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/jiffies.h>	/* For timeout functions */
 40#include <linux/kernel.h>	/* For printk/panic/... */
 41#include <linux/kref.h>		/* For data references */
 42#include <linux/miscdevice.h>	/* For handling misc devices */
 43#include <linux/module.h>	/* For module stuff/... */
 44#include <linux/mutex.h>	/* For mutexes */
 45#include <linux/slab.h>		/* For memory functions */
 46#include <linux/types.h>	/* For standard types (like size_t) */
 
 
 
 47#include <linux/watchdog.h>	/* For watchdog specific items */
 48#include <linux/workqueue.h>	/* For workqueue */
 
 49#include <linux/uaccess.h>	/* For copy_to_user/put_user/... */
 50
 51#include "watchdog_core.h"
 52
 53/*
 54 * struct watchdog_core_data - watchdog core internal data
 55 * @kref:	Reference count.
 56 * @cdev:	The watchdog's Character device.
 57 * @wdd:	Pointer to watchdog device.
 58 * @lock:	Lock for watchdog core.
 59 * @status:	Watchdog core internal status bits.
 60 */
 61struct watchdog_core_data {
 62	struct kref kref;
 63	struct cdev cdev;
 64	struct watchdog_device *wdd;
 65	struct mutex lock;
 66	unsigned long last_keepalive;
 67	unsigned long last_hw_keepalive;
 68	struct delayed_work work;
 69	unsigned long status;		/* Internal status bits */
 70#define _WDOG_DEV_OPEN		0	/* Opened ? */
 71#define _WDOG_ALLOW_RELEASE	1	/* Did we receive the magic char ? */
 72};
 73
 74/* the dev_t structure to store the dynamically allocated watchdog devices */
 75static dev_t watchdog_devt;
 76/* Reference to watchdog device behind /dev/watchdog */
 77static struct watchdog_core_data *old_wd_data;
 78
 79static struct workqueue_struct *watchdog_wq;
 80
 81static inline bool watchdog_need_worker(struct watchdog_device *wdd)
 82{
 83	/* All variables in milli-seconds */
 84	unsigned int hm = wdd->max_hw_heartbeat_ms;
 85	unsigned int t = wdd->timeout * 1000;
 86
 87	/*
 88	 * A worker to generate heartbeat requests is needed if all of the
 89	 * following conditions are true.
 90	 * - Userspace activated the watchdog.
 91	 * - The driver provided a value for the maximum hardware timeout, and
 92	 *   thus is aware that the framework supports generating heartbeat
 93	 *   requests.
 94	 * - Userspace requests a longer timeout than the hardware can handle.
 95	 */
 96	return hm && ((watchdog_active(wdd) && t > hm) ||
 97		      (t && !watchdog_active(wdd) && watchdog_hw_running(wdd)));
 98}
 99
100static long watchdog_next_keepalive(struct watchdog_device *wdd)
101{
102	struct watchdog_core_data *wd_data = wdd->wd_data;
103	unsigned int timeout_ms = wdd->timeout * 1000;
104	unsigned long keepalive_interval;
105	unsigned long last_heartbeat;
106	unsigned long virt_timeout;
107	unsigned int hw_heartbeat_ms;
108
109	virt_timeout = wd_data->last_keepalive + msecs_to_jiffies(timeout_ms);
110	hw_heartbeat_ms = min(timeout_ms, wdd->max_hw_heartbeat_ms);
111	keepalive_interval = msecs_to_jiffies(hw_heartbeat_ms / 2);
112
113	if (!watchdog_active(wdd))
114		return keepalive_interval;
115
116	/*
117	 * To ensure that the watchdog times out wdd->timeout seconds
118	 * after the most recent ping from userspace, the last
119	 * worker ping has to come in hw_heartbeat_ms before this timeout.
120	 */
121	last_heartbeat = virt_timeout - msecs_to_jiffies(hw_heartbeat_ms);
122	return min_t(long, last_heartbeat - jiffies, keepalive_interval);
123}
124
125static inline void watchdog_update_worker(struct watchdog_device *wdd)
126{
127	struct watchdog_core_data *wd_data = wdd->wd_data;
128
129	if (watchdog_need_worker(wdd)) {
130		long t = watchdog_next_keepalive(wdd);
131
132		if (t > 0)
133			mod_delayed_work(watchdog_wq, &wd_data->work, t);
134	} else {
135		cancel_delayed_work(&wd_data->work);
136	}
137}
138
139static int __watchdog_ping(struct watchdog_device *wdd)
140{
141	struct watchdog_core_data *wd_data = wdd->wd_data;
142	unsigned long earliest_keepalive = wd_data->last_hw_keepalive +
143				msecs_to_jiffies(wdd->min_hw_heartbeat_ms);
144	int err;
145
146	if (time_is_after_jiffies(earliest_keepalive)) {
147		mod_delayed_work(watchdog_wq, &wd_data->work,
148				 earliest_keepalive - jiffies);
149		return 0;
150	}
151
152	wd_data->last_hw_keepalive = jiffies;
153
154	if (wdd->ops->ping)
155		err = wdd->ops->ping(wdd);  /* ping the watchdog */
156	else
157		err = wdd->ops->start(wdd); /* restart watchdog */
158
159	watchdog_update_worker(wdd);
160
161	return err;
162}
163
164/*
165 *	watchdog_ping: ping the watchdog.
166 *	@wdd: the watchdog device to ping
167 *
168 *	The caller must hold wd_data->lock.
169 *
170 *	If the watchdog has no own ping operation then it needs to be
171 *	restarted via the start operation. This wrapper function does
172 *	exactly that.
173 *	We only ping when the watchdog device is running.
174 */
175
176static int watchdog_ping(struct watchdog_device *wdd)
177{
178	struct watchdog_core_data *wd_data = wdd->wd_data;
179
180	if (!watchdog_active(wdd) && !watchdog_hw_running(wdd))
181		return 0;
182
183	wd_data->last_keepalive = jiffies;
184	return __watchdog_ping(wdd);
185}
 
