[GitHub/mt8127/android_kernel_alcatel_ttab.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;

	mutex_lock(&wddev->lock);

	if (test_bit(WDOG_UNREGISTERED, &wddev->status)) {
		err = -ENODEV;
		goto out_ping;
	}

	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:
	mutex_unlock(&wddev->lock);
	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;

	mutex_lock(&wddev->lock);

	if (test_bit(WDOG_UNREGISTERED, &wddev->status)) {
		err = -ENODEV;
		goto out_start;
	}

	if (watchdog_active(wddev))
		goto out_start;

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

out_start:
	mutex_unlock(&wddev->lock);
	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;

	mutex_lock(&wddev->lock);

	if (test_bit(WDOG_UNREGISTERED, &wddev->status)) {
		err = -ENODEV;
		goto out_stop;
	}

	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:
	mutex_unlock(&wddev->lock);
	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;

	mutex_lock(&wddev->lock);

	if (test_bit(WDOG_UNREGISTERED, &wddev->status)) {
		err = -ENODEV;
		goto out_status;
	}

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

out_status:
	mutex_unlock(&wddev->lock);
	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 (watchdog_timeout_invalid(wddev, timeout))
		return -EINVAL;

	mutex_lock(&wddev->lock);

	if (test_bit(WDOG_UNREGISTERED, &wddev->status)) {
		err = -ENODEV;
		goto out_timeout;
	}

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

out_timeout:
	mutex_unlock(&wddev->lock);
	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;

	mutex_lock(&wddev->lock);

	if (test_bit(WDOG_UNREGISTERED, &wddev->status)) {
		err = -ENODEV;
		goto out_timeleft;
	}

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

out_timeleft:
	mutex_unlock(&wddev->lock);
	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;

	mutex_lock(&wddev->lock);

	if (test_bit(WDOG_UNREGISTERED, &wddev->status)) {
		err = -ENODEV;
		goto out_ioctl;
	}

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

out_ioctl:
	mutex_unlock(&wddev->lock);
	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 == -ENODEV)
			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;

	if (wdd->ops->ref)
		wdd->ops->ref(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) {
		mutex_lock(&wdd->lock);
		if (!test_bit(WDOG_UNREGISTERED, &wdd->status))
			dev_crit(wdd->dev, "watchdog did not stop!\n");
		mutex_unlock(&wdd->lock);
		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);

	/* Note wdd may be gone after this, do not use after this! */
	if (wdd->ops->unref)
		wdd->ops->unref(wdd);

	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) {
		old_wdd = watchdog;
		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);
			old_wdd = NULL;
			return err;
		}
	}

	/* 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)
{
	mutex_lock(&watchdog->lock);
	set_bit(WDOG_UNREGISTERED, &watchdog->status);
	mutex_unlock(&watchdog->lock);

