*: convert stream-like files from nonseekable_open -> stream_open
[sfrench/cifs-2.6.git] / drivers / watchdog / watchdog_dev.c
1 /*
2  *      watchdog_dev.c
3  *
4  *      (c) Copyright 2008-2011 Alan Cox <alan@lxorguk.ukuu.org.uk>,
5  *                                              All Rights Reserved.
6  *
7  *      (c) Copyright 2008-2011 Wim Van Sebroeck <wim@iguana.be>.
8  *
9  *
10  *      This source code is part of the generic code that can be used
11  *      by all the watchdog timer drivers.
12  *
13  *      This part of the generic code takes care of the following
14  *      misc device: /dev/watchdog.
15  *
16  *      Based on source code of the following authors:
17  *        Matt Domsch <Matt_Domsch@dell.com>,
18  *        Rob Radez <rob@osinvestor.com>,
19  *        Rusty Lynch <rusty@linux.co.intel.com>
20  *        Satyam Sharma <satyam@infradead.org>
21  *        Randy Dunlap <randy.dunlap@oracle.com>
22  *
23  *      This program is free software; you can redistribute it and/or
24  *      modify it under the terms of the GNU General Public License
25  *      as published by the Free Software Foundation; either version
26  *      2 of the License, or (at your option) any later version.
27  *
28  *      Neither Alan Cox, CymruNet Ltd., Wim Van Sebroeck nor Iguana vzw.
29  *      admit liability nor provide warranty for any of this software.
30  *      This material is provided "AS-IS" and at no charge.
31  */
32
33 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
34
35 #include <linux/cdev.h>         /* For character device */
36 #include <linux/errno.h>        /* For the -ENODEV/... values */
37 #include <linux/fs.h>           /* For file operations */
38 #include <linux/init.h>         /* For __init/__exit/... */
39 #include <linux/hrtimer.h>      /* For hrtimers */
40 #include <linux/kernel.h>       /* For printk/panic/... */
41 #include <linux/kref.h>         /* For data references */
42 #include <linux/kthread.h>      /* For kthread_work */
43 #include <linux/miscdevice.h>   /* For handling misc devices */
44 #include <linux/module.h>       /* For module stuff/... */
45 #include <linux/mutex.h>        /* For mutexes */
46 #include <linux/reboot.h>       /* For reboot notifier */
47 #include <linux/slab.h>         /* For memory functions */
48 #include <linux/types.h>        /* For standard types (like size_t) */
49 #include <linux/watchdog.h>     /* For watchdog specific items */
50 #include <linux/uaccess.h>      /* For copy_to_user/put_user/... */
51
52 #include <uapi/linux/sched/types.h>     /* For struct sched_param */
53
54 #include "watchdog_core.h"
55 #include "watchdog_pretimeout.h"
56
57 /*
58  * struct watchdog_core_data - watchdog core internal data
59  * @kref:       Reference count.
60  * @cdev:       The watchdog's Character device.
61  * @wdd:        Pointer to watchdog device.
62  * @lock:       Lock for watchdog core.
63  * @status:     Watchdog core internal status bits.
64  */
65 struct watchdog_core_data {
66         struct kref kref;
67         struct cdev cdev;
68         struct watchdog_device *wdd;
69         struct mutex lock;
70         ktime_t last_keepalive;
71         ktime_t last_hw_keepalive;
72         struct hrtimer timer;
73         struct kthread_work work;
74         unsigned long status;           /* Internal status bits */
75 #define _WDOG_DEV_OPEN          0       /* Opened ? */
76 #define _WDOG_ALLOW_RELEASE     1       /* Did we receive the magic char ? */
77 #define _WDOG_KEEPALIVE         2       /* Did we receive a keepalive ? */
78 };
79
80 /* the dev_t structure to store the dynamically allocated watchdog devices */
81 static dev_t watchdog_devt;
82 /* Reference to watchdog device behind /dev/watchdog */
83 static struct watchdog_core_data *old_wd_data;
84
85 static struct kthread_worker *watchdog_kworker;
86
87 static bool handle_boot_enabled =
88         IS_ENABLED(CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED);
89
90 static inline bool watchdog_need_worker(struct watchdog_device *wdd)
91 {
92         /* All variables in milli-seconds */
93         unsigned int hm = wdd->max_hw_heartbeat_ms;
94         unsigned int t = wdd->timeout * 1000;
95
96         /*
97          * A worker to generate heartbeat requests is needed if all of the
98          * following conditions are true.
99          * - Userspace activated the watchdog.
100          * - The driver provided a value for the maximum hardware timeout, and
101          *   thus is aware that the framework supports generating heartbeat
102          *   requests.
103          * - Userspace requests a longer timeout than the hardware can handle.
104          *
105          * Alternatively, if userspace has not opened the watchdog
106          * device, we take care of feeding the watchdog if it is
107          * running.
