[deliverable/linux.git] / drivers / watchdog / watchdog_dev.c

/*
 *	watchdog_dev.c
 *
 *	(c) Copyright 2008-2011 Alan Cox <alan@lxorguk.ukuu.org.uk>,
 *						All Rights Reserved.
 *
 *	(c) Copyright 2008-2011 Wim Van Sebroeck <wim@iguana.be>.
 *
 *
 *	This source code is part of the generic code that can be used
 *	by all the watchdog timer drivers.
 *
 *	This part of the generic code takes care of the following
 *	misc device: /dev/watchdog.
 *
 *	Based on source code of the following authors:
 *	  Matt Domsch <Matt_Domsch@dell.com>,
 *	  Rob Radez <rob@osinvestor.com>,
 *	  Rusty Lynch <rusty@linux.co.intel.com>
 *	  Satyam Sharma <satyam@infradead.org>
 *	  Randy Dunlap <randy.dunlap@oracle.com>
 *
 *	This program is free software; you can redistribute it and/or
 *	modify it under the terms of the GNU General Public License
 *	as published by the Free Software Foundation; either version
 *	2 of the License, or (at your option) any later version.
 *
 *	Neither Alan Cox, CymruNet Ltd., Wim Van Sebroeck nor Iguana vzw.
 *	admit liability nor provide warranty for any of this software.
 *	This material is provided "AS-IS" and at no charge.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>	/* For module stuff/... */
#include <linux/types.h>	/* For standard types (like size_t) */
#include <linux/errno.h>	/* For the -ENODEV/... values */
#include <linux/kernel.h>	/* For printk/panic/... */
#include <linux/fs.h>		/* For file operations */
#include <linux/watchdog.h>	/* For watchdog specific items */
#include <linux/miscdevice.h>	/* For handling misc devices */
#include <linux/init.h>		/* For __init/__exit/... */
#include <linux/uaccess.h>	/* For copy_to_user/put_user/... */

#include "watchdog_core.h"

/* the dev_t structure to store the dynamically allocated watchdog devices */
static dev_t watchdog_devt;
/* the watchdog device behind /dev/watchdog */
static struct watchdog_device *old_wdd;

/*
 *	watchdog_ping: ping the watchdog.
 *	@wddev: the watchdog device to ping
 *
 *	If the watchdog has no own ping operation then it needs to be
 *	restarted via the start operation. This wrapper function does
 *	exactly that.
 *	We only ping when the watchdog device is running.
 */

static int watchdog_ping(struct watchdog_device *wddev)
{
	int err = 0;

	if (!watchdog_active(wddev))
		goto out_ping;

	if (wddev->ops->ping)
		err = wddev->ops->ping(wddev);  /* ping the watchdog */
	else
		err = wddev->ops->start(wddev); /* restart watchdog */

out_ping:
	return err;
}

/*
 *	watchdog_start: wrapper to start the watchdog.
 *	@wddev: the watchdog device to start
 *
 *	Start the watchdog if it is not active and mark it active.
 *	This function returns zero on success or a negative errno code for
 *	failure.
 */

static int watchdog_start(struct watchdog_device *wddev)
{
	int err = 0;

	if (watchdog_active(wddev))
		goto out_start;

	err = wddev->ops->start(wddev);
	if (err == 0)
		set_bit(WDOG_ACTIVE, &wddev->status);

out_start:
	return err;
}

/*
 *	watchdog_stop: wrapper to stop the watchdog.
 *	@wddev: the watchdog device to stop
 *
 *	Stop the watchdog if it is still active and unmark it active.
 *	This function returns zero on success or a negative errno code for
 *	failure.
 *	If the 'nowayout' feature was set, the watchdog cannot be stopped.
 */

static int watchdog_stop(struct watchdog_device *wddev)
{
	int err = 0;

	if (!watchdog_active(wddev))
		goto out_stop;

	if (test_bit(WDOG_NO_WAY_OUT, &wddev->status)) {
		dev_info(wddev->dev, "nowayout prevents watchdog being stopped!\n");
		err = -EBUSY;
		goto out_stop;
	}

	err = wddev->ops->stop(wddev);
	if (err == 0)
		clear_bit(WDOG_ACTIVE, &wddev->status);

out_stop:
	return err;
}

/*
 *	watchdog_get_status: wrapper to get the watchdog status
 *	@wddev: the watchdog device to get the status from
 *	@status: the status of the watchdog device
 *
 *	Get the watchdog's status flags.
 */

static int watchdog_get_status(struct watchdog_device *wddev,
							unsigned int *status)
{
	int err = 0;