	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;
7a879824 HG	65
f4e9c82f HG	66	mutex_lock(&wddev->lock);
f4e9c82f HG	67
e907df32 HG	68	if (test_bit(WDOG_UNREGISTERED, &wddev->status)) {
	69	err = -ENODEV;
	70	goto out_ping;
	71	}
	72
7a879824 HG	73	if (!watchdog_active(wddev))
	74	goto out_ping;
	75
	76	if (wddev->ops->ping)
	77	err = wddev->ops->ping(wddev); /* ping the watchdog */
	78	else
	79	err = wddev->ops->start(wddev); /* restart watchdog */
	80
	81	out_ping:
f4e9c82f	82	mutex_unlock(&wddev->lock);
7a879824	83	return err;
234445b4 WVS	84	}
	85
	86	/*
	87	* watchdog_start: wrapper to start the watchdog.
	88	* @wddev: the watchdog device to start
	89	*
	90	* Start the watchdog if it is not active and mark it active.
	91	* This function returns zero on success or a negative errno code for
	92	* failure.
	93	*/
	94
	95	static int watchdog_start(struct watchdog_device *wddev)
	96	{
7a879824	97	int err = 0;
234445b4	98
f4e9c82f HG	99	mutex_lock(&wddev->lock);
f4e9c82f HG	100
e907df32 HG	101	if (test_bit(WDOG_UNREGISTERED, &wddev->status)) {
	102	err = -ENODEV;
	103	goto out_start;
	104	}
	105
7a879824 HG	106	if (watchdog_active(wddev))
7a879824 HG	107	goto out_start;
234445b4	108
7a879824 HG	109	err = wddev->ops->start(wddev);
7a879824 HG	110	if (err == 0)
cb7efc02	111	set_bit(WDOG_ACTIVE, &wddev->status);
7a879824 HG	112
7a879824 HG	113	out_start:
f4e9c82f	114	mutex_unlock(&wddev->lock);
7a879824	115	return err;
234445b4 WVS	116	}
	117
	118	/*
	119	* watchdog_stop: wrapper to stop the watchdog.
	120	* @wddev: the watchdog device to stop
	121	*
	122	* Stop the watchdog if it is still active and unmark it active.
	123	* This function returns zero on success or a negative errno code for
	124	* failure.
7e192b9c	125	* If the 'nowayout' feature was set, the watchdog cannot be stopped.
234445b4 WVS	126	*/
	127
	128	static int watchdog_stop(struct watchdog_device *wddev)
	129	{
7a879824 HG	130	int err = 0;
7a879824 HG	131
f4e9c82f HG	132	mutex_lock(&wddev->lock);
f4e9c82f HG	133
e907df32 HG	134	if (test_bit(WDOG_UNREGISTERED, &wddev->status)) {
	135	err = -ENODEV;
	136	goto out_stop;
	137	}
	138
7a879824 HG	139	if (!watchdog_active(wddev))
7a879824 HG	140	goto out_stop;
7e192b9c	141
cb7efc02	142	if (test_bit(WDOG_NO_WAY_OUT, &wddev->status)) {
3dfd6218	143	dev_info(wddev->dev, "nowayout prevents watchdog being stopped!\n");
7a879824 HG	144	err = -EBUSY;
7a879824 HG	145	goto out_stop;
7e192b9c	146	}
234445b4	147
7a879824 HG	148	err = wddev->ops->stop(wddev);
7a879824 HG	149	if (err == 0)
cb7efc02	150	clear_bit(WDOG_ACTIVE, &wddev->status);
7a879824 HG	151
7a879824 HG	152	out_stop:
f4e9c82f	153	mutex_unlock(&wddev->lock);
7a879824 HG	154	return err;
	155	}
	156
	157	/*
	158	* watchdog_get_status: wrapper to get the watchdog status
	159	* @wddev: the watchdog device to get the status from
	160	* @status: the status of the watchdog device
	161	*
	162	* Get the watchdog's status flags.
	163	*/
	164
	165	static int watchdog_get_status(struct watchdog_device *wddev,
	166	unsigned int *status)
	167	{
	168	int err = 0;
	169
	170	*status = 0;
	171	if (!wddev->ops->status)
	172	return -EOPNOTSUPP;
	173
f4e9c82f HG	174	mutex_lock(&wddev->lock);
f4e9c82f HG	175
e907df32 HG	176	if (test_bit(WDOG_UNREGISTERED, &wddev->status)) {