186
187static void watchdog_ping_work(struct work_struct *work)
188{
189	struct watchdog_core_data *wd_data;
190	struct watchdog_device *wdd;
191
192	wd_data = container_of(to_delayed_work(work), struct watchdog_core_data,
193			       work);
 
 
194
195	mutex_lock(&wd_data->lock);
196	wdd = wd_data->wdd;
197	if (wdd && (watchdog_active(wdd) || watchdog_hw_running(wdd)))
198		__watchdog_ping(wdd);
199	mutex_unlock(&wd_data->lock);
200}
201
202/*
203 *	watchdog_start: wrapper to start the watchdog.
204 *	@wdd: the watchdog device to start
205 *
206 *	The caller must hold wd_data->lock.
207 *
208 *	Start the watchdog if it is not active and mark it active.
209 *	This function returns zero on success or a negative errno code for
210 *	failure.
211 */
212
213static int watchdog_start(struct watchdog_device *wdd)
214{
215	struct watchdog_core_data *wd_data = wdd->wd_data;
216	unsigned long started_at;
217	int err;
218
219	if (watchdog_active(wdd))
220		return 0;
221
222	started_at = jiffies;
223	if (watchdog_hw_running(wdd) && wdd->ops->ping)
224		err = wdd->ops->ping(wdd);
225	else
226		err = wdd->ops->start(wdd);
227	if (err == 0) {
228		set_bit(WDOG_ACTIVE, &wdd->status);
229		wd_data->last_keepalive = started_at;
230		watchdog_update_worker(wdd);
231	}
232
 
 
 
 
 
 
 
 
 
