Release 4.11 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/cdev.h>		/* For character device */
#include <linux/errno.h>	/* For the -ENODEV/... values */
#include <linux/fs.h>		/* For file operations */
#include <linux/init.h>		/* For __init/__exit/... */
#include <linux/jiffies.h>	/* For timeout functions */
#include <linux/kernel.h>	/* For printk/panic/... */
#include <linux/kref.h>		/* For data references */
#include <linux/miscdevice.h>	/* For handling misc devices */
#include <linux/module.h>	/* For module stuff/... */
#include <linux/mutex.h>	/* For mutexes */
#include <linux/slab.h>		/* For memory functions */
#include <linux/types.h>	/* For standard types (like size_t) */
#include <linux/watchdog.h>	/* For watchdog specific items */
#include <linux/workqueue.h>	/* For workqueue */
#include <linux/uaccess.h>	/* For copy_to_user/put_user/... */

#include "watchdog_core.h"
#include "watchdog_pretimeout.h"

/*
 * struct watchdog_core_data - watchdog core internal data
 * @kref:       Reference count.
 * @cdev:       The watchdog's Character device.
 * @wdd:        Pointer to watchdog device.
 * @lock:       Lock for watchdog core.
 * @status:     Watchdog core internal status bits.
 */

struct watchdog_core_data {
	
struct kref kref;
	
struct cdev cdev;
	
struct watchdog_device *wdd;
	
struct mutex lock;
	
unsigned long last_keepalive;
	
unsigned long last_hw_keepalive;
	
struct delayed_work work;
	
unsigned long status;		/* Internal status bits */

#define _WDOG_DEV_OPEN		0	/* Opened ? */

#define _WDOG_ALLOW_RELEASE	1	/* Did we receive the magic char ? */

#define _WDOG_KEEPALIVE		2	/* Did we receive a keepalive ? */
};

/* the dev_t structure to store the dynamically allocated watchdog devices */

static dev_t watchdog_devt;
/* Reference to watchdog device behind /dev/watchdog */

static struct watchdog_core_data *old_wd_data;


static struct workqueue_struct *watchdog_wq;



static inline bool watchdog_need_worker(struct watchdog_device *wdd)
{
	/* All variables in milli-seconds */
	unsigned int hm = wdd->max_hw_heartbeat_ms;
	unsigned int t = wdd->timeout * 1000;

	/*
         * A worker to generate heartbeat requests is needed if all of the
         * following conditions are true.
         * - Userspace activated the watchdog.
         * - The driver provided a value for the maximum hardware timeout, and
         *   thus is aware that the framework supports generating heartbeat
         *   requests.
         * - Userspace requests a longer timeout than the hardware can handle.
         *
         * Alternatively, if userspace has not opened the watchdog
         * device, we take care of feeding the watchdog if it is
         * running.
         */
	return (hm && watchdog_active(wdd) && t > hm) ||
		(t && !watchdog_active(wdd) && watchdog_hw_running(wdd));
}

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static long watchdog_next_keepalive(struct watchdog_device *wdd)
{
	struct watchdog_core_data *wd_data = wdd->wd_data;
	unsigned int timeout_ms = wdd->timeout * 1000;
	unsigned long keepalive_interval;
	unsigned long last_heartbeat;
	unsigned long virt_timeout;
	unsigned int hw_heartbeat_ms;

	virt_timeout = wd_data->last_keepalive + msecs_to_jiffies(timeout_ms);
	hw_heartbeat_ms = min_not_zero(timeout_ms, wdd->max_hw_heartbeat_ms);
	keepalive_interval = msecs_to_jiffies(hw_heartbeat_ms / 2);

	if (!watchdog_active(wdd))
		return keepalive_interval;

	/*
         * To ensure that the watchdog times out wdd->timeout seconds
         * after the most recent ping from userspace, the last
         * worker ping has to come in hw_heartbeat_ms before this timeout.
         */
	last_heartbeat = virt_timeout - msecs_to_jiffies(hw_heartbeat_ms);
	return min_t(long, last_heartbeat - jiffies, keepalive_interval);
}