	*status = 0;
	if (!wddev->ops->status)
		return -EOPNOTSUPP;

	*status = wddev->ops->status(wddev);

	return err;
}

/*
 *	watchdog_set_timeout: set the watchdog timer timeout
 *	@wddev: the watchdog device to set the timeout for
 *	@timeout: timeout to set in seconds
 */

static int watchdog_set_timeout(struct watchdog_device *wddev,
							unsigned int timeout)
{
	int err;

	if ((wddev->ops->set_timeout == NULL) ||
	    !(wddev->info->options & WDIOF_SETTIMEOUT))
		return -EOPNOTSUPP;

	if ((wddev->max_timeout != 0) &&
	    (timeout < wddev->min_timeout || timeout > wddev->max_timeout))
		return -EINVAL;

	err = wddev->ops->set_timeout(wddev, timeout);

	return err;
}

/*
 *	watchdog_get_timeleft: wrapper to get the time left before a reboot
 *	@wddev: the watchdog device to get the remaining time from
 *	@timeleft: the time that's left
 *
 *	Get the time before a watchdog will reboot (if not pinged).
 */

static int watchdog_get_timeleft(struct watchdog_device *wddev,
							unsigned int *timeleft)
{
	int err = 0;

	*timeleft = 0;
	if (!wddev->ops->get_timeleft)
		return -EOPNOTSUPP;

	*timeleft = wddev->ops->get_timeleft(wddev);

	return err;
}

/*
 *	watchdog_ioctl_op: call the watchdog drivers ioctl op if defined
 *	@wddev: the watchdog device to do the ioctl on
 *	@cmd: watchdog command
 *	@arg: argument pointer
 */

static int watchdog_ioctl_op(struct watchdog_device *wddev, unsigned int cmd,
							unsigned long arg)
{
	int err;

	if (!wddev->ops->ioctl)
		return -ENOIOCTLCMD;

	err = wddev->ops->ioctl(wddev, cmd, arg);

	return err;
}

/*
 *	watchdog_write: writes to the watchdog.
 *	@file: file from VFS
 *	@data: user address of data
 *	@len: length of data
 *	@ppos: pointer to the file offset
 *
 *	A write to a watchdog device is defined as a keepalive ping.
 *	Writing the magic 'V' sequence allows the next close to turn
 *	off the watchdog (if 'nowayout' is not set).
 */

static ssize_t watchdog_write(struct file *file, const char __user *data,
						size_t len, loff_t *ppos)
{
	struct watchdog_device *wdd = file->private_data;
	size_t i;
	char c;

	if (len == 0)
		return 0;

	/*
	 * Note: just in case someone wrote the magic character
	 * five months ago...
	 */
	clear_bit(WDOG_ALLOW_RELEASE, &wdd->status);

	/* scan to see whether or not we got the magic character */
	for (i = 0; i != len; i++) {
		if (get_user(c, data + i))
			return -EFAULT;
		if (c == 'V')
			set_bit(WDOG_ALLOW_RELEASE, &wdd->status);
	}

	/* someone wrote to us, so we send the watchdog a keepalive ping */
	watchdog_ping(wdd);

	return len;
}

/*
 *	watchdog_ioctl: handle the different ioctl's for the watchdog device.
 *	@file: file handle to the device
 *	@cmd: watchdog command
 *	@arg: argument pointer
 *
 *	The watchdog API defines a common set of functions for all watchdogs
 *	according to their available features.
 */

static long watchdog_ioctl(struct file *file, unsigned int cmd,
							unsigned long arg)
{
	struct watchdog_device *wdd = file->private_data;
	void __user *argp = (void __user *)arg;
	int __user *p = argp;
	unsigned int val;
	int err;

	err = watchdog_ioctl_op(wdd, cmd, arg);
	if (err != -ENOIOCTLCMD)
		return err;