108          */
109         return (hm && watchdog_active(wdd) && t > hm) ||
110                 (t && !watchdog_active(wdd) && watchdog_hw_running(wdd));
111 }
112
113 static ktime_t watchdog_next_keepalive(struct watchdog_device *wdd)
114 {
115         struct watchdog_core_data *wd_data = wdd->wd_data;
116         unsigned int timeout_ms = wdd->timeout * 1000;
117         ktime_t keepalive_interval;
118         ktime_t last_heartbeat, latest_heartbeat;
119         ktime_t virt_timeout;
120         unsigned int hw_heartbeat_ms;
121
122         virt_timeout = ktime_add(wd_data->last_keepalive,
123                                  ms_to_ktime(timeout_ms));
124         hw_heartbeat_ms = min_not_zero(timeout_ms, wdd->max_hw_heartbeat_ms);
125         keepalive_interval = ms_to_ktime(hw_heartbeat_ms / 2);
126
127         if (!watchdog_active(wdd))
128                 return keepalive_interval;
129
130         /*
131          * To ensure that the watchdog times out wdd->timeout seconds
132          * after the most recent ping from userspace, the last
133          * worker ping has to come in hw_heartbeat_ms before this timeout.
134          */
135         last_heartbeat = ktime_sub(virt_timeout, ms_to_ktime(hw_heartbeat_ms));
136         latest_heartbeat = ktime_sub(last_heartbeat, ktime_get());
137         if (ktime_before(latest_heartbeat, keepalive_interval))
138                 return latest_heartbeat;
139         return keepalive_interval;
140 }
141
142 static inline void watchdog_update_worker(struct watchdog_device *wdd)
143 {
144         struct watchdog_core_data *wd_data = wdd->wd_data;
145
146         if (watchdog_need_worker(wdd)) {
147                 ktime_t t = watchdog_next_keepalive(wdd);
148
149                 if (t > 0)
150                         hrtimer_start(&wd_data->timer, t, HRTIMER_MODE_REL);
151         } else {
152                 hrtimer_cancel(&wd_data->timer);
153         }
154 }
155
156 static int __watchdog_ping(struct watchdog_device *wdd)
157 {
158         struct watchdog_core_data *wd_data = wdd->wd_data;
159         ktime_t earliest_keepalive, now;
160         int err;
161
162         earliest_keepalive = ktime_add(wd_data->last_hw_keepalive,
163                                        ms_to_ktime(wdd->min_hw_heartbeat_ms));
164         now = ktime_get();
165
166         if (ktime_after(earliest_keepalive, now)) {
167                 hrtimer_start(&wd_data->timer,
168                               ktime_sub(earliest_keepalive, now),
169                               HRTIMER_MODE_REL);
170                 return 0;
171         }
172
173         wd_data->last_hw_keepalive = now;
174
175         if (wdd->ops->ping)
176                 err = wdd->ops->ping(wdd);  /* ping the watchdog */
177         else
178                 err = wdd->ops->start(wdd); /* restart watchdog */
179
180         watchdog_update_worker(wdd);
181
182         return err;
183 }
184
185 /*
186  *      watchdog_ping: ping the watchdog.
187  *      @wdd: the watchdog device to ping
188  *
189  *      The caller must hold wd_data->lock.
190  *
191  *      If the watchdog has no own ping operation then it needs to be
192  *      restarted via the start operation. This wrapper function does
193  *      exactly that.
194  *      We only ping when the watchdog device is running.
195  */
196
197 static int watchdog_ping(struct watchdog_device *wdd)
198 {
199         struct watchdog_core_data *wd_data = wdd->wd_data;
200
201         if (!watchdog_active(wdd) && !watchdog_hw_running(wdd))
202                 return 0;
203
204         set_bit(_WDOG_KEEPALIVE, &wd_data->status);
205
206         wd_data->last_keepalive = ktime_get();
207         return __watchdog_ping(wdd);
208 }
209
210 static bool watchdog_worker_should_ping(struct watchdog_core_data *wd_data)
211 {
212         struct watchdog_device *wdd = wd_data->wdd;
213
214         return wdd && (watchdog_active(wdd) || watchdog_hw_running(wdd));
215 }
216
217 static void watchdog_ping_work(struct kthread_work *work)
218 {
219         struct watchdog_core_data *wd_data;
220
221         wd_data = container_of(work, struct watchdog_core_data, work);
222
223         mutex_lock(&wd_data->lock);
224         if (watchdog_worker_should_ping(wd_data))
225                 __watchdog_ping(wd_data->wdd);
226         mutex_unlock(&wd_data->lock);
227 }
228
229 static enum hrtimer_restart watchdog_timer_expired(struct hrtimer *timer)
230 {
231         struct watchdog_core_data *wd_data;
232
233         wd_data = container_of(timer, struct watchdog_core_data, timer);
234
235         kthread_queue_work(watchdog_kworker, &wd_data->work);
236         return HRTIMER_NORESTART;
237 }
238
239 /*
240  *      watchdog_start: wrapper to start the watchdog.
241  *      @wdd: the watchdog device to start
242  *
243  *      The caller must hold wd_data->lock.
244  *
245  *      Start the watchdog if it is not active and mark it active.
246  *      This function returns zero on success or a negative errno code for
247  *      failure.
248  */
249
250 static int watchdog_start(struct watchdog_device *wdd)
251 {
252         struct watchdog_core_data *wd_data = wdd->wd_data;
253         ktime_t started_at;
254         int err;
255
256         if (watchdog_active(wdd))
257                 return 0;
258
259         set_bit(_WDOG_KEEPALIVE, &wd_data->status);
260
261         started_at = ktime_get();
262         if (watchdog_hw_running(wdd) && wdd->ops->ping)
263                 err = wdd->ops->ping(wdd);
264         else
265                 err = wdd->ops->start(wdd);
266         if (err == 0) {
267                 set_bit(WDOG_ACTIVE, &wdd->status);
268                 wd_data->last_keepalive = started_at;
269                 watchdog_update_worker(wdd);
270         }
271
272         return err;
273 }
274
275 /*
276  *      watchdog_stop: wrapper to stop the watchdog.