233	return err;
234}
235
236/*
237 *	watchdog_stop: wrapper to stop the watchdog.
238 *	@wdd: the watchdog device to stop
239 *
240 *	The caller must hold wd_data->lock.
241 *
242 *	Stop the watchdog if it is still active and unmark it active.
243 *	This function returns zero on success or a negative errno code for
244 *	failure.
245 *	If the 'nowayout' feature was set, the watchdog cannot be stopped.
246 */
247
248static int watchdog_stop(struct watchdog_device *wdd)
249{
250	int err = 0;
251
252	if (!watchdog_active(wdd))
253		return 0;
254
255	if (test_bit(WDOG_NO_WAY_OUT, &wdd->status)) {
256		pr_info("watchdog%d: nowayout prevents watchdog being stopped!\n",
257			wdd->id);
258		return -EBUSY;
259	}
260
261	if (wdd->ops->stop)
262		err = wdd->ops->stop(wdd);
263	else
264		set_bit(WDOG_HW_RUNNING, &wdd->status);
265
266	if (err == 0) {
267		clear_bit(WDOG_ACTIVE, &wdd->status);
268		watchdog_update_worker(wdd);
 
269	}
270
 
 
 
 
 
 
271	return err;
272}
273
274/*
275 *	watchdog_get_status: wrapper to get the watchdog status
276 *	@wdd: the watchdog device to get the status from
277 *
278 *	The caller must hold wd_data->lock.
279 *
280 *	Get the watchdog's status flags.
281 */
282
283static unsigned int watchdog_get_status(struct watchdog_device *wdd)
 
284{
285	if (!wdd->ops->status)
286		return 0;
 
 
 
 
 
 
 
 
 
 
287
288	return wdd->ops->status(wdd);
 
 
 
 
289}
290
291/*
292 *	watchdog_set_timeout: set the watchdog timer timeout
293 *	@wdd: the watchdog device to set the timeout for
294 *	@timeout: timeout to set in seconds
295 *
296 *	The caller must hold wd_data->lock.
297 */
298
299static int watchdog_set_timeout(struct watchdog_device *wdd,
300							unsigned int timeout)
301{
302	int err = 0;
303
304	if (!(wdd->info->options & WDIOF_SETTIMEOUT))
 
305		return -EOPNOTSUPP;
306
307	if (watchdog_timeout_invalid(wdd, timeout))
308		return -EINVAL;
309
310	if (wdd->ops->set_timeout)
311		err = wdd->ops->set_timeout(wdd, timeout);
312	else
313		wdd->timeout = timeout;
 
 
314
315	watchdog_update_worker(wdd);
316
 
 
317	return err;
318}
319
320/*
321 *	watchdog_get_timeleft: wrapper to get the time left before a reboot
322 *	@wdd: the watchdog device to get the remaining time from
323 *	@timeleft: the time that's left
324 *
325 *	The caller must hold wd_data->lock.
326 *
327 *	Get the time before a watchdog will reboot (if not pinged).
328 */
329
330static int watchdog_get_timeleft(struct watchdog_device *wdd,
331							unsigned int *timeleft)
332{
333	*timeleft = 0;
334
335	if (!wdd->ops->get_timeleft)
 