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static inline void watchdog_update_worker(struct watchdog_device *wdd)
{
	struct watchdog_core_data *wd_data = wdd->wd_data;

	if (watchdog_need_worker(wdd)) {
		long t = watchdog_next_keepalive(wdd);

		if (t > 0)
			mod_delayed_work(watchdog_wq, &wd_data->work, t);
	} else {
		cancel_delayed_work(&wd_data->work);
	}
}

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static int __watchdog_ping(struct watchdog_device *wdd)
{
	struct watchdog_core_data *wd_data = wdd->wd_data;
	unsigned long earliest_keepalive = wd_data->last_hw_keepalive +
				msecs_to_jiffies(wdd->min_hw_heartbeat_ms);
	int err;

	if (time_is_after_jiffies(earliest_keepalive)) {
		mod_delayed_work(watchdog_wq, &wd_data->work,
				 earliest_keepalive - jiffies);
		return 0;
	}

	wd_data->last_hw_keepalive = jiffies;

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

	watchdog_update_worker(wdd);

	return err;
}

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/*
 *      watchdog_ping: ping the watchdog.
 *      @wdd: the watchdog device to ping
 *
 *      The caller must hold wd_data->lock.
 *
 *      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 *wdd)
{
	struct watchdog_core_data *wd_data = wdd->wd_data;

	if (!watchdog_active(wdd) && !watchdog_hw_running(wdd))
		return 0;

	set_bit(_WDOG_KEEPALIVE, &wd_data->status);

	wd_data->last_keepalive = jiffies;
	return __watchdog_ping(wdd);
}

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static void watchdog_ping_work(struct work_struct *work)
{
	struct watchdog_core_data *wd_data;
	struct watchdog_device *wdd;

	wd_data = container_of(to_delayed_work(work), struct watchdog_core_data,
			       work);

	mutex_lock(&wd_data->lock);
	wdd = wd_data->wdd;
	if (wdd && (watchdog_active(wdd) || watchdog_hw_running(wdd)))
		__watchdog_ping(wdd);
	mutex_unlock(&wd_data->lock);
}

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/*
 *      watchdog_start: wrapper to start the watchdog.
 *      @wdd: the watchdog device to start
 *
 *      The caller must hold wd_data->lock.
 *
 *      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 *wdd)
{
	struct watchdog_core_data *wd_data = wdd->wd_data;
	unsigned long started_at;
	int err;

	if (watchdog_active(wdd))
		return 0;

	set_bit(_WDOG_KEEPALIVE, &wd_data->status);

	started_at = jiffies;
	if (watchdog_hw_running(wdd) && wdd->ops->ping)
		err = wdd->ops->ping(wdd);
	else
		err = wdd->ops->start(wdd);
	if (err == 0) {
		set_bit(WDOG_ACTIVE, &wdd->status);
		wd_data->last_keepalive = started_at;
		watchdog_update_worker(wdd);
	}

	return err;
}

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/*
 *      watchdog_stop: wrapper to stop the watchdog.
 *      @wdd: the watchdog device to stop
 *
 *      The caller must hold wd_data->lock.
 *
 *      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 *wdd)
{
	int err = 0;

	if (!watchdog_active(wdd))
		return 0;

	if (test_bit(WDOG_NO_WAY_OUT, &wdd->status)) {
		pr_info("watchdog%d: nowayout prevents watchdog being stopped!\n",
			wdd->id);
		return -EBUSY;
	}

	if (wdd->ops->stop) {
		clear_bit(WDOG_HW_RUNNING, &wdd->status);
		err = wdd->ops->stop(wdd);
	} else {
		set_bit(WDOG_HW_RUNNING, &wdd->status);
	}

	if (err == 0) {
		clear_bit(WDOG_ACTIVE, &wdd->status);
		watchdog_update_worker(wdd);
	}

