2011-07-22 12:55:18 -06:00
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/*
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* watchdog_core.c
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*
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* (c) Copyright 2008-2011 Alan Cox <alan@lxorguk.ukuu.org.uk>,
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* All Rights Reserved.
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*
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* (c) Copyright 2008-2011 Wim Van Sebroeck <wim@iguana.be>.
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*
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* This source code is part of the generic code that can be used
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* by all the watchdog timer drivers.
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*
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* Based on source code of the following authors:
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* Matt Domsch <Matt_Domsch@dell.com>,
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* Rob Radez <rob@osinvestor.com>,
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* Rusty Lynch <rusty@linux.co.intel.com>
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* Satyam Sharma <satyam@infradead.org>
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* Randy Dunlap <randy.dunlap@oracle.com>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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* Neither Alan Cox, CymruNet Ltd., Wim Van Sebroeck nor Iguana vzw.
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* admit liability nor provide warranty for any of this software.
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* This material is provided "AS-IS" and at no charge.
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/module.h> /* For EXPORT_SYMBOL/module stuff/... */
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#include <linux/types.h> /* For standard types */
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#include <linux/errno.h> /* For the -ENODEV/... values */
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#include <linux/kernel.h> /* For printk/panic/... */
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#include <linux/watchdog.h> /* For watchdog specific items */
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#include <linux/init.h> /* For __init/__exit/... */
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2012-05-10 13:48:59 -06:00
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#include <linux/idr.h> /* For ida_* macros */
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2012-05-11 04:00:20 -06:00
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#include <linux/err.h> /* For IS_ERR macros */
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2013-01-08 03:04:10 -07:00
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#include <linux/of.h> /* For of_get_timeout_sec */
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2011-07-22 12:55:18 -06:00
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2012-05-21 07:31:06 -06:00
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#include "watchdog_core.h" /* For watchdog_dev_register/... */
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2011-07-22 12:55:18 -06:00
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2012-05-10 13:48:59 -06:00
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static DEFINE_IDA(watchdog_ida);
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2012-05-11 04:00:20 -06:00
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static struct class *watchdog_class;
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2012-05-10 13:48:59 -06:00
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2015-06-09 10:55:02 -06:00
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/*
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* Deferred Registration infrastructure.
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*
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* Sometimes watchdog drivers needs to be loaded as soon as possible,
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* for example when it's impossible to disable it. To do so,
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* raising the initcall level of the watchdog driver is a solution.
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* But in such case, the miscdev is maybe not ready (subsys_initcall), and
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* watchdog_core need miscdev to register the watchdog as a char device.
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*
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* The deferred registration infrastructure offer a way for the watchdog
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* subsystem to register a watchdog properly, even before miscdev is ready.
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*/
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static DEFINE_MUTEX(wtd_deferred_reg_mutex);
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static LIST_HEAD(wtd_deferred_reg_list);
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static bool wtd_deferred_reg_done;
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static int watchdog_deferred_registration_add(struct watchdog_device *wdd)
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{
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list_add_tail(&wdd->deferred,
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&wtd_deferred_reg_list);
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return 0;
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}
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static void watchdog_deferred_registration_del(struct watchdog_device *wdd)
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{
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struct list_head *p, *n;
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struct watchdog_device *wdd_tmp;
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list_for_each_safe(p, n, &wtd_deferred_reg_list) {
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wdd_tmp = list_entry(p, struct watchdog_device,
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deferred);
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if (wdd_tmp == wdd) {
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list_del(&wdd_tmp->deferred);
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break;
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}
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}
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}
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2013-01-08 03:04:10 -07:00
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static void watchdog_check_min_max_timeout(struct watchdog_device *wdd)
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{
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/*
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* Check that we have valid min and max timeout values, if
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* not reset them both to 0 (=not used or unknown)
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*/
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if (wdd->min_timeout > wdd->max_timeout) {
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pr_info("Invalid min and max timeout values, resetting to 0!\n");
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wdd->min_timeout = 0;
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wdd->max_timeout = 0;
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}
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}
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/**
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* watchdog_init_timeout() - initialize the timeout field
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* @timeout_parm: timeout module parameter
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* @dev: Device that stores the timeout-sec property
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*
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* Initialize the timeout field of the watchdog_device struct with either the
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* timeout module parameter (if it is valid value) or the timeout-sec property
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* (only if it is a valid value and the timeout_parm is out of bounds).
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* If none of them are valid then we keep the old value (which should normally
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* be the default timeout value.
