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drivers/watchdog/watchdog_core.c
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watchdog: WatchDo...
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/*
* watchdog_core.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.
*
* 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 EXPORT_SYMBOL/module stuff/... */
#include <linux/types.h> /* For standard types */
#include <linux/errno.h> /* For the -ENODEV/... values */
#include <linux/kernel.h> /* For printk/panic/... */
#include <linux/watchdog.h> /* For watchdog specific items */
#include <linux/init.h> /* For __init/__exit/... */
#include "watchdog_dev.h" /* For watchdog_dev_register/... */
/**
* watchdog_register_device() - register a watchdog device
* @wdd: watchdog device
*
* Register a watchdog device with the kernel so that the
* watchdog timer can be accessed from userspace.
*
* A zero is returned on success and a negative errno code for
* failure.
*/
int watchdog_register_device(struct watchdog_device *wdd)
{
int ret;
if (wdd == NULL || wdd->info == NULL || wdd->ops == NULL)
return -EINVAL;
/* Mandatory operations need to be supported */
if (wdd->ops->start == NULL || wdd->ops->stop == NULL)
return -EINVAL;
/*
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* Check that we have valid min and max timeout values, if
* not reset them both to 0 (=not used or unknown)
*/
if (wdd->min_timeout > wdd->max_timeout) {
pr_info("Invalid min and max timeout values, resetting to 0!
");
wdd->min_timeout = 0;
wdd->max_timeout = 0;
}
/*
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* Note: now that all watchdog_device data has been verified, we
* will not check this anymore in other functions. If data gets
* corrupted in a later stage then we expect a kernel panic!
*/
/* We only support 1 watchdog device via the /dev/watchdog interface */
ret = watchdog_dev_register(wdd);
if (ret) {
pr_err("error registering /dev/watchdog (err=%d).
", ret);
return ret;
}
return 0;
}
EXPORT_SYMBOL_GPL(watchdog_register_device);
/**
* watchdog_unregister_device() - unregister a watchdog device
* @wdd: watchdog device to unregister
*
* Unregister a watchdog device that was previously successfully
* registered with watchdog_register_device().
*/
void watchdog_unregister_device(struct watchdog_device *wdd)
{
int ret;
if (wdd == NULL)
return;
ret = watchdog_dev_unregister(wdd);
if (ret)
pr_err("error unregistering /dev/watchdog (err=%d).
", ret);
}
EXPORT_SYMBOL_GPL(watchdog_unregister_device);
MODULE_AUTHOR("Alan Cox <alan@lxorguk.ukuu.org.uk>");
MODULE_AUTHOR("Wim Van Sebroeck <wim@iguana.be>");
MODULE_DESCRIPTION("WatchDog Timer Driver Core");
MODULE_LICENSE("GPL");
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