	return err;
}

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/*
 *      watchdog_get_status: wrapper to get the watchdog status
 *      @wdd: the watchdog device to get the status from
 *
 *      The caller must hold wd_data->lock.
 *
 *      Get the watchdog's status flags.
 */



static unsigned int watchdog_get_status(struct watchdog_device *wdd)
{
	struct watchdog_core_data *wd_data = wdd->wd_data;
	unsigned int status;

	if (wdd->ops->status)
		status = wdd->ops->status(wdd);
	else
		status = wdd->bootstatus & (WDIOF_CARDRESET |
					    WDIOF_OVERHEAT |
					    WDIOF_FANFAULT |
					    WDIOF_EXTERN1 |
					    WDIOF_EXTERN2 |
					    WDIOF_POWERUNDER |
					    WDIOF_POWEROVER);

	if (test_bit(_WDOG_ALLOW_RELEASE, &wd_data->status))
		status |= WDIOF_MAGICCLOSE;

	if (test_and_clear_bit(_WDOG_KEEPALIVE, &wd_data->status))
		status |= WDIOF_KEEPALIVEPING;

	return status;
}

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/*
 *      watchdog_set_timeout: set the watchdog timer timeout
 *      @wdd: the watchdog device to set the timeout for
 *      @timeout: timeout to set in seconds
 *
 *      The caller must hold wd_data->lock.
 */



static int watchdog_set_timeout(struct watchdog_device *wdd,
							unsigned int timeout)
{
	int err = 0;

	if (!(wdd->info->options & WDIOF_SETTIMEOUT))
		return -EOPNOTSUPP;

	if (watchdog_timeout_invalid(wdd, timeout))
		return -EINVAL;

	if (wdd->ops->set_timeout) {
		err = wdd->ops->set_timeout(wdd, timeout);
	} else {
		wdd->timeout = timeout;
		/* Disable pretimeout if it doesn't fit the new timeout */
		if (wdd->pretimeout >= wdd->timeout)
			wdd->pretimeout = 0;
	}

	watchdog_update_worker(wdd);

	return err;
}

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Wolfram Sang
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/*
 *      watchdog_set_pretimeout: set the watchdog timer pretimeout
 *      @wdd: the watchdog device to set the timeout for
 *      @timeout: pretimeout to set in seconds
 */



static int watchdog_set_pretimeout(struct watchdog_device *wdd,
				   unsigned int timeout)
{
	int err = 0;

	if (!(wdd->info->options & WDIOF_PRETIMEOUT))
		return -EOPNOTSUPP;

	if (watchdog_pretimeout_invalid(wdd, timeout))
		return -EINVAL;

	if (wdd->ops->set_pretimeout)
		err = wdd->ops->set_pretimeout(wdd, timeout);
	else
		wdd->pretimeout = timeout;

	return err;
}

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/*
 *      watchdog_get_timeleft: wrapper to get the time left before a reboot
 *      @wdd: the watchdog device to get the remaining time from
 *      @timeleft: the time that's left
 *
 *      The caller must hold wd_data->lock.
 *
 *      Get the time before a watchdog will reboot (if not pinged).
 */



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

	if (!wdd->ops->get_timeleft)
		return -EOPNOTSUPP;

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

	return 0;
}

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#ifdef CONFIG_WATCHDOG_SYSFS


static ssize_t nowayout_show(struct device *dev, struct device_attribute *attr,
				char *buf)
{
	struct watchdog_device *wdd = dev_get_drvdata(dev);

	return sprintf(buf, "%d\n", !!test_bit(WDOG_NO_WAY_OUT, &wdd->status));
}
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static DEVICE_ATTR_RO(nowayout);



static ssize_t status_show(struct device *dev, struct device_attribute *attr,
				char *buf)
{
	struct watchdog_device *wdd = dev_get_drvdata(dev);
	struct watchdog_core_data *wd_data = wdd->wd_data;
	unsigned int status;