336		return -EOPNOTSUPP;
337
338	*timeleft = wdd->ops->get_timeleft(wdd);
339
340	return 0;
341}
342
343#ifdef CONFIG_WATCHDOG_SYSFS
344static ssize_t nowayout_show(struct device *dev, struct device_attribute *attr,
345				char *buf)
346{
347	struct watchdog_device *wdd = dev_get_drvdata(dev);
348
349	return sprintf(buf, "%d\n", !!test_bit(WDOG_NO_WAY_OUT, &wdd->status));
350}
351static DEVICE_ATTR_RO(nowayout);
352
353static ssize_t status_show(struct device *dev, struct device_attribute *attr,
354				char *buf)
355{
356	struct watchdog_device *wdd = dev_get_drvdata(dev);
357	struct watchdog_core_data *wd_data = wdd->wd_data;
358	unsigned int status;
359
360	mutex_lock(&wd_data->lock);
361	status = watchdog_get_status(wdd);
362	mutex_unlock(&wd_data->lock);
363
364	return sprintf(buf, "%u\n", status);
365}
366static DEVICE_ATTR_RO(status);
367
368static ssize_t bootstatus_show(struct device *dev,
369				struct device_attribute *attr, char *buf)
370{
371	struct watchdog_device *wdd = dev_get_drvdata(dev);
372
373	return sprintf(buf, "%u\n", wdd->bootstatus);
374}
375static DEVICE_ATTR_RO(bootstatus);
376
377static ssize_t timeleft_show(struct device *dev, struct device_attribute *attr,
378				char *buf)
379{
380	struct watchdog_device *wdd = dev_get_drvdata(dev);
381	struct watchdog_core_data *wd_data = wdd->wd_data;
382	ssize_t status;
383	unsigned int val;
384
385	mutex_lock(&wd_data->lock);
386	status = watchdog_get_timeleft(wdd, &val);
387	mutex_unlock(&wd_data->lock);
388	if (!status)
389		status = sprintf(buf, "%u\n", val);
390
391	return status;
392}
393static DEVICE_ATTR_RO(timeleft);
394
395static ssize_t timeout_show(struct device *dev, struct device_attribute *attr,
396				char *buf)
397{
398	struct watchdog_device *wdd = dev_get_drvdata(dev);
399
400	return sprintf(buf, "%u\n", wdd->timeout);
401}
402static DEVICE_ATTR_RO(timeout);
403
404static ssize_t identity_show(struct device *dev, struct device_attribute *attr,
405				char *buf)
406{
407	struct watchdog_device *wdd = dev_get_drvdata(dev);
408
409	return sprintf(buf, "%s\n", wdd->info->identity);
410}
411static DEVICE_ATTR_RO(identity);
412
413static ssize_t state_show(struct device *dev, struct device_attribute *attr,
414				char *buf)
415{
416	struct watchdog_device *wdd = dev_get_drvdata(dev);
417
418	if (watchdog_active(wdd))
419		return sprintf(buf, "active\n");
420
421	return sprintf(buf, "inactive\n");
422}
423static DEVICE_ATTR_RO(state);
424
425static umode_t wdt_is_visible(struct kobject *kobj, struct attribute *attr,
426				int n)
427{
428	struct device *dev = container_of(kobj, struct device, kobj);
429	struct watchdog_device *wdd = dev_get_drvdata(dev);
430	umode_t mode = attr->mode;
431
432	if (attr == &dev_attr_status.attr && !wdd->ops->status)
433		mode = 0;
434	else if (attr == &dev_attr_timeleft.attr && !wdd->ops->get_timeleft)
435		mode = 0;
436
437	return mode;
 
 
438}
439static struct attribute *wdt_attrs[] = {
440	&dev_attr_state.attr,
441	&dev_attr_identity.attr,
442	&dev_attr_timeout.attr,
443	&dev_attr_timeleft.attr,
444	&dev_attr_bootstatus.attr,
445	&dev_attr_status.attr,
446	&dev_attr_nowayout.attr,
447	NULL,
448};
449
450static const struct attribute_group wdt_group = {
451	.attrs = wdt_attrs,
452	.is_visible = wdt_is_visible,
453};
454__ATTRIBUTE_GROUPS(wdt);
455#else
456#define wdt_groups	NULL
457#endif
458
459/*
460 *	watchdog_ioctl_op: call the watchdog drivers ioctl op if defined
461 *	@wdd: the watchdog device to do the ioctl on
462 *	@cmd: watchdog command
463 *	@arg: argument pointer
464 *
465 *	The caller must hold wd_data->lock.
466 */
467
468static int watchdog_ioctl_op(struct watchdog_device *wdd, unsigned int cmd,
469							unsigned long arg)
470{
471	if (!wdd->ops->ioctl)
 
 
472		return -ENOIOCTLCMD;
473
474	return wdd->ops->ioctl(wdd, cmd, arg);
 
 
 
 
 
 
 
 
 
 
 
