1/*
2 * FIXME: add wdrtas_get_status and wdrtas_get_boot_status as soon as
3 * RTAS calls are available
4 */
5
6/*
7 * RTAS watchdog driver
8 *
9 * (C) Copyright IBM Corp. 2005
10 * device driver to exploit watchdog RTAS functions
11 *
12 * Authors : Utz Bacher <utz.bacher@de.ibm.com>
13 *
14 * This program is free software; you can redistribute it and/or modify
15 * it under the terms of the GNU General Public License as published by
16 * the Free Software Foundation; either version 2, or (at your option)
17 * any later version.
18 *
19 * This program is distributed in the hope that it will be useful,
20 * but WITHOUT ANY WARRANTY; without even the implied warranty of
21 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
22 * GNU General Public License for more details.
23 *
24 * You should have received a copy of the GNU General Public License
25 * along with this program; if not, write to the Free Software
26 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
27 */
28
29#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
30
31#include <linux/fs.h>
32#include <linux/init.h>
33#include <linux/kernel.h>
34#include <linux/miscdevice.h>
35#include <linux/module.h>
36#include <linux/notifier.h>
37#include <linux/reboot.h>
38#include <linux/types.h>
39#include <linux/watchdog.h>
40#include <linux/uaccess.h>
41
42#include <asm/rtas.h>
43
44#define WDRTAS_MAGIC_CHAR		42
45#define WDRTAS_SUPPORTED_MASK		(WDIOF_SETTIMEOUT | \
46					 WDIOF_MAGICCLOSE)
47
48MODULE_AUTHOR("Utz Bacher <utz.bacher@de.ibm.com>");
49MODULE_DESCRIPTION("RTAS watchdog driver");
50MODULE_LICENSE("GPL");
51
52static bool wdrtas_nowayout = WATCHDOG_NOWAYOUT;
53static atomic_t wdrtas_miscdev_open = ATOMIC_INIT(0);
54static char wdrtas_expect_close;
55
56static int wdrtas_interval;
57
58#define WDRTAS_THERMAL_SENSOR		3
59static int wdrtas_token_get_sensor_state;
60#define WDRTAS_SURVEILLANCE_IND		9000
61static int wdrtas_token_set_indicator;
62#define WDRTAS_SP_SPI			28
63static int wdrtas_token_get_sp;
64static int wdrtas_token_event_scan;
65
66#define WDRTAS_DEFAULT_INTERVAL		300
67
68#define WDRTAS_LOGBUFFER_LEN		128
69static char wdrtas_logbuffer[WDRTAS_LOGBUFFER_LEN];
70
71
72/*** watchdog access functions */
73
74/**
75 * wdrtas_set_interval - sets the watchdog interval
76 * @interval: new interval
77 *
78 * returns 0 on success, <0 on failures
79 *
80 * wdrtas_set_interval sets the watchdog keepalive interval by calling the
81 * RTAS function set-indicator (surveillance). The unit of interval is
82 * seconds.
83 */
84
85static int wdrtas_set_interval(int interval)
86{
87	long result;
88	static int print_msg = 10;
89
90	/* rtas uses minutes */
91	interval = (interval + 59) / 60;
92
93	result = rtas_call(wdrtas_token_set_indicator, 3, 1, NULL,
94			   WDRTAS_SURVEILLANCE_IND, 0, interval);
95	if (result < 0 && print_msg) {
96		pr_err("setting the watchdog to %i timeout failed: %li\n",
97		       interval, result);
98		print_msg--;
99	}
100
101	return result;
102}
103
104#define WDRTAS_SP_SPI_LEN 4
105
106/**
107 * wdrtas_get_interval - returns the current watchdog interval
108 * @fallback_value: value (in seconds) to use, if the RTAS call fails
109 *
110 * returns the interval
111 *
112 * wdrtas_get_interval returns the current watchdog keepalive interval
113 * as reported by the RTAS function ibm,get-system-parameter. The unit
114 * of the return value is seconds.