	mutex_lock(&wd_data->lock);
	status = watchdog_get_status(wdd);
	mutex_unlock(&wd_data->lock);

	return sprintf(buf, "0x%x\n", status);
}
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static DEVICE_ATTR_RO(status);



static ssize_t bootstatus_show(struct device *dev,
				struct device_attribute *attr, char *buf)
{
	struct watchdog_device *wdd = dev_get_drvdata(dev);

	return sprintf(buf, "%u\n", wdd->bootstatus);
}
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static DEVICE_ATTR_RO(bootstatus);



static ssize_t timeleft_show(struct device *dev, struct device_attribute *attr,
				char *buf)
{
	struct watchdog_device *wdd = dev_get_drvdata(dev);
	struct watchdog_core_data *wd_data = wdd->wd_data;
	ssize_t status;
	unsigned int val;

	mutex_lock(&wd_data->lock);
	status = watchdog_get_timeleft(wdd, &val);
	mutex_unlock(&wd_data->lock);
	if (!status)
		status = sprintf(buf, "%u\n", val);

	return status;
}
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static DEVICE_ATTR_RO(timeleft);



static ssize_t timeout_show(struct device *dev, struct device_attribute *attr,
				char *buf)
{
	struct watchdog_device *wdd = dev_get_drvdata(dev);

	return sprintf(buf, "%u\n", wdd->timeout);
}
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static DEVICE_ATTR_RO(timeout);



static ssize_t pretimeout_show(struct device *dev,
			       struct device_attribute *attr, char *buf)
{
	struct watchdog_device *wdd = dev_get_drvdata(dev);

	return sprintf(buf, "%u\n", wdd->pretimeout);
}
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static DEVICE_ATTR_RO(pretimeout);



static ssize_t identity_show(struct device *dev, struct device_attribute *attr,
				char *buf)
{
	struct watchdog_device *wdd = dev_get_drvdata(dev);

	return sprintf(buf, "%s\n", wdd->info->identity);
}
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static DEVICE_ATTR_RO(identity);



static ssize_t state_show(struct device *dev, struct device_attribute *attr,
				char *buf)
{
	struct watchdog_device *wdd = dev_get_drvdata(dev);

	if (watchdog_active(wdd))
		return sprintf(buf, "active\n");

	return sprintf(buf, "inactive\n");
}
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static DEVICE_ATTR_RO(state);



static ssize_t pretimeout_available_governors_show(struct device *dev,
				   struct device_attribute *attr, char *buf)
{
	return watchdog_pretimeout_available_governors_get(buf);
}
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static DEVICE_ATTR_RO(pretimeout_available_governors);



static ssize_t pretimeout_governor_show(struct device *dev,
					struct device_attribute *attr,
					char *buf)
{
	struct watchdog_device *wdd = dev_get_drvdata(dev);

	return watchdog_pretimeout_governor_get(wdd, buf);
}

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static ssize_t pretimeout_governor_store(struct device *dev,
					 struct device_attribute *attr,
					 const char *buf, size_t count)
{
	struct watchdog_device *wdd = dev_get_drvdata(dev);
	int ret = watchdog_pretimeout_governor_set(wdd, buf);

	if (!ret)
		ret = count;

	return ret;
}
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static DEVICE_ATTR_RW(pretimeout_governor);



static umode_t wdt_is_visible(struct kobject *kobj, struct attribute *attr,
				int n)
{
	struct device *dev = container_of(kobj, struct device, kobj);
	struct watchdog_device *wdd = dev_get_drvdata(dev);
	umode_t mode = attr->mode;