	switch (cmd) {
	case WDIOC_GETSUPPORT:
		return copy_to_user(argp, wdd->info,
			sizeof(struct watchdog_info)) ? -EFAULT : 0;
	case WDIOC_GETSTATUS:
		err = watchdog_get_status(wdd, &val);
		if (err)
			return err;
		return put_user(val, p);
	case WDIOC_GETBOOTSTATUS:
		return put_user(wdd->bootstatus, p);
	case WDIOC_SETOPTIONS:
		if (get_user(val, p))
			return -EFAULT;
		if (val & WDIOS_DISABLECARD) {
			err = watchdog_stop(wdd);
			if (err < 0)
				return err;
		}
		if (val & WDIOS_ENABLECARD) {
			err = watchdog_start(wdd);
			if (err < 0)
				return err;
		}
		return 0;
	case WDIOC_KEEPALIVE:
		if (!(wdd->info->options & WDIOF_KEEPALIVEPING))
			return -EOPNOTSUPP;
		watchdog_ping(wdd);
		return 0;
	case WDIOC_SETTIMEOUT:
		if (get_user(val, p))
			return -EFAULT;
		err = watchdog_set_timeout(wdd, val);
		if (err < 0)
			return err;
		/* If the watchdog is active then we send a keepalive ping
		 * to make sure that the watchdog keep's running (and if
		 * possible that it takes the new timeout) */
		watchdog_ping(wdd);
		/* Fall */
	case WDIOC_GETTIMEOUT:
		/* timeout == 0 means that we don't know the timeout */
		if (wdd->timeout == 0)
			return -EOPNOTSUPP;
		return put_user(wdd->timeout, p);
	case WDIOC_GETTIMELEFT:
		err = watchdog_get_timeleft(wdd, &val);
		if (err)
			return err;
		return put_user(val, p);
	default:
		return -ENOTTY;
	}
}

/*
 *	watchdog_open: open the /dev/watchdog* devices.
 *	@inode: inode of device
 *	@file: file handle to device
 *
 *	When the /dev/watchdog* device gets opened, we start the watchdog.
 *	Watch out: the /dev/watchdog device is single open, so we make sure
 *	it can only be opened once.
 */

static int watchdog_open(struct inode *inode, struct file *file)
{
	int err = -EBUSY;
	struct watchdog_device *wdd;

	/* Get the corresponding watchdog device */
	if (imajor(inode) == MISC_MAJOR)
		wdd = old_wdd;
	else
		wdd = container_of(inode->i_cdev, struct watchdog_device, cdev);

	/* the watchdog is single open! */
	if (test_and_set_bit(WDOG_DEV_OPEN, &wdd->status))
		return -EBUSY;

	/*
	 * If the /dev/watchdog device is open, we don't want the module
	 * to be unloaded.
	 */
	if (!try_module_get(wdd->ops->owner))
		goto out;

	err = watchdog_start(wdd);
	if (err < 0)
		goto out_mod;

	file->private_data = wdd;

	/* dev/watchdog is a virtual (and thus non-seekable) filesystem */
	return nonseekable_open(inode, file);

out_mod:
	module_put(wdd->ops->owner);
out:
	clear_bit(WDOG_DEV_OPEN, &wdd->status);
	return err;
}

/*
 *	watchdog_release: release the watchdog device.
 *	@inode: inode of device
 *	@file: file handle to device
 *
 *	This is the code for when /dev/watchdog gets closed. We will only
 *	stop the watchdog when we have received the magic char (and nowayout
 *	was not set), else the watchdog will keep running.
 */

static int watchdog_release(struct inode *inode, struct file *file)
{
	struct watchdog_device *wdd = file->private_data;
	int err = -EBUSY;

	/*
	 * We only stop the watchdog if we received the magic character
	 * or if WDIOF_MAGICCLOSE is not set. If nowayout was set then
	 * watchdog_stop will fail.
	 */
	if (test_and_clear_bit(WDOG_ALLOW_RELEASE, &wdd->status) ||
	    !(wdd->info->options & WDIOF_MAGICCLOSE))
		err = watchdog_stop(wdd);

	/* If the watchdog was not stopped, send a keepalive ping */
	if (err < 0) {
		dev_crit(wdd->dev, "watchdog did not stop!\n");
		watchdog_ping(wdd);
	}

	/* Allow the owner module to be unloaded again */
	module_put(wdd->ops->owner);

	/* make sure that /dev/watchdog can be re-opened */
	clear_bit(WDOG_DEV_OPEN, &wdd->status);

	return 0;
}

static const struct file_operations watchdog_fops = {
	.owner		= THIS_MODULE,
	.write		= watchdog_write,
	.unlocked_ioctl	= watchdog_ioctl,
	.open		= watchdog_open,
	.release	= watchdog_release,
};

static struct miscdevice watchdog_miscdev = {
	.minor		= WATCHDOG_MINOR,
	.name		= "watchdog",
	.fops		= &watchdog_fops,
};