475}
476
477/*
478 *	watchdog_write: writes to the watchdog.
479 *	@file: file from VFS
480 *	@data: user address of data
481 *	@len: length of data
482 *	@ppos: pointer to the file offset
483 *
484 *	A write to a watchdog device is defined as a keepalive ping.
485 *	Writing the magic 'V' sequence allows the next close to turn
486 *	off the watchdog (if 'nowayout' is not set).
487 */
488
489static ssize_t watchdog_write(struct file *file, const char __user *data,
490						size_t len, loff_t *ppos)
491{
492	struct watchdog_core_data *wd_data = file->private_data;
493	struct watchdog_device *wdd;
494	int err;
495	size_t i;
496	char c;
497
498	if (len == 0)
499		return 0;
500
501	/*
502	 * Note: just in case someone wrote the magic character
503	 * five months ago...
504	 */
505	clear_bit(_WDOG_ALLOW_RELEASE, &wd_data->status);
506
507	/* scan to see whether or not we got the magic character */
508	for (i = 0; i != len; i++) {
509		if (get_user(c, data + i))
510			return -EFAULT;
511		if (c == 'V')
512			set_bit(_WDOG_ALLOW_RELEASE, &wd_data->status);
513	}
514
515	/* someone wrote to us, so we send the watchdog a keepalive ping */
516
517	err = -ENODEV;
518	mutex_lock(&wd_data->lock);
519	wdd = wd_data->wdd;
520	if (wdd)
521		err = watchdog_ping(wdd);
522	mutex_unlock(&wd_data->lock);
523
524	if (err < 0)
525		return err;
526
527	return len;
528}
529
530/*
531 *	watchdog_ioctl: handle the different ioctl's for the watchdog device.
532 *	@file: file handle to the device
533 *	@cmd: watchdog command
534 *	@arg: argument pointer
535 *
536 *	The watchdog API defines a common set of functions for all watchdogs
537 *	according to their available features.
538 */
539
540static long watchdog_ioctl(struct file *file, unsigned int cmd,
541							unsigned long arg)
542{
543	struct watchdog_core_data *wd_data = file->private_data;
544	void __user *argp = (void __user *)arg;
545	struct watchdog_device *wdd;
546	int __user *p = argp;
547	unsigned int val;
548	int err;
549
550	mutex_lock(&wd_data->lock);
551
552	wdd = wd_data->wdd;
553	if (!wdd) {
554		err = -ENODEV;
555		goto out_ioctl;
556	}
557
558	err = watchdog_ioctl_op(wdd, cmd, arg);
559	if (err != -ENOIOCTLCMD)
560		goto out_ioctl;
561
562	switch (cmd) {
563	case WDIOC_GETSUPPORT:
564		err = copy_to_user(argp, wdd->info,
565			sizeof(struct watchdog_info)) ? -EFAULT : 0;
566		break;
567	case WDIOC_GETSTATUS:
568		val = watchdog_get_status(wdd);
569		err = put_user(val, p);
570		break;
 
571	case WDIOC_GETBOOTSTATUS:
572		err = put_user(wdd->bootstatus, p);
573		break;
574	case WDIOC_SETOPTIONS:
575		if (get_user(val, p)) {
576			err = -EFAULT;
577			break;
578		}
579		if (val & WDIOS_DISABLECARD) {
580			err = watchdog_stop(wdd);
581			if (err < 0)
582				break;
583		}
584		if (val & WDIOS_ENABLECARD)
585			err = watchdog_start(wdd);
586		break;
587	case WDIOC_KEEPALIVE:
588		if (!(wdd->info->options & WDIOF_KEEPALIVEPING)) {
589			err = -EOPNOTSUPP;
590			break;
591		}
592		err = watchdog_ping(wdd);
593		break;
 
 
 