	if (attr == &dev_attr_timeleft.attr && !wdd->ops->get_timeleft)
		mode = 0;
	else if (attr == &dev_attr_pretimeout.attr &&
		 !(wdd->info->options & WDIOF_PRETIMEOUT))
		mode = 0;
	else if ((attr == &dev_attr_pretimeout_governor.attr ||
		  attr == &dev_attr_pretimeout_available_governors.attr) &&
		 (!(wdd->info->options & WDIOF_PRETIMEOUT) ||
		  !IS_ENABLED(CONFIG_WATCHDOG_PRETIMEOUT_GOV)))
		mode = 0;

	return mode;
}
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static struct attribute *wdt_attrs[] = {
	&dev_attr_state.attr,
	&dev_attr_identity.attr,
	&dev_attr_timeout.attr,
	&dev_attr_pretimeout.attr,
	&dev_attr_timeleft.attr,
	&dev_attr_bootstatus.attr,
	&dev_attr_status.attr,
	&dev_attr_nowayout.attr,
	&dev_attr_pretimeout_governor.attr,
	&dev_attr_pretimeout_available_governors.attr,
	NULL,
};


static const struct attribute_group wdt_group = {
	.attrs = wdt_attrs,
	.is_visible = wdt_is_visible,
};

__ATTRIBUTE_GROUPS(wdt);
#else

#define wdt_groups	NULL
#endif

/*
 *      watchdog_ioctl_op: call the watchdog drivers ioctl op if defined
 *      @wdd: the watchdog device to do the ioctl on
 *      @cmd: watchdog command
 *      @arg: argument pointer
 *
 *      The caller must hold wd_data->lock.
 */



static int watchdog_ioctl_op(struct watchdog_device *wdd, unsigned int cmd,
							unsigned long arg)
{
	if (!wdd->ops->ioctl)
		return -ENOIOCTLCMD;

	return wdd->ops->ioctl(wdd, cmd, arg);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Hans de Goede
32
69.57%
2
33.33%
Guenter Roeck
12
26.09%
2
33.33%
Wim Van Sebroeck
2
4.35%
2
33.33%
Total
46
100.00%
6
100.00%

/*
 *      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_core_data *wd_data = file->private_data;
	struct watchdog_device *wdd;
	int err;
	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, &wd_data->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, &wd_data->status);
	}

	/* someone wrote to us, so we send the watchdog a keepalive ping */

	err = -ENODEV;
	mutex_lock(&wd_data->lock);
	wdd = wd_data->wdd;
	if (wdd)
		err = watchdog_ping(wdd);
	mutex_unlock(&wd_data->lock);

	if (err < 0)
		return err;

	return len;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Wim Van Sebroeck
102
61.82%
2
40.00%
Guenter Roeck
45
27.27%
1
20.00%
Alexander Usyskin
11
6.67%
1
20.00%
Alan Cox
7
4.24%
1
20.00%
Total
165
100.00%
5
100.00%

/*
 *      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_core_data *wd_data = file->private_data;
	void __user *argp = (void __user *)arg;
	struct watchdog_device *wdd;
	int __user *p = argp;
	unsigned int val;
	int err;

	mutex_lock(&wd_data->lock);