115 */
116static int wdrtas_get_interval(int fallback_value)
117{
118	long result;
119	char value[WDRTAS_SP_SPI_LEN];
120
121	spin_lock(&rtas_data_buf_lock);
122	memset(rtas_data_buf, 0, WDRTAS_SP_SPI_LEN);
123	result = rtas_call(wdrtas_token_get_sp, 3, 1, NULL,
124			   WDRTAS_SP_SPI, __pa(rtas_data_buf),
125			   WDRTAS_SP_SPI_LEN);
126
127	memcpy(value, rtas_data_buf, WDRTAS_SP_SPI_LEN);
128	spin_unlock(&rtas_data_buf_lock);
129
130	if (value[0] != 0 || value[1] != 2 || value[3] != 0 || result < 0) {
131		pr_warn("could not get sp_spi watchdog timeout (%li). Continuing\n",
132			result);
133		return fallback_value;
134	}
135
136	/* rtas uses minutes */
137	return ((int)value[2]) * 60;
138}
139
140/**
141 * wdrtas_timer_start - starts watchdog
142 *
143 * wdrtas_timer_start starts the watchdog by calling the RTAS function
144 * set-interval (surveillance)
145 */
146static void wdrtas_timer_start(void)
147{
148	wdrtas_set_interval(wdrtas_interval);
149}
150
151/**
152 * wdrtas_timer_stop - stops watchdog
153 *
154 * wdrtas_timer_stop stops the watchdog timer by calling the RTAS function
155 * set-interval (surveillance)
156 */
157static void wdrtas_timer_stop(void)
158{
159	wdrtas_set_interval(0);
160}
161
162/**
163 * wdrtas_timer_keepalive - resets watchdog timer to keep system alive
164 *
165 * wdrtas_timer_keepalive restarts the watchdog timer by calling the
166 * RTAS function event-scan and repeats these calls as long as there are
167 * events available. All events will be dumped.
168 */
169static void wdrtas_timer_keepalive(void)
170{
171	long result;
172
173	do {
174		result = rtas_call(wdrtas_token_event_scan, 4, 1, NULL,
175				   RTAS_EVENT_SCAN_ALL_EVENTS, 0,
176				   (void *)__pa(wdrtas_logbuffer),
177				   WDRTAS_LOGBUFFER_LEN);
178		if (result < 0)
179			pr_err("event-scan failed: %li\n", result);
180		if (result == 0)
181			print_hex_dump(KERN_INFO, "dumping event, data: ",
182				DUMP_PREFIX_OFFSET, 16, 1,
183				wdrtas_logbuffer, WDRTAS_LOGBUFFER_LEN, false);
184	} while (result == 0);
185}
186
187/**
188 * wdrtas_get_temperature - returns current temperature
189 *
190 * returns temperature or <0 on failures
191 *
192 * wdrtas_get_temperature returns the current temperature in Fahrenheit. It
193 * uses the RTAS call get-sensor-state, token 3 to do so
194 */
195static int wdrtas_get_temperature(void)
196{
197	int result;
198	int temperature = 0;
199
200	result = rtas_get_sensor(WDRTAS_THERMAL_SENSOR, 0, &temperature);
201
202	if (result < 0)
203		pr_warn("reading the thermal sensor failed: %i\n", result);
204	else
205		temperature = ((temperature * 9) / 5) + 32; /* fahrenheit */
206
207	return temperature;
208}
209
210/**
211 * wdrtas_get_status - returns the status of the watchdog
212 *
213 * returns a bitmask of defines WDIOF_... as defined in
214 * include/linux/watchdog.h
215 */
216static int wdrtas_get_status(void)
217{
218	return 0; /* TODO */
219}
220
221/**
222 * wdrtas_get_boot_status - returns the reason for the last boot
223 *
224 * returns a bitmask of defines WDIOF_... as defined in
225 * include/linux/watchdog.h, indicating why the watchdog rebooted the system
226 */
227static int wdrtas_get_boot_status(void)
228{
229	return 0; /* TODO */
230}
231
232/*** watchdog API and operations stuff */
233
234/* wdrtas_write - called when watchdog device is written to
235 * @file: file structure
236 * @buf: user buffer with data
237 * @len: amount to data written
238 * @ppos: position in file
239 *
240 * returns the number of successfully processed characters, which is always
241 * the number of bytes passed to this function
242 *
243 * wdrtas_write processes all the data given to it and looks for the magic
244 * character 'V'. This character allows the watchdog device to be closed
245 * properly.
