1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * FIXME: add wdrtas_get_status and wdrtas_get_boot_status as soon as
4 * RTAS calls are available
5 */
6
7/*
8 * RTAS watchdog driver
9 *
10 * (C) Copyright IBM Corp. 2005
11 * device driver to exploit watchdog RTAS functions
12 *
13 * Authors : Utz Bacher <utz.bacher@de.ibm.com>
14 */
15
16#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
17
18#include <linux/fs.h>
19#include <linux/init.h>
20#include <linux/kernel.h>
21#include <linux/miscdevice.h>
22#include <linux/module.h>
23#include <linux/notifier.h>
24#include <linux/reboot.h>
25#include <linux/types.h>
26#include <linux/watchdog.h>
27#include <linux/uaccess.h>
28
29#include <asm/rtas.h>
30
31#define WDRTAS_MAGIC_CHAR		42
32#define WDRTAS_SUPPORTED_MASK		(WDIOF_SETTIMEOUT | \
33					 WDIOF_MAGICCLOSE)
34
35MODULE_AUTHOR("Utz Bacher <utz.bacher@de.ibm.com>");
36MODULE_DESCRIPTION("RTAS watchdog driver");
37MODULE_LICENSE("GPL");
38
39static bool wdrtas_nowayout = WATCHDOG_NOWAYOUT;
40static atomic_t wdrtas_miscdev_open = ATOMIC_INIT(0);
41static char wdrtas_expect_close;
42
43static int wdrtas_interval;
44
45#define WDRTAS_THERMAL_SENSOR		3
46static int wdrtas_token_get_sensor_state;
47#define WDRTAS_SURVEILLANCE_IND		9000
48static int wdrtas_token_set_indicator;
49#define WDRTAS_SP_SPI			28
50static int wdrtas_token_get_sp;
51static int wdrtas_token_event_scan;
52
53#define WDRTAS_DEFAULT_INTERVAL		300
54
55#define WDRTAS_LOGBUFFER_LEN		128
56static char wdrtas_logbuffer[WDRTAS_LOGBUFFER_LEN];
57
58
59/*** watchdog access functions */
60
61/**
62 * wdrtas_set_interval - sets the watchdog interval
63 * @interval: new interval
64 *
65 * returns 0 on success, <0 on failures
66 *
67 * wdrtas_set_interval sets the watchdog keepalive interval by calling the
68 * RTAS function set-indicator (surveillance). The unit of interval is
69 * seconds.
70 */
71
72static int wdrtas_set_interval(int interval)
73{
74	long result;
75	static int print_msg = 10;
76
77	/* rtas uses minutes */
78	interval = (interval + 59) / 60;
79
80	result = rtas_call(wdrtas_token_set_indicator, 3, 1, NULL,
81			   WDRTAS_SURVEILLANCE_IND, 0, interval);
82	if (result < 0 && print_msg) {
83		pr_err("setting the watchdog to %i timeout failed: %li\n",
84		       interval, result);
85		print_msg--;
86	}
87
88	return result;
89}
90
91#define WDRTAS_SP_SPI_LEN 4
92
93/**
94 * wdrtas_get_interval - returns the current watchdog interval
95 * @fallback_value: value (in seconds) to use, if the RTAS call fails
96 *
97 * returns the interval
98 *
99 * wdrtas_get_interval returns the current watchdog keepalive interval
100 * as reported by the RTAS function ibm,get-system-parameter. The unit
101 * of the return value is seconds.