277  *      @wdd: the watchdog device to stop
278  *
279  *      The caller must hold wd_data->lock.
280  *
281  *      Stop the watchdog if it is still active and unmark it active.
282  *      This function returns zero on success or a negative errno code for
283  *      failure.
284  *      If the 'nowayout' feature was set, the watchdog cannot be stopped.
285  */
286
287 static int watchdog_stop(struct watchdog_device *wdd)
288 {
289         int err = 0;
290
291         if (!watchdog_active(wdd))
292                 return 0;
293
294         if (test_bit(WDOG_NO_WAY_OUT, &wdd->status)) {
295                 pr_info("watchdog%d: nowayout prevents watchdog being stopped!\n",
296                         wdd->id);
297                 return -EBUSY;
298         }
299
300         if (wdd->ops->stop) {
301                 clear_bit(WDOG_HW_RUNNING, &wdd->status);
302                 err = wdd->ops->stop(wdd);
303         } else {
304                 set_bit(WDOG_HW_RUNNING, &wdd->status);
305         }
306
307         if (err == 0) {
308                 clear_bit(WDOG_ACTIVE, &wdd->status);
309                 watchdog_update_worker(wdd);
310         }
311
312         return err;
313 }
314
315 /*
316  *      watchdog_get_status: wrapper to get the watchdog status
317  *      @wdd: the watchdog device to get the status from
318  *
319  *      The caller must hold wd_data->lock.
320  *
321  *      Get the watchdog's status flags.
322  */
323
324 static unsigned int watchdog_get_status(struct watchdog_device *wdd)
325 {
326         struct watchdog_core_data *wd_data = wdd->wd_data;
327         unsigned int status;
328
329         if (wdd->ops->status)
330                 status = wdd->ops->status(wdd);
331         else
332                 status = wdd->bootstatus & (WDIOF_CARDRESET |
333                                             WDIOF_OVERHEAT |
334                                             WDIOF_FANFAULT |
335                                             WDIOF_EXTERN1 |
336                                             WDIOF_EXTERN2 |
337                                             WDIOF_POWERUNDER |
338                                             WDIOF_POWEROVER);
339
340         if (test_bit(_WDOG_ALLOW_RELEASE, &wd_data->status))
341                 status |= WDIOF_MAGICCLOSE;
342
343         if (test_and_clear_bit(_WDOG_KEEPALIVE, &wd_data->status))
344                 status |= WDIOF_KEEPALIVEPING;
345
346         return status;
347 }
348
349 /*
350  *      watchdog_set_timeout: set the watchdog timer timeout
351  *      @wdd: the watchdog device to set the timeout for
352  *      @timeout: timeout to set in seconds
353  *
354  *      The caller must hold wd_data->lock.
355  */
356
357 static int watchdog_set_timeout(struct watchdog_device *wdd,
358                                                         unsigned int timeout)
359 {
360         int err = 0;
361
362         if (!(wdd->info->options & WDIOF_SETTIMEOUT))
363                 return -EOPNOTSUPP;
364
365         if (watchdog_timeout_invalid(wdd, timeout))
366                 return -EINVAL;
367
368         if (wdd->ops->set_timeout) {
369                 err = wdd->ops->set_timeout(wdd, timeout);
370         } else {
371                 wdd->timeout = timeout;
372                 /* Disable pretimeout if it doesn't fit the new timeout */
373                 if (wdd->pretimeout >= wdd->timeout)
374                         wdd->pretimeout = 0;
375         }
376
377         watchdog_update_worker(wdd);
378
379         return err;
380 }
381
382 /*
383  *      watchdog_set_pretimeout: set the watchdog timer pretimeout
384  *      @wdd: the watchdog device to set the timeout for
385  *      @timeout: pretimeout to set in seconds
386  */
387
388 static int watchdog_set_pretimeout(struct watchdog_device *wdd,
389                                    unsigned int timeout)
390 {
391         int err = 0;
392
393         if (!(wdd->info->options & WDIOF_PRETIMEOUT))
394                 return -EOPNOTSUPP;
395
396         if (watchdog_pretimeout_invalid(wdd, timeout))
397                 return -EINVAL;
398
399         if (wdd->ops->set_pretimeout)
400                 err = wdd->ops->set_pretimeout(wdd, timeout);
401         else
402                 wdd->pretimeout = timeout;
403
404         return err;
405 }
406
407 /*
408  *      watchdog_get_timeleft: wrapper to get the time left before a reboot
409  *      @wdd: the watchdog device to get the remaining time from
410  *      @timeleft: the time that's left
411  *
412  *      The caller must hold wd_data->lock.
413  *
414  *      Get the time before a watchdog will reboot (if not pinged).