/*
 *	watchdog_dev_register: register a watchdog device
 *	@watchdog: watchdog device
 *
 *	Register a watchdog device including handling the legacy
 *	/dev/watchdog node. /dev/watchdog is actually a miscdevice and
 *	thus we set it up like that.
 */

int watchdog_dev_register(struct watchdog_device *watchdog)
{
	int err, devno;

	if (watchdog->id == 0) {
		watchdog_miscdev.parent = watchdog->parent;
		err = misc_register(&watchdog_miscdev);
		if (err != 0) {
			pr_err("%s: cannot register miscdev on minor=%d (err=%d).\n",
				watchdog->info->identity, WATCHDOG_MINOR, err);
			if (err == -EBUSY)
				pr_err("%s: a legacy watchdog module is probably present.\n",
					watchdog->info->identity);
			return err;
		}
		old_wdd = watchdog;
	}

	/* Fill in the data structures */
	devno = MKDEV(MAJOR(watchdog_devt), watchdog->id);
	cdev_init(&watchdog->cdev, &watchdog_fops);
	watchdog->cdev.owner = watchdog->ops->owner;

	/* Add the device */
	err  = cdev_add(&watchdog->cdev, devno, 1);
	if (err) {
		pr_err("watchdog%d unable to add device %d:%d\n",
			watchdog->id,  MAJOR(watchdog_devt), watchdog->id);
		if (watchdog->id == 0) {
			misc_deregister(&watchdog_miscdev);
			old_wdd = NULL;
		}
	}
	return err;
}

/*
 *	watchdog_dev_unregister: unregister a watchdog device
 *	@watchdog: watchdog device
 *
 *	Unregister the watchdog and if needed the legacy /dev/watchdog device.
 */

int watchdog_dev_unregister(struct watchdog_device *watchdog)
{
	cdev_del(&watchdog->cdev);
	if (watchdog->id == 0) {
		misc_deregister(&watchdog_miscdev);
		old_wdd = NULL;
	}
	return 0;
}

/*
 *	watchdog_dev_init: init dev part of watchdog core
 *
 *	Allocate a range of chardev nodes to use for watchdog devices
 */

int __init watchdog_dev_init(void)
{
	int err = alloc_chrdev_region(&watchdog_devt, 0, MAX_DOGS, "watchdog");
	if (err < 0)
		pr_err("watchdog: unable to allocate char dev region\n");
	return err;
}

/*
 *	watchdog_dev_exit: exit dev part of watchdog core
 *
 *	Release the range of chardev nodes used for watchdog devices
 */