102 */
103static int wdrtas_get_interval(int fallback_value)
104{
105	long result;
106	char value[WDRTAS_SP_SPI_LEN];
107
108	spin_lock(&rtas_data_buf_lock);
109	memset(rtas_data_buf, 0, WDRTAS_SP_SPI_LEN);
110	result = rtas_call(wdrtas_token_get_sp, 3, 1, NULL,
111			   WDRTAS_SP_SPI, __pa(rtas_data_buf),
112			   WDRTAS_SP_SPI_LEN);
113
114	memcpy(value, rtas_data_buf, WDRTAS_SP_SPI_LEN);
115	spin_unlock(&rtas_data_buf_lock);
116
117	if (value[0] != 0 || value[1] != 2 || value[3] != 0 || result < 0) {
118		pr_warn("could not get sp_spi watchdog timeout (%li). Continuing\n",
119			result);
120		return fallback_value;
121	}
122
123	/* rtas uses minutes */
124	return ((int)value[2]) * 60;
125}
126
127/**
128 * wdrtas_timer_start - starts watchdog
129 *
130 * wdrtas_timer_start starts the watchdog by calling the RTAS function
131 * set-interval (surveillance)
132 */
133static void wdrtas_timer_start(void)
134{
135	wdrtas_set_interval(wdrtas_interval);
136}
137
138/**
139 * wdrtas_timer_stop - stops watchdog
140 *
141 * wdrtas_timer_stop stops the watchdog timer by calling the RTAS function
142 * set-interval (surveillance)
143 */
144static void wdrtas_timer_stop(void)
145{
146	wdrtas_set_interval(0);
147}
148
149/**
150 * wdrtas_timer_keepalive - resets watchdog timer to keep system alive
151 *
152 * wdrtas_timer_keepalive restarts the watchdog timer by calling the
153 * RTAS function event-scan and repeats these calls as long as there are
154 * events available. All events will be dumped.
155 */
156static void wdrtas_timer_keepalive(void)
157{
158	long result;
159
160	do {
161		result = rtas_call(wdrtas_token_event_scan, 4, 1, NULL,
162				   RTAS_EVENT_SCAN_ALL_EVENTS, 0,
163				   (void *)__pa(wdrtas_logbuffer),
164				   WDRTAS_LOGBUFFER_LEN);
165		if (result < 0)
166			pr_err("event-scan failed: %li\n", result);
167		if (result == 0)
168			print_hex_dump(KERN_INFO, "dumping event, data: ",
169				DUMP_PREFIX_OFFSET, 16, 1,
170				wdrtas_logbuffer, WDRTAS_LOGBUFFER_LEN, false);
171	} while (result == 0);
172}
173
174/**
175 * wdrtas_get_temperature - returns current temperature
176 *
177 * returns temperature or <0 on failures
178 *
179 * wdrtas_get_temperature returns the current temperature in Fahrenheit. It
180 * uses the RTAS call get-sensor-state, token 3 to do so
181 */
182static int wdrtas_get_temperature(void)
183{
184	int result;
185	int temperature = 0;
186
187	result = rtas_get_sensor(WDRTAS_THERMAL_SENSOR, 0, &temperature);
188
189	if (result < 0)
190		pr_warn("reading the thermal sensor failed: %i\n", result);
191	else
192		temperature = ((temperature * 9) / 5) + 32; /* fahrenheit */
193
194	return temperature;
195}
196
197/**
198 * wdrtas_get_status - returns the status of the watchdog
199 *
200 * returns a bitmask of defines WDIOF_... as defined in
201 * include/linux/watchdog.h
202 */
203static int wdrtas_get_status(void)
204{
205	return 0; /* TODO */
206}
207
208/**
209 * wdrtas_get_boot_status - returns the reason for the last boot
210 *
211 * returns a bitmask of defines WDIOF_... as defined in
212 * include/linux/watchdog.h, indicating why the watchdog rebooted the system
213 */
214static int wdrtas_get_boot_status(void)
215{
216	return 0; /* TODO */
217}
218
219/*** watchdog API and operations stuff */
220
221/* wdrtas_write - called when watchdog device is written to
222 * @file: file structure
223 * @buf: user buffer with data
224 * @len: amount to data written
225 * @ppos: position in file
226 *
227 * returns the number of successfully processed characters, which is always
228 * the number of bytes passed to this function
229 *
230 * wdrtas_write processes all the data given to it and looks for the magic
231 * character 'V'. This character allows the watchdog device to be closed
232 * properly.