415  */
416
417 static int watchdog_get_timeleft(struct watchdog_device *wdd,
418                                                         unsigned int *timeleft)
419 {
420         *timeleft = 0;
421
422         if (!wdd->ops->get_timeleft)
423                 return -EOPNOTSUPP;
424
425         *timeleft = wdd->ops->get_timeleft(wdd);
426
427         return 0;
428 }
429
430 #ifdef CONFIG_WATCHDOG_SYSFS
431 static ssize_t nowayout_show(struct device *dev, struct device_attribute *attr,
432                                 char *buf)
433 {
434         struct watchdog_device *wdd = dev_get_drvdata(dev);
435
436         return sprintf(buf, "%d\n", !!test_bit(WDOG_NO_WAY_OUT, &wdd->status));
437 }
438 static DEVICE_ATTR_RO(nowayout);
439
440 static ssize_t status_show(struct device *dev, struct device_attribute *attr,
441                                 char *buf)
442 {
443         struct watchdog_device *wdd = dev_get_drvdata(dev);
444         struct watchdog_core_data *wd_data = wdd->wd_data;
445         unsigned int status;
446
447         mutex_lock(&wd_data->lock);
448         status = watchdog_get_status(wdd);
449         mutex_unlock(&wd_data->lock);
450
451         return sprintf(buf, "0x%x\n", status);
452 }
453 static DEVICE_ATTR_RO(status);
454
455 static ssize_t bootstatus_show(struct device *dev,
456                                 struct device_attribute *attr, char *buf)
457 {
458         struct watchdog_device *wdd = dev_get_drvdata(dev);
459
460         return sprintf(buf, "%u\n", wdd->bootstatus);
461 }
462 static DEVICE_ATTR_RO(bootstatus);
463
464 static ssize_t timeleft_show(struct device *dev, struct device_attribute *attr,
465                                 char *buf)
466 {
467         struct watchdog_device *wdd = dev_get_drvdata(dev);
468         struct watchdog_core_data *wd_data = wdd->wd_data;
469         ssize_t status;
470         unsigned int val;
471
472         mutex_lock(&wd_data->lock);
473         status = watchdog_get_timeleft(wdd, &val);
474         mutex_unlock(&wd_data->lock);
475         if (!status)
476                 status = sprintf(buf, "%u\n", val);
477
478         return status;
479 }
480 static DEVICE_ATTR_RO(timeleft);
481
482 static ssize_t timeout_show(struct device *dev, struct device_attribute *attr,
483                                 char *buf)
484 {
485         struct watchdog_device *wdd = dev_get_drvdata(dev);
486
487         return sprintf(buf, "%u\n", wdd->timeout);
488 }
489 static DEVICE_ATTR_RO(timeout);
490
491 static ssize_t pretimeout_show(struct device *dev,
492                                struct device_attribute *attr, char *buf)
493 {
494         struct watchdog_device *wdd = dev_get_drvdata(dev);
495
496         return sprintf(buf, "%u\n", wdd->pretimeout);
497 }
498 static DEVICE_ATTR_RO(pretimeout);
499
500 static ssize_t identity_show(struct device *dev, struct device_attribute *attr,
501                                 char *buf)
502 {
503         struct watchdog_device *wdd = dev_get_drvdata(dev);
504
505         return sprintf(buf, "%s\n", wdd->info->identity);
506 }
507 static DEVICE_ATTR_RO(identity);
508
509 static ssize_t state_show(struct device *dev, struct device_attribute *attr,
510                                 char *buf)
511 {
512         struct watchdog_device *wdd = dev_get_drvdata(dev);
513
514         if (watchdog_active(wdd))
515                 return sprintf(buf, "active\n");
516
517         return sprintf(buf, "inactive\n");
518 }
519 static DEVICE_ATTR_RO(state);
520
521 static ssize_t pretimeout_available_governors_show(struct device *dev,
522                                    struct device_attribute *attr, char *buf)
523 {
524         return watchdog_pretimeout_available_governors_get(buf);
525 }
526 static DEVICE_ATTR_RO(pretimeout_available_governors);
527
528 static ssize_t pretimeout_governor_show(struct device *dev,
529                                         struct device_attribute *attr,
530                                         char *buf)
531 {
532         struct watchdog_device *wdd = dev_get_drvdata(dev);
533
534         return watchdog_pretimeout_governor_get(wdd, buf);
535 }
536
537 static ssize_t pretimeout_governor_store(struct device *dev,
538                                          struct device_attribute *attr,
539                                          const char *buf, size_t count)
540 {
541         struct watchdog_device *wdd = dev_get_drvdata(dev);
542         int ret = watchdog_pretimeout_governor_set(wdd, buf);
543
544         if (!ret)
545                 ret = count;
546
547         return ret;
548 }
549 static DEVICE_ATTR_RW(pretimeout_governor);
550
551 static umode_t wdt_is_visible(struct kobject *kobj, struct attribute *attr,
552                                 int n)
553 {
554         struct device *dev = container_of(kobj, struct device, kobj);
555         struct watchdog_device *wdd = dev_get_drvdata(dev);
556         umode_t mode = attr->mode;
557
558         if (attr == &dev_attr_timeleft.attr && !wdd->ops->get_timeleft)
559                 mode = 0;
560         else if (attr == &dev_attr_pretimeout.attr &&
561                  !(wdd->info->options & WDIOF_PRETIMEOUT))
562                 mode = 0;
563         else if ((attr == &dev_attr_pretimeout_governor.attr ||
564                   attr == &dev_attr_pretimeout_available_governors.attr) &&
565                  (!(wdd->info->options & WDIOF_PRETIMEOUT) ||
566                   !IS_ENABLED(CONFIG_WATCHDOG_PRETIMEOUT_GOV)))
567                 mode = 0;
568
569         return mode;
570 }
571 static struct attribute *wdt_attrs[] = {
572         &dev_attr_state.attr,
573         &dev_attr_identity.attr,
574         &dev_attr_timeout.attr,
575         &dev_attr_pretimeout.attr,
576         &dev_attr_timeleft.attr,
577         &dev_attr_bootstatus.attr,
578         &dev_attr_status.attr,
579         &dev_attr_nowayout.attr,
580         &dev_attr_pretimeout_governor.attr,
581         &dev_attr_pretimeout_available_governors.attr,
582         NULL,
583 };
584
585 static const struct attribute_group wdt_group = {
586         .attrs = wdt_attrs,
587         .is_visible = wdt_is_visible,
588 };
589 __ATTRIBUTE_GROUPS(wdt);
590 #else
591 #define wdt_groups      NULL
592 #endif
593
594 /*
595  *      watchdog_ioctl_op: call the watchdog drivers ioctl op if defined
596  *      @wdd: the watchdog device to do the ioctl on
597  *      @cmd: watchdog command
598  *      @arg: argument pointer
599  *
600  *      The caller must hold wd_data->lock.