void __exit watchdog_dev_exit(void)
{
	unregister_chrdev_region(watchdog_devt, MAX_DOGS);
}
Commit	Line	Data
43316044 WVS	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/module.h> /* For module stuff/... */
	36	#include <linux/types.h> /* For standard types (like size_t) */
	37	#include <linux/errno.h> /* For the -ENODEV/... values */
	38	#include <linux/kernel.h> /* For printk/panic/... */
	39	#include <linux/fs.h> /* For file operations */
	40	#include <linux/watchdog.h> /* For watchdog specific items */
	41	#include <linux/miscdevice.h> /* For handling misc devices */
	42	#include <linux/init.h> /* For __init/__exit/... */
	43	#include <linux/uaccess.h> /* For copy_to_user/put_user/... */
	44
6cfb5aa8	45	#include "watchdog_core.h"
09a46e73	46
45f5fed3 AC	47	/* the dev_t structure to store the dynamically allocated watchdog devices */
45f5fed3 AC	48	static dev_t watchdog_devt;
43316044	49	/* the watchdog device behind /dev/watchdog */
45f5fed3	50	static struct watchdog_device *old_wdd;
43316044 WVS	51
	52	/*
	53	* watchdog_ping: ping the watchdog.
	54	* @wddev: the watchdog device to ping
	55	*
	56	* If the watchdog has no own ping operation then it needs to be
	57	* restarted via the start operation. This wrapper function does
	58	* exactly that.
234445b4	59	* We only ping when the watchdog device is running.
43316044 WVS	60	*/
	61
	62	static int watchdog_ping(struct watchdog_device *wddev)
	63	{
7a879824 HG	64	int err = 0;
	65
	66	if (!watchdog_active(wddev))
	67	goto out_ping;
	68
	69	if (wddev->ops->ping)
	70	err = wddev->ops->ping(wddev); /* ping the watchdog */
	71	else
	72	err = wddev->ops->start(wddev); /* restart watchdog */
	73
	74	out_ping:
	75	return err;
234445b4 WVS	76	}
	77
	78	/*
	79	* watchdog_start: wrapper to start the watchdog.
	80	* @wddev: the watchdog device to start
	81	*
	82	* Start the watchdog if it is not active and mark it active.
	83	* This function returns zero on success or a negative errno code for
	84	* failure.
	85	*/
	86
	87	static int watchdog_start(struct watchdog_device *wddev)
	88	{
7a879824	89	int err = 0;
234445b4	90
7a879824 HG	91	if (watchdog_active(wddev))
7a879824 HG	92	goto out_start;
234445b4	93
7a879824 HG	94	err = wddev->ops->start(wddev);
7a879824 HG	95	if (err == 0)
cb7efc02	96	set_bit(WDOG_ACTIVE, &wddev->status);
7a879824 HG	97
	98	out_start:
	99	return err;
234445b4 WVS	100	}
	101
	102	/*
	103	* watchdog_stop: wrapper to stop the watchdog.
	104	* @wddev: the watchdog device to stop
	105	*
	106	* Stop the watchdog if it is still active and unmark it active.
	107	* This function returns zero on success or a negative errno code for
	108	* failure.
7e192b9c	109	* If the 'nowayout' feature was set, the watchdog cannot be stopped.
234445b4 WVS	110	*/
	111
	112	static int watchdog_stop(struct watchdog_device *wddev)
	113	{
7a879824 HG	114	int err = 0;
	115
	116	if (!watchdog_active(wddev))
	117	goto out_stop;
7e192b9c	118
cb7efc02	119	if (test_bit(WDOG_NO_WAY_OUT, &wddev->status)) {
3dfd6218	120	dev_info(wddev->dev, "nowayout prevents watchdog being stopped!\n");
7a879824 HG	121	err = -EBUSY;
7a879824 HG	122	goto out_stop;
7e192b9c	123	}
234445b4	124
7a879824 HG	125	err = wddev->ops->stop(wddev);
7a879824 HG	126	if (err == 0)
cb7efc02	127	clear_bit(WDOG_ACTIVE, &wddev->status);
7a879824 HG	128
	129	out_stop:
	130	return err;
	131	}
	132
	133	/*
	134	* watchdog_get_status: wrapper to get the watchdog status
	135	* @wddev: the watchdog device to get the status from
	136	* @status: the status of the watchdog device
	137	*
	138	* Get the watchdog's status flags.
	139	*/
	140
	141	static int watchdog_get_status(struct watchdog_device *wddev,
	142	unsigned int *status)
	143	{
	144	int err = 0;
	145
	146	*status = 0;
	147	if (!wddev->ops->status)
	148	return -EOPNOTSUPP;
	149