233 */
234static ssize_t wdrtas_write(struct file *file, const char __user *buf,
235	     size_t len, loff_t *ppos)
236{
237	int i;
238	char c;
239
240	if (!len)
241		goto out;
242
243	if (!wdrtas_nowayout) {
244		wdrtas_expect_close = 0;
245		/* look for 'V' */
246		for (i = 0; i < len; i++) {
247			if (get_user(c, buf + i))
248				return -EFAULT;
249			/* allow to close device */
250			if (c == 'V')
251				wdrtas_expect_close = WDRTAS_MAGIC_CHAR;
252		}
253	}
254
255	wdrtas_timer_keepalive();
256
257out:
258	return len;
259}
260
261/**
262 * wdrtas_ioctl - ioctl function for the watchdog device
263 * @file: file structure
264 * @cmd: command for ioctl
265 * @arg: argument pointer
266 *
267 * returns 0 on success, <0 on failure
268 *
269 * wdrtas_ioctl implements the watchdog API ioctls
270 */
271
272static long wdrtas_ioctl(struct file *file, unsigned int cmd,
273							unsigned long arg)
274{
275	int __user *argp = (void __user *)arg;
276	int i;
277	static const struct watchdog_info wdinfo = {
278		.options = WDRTAS_SUPPORTED_MASK,
279		.firmware_version = 0,
280		.identity = "wdrtas",
281	};
282
283	switch (cmd) {
284	case WDIOC_GETSUPPORT:
285		if (copy_to_user(argp, &wdinfo, sizeof(wdinfo)))
286			return -EFAULT;
287		return 0;
288
289	case WDIOC_GETSTATUS:
290		i = wdrtas_get_status();
291		return put_user(i, argp);
292
293	case WDIOC_GETBOOTSTATUS:
294		i = wdrtas_get_boot_status();
295		return put_user(i, argp);
296
297	case WDIOC_GETTEMP:
298		if (wdrtas_token_get_sensor_state == RTAS_UNKNOWN_SERVICE)
299			return -EOPNOTSUPP;
300
301		i = wdrtas_get_temperature();
302		return put_user(i, argp);
303
304	case WDIOC_SETOPTIONS:
305		if (get_user(i, argp))
306			return -EFAULT;
307		if (i & WDIOS_DISABLECARD)
308			wdrtas_timer_stop();
309		if (i & WDIOS_ENABLECARD) {
310			wdrtas_timer_keepalive();
311			wdrtas_timer_start();
312		}
313		/* not implemented. Done by H8
314		if (i & WDIOS_TEMPPANIC) {
315		} */
316		return 0;
317
318	case WDIOC_KEEPALIVE:
319		wdrtas_timer_keepalive();
320		return 0;
321
322	case WDIOC_SETTIMEOUT:
323		if (get_user(i, argp))
324			return -EFAULT;
325
326		if (wdrtas_set_interval(i))
327			return -EINVAL;
328
329		wdrtas_timer_keepalive();
330
331		if (wdrtas_token_get_sp == RTAS_UNKNOWN_SERVICE)
332			wdrtas_interval = i;
333		else
334			wdrtas_interval = wdrtas_get_interval(i);
335		fallthrough;
336
337	case WDIOC_GETTIMEOUT:
338		return put_user(wdrtas_interval, argp);
339
340	default:
341		return -ENOTTY;
342	}
343}
344
345/**
346 * wdrtas_open - open function of watchdog device
347 * @inode: inode structure
348 * @file: file structure
349 *
350 * returns 0 on success, -EBUSY if the file has been opened already, <0 on
351 * other failures
352 *
353 * function called when watchdog device is opened
354 */
355static int wdrtas_open(struct inode *inode, struct file *file)
356{
357	/* only open once */
358	if (atomic_inc_return(&wdrtas_miscdev_open) > 1) {
359		atomic_dec(&wdrtas_miscdev_open);
360		return -EBUSY;
361	}
362
363	wdrtas_timer_start();
364	wdrtas_timer_keepalive();
365
366	return stream_open(inode, file);
367}
368
369/**
370 * wdrtas_close - close function of watchdog device
371 * @inode: inode structure
372 * @file: file structure
373 *
374 * returns 0 on success
375 *
376 * close function. Always succeeds
377 */
378static int wdrtas_close(struct inode *inode, struct file *file)
379{
380	/* only stop watchdog, if this was announced using 'V' before */
381	if (wdrtas_expect_close == WDRTAS_MAGIC_CHAR)
382		wdrtas_timer_stop();
383	else {
384		pr_warn("got unexpected close. Watchdog not stopped.\n");
385		wdrtas_timer_keepalive();
386	}
387
388	wdrtas_expect_close = 0;
389	atomic_dec(&wdrtas_miscdev_open);
390	return 0;
391}
392
393/**
394 * wdrtas_temp_read - gives back the temperature in fahrenheit
395 * @file: file structure
396 * @buf: user buffer
397 * @count: number of bytes to be read
398 * @ppos: position in file
399 *
400 * returns always 1 or -EFAULT in case of user space copy failures, <0 on
401 * other failures
402 *
403 * wdrtas_temp_read gives the temperature to the users by copying this
404 * value as one byte into the user space buffer. The unit is Fahrenheit...