601  */
602
603 static int watchdog_ioctl_op(struct watchdog_device *wdd, unsigned int cmd,
604                                                         unsigned long arg)
605 {
606         if (!wdd->ops->ioctl)
607                 return -ENOIOCTLCMD;
608
609         return wdd->ops->ioctl(wdd, cmd, arg);
610 }
611
612 /*
613  *      watchdog_write: writes to the watchdog.
614  *      @file: file from VFS
615  *      @data: user address of data
616  *      @len: length of data
617  *      @ppos: pointer to the file offset
618  *
619  *      A write to a watchdog device is defined as a keepalive ping.
620  *      Writing the magic 'V' sequence allows the next close to turn
621  *      off the watchdog (if 'nowayout' is not set).
622  */
623
624 static ssize_t watchdog_write(struct file *file, const char __user *data,
625                                                 size_t len, loff_t *ppos)
626 {
627         struct watchdog_core_data *wd_data = file->private_data;
628         struct watchdog_device *wdd;
629         int err;
630         size_t i;
631         char c;
632
633         if (len == 0)
634                 return 0;
635
636         /*
637          * Note: just in case someone wrote the magic character
638          * five months ago...
639          */
640         clear_bit(_WDOG_ALLOW_RELEASE, &wd_data->status);
641
642         /* scan to see whether or not we got the magic character */
643         for (i = 0; i != len; i++) {
644                 if (get_user(c, data + i))
645                         return -EFAULT;
646                 if (c == 'V')
647                         set_bit(_WDOG_ALLOW_RELEASE, &wd_data->status);
648         }
649
650         /* someone wrote to us, so we send the watchdog a keepalive ping */
651
652         err = -ENODEV;
653         mutex_lock(&wd_data->lock);
654         wdd = wd_data->wdd;
655         if (wdd)
656                 err = watchdog_ping(wdd);
657         mutex_unlock(&wd_data->lock);
658
659         if (err < 0)
660                 return err;
661
662         return len;
663 }
664
665 /*
666  *      watchdog_ioctl: handle the different ioctl's for the watchdog device.
667  *      @file: file handle to the device
668  *      @cmd: watchdog command
669  *      @arg: argument pointer
670  *
671  *      The watchdog API defines a common set of functions for all watchdogs
672  *      according to their available features.
673  */
674
675 static long watchdog_ioctl(struct file *file, unsigned int cmd,
676                                                         unsigned long arg)
677 {
678         struct watchdog_core_data *wd_data = file->private_data;
679         void __user *argp = (void __user *)arg;
680         struct watchdog_device *wdd;
681         int __user *p = argp;
682         unsigned int val;
683         int err;
684
685         mutex_lock(&wd_data->lock);
686
687         wdd = wd_data->wdd;
688         if (!wdd) {
689                 err = -ENODEV;
690                 goto out_ioctl;
691         }
692
693         err = watchdog_ioctl_op(wdd, cmd, arg);
694         if (err != -ENOIOCTLCMD)
695                 goto out_ioctl;
696
697         switch (cmd) {
698         case WDIOC_GETSUPPORT:
699                 err = copy_to_user(argp, wdd->info,
700                         sizeof(struct watchdog_info)) ? -EFAULT : 0;
701                 break;
702         case WDIOC_GETSTATUS:
703                 val = watchdog_get_status(wdd);
704                 err = put_user(val, p);
705                 break;
706         case WDIOC_GETBOOTSTATUS:
707                 err = put_user(wdd->bootstatus, p);
708                 break;
709         case WDIOC_SETOPTIONS:
710                 if (get_user(val, p)) {
711                         err = -EFAULT;
712                         break;
713                 }
714                 if (val & WDIOS_DISABLECARD) {
715                         err = watchdog_stop(wdd);
716                         if (err < 0)
717                                 break;
718                 }
719                 if (val & WDIOS_ENABLECARD)
720                         err = watchdog_start(wdd);
721                 break;
722         case WDIOC_KEEPALIVE:
723                 if (!(wdd->info->options & WDIOF_KEEPALIVEPING)) {
724                         err = -EOPNOTSUPP;
725                         break;
726                 }
727                 err = watchdog_ping(wdd);
728                 break;
729         case WDIOC_SETTIMEOUT:
730                 if (get_user(val, p)) {
731                         err = -EFAULT;
732                         break;
733                 }
734                 err = watchdog_set_timeout(wdd, val);
735                 if (err < 0)
736                         break;
737                 /* If the watchdog is active then we send a keepalive ping
738                  * to make sure that the watchdog keep's running (and if
739                  * possible that it takes the new timeout) */
740                 err = watchdog_ping(wdd);
741                 if (err < 0)
742                         break;
743                 /* fall through */
744         case WDIOC_GETTIMEOUT:
745                 /* timeout == 0 means that we don't know the timeout */
746                 if (wdd->timeout == 0) {
747                         err = -EOPNOTSUPP;
748                         break;
749                 }
750                 err = put_user(wdd->timeout, p);
751                 break;
752         case WDIOC_GETTIMELEFT:
753                 err = watchdog_get_timeleft(wdd, &val);
754                 if (err < 0)
755                         break;
756                 err = put_user(val, p);
757                 break;
758         case WDIOC_SETPRETIMEOUT:
759                 if (get_user(val, p)) {
760                         err = -EFAULT;
761                         break;
762                 }
763                 err = watchdog_set_pretimeout(wdd, val);
764                 break;
765         case WDIOC_GETPRETIMEOUT:
766                 err = put_user(wdd->pretimeout, p);
767                 break;
768         default:
769                 err = -ENOTTY;
770                 break;
771         }
772
773 out_ioctl:
774         mutex_unlock(&wd_data->lock);
775         return err;
776 }
777
778 /*
779  *      watchdog_open: open the /dev/watchdog* devices.