	150	*status = wddev->ops->status(wddev);
	151
	152	return err;
	153	}
	154
	155	/*
	156	* watchdog_set_timeout: set the watchdog timer timeout
	157	* @wddev: the watchdog device to set the timeout for
	158	* @timeout: timeout to set in seconds
	159	*/
	160
	161	static int watchdog_set_timeout(struct watchdog_device *wddev,
	162	unsigned int timeout)
	163	{
	164	int err;
	165
	166	if ((wddev->ops->set_timeout == NULL) \|\|
	167	!(wddev->info->options & WDIOF_SETTIMEOUT))
	168	return -EOPNOTSUPP;
	169
	170	if ((wddev->max_timeout != 0) &&
	171	(timeout < wddev->min_timeout \|\| timeout > wddev->max_timeout))
	172	return -EINVAL;
	173
	174	err = wddev->ops->set_timeout(wddev, timeout);
	175
	176	return err;
	177	}
	178
	179	/*
	180	* watchdog_get_timeleft: wrapper to get the time left before a reboot
	181	* @wddev: the watchdog device to get the remaining time from
	182	* @timeleft: the time that's left
	183	*
	184	* Get the time before a watchdog will reboot (if not pinged).
	185	*/
	186
	187	static int watchdog_get_timeleft(struct watchdog_device *wddev,
	188	unsigned int *timeleft)
	189	{
	190	int err = 0;
	191
192	*timeleft = 0;
193	if (!wddev->ops->get_timeleft)
194	return -EOPNOTSUPP;
195
196	*timeleft = wddev->ops->get_timeleft(wddev);
197
198	return err;
199	}
200
201	/*
202	* watchdog_ioctl_op: call the watchdog drivers ioctl op if defined
203	* @wddev: the watchdog device to do the ioctl on
204	* @cmd: watchdog command
205	* @arg: argument pointer
206	*/
207
208	static int watchdog_ioctl_op(struct watchdog_device *wddev, unsigned int cmd,
209	unsigned long arg)
210	{
211	int err;
212
213	if (!wddev->ops->ioctl)
214	return -ENOIOCTLCMD;
215
216	err = wddev->ops->ioctl(wddev, cmd, arg);
217
218	return err;
43316044 WVS	219	}
	220
	221	/*
	222	* watchdog_write: writes to the watchdog.
	223	* @file: file from VFS
	224	* @data: user address of data
	225	* @len: length of data
	226	* @ppos: pointer to the file offset
	227	*
	228	* A write to a watchdog device is defined as a keepalive ping.
017cf080	229	* Writing the magic 'V' sequence allows the next close to turn
7e192b9c	230	* off the watchdog (if 'nowayout' is not set).
43316044 WVS	231	*/
	232
	233	static ssize_t watchdog_write(struct file file, const char __user data,
	234	size_t len, loff_t *ppos)
	235	{
45f5fed3	236	struct watchdog_device *wdd = file->private_data;
43316044 WVS	237	size_t i;
	238	char c;
	239
	240	if (len == 0)
	241	return 0;
	242
017cf080 WVS	243	/*
	244	* Note: just in case someone wrote the magic character
	245	* five months ago...
	246	*/
	247	clear_bit(WDOG_ALLOW_RELEASE, &wdd->status);
	248
	249	/* scan to see whether or not we got the magic character */
43316044 WVS	250	for (i = 0; i != len; i++) {
	251	if (get_user(c, data + i))
	252	return -EFAULT;
017cf080 WVS	253	if (c == 'V')
017cf080 WVS	254	set_bit(WDOG_ALLOW_RELEASE, &wdd->status);
43316044 WVS	255	}
	256
	257	/* someone wrote to us, so we send the watchdog a keepalive ping */
	258	watchdog_ping(wdd);
	259
	260	return len;
	261	}
	262
2fa03560 WVS	263	/*
	264	* watchdog_ioctl: handle the different ioctl's for the watchdog device.
	265	* @file: file handle to the device
	266	* @cmd: watchdog command
	267	* @arg: argument pointer
	268	*
	269	* The watchdog API defines a common set of functions for all watchdogs
	270	* according to their available features.
	271	*/
	272
	273	static long watchdog_ioctl(struct file *file, unsigned int cmd,
	274	unsigned long arg)
	275	{
45f5fed3	276	struct watchdog_device *wdd = file->private_data;
2fa03560 WVS	277	void __user argp = (void __user )arg;
	278	int __user *p = argp;
	279	unsigned int val;
234445b4	280	int err;
2fa03560	281
7a879824 HG	282	err = watchdog_ioctl_op(wdd, cmd, arg);
	283	if (err != -ENOIOCTLCMD)
	284	return err;
78d88fc0	285
2fa03560 WVS	286	switch (cmd) {