405 */
406static ssize_t wdrtas_temp_read(struct file *file, char __user *buf,
407		 size_t count, loff_t *ppos)
408{
409	int temperature = 0;
410
411	temperature = wdrtas_get_temperature();
412	if (temperature < 0)
413		return temperature;
414
415	if (copy_to_user(buf, &temperature, 1))
416		return -EFAULT;
417
418	return 1;
419}
420
421/**
422 * wdrtas_temp_open - open function of temperature device
423 * @inode: inode structure
424 * @file: file structure
425 *
426 * returns 0 on success, <0 on failure
427 *
428 * function called when temperature device is opened
429 */
430static int wdrtas_temp_open(struct inode *inode, struct file *file)
431{
432	return stream_open(inode, file);
433}
434
435/**
436 * wdrtas_temp_close - close function of temperature device
437 * @inode: inode structure
438 * @file: file structure
439 *
440 * returns 0 on success
441 *
442 * close function. Always succeeds
443 */
444static int wdrtas_temp_close(struct inode *inode, struct file *file)
445{
446	return 0;
447}
448
449/**
450 * wdrtas_reboot - reboot notifier function
451 * @nb: notifier block structure
452 * @code: reboot code
453 * @ptr: unused
454 *
455 * returns NOTIFY_DONE
456 *
457 * wdrtas_reboot stops the watchdog in case of a reboot
458 */
459static int wdrtas_reboot(struct notifier_block *this,
460					unsigned long code, void *ptr)
461{
462	if (code == SYS_DOWN || code == SYS_HALT)
463		wdrtas_timer_stop();
464
465	return NOTIFY_DONE;
466}
467
468/*** initialization stuff */
469
470static const struct file_operations wdrtas_fops = {
471	.owner		= THIS_MODULE,
472	.llseek		= no_llseek,
473	.write		= wdrtas_write,
474	.unlocked_ioctl	= wdrtas_ioctl,
475	.compat_ioctl	= compat_ptr_ioctl,
476	.open		= wdrtas_open,
477	.release	= wdrtas_close,
478};
479
480static struct miscdevice wdrtas_miscdev = {
481	.minor =	WATCHDOG_MINOR,
482	.name =		"watchdog",
483	.fops =		&wdrtas_fops,
484};
485
486static const struct file_operations wdrtas_temp_fops = {
487	.owner		= THIS_MODULE,
488	.llseek		= no_llseek,
489	.read		= wdrtas_temp_read,
490	.open		= wdrtas_temp_open,
491	.release	= wdrtas_temp_close,
492};
493
494static struct miscdevice wdrtas_tempdev = {
495	.minor =	TEMP_MINOR,
496	.name =		"temperature",
497	.fops =		&wdrtas_temp_fops,
498};
499
500static struct notifier_block wdrtas_notifier = {
501	.notifier_call =	wdrtas_reboot,
502};
503
504/**
505 * wdrtas_get_tokens - reads in RTAS tokens
506 *
507 * returns 0 on success, <0 on failure
508 *
509 * wdrtas_get_tokens reads in the tokens for the RTAS calls used in
510 * this watchdog driver. It tolerates, if "get-sensor-state" and
511 * "ibm,get-system-parameter" are not available.