780  *      @inode: inode of device
781  *      @file: file handle to device
782  *
783  *      When the /dev/watchdog* device gets opened, we start the watchdog.
784  *      Watch out: the /dev/watchdog device is single open, so we make sure
785  *      it can only be opened once.
786  */
787
788 static int watchdog_open(struct inode *inode, struct file *file)
789 {
790         struct watchdog_core_data *wd_data;
791         struct watchdog_device *wdd;
792         bool hw_running;
793         int err;
794
795         /* Get the corresponding watchdog device */
796         if (imajor(inode) == MISC_MAJOR)
797                 wd_data = old_wd_data;
798         else
799                 wd_data = container_of(inode->i_cdev, struct watchdog_core_data,
800                                        cdev);
801
802         /* the watchdog is single open! */
803         if (test_and_set_bit(_WDOG_DEV_OPEN, &wd_data->status))
804                 return -EBUSY;
805
806         wdd = wd_data->wdd;
807
808         /*
809          * If the /dev/watchdog device is open, we don't want the module
810          * to be unloaded.
811          */
812         hw_running = watchdog_hw_running(wdd);
813         if (!hw_running && !try_module_get(wdd->ops->owner)) {
814                 err = -EBUSY;
815                 goto out_clear;
816         }
817
818         err = watchdog_start(wdd);
819         if (err < 0)
820                 goto out_mod;
821
822         file->private_data = wd_data;
823
824         if (!hw_running)
825                 kref_get(&wd_data->kref);
826
827         /* dev/watchdog is a virtual (and thus non-seekable) filesystem */
828         return stream_open(inode, file);
829
830 out_mod:
831         module_put(wd_data->wdd->ops->owner);
832 out_clear:
833         clear_bit(_WDOG_DEV_OPEN, &wd_data->status);
834         return err;
835 }
836
837 static void watchdog_core_data_release(struct kref *kref)
838 {
839         struct watchdog_core_data *wd_data;
840
841         wd_data = container_of(kref, struct watchdog_core_data, kref);
842
843         kfree(wd_data);
844 }
845
846 /*
847  *      watchdog_release: release the watchdog device.
848  *      @inode: inode of device
849  *      @file: file handle to device
850  *
851  *      This is the code for when /dev/watchdog gets closed. We will only
852  *      stop the watchdog when we have received the magic char (and nowayout
853  *      was not set), else the watchdog will keep running.
854  */
855
856 static int watchdog_release(struct inode *inode, struct file *file)
857 {
858         struct watchdog_core_data *wd_data = file->private_data;
859         struct watchdog_device *wdd;
860         int err = -EBUSY;
861         bool running;
862
863         mutex_lock(&wd_data->lock);
864
865         wdd = wd_data->wdd;
866         if (!wdd)
867                 goto done;
868
869         /*
870          * We only stop the watchdog if we received the magic character
871          * or if WDIOF_MAGICCLOSE is not set. If nowayout was set then
872          * watchdog_stop will fail.
873          */
874         if (!test_bit(WDOG_ACTIVE, &wdd->status))
875                 err = 0;
876         else if (test_and_clear_bit(_WDOG_ALLOW_RELEASE, &wd_data->status) ||
877                  !(wdd->info->options & WDIOF_MAGICCLOSE))
878                 err = watchdog_stop(wdd);
879
880         /* If the watchdog was not stopped, send a keepalive ping */
881         if (err < 0) {
882                 pr_crit("watchdog%d: watchdog did not stop!\n", wdd->id);
883                 watchdog_ping(wdd);
884         }
885
886         watchdog_update_worker(wdd);
887
888         /* make sure that /dev/watchdog can be re-opened */
889         clear_bit(_WDOG_DEV_OPEN, &wd_data->status);
890
891 done:
892         running = wdd && watchdog_hw_running(wdd);
893         mutex_unlock(&wd_data->lock);
894         /*
895          * Allow the owner module to be unloaded again unless the watchdog
896          * is still running. If the watchdog is still running, it can not
897          * be stopped, and its driver must not be unloaded.