 
594	case WDIOC_SETTIMEOUT:
595		if (get_user(val, p)) {
596			err = -EFAULT;
597			break;
598		}
599		err = watchdog_set_timeout(wdd, val);
600		if (err < 0)
601			break;
602		/* If the watchdog is active then we send a keepalive ping
603		 * to make sure that the watchdog keep's running (and if
604		 * possible that it takes the new timeout) */
605		err = watchdog_ping(wdd);
606		if (err < 0)
607			break;
608		/* Fall */
609	case WDIOC_GETTIMEOUT:
610		/* timeout == 0 means that we don't know the timeout */
611		if (wdd->timeout == 0) {
612			err = -EOPNOTSUPP;
613			break;
614		}
615		err = put_user(wdd->timeout, p);
616		break;
617	case WDIOC_GETTIMELEFT:
618		err = watchdog_get_timeleft(wdd, &val);
619		if (err < 0)
620			break;
621		err = put_user(val, p);
622		break;
623	default:
624		err = -ENOTTY;
625		break;
626	}
627
628out_ioctl:
629	mutex_unlock(&wd_data->lock);
630	return err;
631}
632
633/*
634 *	watchdog_open: open the /dev/watchdog* devices.
635 *	@inode: inode of device
636 *	@file: file handle to device
637 *
638 *	When the /dev/watchdog* device gets opened, we start the watchdog.
639 *	Watch out: the /dev/watchdog device is single open, so we make sure
640 *	it can only be opened once.
641 */
642
643static int watchdog_open(struct inode *inode, struct file *file)
644{
645	struct watchdog_core_data *wd_data;
646	struct watchdog_device *wdd;
647	int err;
648
649	/* Get the corresponding watchdog device */
650	if (imajor(inode) == MISC_MAJOR)
651		wd_data = old_wd_data;
652	else
653		wd_data = container_of(inode->i_cdev, struct watchdog_core_data,
654				       cdev);
655
656	/* the watchdog is single open! */
657	if (test_and_set_bit(_WDOG_DEV_OPEN, &wd_data->status))
658		return -EBUSY;
659
660	wdd = wd_data->wdd;
661
662	/*
663	 * If the /dev/watchdog device is open, we don't want the module
664	 * to be unloaded.
665	 */
666	if (!watchdog_hw_running(wdd) && !try_module_get(wdd->ops->owner)) {
667		err = -EBUSY;
668		goto out_clear;
669	}
670
671	err = watchdog_start(wdd);
672	if (err < 0)
673		goto out_mod;
674
675	file->private_data = wd_data;
676
677	if (!watchdog_hw_running(wdd))
678		kref_get(&wd_data->kref);
679
680	/* dev/watchdog is a virtual (and thus non-seekable) filesystem */
681	return nonseekable_open(inode, file);
682
683out_mod:
684	module_put(wd_data->wdd->ops->owner);
685out_clear:
686	clear_bit(_WDOG_DEV_OPEN, &wd_data->status);
687	return err;
688}
689
690static void watchdog_core_data_release(struct kref *kref)
691{
692	struct watchdog_core_data *wd_data;
693
694	wd_data = container_of(kref, struct watchdog_core_data, kref);
695
696	kfree(wd_data);
697}
698
699/*
700 *	watchdog_release: release the watchdog device.
701 *	@inode: inode of device
702 *	@file: file handle to device
703 *
704 *	This is the code for when /dev/watchdog gets closed. We will only
705 *	stop the watchdog when we have received the magic char (and nowayout
706 *	was not set), else the watchdog will keep running.
707 */
708
709static int watchdog_release(struct inode *inode, struct file *file)
710{
711	struct watchdog_core_data *wd_data = file->private_data;
712	struct watchdog_device *wdd;
713	int err = -EBUSY;
714	bool running;
715
716	mutex_lock(&wd_data->lock);
717
718	wdd = wd_data->wdd;
719	if (!wdd)
720		goto done;
721
722	/*
723	 * We only stop the watchdog if we received the magic character
724	 * or if WDIOF_MAGICCLOSE is not set. If nowayout was set then
725	 * watchdog_stop will fail.
726	 */
727	if (!test_bit(WDOG_ACTIVE, &wdd->status))
728		err = 0;
729	else if (test_and_clear_bit(_WDOG_ALLOW_RELEASE, &wd_data->status) ||
730		 !(wdd->info->options & WDIOF_MAGICCLOSE))
731		err = watchdog_stop(wdd);
732
733	/* If the watchdog was not stopped, send a keepalive ping */
734	if (err < 0) {
735		pr_crit("watchdog%d: watchdog did not stop!\n", wdd->id);
 