	177	err = -ENODEV;
	178	goto out_status;
	179	}
	180
7a879824 HG	181	*status = wddev->ops->status(wddev);
7a879824 HG	182
e907df32	183	out_status:
f4e9c82f	184	mutex_unlock(&wddev->lock);
7a879824 HG	185	return err;
	186	}
	187
	188	/*
	189	* watchdog_set_timeout: set the watchdog timer timeout
	190	* @wddev: the watchdog device to set the timeout for
	191	* @timeout: timeout to set in seconds
	192	*/
	193
	194	static int watchdog_set_timeout(struct watchdog_device *wddev,
	195	unsigned int timeout)
	196	{
	197	int err;
	198
	199	if ((wddev->ops->set_timeout == NULL) \|\|
	200	!(wddev->info->options & WDIOF_SETTIMEOUT))
	201	return -EOPNOTSUPP;
	202
3048253e	203	if (watchdog_timeout_invalid(wddev, timeout))
7a879824 HG	204	return -EINVAL;
7a879824 HG	205
f4e9c82f HG	206	mutex_lock(&wddev->lock);
f4e9c82f HG	207
e907df32 HG	208	if (test_bit(WDOG_UNREGISTERED, &wddev->status)) {
	209	err = -ENODEV;
	210	goto out_timeout;
	211	}
	212
7a879824 HG	213	err = wddev->ops->set_timeout(wddev, timeout);
7a879824 HG	214
e907df32	215	out_timeout:
f4e9c82f	216	mutex_unlock(&wddev->lock);
7a879824 HG	217	return err;
	218	}
	219
	220	/*
	221	* watchdog_get_timeleft: wrapper to get the time left before a reboot
	222	* @wddev: the watchdog device to get the remaining time from
	223	* @timeleft: the time that's left
	224	*
	225	* Get the time before a watchdog will reboot (if not pinged).
	226	*/
	227
	228	static int watchdog_get_timeleft(struct watchdog_device *wddev,
	229	unsigned int *timeleft)
	230	{
	231	int err = 0;
	232
	233	*timeleft = 0;
	234	if (!wddev->ops->get_timeleft)
	235	return -EOPNOTSUPP;
	236
f4e9c82f HG	237	mutex_lock(&wddev->lock);
f4e9c82f HG	238
e907df32 HG	239	if (test_bit(WDOG_UNREGISTERED, &wddev->status)) {
	240	err = -ENODEV;
	241	goto out_timeleft;
	242	}
	243
7a879824 HG	244	*timeleft = wddev->ops->get_timeleft(wddev);
7a879824 HG	245
e907df32	246	out_timeleft:
f4e9c82f	247	mutex_unlock(&wddev->lock);
7a879824 HG	248	return err;
	249	}
	250
	251	/*
	252	* watchdog_ioctl_op: call the watchdog drivers ioctl op if defined
	253	* @wddev: the watchdog device to do the ioctl on
	254	* @cmd: watchdog command
	255	* @arg: argument pointer
	256	*/
	257
	258	static int watchdog_ioctl_op(struct watchdog_device *wddev, unsigned int cmd,
	259	unsigned long arg)
	260	{
	261	int err;
	262
	263	if (!wddev->ops->ioctl)
	264	return -ENOIOCTLCMD;
	265
f4e9c82f HG	266	mutex_lock(&wddev->lock);
f4e9c82f HG	267
e907df32 HG	268	if (test_bit(WDOG_UNREGISTERED, &wddev->status)) {
	269	err = -ENODEV;
	270	goto out_ioctl;
	271	}
	272
7a879824 HG	273	err = wddev->ops->ioctl(wddev, cmd, arg);
7a879824 HG	274
e907df32	275	out_ioctl:
f4e9c82f	276	mutex_unlock(&wddev->lock);
7a879824	277	return err;
43316044 WVS	278	}
	279
	280	/*
	281	* watchdog_write: writes to the watchdog.
	282	* @file: file from VFS
	283	* @data: user address of data
	284	* @len: length of data
	285	* @ppos: pointer to the file offset
	286	*
	287	* A write to a watchdog device is defined as a keepalive ping.
017cf080	288	* Writing the magic 'V' sequence allows the next close to turn
7e192b9c	289	* off the watchdog (if 'nowayout' is not set).
43316044 WVS	290	*/
	291
	292	static ssize_t watchdog_write(struct file file, const char __user data,