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*
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* A zero is returned on success and -EINVAL for failure.
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*/
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int watchdog_init_timeout(struct watchdog_device *wdd,
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unsigned int timeout_parm, struct device *dev)
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{
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unsigned int t = 0;
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int ret = 0;
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watchdog_check_min_max_timeout(wdd);
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2013-10-28 02:47:17 -06:00
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/* try to get the timeout module parameter first */
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2013-11-26 11:22:52 -07:00
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if (!watchdog_timeout_invalid(wdd, timeout_parm) && timeout_parm) {
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2013-01-08 03:04:10 -07:00
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wdd->timeout = timeout_parm;
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return ret;
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}
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if (timeout_parm)
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ret = -EINVAL;
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/* try to get the timeout_sec property */
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if (dev == NULL || dev->of_node == NULL)
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return ret;
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of_property_read_u32(dev->of_node, "timeout-sec", &t);
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2013-11-26 11:22:52 -07:00
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if (!watchdog_timeout_invalid(wdd, t) && t)
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2013-01-08 03:04:10 -07:00
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wdd->timeout = t;
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else
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ret = -EINVAL;
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return ret;
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}
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EXPORT_SYMBOL_GPL(watchdog_init_timeout);
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2015-06-09 10:55:02 -06:00
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static int __watchdog_register_device(struct watchdog_device *wdd)
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2011-07-22 12:55:18 -06:00
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{
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2015-09-02 12:00:17 -06:00
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int ret, id = -1, devno;
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2011-07-22 12:55:18 -06:00
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if (wdd == NULL || wdd->info == NULL || wdd->ops == NULL)
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return -EINVAL;
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/* Mandatory operations need to be supported */
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if (wdd->ops->start == NULL || wdd->ops->stop == NULL)
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return -EINVAL;
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2013-01-08 03:04:10 -07:00
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watchdog_check_min_max_timeout(wdd);
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2011-07-22 13:00:16 -06:00
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2011-07-22 12:55:18 -06:00
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/*
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* Note: now that all watchdog_device data has been verified, we
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* will not check this anymore in other functions. If data gets
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* corrupted in a later stage then we expect a kernel panic!
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*/
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2012-05-22 03:40:26 -06:00
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mutex_init(&wdd->lock);
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2015-09-02 12:00:17 -06:00
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/* Use alias for watchdog id if possible */
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if (wdd->parent) {
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ret = of_alias_get_id(wdd->parent->of_node, "watchdog");
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if (ret >= 0)
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id = ida_simple_get(&watchdog_ida, ret,
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ret + 1, GFP_KERNEL);
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}
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if (id < 0)
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id = ida_simple_get(&watchdog_ida, 0, MAX_DOGS, GFP_KERNEL);
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2012-05-10 13:48:59 -06:00
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if (id < 0)
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return id;
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wdd->id = id;
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2011-07-22 12:55:18 -06:00
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ret = watchdog_dev_register(wdd);
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if (ret) {
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2012-05-10 13:48:59 -06:00
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ida_simple_remove(&watchdog_ida, id);
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if (!(id == 0 && ret == -EBUSY))
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return ret;
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/* Retry in case a legacy watchdog module exists */
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id = ida_simple_get(&watchdog_ida, 1, MAX_DOGS, GFP_KERNEL);
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if (id < 0)
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return id;
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wdd->id = id;
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ret = watchdog_dev_register(wdd);
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if (ret) {
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ida_simple_remove(&watchdog_ida, id);
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return ret;
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}
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2011-07-22 12:55:18 -06:00
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}
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2012-05-11 04:00:20 -06:00
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devno = wdd->cdev.dev;
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wdd->dev = device_create(watchdog_class, wdd->parent, devno,
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NULL, "watchdog%d", wdd->id);
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if (IS_ERR(wdd->dev)) {
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watchdog_dev_unregister(wdd);
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ida_simple_remove(&watchdog_ida, id);
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ret = PTR_ERR(wdd->dev);
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return ret;
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}
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2011-07-22 12:55:18 -06:00
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return 0;
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}
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/**
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2015-06-09 10:55:02 -06:00
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* watchdog_register_device() - register a watchdog device
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* @wdd: watchdog device
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2011-07-22 12:55:18 -06:00
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*
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2015-06-09 10:55:02 -06:00
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* Register a watchdog device with the kernel so that the
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* watchdog timer can be accessed from userspace.