246 */
247static ssize_t wdrtas_write(struct file *file, const char __user *buf,
248	     size_t len, loff_t *ppos)
249{
250	int i;
251	char c;
252
253	if (!len)
254		goto out;
255
256	if (!wdrtas_nowayout) {
257		wdrtas_expect_close = 0;
258		/* look for 'V' */
259		for (i = 0; i < len; i++) {
260			if (get_user(c, buf + i))
261				return -EFAULT;
262			/* allow to close device */
263			if (c == 'V')
264				wdrtas_expect_close = WDRTAS_MAGIC_CHAR;
265		}
266	}
267
268	wdrtas_timer_keepalive();
269
270out:
271	return len;
272}
273
274/**
275 * wdrtas_ioctl - ioctl function for the watchdog device
276 * @file: file structure
277 * @cmd: command for ioctl
278 * @arg: argument pointer
279 *
280 * returns 0 on success, <0 on failure
281 *
282 * wdrtas_ioctl implements the watchdog API ioctls
283 */
284
285static long wdrtas_ioctl(struct file *file, unsigned int cmd,
286							unsigned long arg)
287{
288	int __user *argp = (void __user *)arg;
289	int i;
290	static const struct watchdog_info wdinfo = {
291		.options = WDRTAS_SUPPORTED_MASK,
292		.firmware_version = 0,
293		.identity = "wdrtas",
294	};
295
296	switch (cmd) {
297	case WDIOC_GETSUPPORT:
298		if (copy_to_user(argp, &wdinfo, sizeof(wdinfo)))
299			return -EFAULT;
300		return 0;
301
302	case WDIOC_GETSTATUS:
303		i = wdrtas_get_status();
304		return put_user(i, argp);
305
306	case WDIOC_GETBOOTSTATUS:
307		i = wdrtas_get_boot_status();
308		return put_user(i, argp);
309
310	case WDIOC_GETTEMP:
311		if (wdrtas_token_get_sensor_state == RTAS_UNKNOWN_SERVICE)
312			return -EOPNOTSUPP;
313
314		i = wdrtas_get_temperature();
315		return put_user(i, argp);
316
317	case WDIOC_SETOPTIONS:
318		if (get_user(i, argp))
319			return -EFAULT;
320		if (i & WDIOS_DISABLECARD)
321			wdrtas_timer_stop();
322		if (i & WDIOS_ENABLECARD) {
323			wdrtas_timer_keepalive();
324			wdrtas_timer_start();
325		}
326		/* not implemented. Done by H8
327		if (i & WDIOS_TEMPPANIC) {
328		} */
329		return 0;
330
331	case WDIOC_KEEPALIVE:
332		wdrtas_timer_keepalive();
333		return 0;
334
335	case WDIOC_SETTIMEOUT:
336		if (get_user(i, argp))
337			return -EFAULT;
338
339		if (wdrtas_set_interval(i))
340			return -EINVAL;
341
342		wdrtas_timer_keepalive();
343
344		if (wdrtas_token_get_sp == RTAS_UNKNOWN_SERVICE)
345			wdrtas_interval = i;
346		else
347			wdrtas_interval = wdrtas_get_interval(i);
348		/* fallthrough */
349
350	case WDIOC_GETTIMEOUT:
351		return put_user(wdrtas_interval, argp);
352
353	default:
354		return -ENOTTY;
355	}
356}
357
358/**
359 * wdrtas_open - open function of watchdog device
360 * @inode: inode structure
361 * @file: file structure
362 *
363 * returns 0 on success, -EBUSY if the file has been opened already, <0 on
364 * other failures
365 *
366 * function called when watchdog device is opened
367 */
368static int wdrtas_open(struct inode *inode, struct file *file)
369{
370	/* only open once */
371	if (atomic_inc_return(&wdrtas_miscdev_open) > 1) {
372		atomic_dec(&wdrtas_miscdev_open);
373		return -EBUSY;
374	}
375
376	wdrtas_timer_start();
377	wdrtas_timer_keepalive();
378
379	return nonseekable_open(inode, file);
380}
381
382/**
383 * wdrtas_close - close function of watchdog device
384 * @inode: inode structure
385 * @file: file structure
386 *
387 * returns 0 on success
388 *
389 * close function. Always succeeds
390 */
391static int wdrtas_close(struct inode *inode, struct file *file)
392{
393	/* only stop watchdog, if this was announced using 'V' before */
394	if (wdrtas_expect_close == WDRTAS_MAGIC_CHAR)
395		wdrtas_timer_stop();
396	else {
397		pr_warn("got unexpected close. Watchdog not stopped.\n");
398		wdrtas_timer_keepalive();
399	}
400
401	wdrtas_expect_close = 0;
402	atomic_dec(&wdrtas_miscdev_open);
403	return 0;
404}
405
406/**
407 * wdrtas_temp_read - gives back the temperature in fahrenheit
408 * @file: file structure
409 * @buf: user buffer
410 * @count: number of bytes to be read
411 * @ppos: position in file
412 *
413 * returns always 1 or -EFAULT in case of user space copy failures, <0 on
414 * other failures
415 *
416 * wdrtas_temp_read gives the temperature to the users by copying this
417 * value as one byte into the user space buffer. The unit is Fahrenheit...