	293	size_t len, loff_t *ppos)
	294	{
45f5fed3	295	struct watchdog_device *wdd = file->private_data;
43316044 WVS	296	size_t i;
	297	char c;
	298
	299	if (len == 0)
	300	return 0;
	301
017cf080 WVS	302	/*
	303	* Note: just in case someone wrote the magic character
	304	* five months ago...
	305	*/
	306	clear_bit(WDOG_ALLOW_RELEASE, &wdd->status);
	307
	308	/* scan to see whether or not we got the magic character */
43316044 WVS	309	for (i = 0; i != len; i++) {
	310	if (get_user(c, data + i))
	311	return -EFAULT;
017cf080 WVS	312	if (c == 'V')
017cf080 WVS	313	set_bit(WDOG_ALLOW_RELEASE, &wdd->status);
43316044 WVS	314	}
	315
	316	/* someone wrote to us, so we send the watchdog a keepalive ping */
	317	watchdog_ping(wdd);
	318
	319	return len;
	320	}
	321
2fa03560 WVS	322	/*
	323	* watchdog_ioctl: handle the different ioctl's for the watchdog device.
	324	* @file: file handle to the device
	325	* @cmd: watchdog command
	326	* @arg: argument pointer
	327	*
	328	* The watchdog API defines a common set of functions for all watchdogs
	329	* according to their available features.
	330	*/
	331
	332	static long watchdog_ioctl(struct file *file, unsigned int cmd,
	333	unsigned long arg)
	334	{
45f5fed3	335	struct watchdog_device *wdd = file->private_data;
2fa03560 WVS	336	void __user argp = (void __user )arg;
	337	int __user *p = argp;
	338	unsigned int val;
234445b4	339	int err;
2fa03560	340
7a879824 HG	341	err = watchdog_ioctl_op(wdd, cmd, arg);
	342	if (err != -ENOIOCTLCMD)
	343	return err;
78d88fc0	344
2fa03560 WVS	345	switch (cmd) {
	346	case WDIOC_GETSUPPORT:
	347	return copy_to_user(argp, wdd->info,
	348	sizeof(struct watchdog_info)) ? -EFAULT : 0;
	349	case WDIOC_GETSTATUS:
7a879824	350	err = watchdog_get_status(wdd, &val);
8b9468d4	351	if (err == -ENODEV)
7a879824	352	return err;
2fa03560 WVS	353	return put_user(val, p);
	354	case WDIOC_GETBOOTSTATUS:
	355	return put_user(wdd->bootstatus, p);
234445b4 WVS	356	case WDIOC_SETOPTIONS:
	357	if (get_user(val, p))
	358	return -EFAULT;
	359	if (val & WDIOS_DISABLECARD) {
	360	err = watchdog_stop(wdd);
	361	if (err < 0)
	362	return err;
	363	}
	364	if (val & WDIOS_ENABLECARD) {
	365	err = watchdog_start(wdd);
	366	if (err < 0)
	367	return err;
	368	}
	369	return 0;
c2dc00e4 WVS	370	case WDIOC_KEEPALIVE:
	371	if (!(wdd->info->options & WDIOF_KEEPALIVEPING))
	372	return -EOPNOTSUPP;
	373	watchdog_ping(wdd);
	374	return 0;
014d694e	375	case WDIOC_SETTIMEOUT:
014d694e WVS	376	if (get_user(val, p))
014d694e WVS	377	return -EFAULT;
7a879824	378	err = watchdog_set_timeout(wdd, val);
014d694e WVS	379	if (err < 0)
014d694e WVS	380	return err;
014d694e WVS	381	/* If the watchdog is active then we send a keepalive ping
	382	* to make sure that the watchdog keep's running (and if
	383	* possible that it takes the new timeout) */
	384	watchdog_ping(wdd);
	385	/* Fall */
	386	case WDIOC_GETTIMEOUT:
	387	/* timeout == 0 means that we don't know the timeout */
	388	if (wdd->timeout == 0)
	389	return -EOPNOTSUPP;
	390	return put_user(wdd->timeout, p);
fd7b673c	391	case WDIOC_GETTIMELEFT:
7a879824 HG	392	err = watchdog_get_timeleft(wdd, &val);
	393	if (err)
	394	return err;
	395	return put_user(val, p);
2fa03560 WVS	396	default:
	397	return -ENOTTY;
