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
35 MODULE_AUTHOR("Utz Bacher <utz.bacher@de.ibm.com>");
36 MODULE_DESCRIPTION("RTAS watchdog driver");
37 MODULE_LICENSE("GPL");
38
39 static bool wdrtas_nowayout = WATCHDOG_NOWAYOUT;
40 static atomic_t wdrtas_miscdev_open = ATOMIC_INIT(0);
41 static char wdrtas_expect_close;
42
43 static int wdrtas_interval;
44
45 #define WDRTAS_THERMAL_SENSOR 3
46 static int wdrtas_token_get_sensor_state;
47 #define WDRTAS_SURVEILLANCE_IND 9000
48 static int wdrtas_token_set_indicator;
49 #define WDRTAS_SP_SPI 28
50 static int wdrtas_token_get_sp;
51 static int wdrtas_token_event_scan;
52
53 #define WDRTAS_DEFAULT_INTERVAL 300
54
55 #define WDRTAS_LOGBUFFER_LEN 128
56 static 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
wdrtas_set_interval(int interval)72 static 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 */
wdrtas_get_interval(int fallback_value)103 static 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 */
wdrtas_timer_start(void)133 static 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 */
wdrtas_timer_stop(void)144 static 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 */
wdrtas_timer_keepalive(void)156 static 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 */
wdrtas_get_temperature(void)182 static 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 */
wdrtas_get_status(void)203 static 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 */
wdrtas_get_boot_status(void)214 static 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 */
wdrtas_write(struct file * file,const char __user * buf,size_t len,loff_t * ppos)234 static 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
257 out:
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
wdrtas_ioctl(struct file * file,unsigned int cmd,unsigned long arg)272 static 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 */
wdrtas_open(struct inode * inode,struct file * file)355 static 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 */
wdrtas_close(struct inode * inode,struct file * file)378 static 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 */
wdrtas_temp_read(struct file * file,char __user * buf,size_t count,loff_t * ppos)406 static 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 */
wdrtas_temp_open(struct inode * inode,struct file * file)430 static 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 */
wdrtas_temp_close(struct inode * inode,struct file * file)444 static 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 */
wdrtas_reboot(struct notifier_block * this,unsigned long code,void * ptr)459 static 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
470 static 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
480 static struct miscdevice wdrtas_miscdev = {
481 .minor = WATCHDOG_MINOR,
482 .name = "watchdog",
483 .fops = &wdrtas_fops,
484 };
485
486 static 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
494 static struct miscdevice wdrtas_tempdev = {
495 .minor = TEMP_MINOR,
496 .name = "temperature",
497 .fops = &wdrtas_temp_fops,
498 };
499
500 static 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 */
wdrtas_get_tokens(void)513 static 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 */
wdrtas_unregister_devs(void)547 static 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 */
wdrtas_register_devs(void)562 static 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 */
wdrtas_init(void)590 static 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 */
wdrtas_exit(void)617 static 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
627 module_init(wdrtas_init);
628 module_exit(wdrtas_exit);
629
