

	wdrtas_token_get_sp = rtas_token("ibm,get-system-parameter");
	if (wdrtas_token_get_sp == RTAS_UNKNOWN_SERVICE) {
		pr_warn("couldn't get token for ibm,get-system-parameter. Trying to continue with a default timeout value of %i seconds.\n",
			WDRTAS_DEFAULT_INTERVAL);
	}

	wdrtas_token_set_indicator = rtas_token("set-indicator");
	if (wdrtas_token_set_indicator == RTAS_UNKNOWN_SERVICE) {
		pr_err("couldn't get token for set-indicator. Terminating watchdog code.\n");
		return -EIO;
	}

	wdrtas_token_event_scan = rtas_token("event-scan");
	if (wdrtas_token_event_scan == RTAS_UNKNOWN_SERVICE) {
		pr_err("couldn't get token for event-scan. Terminating watchdog code.\n");
		return -EIO;
	}

	return 0;
}

/**
 * wdrtas_unregister_devs - unregisters the misc dev handlers
 *
 * wdrtas_register_devs unregisters the watchdog and temperature watchdog
 * misc devs
 */
static void wdrtas_unregister_devs(void)
{
	misc_deregister(&wdrtas_miscdev);
	if (wdrtas_token_get_sensor_state != RTAS_UNKNOWN_SERVICE)
		misc_deregister(&wdrtas_tempdev);
}

/**
 * wdrtas_register_devs - registers the misc dev handlers
 *
 * returns 0 on success, <0 on failure
 *
 * wdrtas_register_devs registers the watchdog and temperature watchdog
 * misc devs
 */
static int wdrtas_register_devs(void)
{
	int result;

	result = misc_register(&wdrtas_miscdev);
	if (result) {
		pr_err("couldn't register watchdog misc device. Terminating watchdog code.\n");
		return result;
	}

	if (wdrtas_token_get_sensor_state != RTAS_UNKNOWN_SERVICE) {
		result = misc_register(&wdrtas_tempdev);
		if (result) {
			pr_warn("couldn't register watchdog temperature misc device. Continuing without temperature support.\n");
			wdrtas_token_get_sensor_state = RTAS_UNKNOWN_SERVICE;
		}
	}

	return 0;
}

/**
 * wdrtas_init - init function of the watchdog driver
 *
 * returns 0 on success, <0 on failure
 *
 * registers the file handlers and the reboot notifier
 */
static int __init wdrtas_init(void)
{
	if (wdrtas_get_tokens())
		return -ENODEV;

	if (wdrtas_register_devs())
		return -ENODEV;

	if (register_reboot_notifier(&wdrtas_notifier)) {
		pr_err("could not register reboot notifier. Terminating watchdog code.\n");
		wdrtas_unregister_devs();
		return -ENODEV;
	}

	if (wdrtas_token_get_sp == RTAS_UNKNOWN_SERVICE)
		wdrtas_interval = WDRTAS_DEFAULT_INTERVAL;
	else
		wdrtas_interval = wdrtas_get_interval(WDRTAS_DEFAULT_INTERVAL);

	return 0;
}

/**
 * wdrtas_exit - exit function of the watchdog driver
 *
 * unregisters the file handlers and the reboot notifier
 */
static void __exit wdrtas_exit(void)
{
	if (!wdrtas_nowayout)
		wdrtas_timer_stop();

	wdrtas_unregister_devs();

	unregister_reboot_notifier(&wdrtas_notifier);
}

module_init(wdrtas_init);
module_exit(wdrtas_exit);