 
 
736		watchdog_ping(wdd);
737	}
738
739	cancel_delayed_work_sync(&wd_data->work);
740	watchdog_update_worker(wdd);
741
742	/* make sure that /dev/watchdog can be re-opened */
743	clear_bit(_WDOG_DEV_OPEN, &wd_data->status);
 
 
 
 
744
745done:
746	running = wdd && watchdog_hw_running(wdd);
747	mutex_unlock(&wd_data->lock);
748	/*
749	 * Allow the owner module to be unloaded again unless the watchdog
750	 * is still running. If the watchdog is still running, it can not
751	 * be stopped, and its driver must not be unloaded.
752	 */
753	if (!running) {
754		module_put(wd_data->cdev.owner);
755		kref_put(&wd_data->kref, watchdog_core_data_release);
756	}
757	return 0;
758}
759
760static const struct file_operations watchdog_fops = {
761	.owner		= THIS_MODULE,
762	.write		= watchdog_write,
763	.unlocked_ioctl	= watchdog_ioctl,
764	.open		= watchdog_open,
765	.release	= watchdog_release,
766};
767
768static struct miscdevice watchdog_miscdev = {
769	.minor		= WATCHDOG_MINOR,
770	.name		= "watchdog",
771	.fops		= &watchdog_fops,
772};
773
774/*
775 *	watchdog_cdev_register: register watchdog character device
776 *	@wdd: watchdog device
777 *	@devno: character device number
778 *
779 *	Register a watchdog character device including handling the legacy
780 *	/dev/watchdog node. /dev/watchdog is actually a miscdevice and
781 *	thus we set it up like that.
782 */
783
784static int watchdog_cdev_register(struct watchdog_device *wdd, dev_t devno)
785{
786	struct watchdog_core_data *wd_data;
787	int err;
788
789	wd_data = kzalloc(sizeof(struct watchdog_core_data), GFP_KERNEL);
790	if (!wd_data)
791		return -ENOMEM;
792	kref_init(&wd_data->kref);
793	mutex_init(&wd_data->lock);
794
795	wd_data->wdd = wdd;
796	wdd->wd_data = wd_data;
797
798	if (!watchdog_wq)
799		return -ENODEV;
800
801	INIT_DELAYED_WORK(&wd_data->work, watchdog_ping_work);
802
803	if (wdd->id == 0) {
804		old_wd_data = wd_data;
805		watchdog_miscdev.parent = wdd->parent;
806		err = misc_register(&watchdog_miscdev);
807		if (err != 0) {
808			pr_err("%s: cannot register miscdev on minor=%d (err=%d).\n",
809				wdd->info->identity, WATCHDOG_MINOR, err);
810			if (err == -EBUSY)
811				pr_err("%s: a legacy watchdog module is probably present.\n",
812					wdd->info->identity);
813			old_wd_data = NULL;
814			kfree(wd_data);
815			return err;
816		}
817	}
818
819	/* Fill in the data structures */
820	cdev_init(&wd_data->cdev, &watchdog_fops);
821	wd_data->cdev.owner = wdd->ops->owner;
 
822
823	/* Add the device */
824	err = cdev_add(&wd_data->cdev, devno, 1);
825	if (err) {
826		pr_err("watchdog%d unable to add device %d:%d\n",
827			wdd->id,  MAJOR(watchdog_devt), wdd->id);
828		if (wdd->id == 0) {
829			misc_deregister(&watchdog_miscdev);
830			old_wd_data = NULL;
831			kref_put(&wd_data->kref, watchdog_core_data_release);
832		}
833		return err;
834	}
835
836	/* Record time of most recent heartbeat as 'just before now'. */
837	wd_data->last_hw_keepalive = jiffies - 1;
838
839	/*
840	 * If the watchdog is running, prevent its driver from being unloaded,
841	 * and schedule an immediate ping.
842	 */
843	if (watchdog_hw_running(wdd)) {
844		__module_get(wdd->ops->owner);
845		kref_get(&wd_data->kref);
846		queue_delayed_work(watchdog_wq, &wd_data->work, 0);
847	}
848
849	return 0;
850}
851
852/*
853 *	watchdog_cdev_unregister: unregister watchdog character device
854 *	@watchdog: watchdog device
855 *
856 *	Unregister watchdog character device and if needed the legacy
857 *	/dev/watchdog device.
858 */
859
860static void watchdog_cdev_unregister(struct watchdog_device *wdd)
861{
862	struct watchdog_core_data *wd_data = wdd->wd_data;
 