	wdd = wd_data->wdd;
	if (!wdd) {
		err = -ENODEV;
		goto out_ioctl;
	}

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

	switch (cmd) {
	case WDIOC_GETSUPPORT:
		err = copy_to_user(argp, wdd->info,
			sizeof(struct watchdog_info)) ? -EFAULT : 0;
		break;
	case WDIOC_GETSTATUS:
		val = watchdog_get_status(wdd);
		err = put_user(val, p);
		break;
	case WDIOC_GETBOOTSTATUS:
		err = put_user(wdd->bootstatus, p);
		break;
	case WDIOC_SETOPTIONS:
		if (get_user(val, p)) {
			err = -EFAULT;
			break;
		}
		if (val & WDIOS_DISABLECARD) {
			err = watchdog_stop(wdd);
			if (err < 0)
				break;
		}
		if (val & WDIOS_ENABLECARD)
			err = watchdog_start(wdd);
		break;
	case WDIOC_KEEPALIVE:
		if (!(wdd->info->options & WDIOF_KEEPALIVEPING)) {
			err = -EOPNOTSUPP;
			break;
		}
		err = watchdog_ping(wdd);
		break;
	case WDIOC_SETTIMEOUT:
		if (get_user(val, p)) {
			err = -EFAULT;
			break;
		}
		err = watchdog_set_timeout(wdd, val);
		if (err < 0)
			break;
		/* 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) */
		err = watchdog_ping(wdd);
		if (err < 0)
			break;
		/* Fall */
	case WDIOC_GETTIMEOUT:
		/* timeout == 0 means that we don't know the timeout */
		if (wdd->timeout == 0) {
			err = -EOPNOTSUPP;
			break;
		}
		err = put_user(wdd->timeout, p);
		break;
	case WDIOC_GETTIMELEFT:
		err = watchdog_get_timeleft(wdd, &val);
		if (err < 0)
			break;
		err = put_user(val, p);
		break;
	case WDIOC_SETPRETIMEOUT:
		if (get_user(val, p)) {
			err = -EFAULT;
			break;
		}
		err = watchdog_set_pretimeout(wdd, val);
		break;
	case WDIOC_GETPRETIMEOUT:
		err = put_user(wdd->pretimeout, p);
		break;
	default:
		err = -ENOTTY;
		break;
	}

out_ioctl:
	mutex_unlock(&wd_data->lock);
	return err;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Wim Van Sebroeck
245
55.30%
5
45.45%
Guenter Roeck
110
24.83%
1
9.09%
Wolfram Sang
45
10.16%
1
9.09%
Hans de Goede
17
3.84%
1
9.09%
Viresh Kumar
11
2.48%
1
9.09%
Alexander Usyskin
8
1.81%
1
9.09%
Alan Cox
7
1.58%
1
9.09%
Total
443
100.00%
11
100.00%

/*
 *      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)
{
	struct watchdog_core_data *wd_data;
	struct watchdog_device *wdd;
	int err;

	/* Get the corresponding watchdog device */
	if (imajor(inode) == MISC_MAJOR)
		wd_data = old_wd_data;
	else
		wd_data = container_of(inode->i_cdev, struct watchdog_core_data,
				       cdev);

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

	wdd = wd_data->wdd;

	/*
         * If the /dev/watchdog device is open, we don't want the module
         * to be unloaded.
         */
	if (!watchdog_hw_running(wdd) && !try_module_get(wdd->ops->owner)) {
		err = -EBUSY;
		goto out_clear;
	}

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

	file->private_data = wd_data;

	if (!watchdog_hw_running(wdd))
		kref_get(&wd_data->kref);

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

out_mod:
	module_put(wd_data->wdd->ops->owner);
out_clear:
	clear_bit(_WDOG_DEV_OPEN, &wd_data->status);
	return err;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Wim Van Sebroeck
95
51.35%
2
33.33%
Guenter Roeck
52
28.11%
2
33.33%
Alan Cox
35
18.92%
1
16.67%
Hans de Goede
3
1.62%
1
16.67%
Total
185
100.00%
6
100.00%



static void watchdog_core_data_release(struct kref *kref)
{
	struct watchdog_core_data *wd_data;

	wd_data = container_of(kref, struct watchdog_core_data, kref);

	kfree(wd_data);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Guenter Roeck
33
100.00%
1
100.00%
Total
33
100.00%
1
100.00%

/*
 *      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_core_data *wd_data = file->private_data;
	struct watchdog_device *wdd;
	int err = -EBUSY;
	bool running;

	mutex_lock(&wd_data->lock);

	wdd = wd_data->wdd;
	if (!wdd)
		goto done;

	/*
         * 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_bit(WDOG_ACTIVE, &wdd->status))
		err = 0;
	else if (test_and_clear_bit(_WDOG_ALLOW_RELEASE, &wd_data->status) ||
		 !(wdd->info->options & WDIOF_MAGICCLOSE))
		err = watchdog_stop(wdd);