	287	case WDIOC_GETSUPPORT:
	288	return copy_to_user(argp, wdd->info,
	289	sizeof(struct watchdog_info)) ? -EFAULT : 0;
	290	case WDIOC_GETSTATUS:
7a879824 HG	291	err = watchdog_get_status(wdd, &val);
	292	if (err)
	293	return err;
2fa03560 WVS	294	return put_user(val, p);
	295	case WDIOC_GETBOOTSTATUS:
	296	return put_user(wdd->bootstatus, p);
234445b4 WVS	297	case WDIOC_SETOPTIONS:
	298	if (get_user(val, p))
	299	return -EFAULT;
	300	if (val & WDIOS_DISABLECARD) {
	301	err = watchdog_stop(wdd);
	302	if (err < 0)
	303	return err;
	304	}
	305	if (val & WDIOS_ENABLECARD) {
	306	err = watchdog_start(wdd);
	307	if (err < 0)
	308	return err;
	309	}
	310	return 0;
c2dc00e4 WVS	311	case WDIOC_KEEPALIVE:
	312	if (!(wdd->info->options & WDIOF_KEEPALIVEPING))
	313	return -EOPNOTSUPP;
	314	watchdog_ping(wdd);
	315	return 0;
014d694e	316	case WDIOC_SETTIMEOUT:
014d694e WVS	317	if (get_user(val, p))
014d694e WVS	318	return -EFAULT;
7a879824	319	err = watchdog_set_timeout(wdd, val);
014d694e WVS	320	if (err < 0)
014d694e WVS	321	return err;
014d694e WVS	322	/* If the watchdog is active then we send a keepalive ping
	323	* to make sure that the watchdog keep's running (and if
	324	* possible that it takes the new timeout) */
	325	watchdog_ping(wdd);
	326	/* Fall */
	327	case WDIOC_GETTIMEOUT:
	328	/* timeout == 0 means that we don't know the timeout */
	329	if (wdd->timeout == 0)
	330	return -EOPNOTSUPP;
	331	return put_user(wdd->timeout, p);
fd7b673c	332	case WDIOC_GETTIMELEFT:
7a879824 HG	333	err = watchdog_get_timeleft(wdd, &val);
	334	if (err)
	335	return err;
	336	return put_user(val, p);
2fa03560 WVS	337	default:
	338	return -ENOTTY;
	339	}
	340	}
	341
43316044	342	/*
45f5fed3	343	* watchdog_open: open the /dev/watchdog* devices.
43316044 WVS	344	* @inode: inode of device
	345	* @file: file handle to device
	346	*
45f5fed3	347	* When the /dev/watchdog* device gets opened, we start the watchdog.
43316044 WVS	348	* Watch out: the /dev/watchdog device is single open, so we make sure
	349	* it can only be opened once.
	350	*/
	351
	352	static int watchdog_open(struct inode inode, struct file file)
	353	{
	354	int err = -EBUSY;
45f5fed3 AC	355	struct watchdog_device *wdd;
	356
	357	/* Get the corresponding watchdog device */
	358	if (imajor(inode) == MISC_MAJOR)
	359	wdd = old_wdd;
	360	else
	361	wdd = container_of(inode->i_cdev, struct watchdog_device, cdev);
43316044 WVS	362
	363	/* the watchdog is single open! */
	364	if (test_and_set_bit(WDOG_DEV_OPEN, &wdd->status))
	365	return -EBUSY;
	366
	367	/*
	368	* If the /dev/watchdog device is open, we don't want the module
	369	* to be unloaded.
	370	*/
	371	if (!try_module_get(wdd->ops->owner))
	372	goto out;
	373
234445b4	374	err = watchdog_start(wdd);
43316044 WVS	375	if (err < 0)
	376	goto out_mod;
	377
45f5fed3 AC	378	file->private_data = wdd;
45f5fed3 AC	379
43316044 WVS	380	/* dev/watchdog is a virtual (and thus non-seekable) filesystem */
	381	return nonseekable_open(inode, file);
	382
	383	out_mod:
	384	module_put(wdd->ops->owner);
	385	out:
	386	clear_bit(WDOG_DEV_OPEN, &wdd->status);
	387	return err;
	388	}
	389
	390	/*
45f5fed3 AC	391	* watchdog_release: release the watchdog device.
	392	* @inode: inode of device
	393	* @file: file handle to device
43316044	394	*
017cf080	395	* This is the code for when /dev/watchdog gets closed. We will only
7e192b9c WVS	396	* stop the watchdog when we have received the magic char (and nowayout
7e192b9c WVS	397	* was not set), else the watchdog will keep running.
43316044 WVS	398	*/
	399
	400	static int watchdog_release(struct inode inode, struct file file)
	401	{
45f5fed3	402	struct watchdog_device *wdd = file->private_data;
017cf080 WVS	403	int err = -EBUSY;
	404
	405	/*
	406	* We only stop the watchdog if we received the magic character