	398	}
	399	}
	400
43316044	401	/*
45f5fed3	402	* watchdog_open: open the /dev/watchdog* devices.
43316044 WVS	403	* @inode: inode of device
	404	* @file: file handle to device
	405	*
45f5fed3	406	* When the /dev/watchdog* device gets opened, we start the watchdog.
43316044 WVS	407	* Watch out: the /dev/watchdog device is single open, so we make sure
	408	* it can only be opened once.
	409	*/
	410
	411	static int watchdog_open(struct inode inode, struct file file)
	412	{
	413	int err = -EBUSY;
45f5fed3 AC	414	struct watchdog_device *wdd;
	415
	416	/* Get the corresponding watchdog device */
	417	if (imajor(inode) == MISC_MAJOR)
	418	wdd = old_wdd;
	419	else
	420	wdd = container_of(inode->i_cdev, struct watchdog_device, cdev);
43316044 WVS	421
	422	/* the watchdog is single open! */
	423	if (test_and_set_bit(WDOG_DEV_OPEN, &wdd->status))
	424	return -EBUSY;
	425
	426	/*
	427	* If the /dev/watchdog device is open, we don't want the module
	428	* to be unloaded.
	429	*/
	430	if (!try_module_get(wdd->ops->owner))
	431	goto out;
	432
234445b4	433	err = watchdog_start(wdd);
43316044 WVS	434	if (err < 0)
	435	goto out_mod;
	436
45f5fed3 AC	437	file->private_data = wdd;
45f5fed3 AC	438
e907df32 HG	439	if (wdd->ops->ref)
	440	wdd->ops->ref(wdd);
	441
43316044 WVS	442	/* dev/watchdog is a virtual (and thus non-seekable) filesystem */
	443	return nonseekable_open(inode, file);
	444
	445	out_mod:
	446	module_put(wdd->ops->owner);
	447	out:
	448	clear_bit(WDOG_DEV_OPEN, &wdd->status);
	449	return err;
	450	}
	451
	452	/*
45f5fed3 AC	453	* watchdog_release: release the watchdog device.
	454	* @inode: inode of device
	455	* @file: file handle to device
43316044	456	*
017cf080	457	* This is the code for when /dev/watchdog gets closed. We will only
7e192b9c WVS	458	* stop the watchdog when we have received the magic char (and nowayout
7e192b9c WVS	459	* was not set), else the watchdog will keep running.
43316044 WVS	460	*/
	461
	462	static int watchdog_release(struct inode inode, struct file file)
	463	{
45f5fed3	464	struct watchdog_device *wdd = file->private_data;
017cf080 WVS	465	int err = -EBUSY;
	466
	467	/*
	468	* We only stop the watchdog if we received the magic character
7e192b9c WVS	469	* or if WDIOF_MAGICCLOSE is not set. If nowayout was set then
7e192b9c WVS	470	* watchdog_stop will fail.
017cf080 WVS	471	*/
	472	if (test_and_clear_bit(WDOG_ALLOW_RELEASE, &wdd->status) \|\|
	473	!(wdd->info->options & WDIOF_MAGICCLOSE))
	474	err = watchdog_stop(wdd);
43316044	475
017cf080	476	/* If the watchdog was not stopped, send a keepalive ping */
234445b4	477	if (err < 0) {
e907df32 HG	478	mutex_lock(&wdd->lock);
	479	if (!test_bit(WDOG_UNREGISTERED, &wdd->status))
	480	dev_crit(wdd->dev, "watchdog did not stop!\n");
	481	mutex_unlock(&wdd->lock);
43316044 WVS	482	watchdog_ping(wdd);
	483	}
	484
	485	/* Allow the owner module to be unloaded again */
	486	module_put(wdd->ops->owner);
	487
	488	/* make sure that /dev/watchdog can be re-opened */
	489	clear_bit(WDOG_DEV_OPEN, &wdd->status);
	490
e907df32 HG	491	/* Note wdd may be gone after this, do not use after this! */
	492	if (wdd->ops->unref)
	493	wdd->ops->unref(wdd);
	494
43316044 WVS	495	return 0;
	496	}
	497
	498	static const struct file_operations watchdog_fops = {