898          */
899         if (!running) {
900                 module_put(wd_data->cdev.owner);
901                 kref_put(&wd_data->kref, watchdog_core_data_release);
902         }
903         return 0;
904 }
905
906 static const struct file_operations watchdog_fops = {
907         .owner          = THIS_MODULE,
908         .write          = watchdog_write,
909         .unlocked_ioctl = watchdog_ioctl,
910         .open           = watchdog_open,
911         .release        = watchdog_release,
912 };
913
914 static struct miscdevice watchdog_miscdev = {
915         .minor          = WATCHDOG_MINOR,
916         .name           = "watchdog",
917         .fops           = &watchdog_fops,
918 };
919
920 /*
921  *      watchdog_cdev_register: register watchdog character device
922  *      @wdd: watchdog device
923  *      @devno: character device number
924  *
925  *      Register a watchdog character device including handling the legacy
926  *      /dev/watchdog node. /dev/watchdog is actually a miscdevice and
927  *      thus we set it up like that.
928  */
929
930 static int watchdog_cdev_register(struct watchdog_device *wdd, dev_t devno)
931 {
932         struct watchdog_core_data *wd_data;
933         int err;
934
935         wd_data = kzalloc(sizeof(struct watchdog_core_data), GFP_KERNEL);
936         if (!wd_data)
937                 return -ENOMEM;
938         kref_init(&wd_data->kref);
939         mutex_init(&wd_data->lock);
940
941         wd_data->wdd = wdd;
942         wdd->wd_data = wd_data;
943
944         if (IS_ERR_OR_NULL(watchdog_kworker))
945                 return -ENODEV;
946
947         kthread_init_work(&wd_data->work, watchdog_ping_work);
948         hrtimer_init(&wd_data->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
949         wd_data->timer.function = watchdog_timer_expired;
950
951         if (wdd->id == 0) {
952                 old_wd_data = wd_data;
953                 watchdog_miscdev.parent = wdd->parent;
954                 err = misc_register(&watchdog_miscdev);
955                 if (err != 0) {
956                         pr_err("%s: cannot register miscdev on minor=%d (err=%d).\n",
957                                 wdd->info->identity, WATCHDOG_MINOR, err);
958                         if (err == -EBUSY)
959                                 pr_err("%s: a legacy watchdog module is probably present.\n",
960                                         wdd->info->identity);
961                         old_wd_data = NULL;
962                         kfree(wd_data);
963                         return err;
964                 }
965         }
966
967         /* Fill in the data structures */
968         cdev_init(&wd_data->cdev, &watchdog_fops);
969         wd_data->cdev.owner = wdd->ops->owner;
970
971         /* Add the device */
972         err = cdev_add(&wd_data->cdev, devno, 1);
973         if (err) {
974                 pr_err("watchdog%d unable to add device %d:%d\n",
975                         wdd->id,  MAJOR(watchdog_devt), wdd->id);
976                 if (wdd->id == 0) {
977                         misc_deregister(&watchdog_miscdev);
978                         old_wd_data = NULL;
979                         kref_put(&wd_data->kref, watchdog_core_data_release);
980                 }
981                 return err;
982         }
983
984         /* Record time of most recent heartbeat as 'just before now'. */
985         wd_data->last_hw_keepalive = ktime_sub(ktime_get(), 1);
986
987         /*
988          * If the watchdog is running, prevent its driver from being unloaded,
989          * and schedule an immediate ping.
990          */
991         if (watchdog_hw_running(wdd)) {
992                 __module_get(wdd->ops->owner);
993                 kref_get(&wd_data->kref);
994                 if (handle_boot_enabled)
995                         hrtimer_start(&wd_data->timer, 0, HRTIMER_MODE_REL);
996                 else
997                         pr_info("watchdog%d running and kernel based pre-userspace handler disabled\n",
998                                 wdd->id);
999         }
1000
1001         return 0;
1002 }
1003
1004 /*
1005  *      watchdog_cdev_unregister: unregister watchdog character device
1006  *      @watchdog: watchdog device
1007  *
1008  *      Unregister watchdog character device and if needed the legacy
1009  *      /dev/watchdog device.