 
863
864	cdev_del(&wd_data->cdev);
865	if (wdd->id == 0) {
866		misc_deregister(&watchdog_miscdev);
867		old_wd_data = NULL;
868	}
869
870	mutex_lock(&wd_data->lock);
871	wd_data->wdd = NULL;
872	wdd->wd_data = NULL;
873	mutex_unlock(&wd_data->lock);
874
875	cancel_delayed_work_sync(&wd_data->work);
876
877	kref_put(&wd_data->kref, watchdog_core_data_release);
878}
879
880static struct class watchdog_class = {
881	.name =		"watchdog",
882	.owner =	THIS_MODULE,
883	.dev_groups =	wdt_groups,
884};
885
886/*
887 *	watchdog_dev_register: register a watchdog device
888 *	@wdd: watchdog device
889 *
890 *	Register a watchdog device including handling the legacy
891 *	/dev/watchdog node. /dev/watchdog is actually a miscdevice and
892 *	thus we set it up like that.
893 */
894
895int watchdog_dev_register(struct watchdog_device *wdd)
896{
897	struct device *dev;
898	dev_t devno;
899	int ret;
900
901	devno = MKDEV(MAJOR(watchdog_devt), wdd->id);
902
903	ret = watchdog_cdev_register(wdd, devno);
904	if (ret)
905		return ret;
906
907	dev = device_create_with_groups(&watchdog_class, wdd->parent,
908					devno, wdd, wdd->groups,
909					"watchdog%d", wdd->id);
910	if (IS_ERR(dev)) {
911		watchdog_cdev_unregister(wdd);
912		return PTR_ERR(dev);
913	}
914
915	return ret;
916}
917
918/*
919 *	watchdog_dev_unregister: unregister a watchdog device
920 *	@watchdog: watchdog device
921 *
922 *	Unregister watchdog device and if needed the legacy
923 *	/dev/watchdog device.
924 */
925
926void watchdog_dev_unregister(struct watchdog_device *wdd)
927{
928	device_destroy(&watchdog_class, wdd->wd_data->cdev.dev);
929	watchdog_cdev_unregister(wdd);
930}
931
932/*
933 *	watchdog_dev_init: init dev part of watchdog core
934 *
935 *	Allocate a range of chardev nodes to use for watchdog devices
936 */
937
938int __init watchdog_dev_init(void)
939{
940	int err;
941
942	watchdog_wq = alloc_workqueue("watchdogd",
943				      WQ_HIGHPRI | WQ_MEM_RECLAIM, 0);
944	if (!watchdog_wq) {
945		pr_err("Failed to create watchdog workqueue\n");
946		return -ENOMEM;
947	}
948
949	err = class_register(&watchdog_class);
950	if (err < 0) {
951		pr_err("couldn't register class\n");
952		return err;
953	}
954
955	err = alloc_chrdev_region(&watchdog_devt, 0, MAX_DOGS, "watchdog");
956	if (err < 0) {
957		pr_err("watchdog: unable to allocate char dev region\n");
958		class_unregister(&watchdog_class);
959		return err;
960	}
961
962	return 0;
963}
964
965/*
966 *	watchdog_dev_exit: exit dev part of watchdog core
967 *
968 *	Release the range of chardev nodes used for watchdog devices
969 */
970
971void __exit watchdog_dev_exit(void)
972{
973	unregister_chrdev_region(watchdog_devt, MAX_DOGS);
974	class_unregister(&watchdog_class);
975	destroy_workqueue(watchdog_wq);
976}