linux-imx

/*

 *  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/reboot.h>   /* For restart handler */

#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 <linux/of.h>       /* For of_get_timeout_sec */

​

#include "watchdog_core.h"  /* For watchdog_dev_register/... */

​

static DEFINE_IDA(watchdog_ida);

​

/*

 * Deferred Registration infrastructure.

 *

 * Sometimes watchdog drivers needs to be loaded as soon as possible,

 * for example when it's impossible to disable it. To do so,

 * raising the initcall level of the watchdog driver is a solution.

 * But in such case, the miscdev is maybe not ready (subsys_initcall), and

 * watchdog_core need miscdev to register the watchdog as a char device.

 *

 * The deferred registration infrastructure offer a way for the watchdog

 * subsystem to register a watchdog properly, even before miscdev is ready.

 */

​

static DEFINE_MUTEX(wtd_deferred_reg_mutex);

static LIST_HEAD(wtd_deferred_reg_list);

static bool wtd_deferred_reg_done;

​

static int watchdog_deferred_registration_add(struct watchdog_device *wdd)

{

    list_add_tail(&wdd->deferred,

              &wtd_deferred_reg_list);

    return 0;

}

​

static void watchdog_deferred_registration_del(struct watchdog_device *wdd)

{

    struct list_head *p, *n;

    struct watchdog_device *wdd_tmp;

​

    list_for_each_safe(p, n, &wtd_deferred_reg_list) {

        wdd_tmp = list_entry(p, struct watchdog_device,

                     deferred);

        if (wdd_tmp == wdd) {

            list_del(&wdd_tmp->deferred);

            break;

        }

    }

}

​

static void watchdog_check_min_max_timeout(struct watchdog_device *wdd)

{

    /*

     * Check that we have valid min and max timeout values, if

     * not reset them both to 0 (=not used or unknown)

     */

    if (!wdd->max_hw_heartbeat_ms && wdd->min_timeout > wdd->max_timeout) {

        pr_info("Invalid min and max timeout values, resetting to 0!\n");