	499	.owner = THIS_MODULE,
	500	.write = watchdog_write,
2fa03560	501	.unlocked_ioctl = watchdog_ioctl,
43316044 WVS	502	.open = watchdog_open,
	503	.release = watchdog_release,
	504	};
	505
	506	static struct miscdevice watchdog_miscdev = {
	507	.minor = WATCHDOG_MINOR,
	508	.name = "watchdog",
	509	.fops = &watchdog_fops,
	510	};
	511
	512	/*
45f5fed3	513	* watchdog_dev_register: register a watchdog device
43316044 WVS	514	* @watchdog: watchdog device
43316044 WVS	515	*
45f5fed3 AC	516	* Register a watchdog device including handling the legacy
	517	* /dev/watchdog node. /dev/watchdog is actually a miscdevice and
	518	* thus we set it up like that.
43316044 WVS	519	*/
	520
	521	int watchdog_dev_register(struct watchdog_device *watchdog)
	522	{
45f5fed3 AC	523	int err, devno;
	524
	525	if (watchdog->id == 0) {
60403f7a	526	old_wdd = watchdog;
d6b469d9	527	watchdog_miscdev.parent = watchdog->parent;
45f5fed3 AC	528	err = misc_register(&watchdog_miscdev);
	529	if (err != 0) {
	530	pr_err("%s: cannot register miscdev on minor=%d (err=%d).\n",
	531	watchdog->info->identity, WATCHDOG_MINOR, err);
	532	if (err == -EBUSY)
	533	pr_err("%s: a legacy watchdog module is probably present.\n",
	534	watchdog->info->identity);
60403f7a	535	old_wdd = NULL;
45f5fed3 AC	536	return err;
45f5fed3 AC	537	}
43316044 WVS	538	}
43316044 WVS	539
45f5fed3 AC	540	/* Fill in the data structures */
	541	devno = MKDEV(MAJOR(watchdog_devt), watchdog->id);
	542	cdev_init(&watchdog->cdev, &watchdog_fops);
	543	watchdog->cdev.owner = watchdog->ops->owner;
	544
	545	/* Add the device */
	546	err = cdev_add(&watchdog->cdev, devno, 1);
	547	if (err) {
	548	pr_err("watchdog%d unable to add device %d:%d\n",
	549	watchdog->id, MAJOR(watchdog_devt), watchdog->id);
	550	if (watchdog->id == 0) {
	551	misc_deregister(&watchdog_miscdev);
	552	old_wdd = NULL;
	553	}
43316044	554	}
43316044 WVS	555	return err;
	556	}
	557
	558	/*
45f5fed3	559	* watchdog_dev_unregister: unregister a watchdog device
43316044 WVS	560	* @watchdog: watchdog device
43316044 WVS	561	*
45f5fed3	562	* Unregister the watchdog and if needed the legacy /dev/watchdog device.
43316044 WVS	563	*/
	564
	565	int watchdog_dev_unregister(struct watchdog_device *watchdog)
	566	{
e907df32 HG	567	mutex_lock(&watchdog->lock);
	568	set_bit(WDOG_UNREGISTERED, &watchdog->status);
	569	mutex_unlock(&watchdog->lock);
	570
45f5fed3 AC	571	cdev_del(&watchdog->cdev);
	572	if (watchdog->id == 0) {
	573	misc_deregister(&watchdog_miscdev);
	574	old_wdd = NULL;
43316044	575	}
43316044 WVS	576	return 0;
43316044 WVS	577	}
45f5fed3 AC	578
	579	/*
	580	* watchdog_dev_init: init dev part of watchdog core
	581	*
	582	* Allocate a range of chardev nodes to use for watchdog devices
	583	*/
	584
	585	int __init watchdog_dev_init(void)
	586	{
	587	int err = alloc_chrdev_region(&watchdog_devt, 0, MAX_DOGS, "watchdog");
	588	if (err < 0)
	589	pr_err("watchdog: unable to allocate char dev region\n");
	590	return err;
	591	}
	592
	593	/*
	594	* watchdog_dev_exit: exit dev part of watchdog core
	595	*
	596	* Release the range of chardev nodes used for watchdog devices
	597	*/
	598
	599	void __exit watchdog_dev_exit(void)
	600	{
	601	unregister_chrdev_region(watchdog_devt, MAX_DOGS);
	602	}