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*
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* A zero is returned on success and a negative errno code for
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* failure.
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2011-07-22 12:55:18 -06:00
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*/
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2015-06-09 10:55:02 -06:00
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int watchdog_register_device(struct watchdog_device *wdd)
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{
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int ret;
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mutex_lock(&wtd_deferred_reg_mutex);
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if (wtd_deferred_reg_done)
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ret = __watchdog_register_device(wdd);
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else
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ret = watchdog_deferred_registration_add(wdd);
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mutex_unlock(&wtd_deferred_reg_mutex);
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return ret;
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}
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EXPORT_SYMBOL_GPL(watchdog_register_device);
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static void __watchdog_unregister_device(struct watchdog_device *wdd)
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2011-07-22 12:55:18 -06:00
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{
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int ret;
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2012-09-09 22:41:15 -06:00
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int devno;
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2011-07-22 12:55:18 -06:00
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if (wdd == NULL)
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return;
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2012-09-09 22:41:15 -06:00
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devno = wdd->cdev.dev;
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2011-07-22 12:55:18 -06:00
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ret = watchdog_dev_unregister(wdd);
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if (ret)
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2012-02-15 16:06:19 -07:00
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pr_err("error unregistering /dev/watchdog (err=%d)\n", ret);
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2012-05-11 04:00:20 -06:00
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device_destroy(watchdog_class, devno);
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2012-05-10 13:48:59 -06:00
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ida_simple_remove(&watchdog_ida, wdd->id);
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2012-05-11 04:00:20 -06:00
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wdd->dev = NULL;
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2011-07-22 12:55:18 -06:00
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}
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2015-06-09 10:55:02 -06:00
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/**
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* watchdog_unregister_device() - unregister a watchdog device
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* @wdd: watchdog device to unregister
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*
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* Unregister a watchdog device that was previously successfully
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* registered with watchdog_register_device().
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*/
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void watchdog_unregister_device(struct watchdog_device *wdd)
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{
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mutex_lock(&wtd_deferred_reg_mutex);
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if (wtd_deferred_reg_done)
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__watchdog_unregister_device(wdd);
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else
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watchdog_deferred_registration_del(wdd);
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mutex_unlock(&wtd_deferred_reg_mutex);
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}
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2011-07-22 12:55:18 -06:00
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EXPORT_SYMBOL_GPL(watchdog_unregister_device);
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2015-06-09 10:55:02 -06:00
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static int __init watchdog_deferred_registration(void)
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{
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mutex_lock(&wtd_deferred_reg_mutex);
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wtd_deferred_reg_done = true;
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while (!list_empty(&wtd_deferred_reg_list)) {
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struct watchdog_device *wdd;
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wdd = list_first_entry(&wtd_deferred_reg_list,
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struct watchdog_device, deferred);
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list_del(&wdd->deferred);
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__watchdog_register_device(wdd);
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}
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mutex_unlock(&wtd_deferred_reg_mutex);
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return 0;
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}
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2012-05-10 13:48:59 -06:00
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static int __init watchdog_init(void)
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{
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2012-05-11 04:00:20 -06:00
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int err;
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watchdog_class = class_create(THIS_MODULE, "watchdog");
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if (IS_ERR(watchdog_class)) {
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pr_err("couldn't create class\n");
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return PTR_ERR(watchdog_class);
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}
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err = watchdog_dev_init();
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if (err < 0) {
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class_destroy(watchdog_class);
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return err;
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}
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2015-06-09 10:55:02 -06:00
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watchdog_deferred_registration();
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2012-05-11 04:00:20 -06:00
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return 0;
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2012-05-10 13:48:59 -06:00
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}
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static void __exit watchdog_exit(void)
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{
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watchdog_dev_exit();
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2012-05-11 04:00:20 -06:00
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class_destroy(watchdog_class);
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2012-05-10 13:48:59 -06:00
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ida_destroy(&watchdog_ida);
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}
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2015-06-09 10:55:02 -06:00
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subsys_initcall_sync(watchdog_init);
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2012-05-10 13:48:59 -06:00
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module_exit(watchdog_exit);
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2011-07-22 12:55:18 -06:00
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MODULE_AUTHOR("Alan Cox <alan@lxorguk.ukuu.org.uk>");
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MODULE_AUTHOR("Wim Van Sebroeck <wim@iguana.be>");
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MODULE_DESCRIPTION("WatchDog Timer Driver Core");
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MODULE_LICENSE("GPL");
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