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

	watchdog_update_worker(wdd);

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

done:
	running = wdd && watchdog_hw_running(wdd);
	mutex_unlock(&wd_data->lock);
	/*
         * Allow the owner module to be unloaded again unless the watchdog
         * is still running. If the watchdog is still running, it can not
         * be stopped, and its driver must not be unloaded.
         */
	if (!running) {
		module_put(wd_data->cdev.owner);
		kref_put(&wd_data->kref, watchdog_core_data_release);
	}
	return 0;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Guenter Roeck
81
40.91%
4
33.33%
Wim Van Sebroeck
73
36.87%
4
33.33%
Hans de Goede
18
9.09%
1
8.33%
Hector Palacios
18
9.09%
1
8.33%
Alan Cox
8
4.04%
2
16.67%
Total
198
100.00%
12
100.00%


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



static int watchdog_cdev_register(struct watchdog_device *wdd, dev_t devno)
{
	struct watchdog_core_data *wd_data;
	int err;

	wd_data = kzalloc(sizeof(struct watchdog_core_data), GFP_KERNEL);
	if (!wd_data)
		return -ENOMEM;
	kref_init(&wd_data->kref);
	mutex_init(&wd_data->lock);

	wd_data->wdd = wdd;
	wdd->wd_data = wd_data;

	if (!watchdog_wq)
		return -ENODEV;

	INIT_DELAYED_WORK(&wd_data->work, watchdog_ping_work);

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

	/* Fill in the data structures */
	cdev_init(&wd_data->cdev, &watchdog_fops);
	wd_data->cdev.owner = wdd->ops->owner;

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

	/* Record time of most recent heartbeat as 'just before now'. */
	wd_data->last_hw_keepalive = jiffies - 1;

	/*
         * If the watchdog is running, prevent its driver from being unloaded,
         * and schedule an immediate ping.
         */
	if (watchdog_hw_running(wdd)) {
		__module_get(wdd->ops->owner);
		kref_get(&wd_data->kref);
		queue_delayed_work(watchdog_wq, &wd_data->work, 0);
	}

	return 0;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Guenter Roeck
167
52.02%
7
70.00%
Alan Cox
101
31.46%
2
20.00%
Wim Van Sebroeck
53
16.51%
1
10.00%
Total
321
100.00%
10
100.00%

/*
 *      watchdog_cdev_unregister: unregister watchdog character device
 *      @watchdog: watchdog device
 *
 *      Unregister watchdog character device and if needed the legacy
 *      /dev/watchdog device.
 */



static void watchdog_cdev_unregister(struct watchdog_device *wdd)
{
	struct watchdog_core_data *wd_data = wdd->wd_data;

	cdev_del(&wd_data->cdev);
	if (wdd->id == 0) {
		misc_deregister(&watchdog_miscdev);
		old_wd_data = NULL;
	}

	mutex_lock(&wd_data->lock);
	wd_data->wdd = NULL;
	wdd->wd_data = NULL;
	mutex_unlock(&wd_data->lock);

	if (watchdog_active(wdd) &&
	    test_bit(WDOG_STOP_ON_UNREGISTER, &wdd->status)) {
		watchdog_stop(wdd);
	}

	cancel_delayed_work_sync(&wd_data->work);

	kref_put(&wd_data->kref, watchdog_core_data_release);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Guenter Roeck
85
72.03%
5
62.50%
Wim Van Sebroeck
22
18.64%
1
12.50%
Alan Cox
10
8.47%
1
12.50%
Hans de Goede
1
0.85%
1
12.50%
Total
118
100.00%
8
100.00%


static struct class watchdog_class = {
	.name =		"watchdog",
	.owner =	THIS_MODULE,
	.dev_groups =	wdt_groups,
};

