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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 <linux/idr.h> /* For ida_* macros */
#include <linux/err.h> /* For IS_ERR macros */
#include "watchdog_core.h" /* For watchdog_dev_register/... */
static DEFINE_IDA(watchdog_ida);
static struct class *watchdog_class;
/**
* 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, id, devno;
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;
/*
* 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!\n");
wdd->min_timeout = 0;
wdd->max_timeout = 0;
}
/*
* 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!
*/
mutex_init(&wdd->lock);
id = ida_simple_get(&watchdog_ida, 0, MAX_DOGS, GFP_KERNEL);
if (id < 0)
return id;
wdd->id = id;
ret = watchdog_dev_register(wdd);
if (ret) {
ida_simple_remove(&watchdog_ida, id);
if (!(id == 0 && ret == -EBUSY))
return ret;
/* Retry in case a legacy watchdog module exists */
id = ida_simple_get(&watchdog_ida, 1, MAX_DOGS, GFP_KERNEL);
if (id < 0)
return id;
wdd->id = id;
ret = watchdog_dev_register(wdd);
if (ret) {
ida_simple_remove(&watchdog_ida, id);
return ret;
}
}
devno = wdd->cdev.dev;
wdd->dev = device_create(watchdog_class, wdd->parent, devno,
NULL, "watchdog%d", wdd->id);
if (IS_ERR(wdd->dev)) {
watchdog_dev_unregister(wdd);
ida_simple_remove(&watchdog_ida, id);
ret = PTR_ERR(wdd->dev);
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;
int devno;
if (wdd == NULL)
return;
devno = wdd->cdev.dev;
ret = watchdog_dev_unregister(wdd);
if (ret)
pr_err("error unregistering /dev/watchdog (err=%d)\n", ret);
device_destroy(watchdog_class, devno);
ida_simple_remove(&watchdog_ida, wdd->id);
wdd->dev = NULL;
}
EXPORT_SYMBOL_GPL(watchdog_unregister_device);
static int __init watchdog_init(void)
{
int err;
watchdog_class = class_create(THIS_MODULE, "watchdog");
if (IS_ERR(watchdog_class)) {
pr_err("couldn't create class\n");
return PTR_ERR(watchdog_class);
}
err = watchdog_dev_init();
if (err < 0) {
class_destroy(watchdog_class);
return err;
}
return 0;
}
static void __exit watchdog_exit(void)
{
watchdog_dev_exit();
class_destroy(watchdog_class);
ida_destroy(&watchdog_ida);
}
subsys_initcall(watchdog_init);
module_exit(watchdog_exit);
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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