7e192b9c WVS	407	* or if WDIOF_MAGICCLOSE is not set. If nowayout was set then
7e192b9c WVS	408	* watchdog_stop will fail.
017cf080 WVS	409	*/
	410	if (test_and_clear_bit(WDOG_ALLOW_RELEASE, &wdd->status) \|\|
	411	!(wdd->info->options & WDIOF_MAGICCLOSE))
	412	err = watchdog_stop(wdd);
43316044	413
017cf080	414	/* If the watchdog was not stopped, send a keepalive ping */
234445b4	415	if (err < 0) {
3dfd6218	416	dev_crit(wdd->dev, "watchdog did not stop!\n");
43316044 WVS	417	watchdog_ping(wdd);
	418	}
	419
	420	/* Allow the owner module to be unloaded again */
	421	module_put(wdd->ops->owner);
	422
	423	/* make sure that /dev/watchdog can be re-opened */
	424	clear_bit(WDOG_DEV_OPEN, &wdd->status);
	425
	426	return 0;
	427	}
	428
	429	static const struct file_operations watchdog_fops = {
	430	.owner = THIS_MODULE,
	431	.write = watchdog_write,
2fa03560	432	.unlocked_ioctl = watchdog_ioctl,
43316044 WVS	433	.open = watchdog_open,
	434	.release = watchdog_release,
	435	};
	436
	437	static struct miscdevice watchdog_miscdev = {
	438	.minor = WATCHDOG_MINOR,
	439	.name = "watchdog",
	440	.fops = &watchdog_fops,
	441	};
	442
	443	/*
45f5fed3	444	* watchdog_dev_register: register a watchdog device
43316044 WVS	445	* @watchdog: watchdog device
43316044 WVS	446	*
45f5fed3 AC	447	* Register a watchdog device including handling the legacy
	448	* /dev/watchdog node. /dev/watchdog is actually a miscdevice and
	449	* thus we set it up like that.
43316044 WVS	450	*/
	451
	452	int watchdog_dev_register(struct watchdog_device *watchdog)
	453	{
45f5fed3 AC	454	int err, devno;
	455
	456	if (watchdog->id == 0) {
d6b469d9	457	watchdog_miscdev.parent = watchdog->parent;
45f5fed3 AC	458	err = misc_register(&watchdog_miscdev);
	459	if (err != 0) {
	460	pr_err("%s: cannot register miscdev on minor=%d (err=%d).\n",
	461	watchdog->info->identity, WATCHDOG_MINOR, err);
	462	if (err == -EBUSY)
	463	pr_err("%s: a legacy watchdog module is probably present.\n",
	464	watchdog->info->identity);
	465	return err;
	466	}
	467	old_wdd = watchdog;
43316044 WVS	468	}
43316044 WVS	469
45f5fed3 AC	470	/* Fill in the data structures */
	471	devno = MKDEV(MAJOR(watchdog_devt), watchdog->id);
	472	cdev_init(&watchdog->cdev, &watchdog_fops);
	473	watchdog->cdev.owner = watchdog->ops->owner;
	474
	475	/* Add the device */
	476	err = cdev_add(&watchdog->cdev, devno, 1);
	477	if (err) {
	478	pr_err("watchdog%d unable to add device %d:%d\n",
	479	watchdog->id, MAJOR(watchdog_devt), watchdog->id);
	480	if (watchdog->id == 0) {
	481	misc_deregister(&watchdog_miscdev);
	482	old_wdd = NULL;
	483	}
43316044	484	}
43316044 WVS	485	return err;
	486	}
	487
	488	/*
45f5fed3	489	* watchdog_dev_unregister: unregister a watchdog device
43316044 WVS	490	* @watchdog: watchdog device
43316044 WVS	491	*
45f5fed3	492	* Unregister the watchdog and if needed the legacy /dev/watchdog device.
43316044 WVS	493	*/
	494
	495	int watchdog_dev_unregister(struct watchdog_device *watchdog)
	496	{
45f5fed3 AC	497	cdev_del(&watchdog->cdev);
	498	if (watchdog->id == 0) {
	499	misc_deregister(&watchdog_miscdev);
	500	old_wdd = NULL;
43316044	501	}
43316044 WVS	502	return 0;
43316044 WVS	503	}
45f5fed3 AC	504
	505	/*
	506	* watchdog_dev_init: init dev part of watchdog core
	507	*
	508	* Allocate a range of chardev nodes to use for watchdog devices
	509	*/
	510
	511	int __init watchdog_dev_init(void)
	512	{
	513	int err = alloc_chrdev_region(&watchdog_devt, 0, MAX_DOGS, "watchdog");
	514	if (err < 0)
	515	pr_err("watchdog: unable to allocate char dev region\n");
	516	return err;
	517	}
	518
	519	/*
	520	* watchdog_dev_exit: exit dev part of watchdog core
	521	*
	522	* Release the range of chardev nodes used for watchdog devices
	523	*/
	524
	525	void __exit watchdog_dev_exit(void)
	526	{
	527	unregister_chrdev_region(watchdog_devt, MAX_DOGS);
	528	}