/*
 *      watchdog_dev_register: register a watchdog device
 *      @wdd: 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 *wdd)
{
	struct device *dev;
	dev_t devno;
	int ret;

	devno = MKDEV(MAJOR(watchdog_devt), wdd->id);

	ret = watchdog_cdev_register(wdd, devno);
	if (ret)
		return ret;

	dev = device_create_with_groups(&watchdog_class, wdd->parent,
					devno, wdd, wdd->groups,
					"watchdog%d", wdd->id);
	if (IS_ERR(dev)) {
		watchdog_cdev_unregister(wdd);
		return PTR_ERR(dev);
	}

	ret = watchdog_register_pretimeout(wdd);
	if (ret) {
		device_destroy(&watchdog_class, devno);
		watchdog_cdev_unregister(wdd);
	}

	return ret;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Guenter Roeck
98
77.78%
2
50.00%
Vladimir Zapolskiy
26
20.63%
1
25.00%
Pratyush Anand
2
1.59%
1
25.00%
Total
126
100.00%
4
100.00%

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



void watchdog_dev_unregister(struct watchdog_device *wdd)
{
	watchdog_unregister_pretimeout(wdd);
	device_destroy(&watchdog_class, wdd->wd_data->cdev.dev);
	watchdog_cdev_unregister(wdd);
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Guenter Roeck
29
85.29%
3
75.00%
Vladimir Zapolskiy
5
14.71%
1
25.00%
Total
34
100.00%
4
100.00%

/*
 *      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;

	watchdog_wq = alloc_workqueue("watchdogd",
				      WQ_HIGHPRI | WQ_MEM_RECLAIM, 0);
	if (!watchdog_wq) {
		pr_err("Failed to create watchdog workqueue\n");
		return -ENOMEM;
	}

	err = class_register(&watchdog_class);
	if (err < 0) {
		pr_err("couldn't register class\n");
		goto err_register;
	}

	err = alloc_chrdev_region(&watchdog_devt, 0, MAX_DOGS, "watchdog");
	if (err < 0) {
		pr_err("watchdog: unable to allocate char dev region\n");
		goto err_alloc;
	}

	return 0;

err_alloc:
	class_unregister(&watchdog_class);
err_register:
	destroy_workqueue(watchdog_wq);
	return err;
}

Contributors
Person
Tokens
Prop
Commits
CommitProp
Pratyush Anand
34
29.57%
1
16.67%
Guenter Roeck
30
26.09%
2
33.33%
Alan Cox
26
22.61%
1
16.67%
Wei Yongjun
19
16.52%
1
16.67%
Wim Van Sebroeck
6
5.22%
1
16.67%
Total
115
100.00%
6
100.00%

/*
 *      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);
	class_unregister(&watchdog_class);
	destroy_workqueue(watchdog_wq);
}
Contributors
Person
Tokens
Prop
Commits
CommitProp
Alan Cox
15
57.69%
1
33.33%
Pratyush Anand
6
23.08%
1
33.33%
Guenter Roeck
5
19.23%
1
33.33%
Total
26
100.00%
3
100.00%

Overall Contributors
Person
Tokens
Prop
Commits
CommitProp
Guenter Roeck
1600
40.22%
15
34.88%
Wim Van Sebroeck
818
20.56%
9
20.93%
Pratyush Anand
606
15.23%
2
4.65%
Wolfram Sang
226
5.68%
1
2.33%
Vladimir Zapolskiy
218
5.48%
3
6.98%
Hans de Goede
218
5.48%
2
4.65%
Alan Cox
215
5.40%
3
6.98%
Alexander Usyskin
19
0.48%
1
2.33%
Wei Yongjun
19
0.48%
1
2.33%
Hector Palacios
18
0.45%
1
2.33%
Viresh Kumar
12
0.30%
2
4.65%
Fabio Porcedda
4
0.10%
1
2.33%
Rasmus Villemoes
3
0.08%
1
2.33%
H Hartley Sweeten
2
0.05%
1
2.33%
Total
3978
100.00%
43
100.00%
Directory: drivers/watchdog

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