418 */
419static ssize_t wdrtas_temp_read(struct file *file, char __user *buf,
420		 size_t count, loff_t *ppos)
421{
422	int temperature = 0;
423
424	temperature = wdrtas_get_temperature();
425	if (temperature < 0)
426		return temperature;
427
428	if (copy_to_user(buf, &temperature, 1))
429		return -EFAULT;
430
431	return 1;
432}
433
434/**
435 * wdrtas_temp_open - open function of temperature device
436 * @inode: inode structure
437 * @file: file structure
438 *
439 * returns 0 on success, <0 on failure
440 *
441 * function called when temperature device is opened
442 */
443static int wdrtas_temp_open(struct inode *inode, struct file *file)
444{
445	return nonseekable_open(inode, file);
446}
447
448/**
449 * wdrtas_temp_close - close function of temperature device
450 * @inode: inode structure
451 * @file: file structure
452 *
453 * returns 0 on success
454 *
455 * close function. Always succeeds
456 */
457static int wdrtas_temp_close(struct inode *inode, struct file *file)
458{
459	return 0;
460}
461
462/**
463 * wdrtas_reboot - reboot notifier function
464 * @nb: notifier block structure
465 * @code: reboot code
466 * @ptr: unused
467 *
468 * returns NOTIFY_DONE
469 *
470 * wdrtas_reboot stops the watchdog in case of a reboot
471 */
472static int wdrtas_reboot(struct notifier_block *this,
473					unsigned long code, void *ptr)
474{
475	if (code == SYS_DOWN || code == SYS_HALT)
476		wdrtas_timer_stop();
477
478	return NOTIFY_DONE;
479}
480
481/*** initialization stuff */
482
483static const struct file_operations wdrtas_fops = {
484	.owner		= THIS_MODULE,
485	.llseek		= no_llseek,
486	.write		= wdrtas_write,
487	.unlocked_ioctl	= wdrtas_ioctl,
488	.open		= wdrtas_open,
489	.release	= wdrtas_close,
490};
491
492static struct miscdevice wdrtas_miscdev = {
493	.minor =	WATCHDOG_MINOR,
494	.name =		"watchdog",
495	.fops =		&wdrtas_fops,
496};
497
498static const struct file_operations wdrtas_temp_fops = {
499	.owner		= THIS_MODULE,
500	.llseek		= no_llseek,
501	.read		= wdrtas_temp_read,
502	.open		= wdrtas_temp_open,
503	.release	= wdrtas_temp_close,
504};
505
506static struct miscdevice wdrtas_tempdev = {
507	.minor =	TEMP_MINOR,
508	.name =		"temperature",
509	.fops =		&wdrtas_temp_fops,
510};
511
512static struct notifier_block wdrtas_notifier = {
513	.notifier_call =	wdrtas_reboot,
514};
515
516/**
517 * wdrtas_get_tokens - reads in RTAS tokens
518 *
519 * returns 0 on success, <0 on failure
520 *
521 * wdrtas_get_tokens reads in the tokens for the RTAS calls used in
522 * this watchdog driver. It tolerates, if "get-sensor-state" and
523 * "ibm,get-system-parameter" are not available.