512 */
513static int wdrtas_get_tokens(void)
514{
515	wdrtas_token_get_sensor_state = rtas_token("get-sensor-state");
516	if (wdrtas_token_get_sensor_state == RTAS_UNKNOWN_SERVICE) {
517		pr_warn("couldn't get token for get-sensor-state. Trying to continue without temperature support.\n");
518	}
519
520	wdrtas_token_get_sp = rtas_token("ibm,get-system-parameter");
521	if (wdrtas_token_get_sp == RTAS_UNKNOWN_SERVICE) {
522		pr_warn("couldn't get token for ibm,get-system-parameter. Trying to continue with a default timeout value of %i seconds.\n",
523			WDRTAS_DEFAULT_INTERVAL);
524	}
525
526	wdrtas_token_set_indicator = rtas_token("set-indicator");
527	if (wdrtas_token_set_indicator == RTAS_UNKNOWN_SERVICE) {
528		pr_err("couldn't get token for set-indicator. Terminating watchdog code.\n");
529		return -EIO;
530	}
531
532	wdrtas_token_event_scan = rtas_token("event-scan");
533	if (wdrtas_token_event_scan == RTAS_UNKNOWN_SERVICE) {
534		pr_err("couldn't get token for event-scan. Terminating watchdog code.\n");
535		return -EIO;
536	}
537
538	return 0;
539}
540
541/**
542 * wdrtas_unregister_devs - unregisters the misc dev handlers
543 *
544 * wdrtas_register_devs unregisters the watchdog and temperature watchdog
545 * misc devs
546 */
547static void wdrtas_unregister_devs(void)
548{
549	misc_deregister(&wdrtas_miscdev);
550	if (wdrtas_token_get_sensor_state != RTAS_UNKNOWN_SERVICE)
551		misc_deregister(&wdrtas_tempdev);
552}
553
554/**
555 * wdrtas_register_devs - registers the misc dev handlers
556 *
557 * returns 0 on success, <0 on failure
558 *
559 * wdrtas_register_devs registers the watchdog and temperature watchdog
560 * misc devs
561 */
562static int wdrtas_register_devs(void)
563{
564	int result;
565
566	result = misc_register(&wdrtas_miscdev);
567	if (result) {
568		pr_err("couldn't register watchdog misc device. Terminating watchdog code.\n");
569		return result;
570	}
571
572	if (wdrtas_token_get_sensor_state != RTAS_UNKNOWN_SERVICE) {
573		result = misc_register(&wdrtas_tempdev);
574		if (result) {
575			pr_warn("couldn't register watchdog temperature misc device. Continuing without temperature support.\n");
576			wdrtas_token_get_sensor_state = RTAS_UNKNOWN_SERVICE;
577		}
578	}
579
580	return 0;
581}
582
583/**
584 * wdrtas_init - init function of the watchdog driver
585 *
586 * returns 0 on success, <0 on failure
587 *
588 * registers the file handlers and the reboot notifier
589 */
590static int __init wdrtas_init(void)
591{
592	if (wdrtas_get_tokens())
593		return -ENODEV;
594
595	if (wdrtas_register_devs())
596		return -ENODEV;
597
598	if (register_reboot_notifier(&wdrtas_notifier)) {
599		pr_err("could not register reboot notifier. Terminating watchdog code.\n");
600		wdrtas_unregister_devs();
601		return -ENODEV;
602	}
603
604	if (wdrtas_token_get_sp == RTAS_UNKNOWN_SERVICE)
605		wdrtas_interval = WDRTAS_DEFAULT_INTERVAL;
606	else
607		wdrtas_interval = wdrtas_get_interval(WDRTAS_DEFAULT_INTERVAL);
608
609	return 0;
610}
611
612/**
613 * wdrtas_exit - exit function of the watchdog driver
614 *
615 * unregisters the file handlers and the reboot notifier
616 */
617static void __exit wdrtas_exit(void)
618{
619	if (!wdrtas_nowayout)
620		wdrtas_timer_stop();
621
622	wdrtas_unregister_devs();
623
624	unregister_reboot_notifier(&wdrtas_notifier);
625}
626
627module_init(wdrtas_init);
628module_exit(wdrtas_exit);
629