1010  */
1011
1012 static void watchdog_cdev_unregister(struct watchdog_device *wdd)
1013 {
1014         struct watchdog_core_data *wd_data = wdd->wd_data;
1015
1016         cdev_del(&wd_data->cdev);
1017         if (wdd->id == 0) {
1018                 misc_deregister(&watchdog_miscdev);
1019                 old_wd_data = NULL;
1020         }
1021
1022         if (watchdog_active(wdd) &&
1023             test_bit(WDOG_STOP_ON_UNREGISTER, &wdd->status)) {
1024                 watchdog_stop(wdd);
1025         }
1026
1027         mutex_lock(&wd_data->lock);
1028         wd_data->wdd = NULL;
1029         wdd->wd_data = NULL;
1030         mutex_unlock(&wd_data->lock);
1031
1032         hrtimer_cancel(&wd_data->timer);
1033         kthread_cancel_work_sync(&wd_data->work);
1034
1035         kref_put(&wd_data->kref, watchdog_core_data_release);
1036 }
1037
1038 static struct class watchdog_class = {
1039         .name =         "watchdog",
1040         .owner =        THIS_MODULE,
1041         .dev_groups =   wdt_groups,
1042 };
1043
1044 static int watchdog_reboot_notifier(struct notifier_block *nb,
1045                                     unsigned long code, void *data)
1046 {
1047         struct watchdog_device *wdd;
1048
1049         wdd = container_of(nb, struct watchdog_device, reboot_nb);
1050         if (code == SYS_DOWN || code == SYS_HALT) {
1051                 if (watchdog_active(wdd)) {
1052                         int ret;
1053
1054                         ret = wdd->ops->stop(wdd);
1055                         if (ret)
1056                                 return NOTIFY_BAD;
1057                 }
1058         }
1059
1060         return NOTIFY_DONE;
1061 }
1062
1063 /*
1064  *      watchdog_dev_register: register a watchdog device
1065  *      @wdd: watchdog device
1066  *
1067  *      Register a watchdog device including handling the legacy
1068  *      /dev/watchdog node. /dev/watchdog is actually a miscdevice and
1069  *      thus we set it up like that.
1070  */
1071
1072 int watchdog_dev_register(struct watchdog_device *wdd)
1073 {
1074         struct device *dev;
1075         dev_t devno;
1076         int ret;
1077
1078         devno = MKDEV(MAJOR(watchdog_devt), wdd->id);
1079
1080         ret = watchdog_cdev_register(wdd, devno);
1081         if (ret)
1082                 return ret;
1083
1084         dev = device_create_with_groups(&watchdog_class, wdd->parent,
1085                                         devno, wdd, wdd->groups,
1086                                         "watchdog%d", wdd->id);
1087         if (IS_ERR(dev)) {
1088                 watchdog_cdev_unregister(wdd);
1089                 return PTR_ERR(dev);
1090         }
1091
1092         ret = watchdog_register_pretimeout(wdd);
1093         if (ret) {
1094                 device_destroy(&watchdog_class, devno);
1095                 watchdog_cdev_unregister(wdd);
1096                 return ret;
1097         }
1098
1099         if (test_bit(WDOG_STOP_ON_REBOOT, &wdd->status)) {
1100                 wdd->reboot_nb.notifier_call = watchdog_reboot_notifier;
1101
1102                 ret = devm_register_reboot_notifier(dev, &wdd->reboot_nb);
1103                 if (ret) {
1104                         pr_err("watchdog%d: Cannot register reboot notifier (%d)\n",
1105                                wdd->id, ret);
1106                         watchdog_dev_unregister(wdd);
1107                 }
1108         }
1109
1110         return ret;
1111 }
1112
1113 /*
1114  *      watchdog_dev_unregister: unregister a watchdog device
1115  *      @watchdog: watchdog device
1116  *
1117  *      Unregister watchdog device and if needed the legacy
1118  *      /dev/watchdog device.
1119  */
1120
1121 void watchdog_dev_unregister(struct watchdog_device *wdd)
1122 {
1123         watchdog_unregister_pretimeout(wdd);
1124         device_destroy(&watchdog_class, wdd->wd_data->cdev.dev);
1125         watchdog_cdev_unregister(wdd);
1126 }
1127
1128 /*
1129  *      watchdog_dev_init: init dev part of watchdog core
1130  *
1131  *      Allocate a range of chardev nodes to use for watchdog devices
1132  */
1133
1134 int __init watchdog_dev_init(void)
1135 {
1136         int err;
1137         struct sched_param param = {.sched_priority = MAX_RT_PRIO - 1,};
1138
1139         watchdog_kworker = kthread_create_worker(0, "watchdogd");
1140         if (IS_ERR(watchdog_kworker)) {
1141                 pr_err("Failed to create watchdog kworker\n");
1142                 return PTR_ERR(watchdog_kworker);
1143         }
1144         sched_setscheduler(watchdog_kworker->task, SCHED_FIFO, &param);
1145
1146         err = class_register(&watchdog_class);
1147         if (err < 0) {
1148                 pr_err("couldn't register class\n");
1149                 goto err_register;
1150         }
1151
1152         err = alloc_chrdev_region(&watchdog_devt, 0, MAX_DOGS, "watchdog");
1153         if (err < 0) {
1154                 pr_err("watchdog: unable to allocate char dev region\n");
1155                 goto err_alloc;
1156         }
1157
1158         return 0;
1159
1160 err_alloc:
1161         class_unregister(&watchdog_class);
1162 err_register:
1163         kthread_destroy_worker(watchdog_kworker);
1164         return err;
1165 }
1166
1167 /*
1168  *      watchdog_dev_exit: exit dev part of watchdog core
1169  *
1170  *      Release the range of chardev nodes used for watchdog devices
1171  */
1172
1173 void __exit watchdog_dev_exit(void)
1174 {
1175         unregister_chrdev_region(watchdog_devt, MAX_DOGS);
1176         class_unregister(&watchdog_class);
1177         kthread_destroy_worker(watchdog_kworker);
1178 }
1179
1180 module_param(handle_boot_enabled, bool, 0444);
1181 MODULE_PARM_DESC(handle_boot_enabled,
1182         "Watchdog core auto-updates boot enabled watchdogs before userspace takes over (default="
1183         __MODULE_STRING(IS_ENABLED(CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED)) ")");