524 */
525static int wdrtas_get_tokens(void)
526{
527	wdrtas_token_get_sensor_state = rtas_token("get-sensor-state");
528	if (wdrtas_token_get_sensor_state == RTAS_UNKNOWN_SERVICE) {
529		pr_warn("couldn't get token for get-sensor-state. Trying to continue without temperature support.\n");
530	}
531
532	wdrtas_token_get_sp = rtas_token("ibm,get-system-parameter");
533	if (wdrtas_token_get_sp == RTAS_UNKNOWN_SERVICE) {
534		pr_warn("couldn't get token for ibm,get-system-parameter. Trying to continue with a default timeout value of %i seconds.\n",
535			WDRTAS_DEFAULT_INTERVAL);
536	}
537
538	wdrtas_token_set_indicator = rtas_token("set-indicator");
539	if (wdrtas_token_set_indicator == RTAS_UNKNOWN_SERVICE) {
540		pr_err("couldn't get token for set-indicator. Terminating watchdog code.\n");
541		return -EIO;
542	}
543
544	wdrtas_token_event_scan = rtas_token("event-scan");
545	if (wdrtas_token_event_scan == RTAS_UNKNOWN_SERVICE) {
546		pr_err("couldn't get token for event-scan. Terminating watchdog code.\n");
547		return -EIO;
548	}
549
550	return 0;
551}
552
553/**
554 * wdrtas_unregister_devs - unregisters the misc dev handlers
555 *
556 * wdrtas_register_devs unregisters the watchdog and temperature watchdog
557 * misc devs
558 */
559static void wdrtas_unregister_devs(void)
560{
561	misc_deregister(&wdrtas_miscdev);
562	if (wdrtas_token_get_sensor_state != RTAS_UNKNOWN_SERVICE)
563		misc_deregister(&wdrtas_tempdev);
564}
565
566/**
567 * wdrtas_register_devs - registers the misc dev handlers
568 *
569 * returns 0 on success, <0 on failure
570 *
571 * wdrtas_register_devs registers the watchdog and temperature watchdog
572 * misc devs
573 */
574static int wdrtas_register_devs(void)
575{
576	int result;
577
578	result = misc_register(&wdrtas_miscdev);
579	if (result) {
580		pr_err("couldn't register watchdog misc device. Terminating watchdog code.\n");
581		return result;
582	}
583
584	if (wdrtas_token_get_sensor_state != RTAS_UNKNOWN_SERVICE) {
585		result = misc_register(&wdrtas_tempdev);
586		if (result) {
587			pr_warn("couldn't register watchdog temperature misc device. Continuing without temperature support.\n");
588			wdrtas_token_get_sensor_state = RTAS_UNKNOWN_SERVICE;
589		}
590	}
591
592	return 0;
593}
594
595/**
596 * wdrtas_init - init function of the watchdog driver
597 *
598 * returns 0 on success, <0 on failure
599 *
600 * registers the file handlers and the reboot notifier
601 */
602static int __init wdrtas_init(void)
603{
604	if (wdrtas_get_tokens())
605		return -ENODEV;
606
607	if (wdrtas_register_devs())
608		return -ENODEV;
609
610	if (register_reboot_notifier(&wdrtas_notifier)) {
611		pr_err("could not register reboot notifier. Terminating watchdog code.\n");
612		wdrtas_unregister_devs();
613		return -ENODEV;
614	}
615
616	if (wdrtas_token_get_sp == RTAS_UNKNOWN_SERVICE)
617		wdrtas_interval = WDRTAS_DEFAULT_INTERVAL;
618	else
619		wdrtas_interval = wdrtas_get_interval(WDRTAS_DEFAULT_INTERVAL);
620
621	return 0;
622}
623
624/**
625 * wdrtas_exit - exit function of the watchdog driver
626 *
627 * unregisters the file handlers and the reboot notifier
628 */
629static void __exit wdrtas_exit(void)
630{
631	if (!wdrtas_nowayout)
632		wdrtas_timer_stop();
633
634	wdrtas_unregister_devs();
635
636	unregister_reboot_notifier(&wdrtas_notifier);
637}
638
639module_init(wdrtas_init);
640module_exit(wdrtas_exit);
641