linux-imx

/*

 *  Acquire Single Board Computer Watchdog Timer driver

 *

 *  Based on wdt.c. Original copyright messages:

 *

 *  (c) Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>,

 *                      All Rights Reserved.

 *

 *  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 nor CymruNet Ltd. admit liability nor provide

 *  warranty for any of this software. This material is provided

 *  "AS-IS" and at no charge.

 *

 *  (c) Copyright 1995    Alan Cox <alan@lxorguk.ukuu.org.uk>

 *

 *  14-Dec-2001 Matt Domsch <Matt_Domsch@dell.com>

 *      Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT

 *      Can't add timeout - driver doesn't allow changing value

 */

​

/*

 *  Theory of Operation:

 *      The Watch-Dog Timer is provided to ensure that standalone

 *      Systems can always recover from catastrophic conditions that

 *      caused the CPU to crash. This condition may have occurred by

 *      external EMI or a software bug. When the CPU stops working

 *      correctly, hardware on the board will either perform a hardware

 *      reset (cold boot) or a non-maskable interrupt (NMI) to bring the

 *      system back to a known state.

 *

 *      The Watch-Dog Timer is controlled by two I/O Ports.

 *        443 hex   - Read  - Enable or refresh the Watch-Dog Timer

 *        043 hex   - Read  - Disable the Watch-Dog Timer

 *

 *      To enable the Watch-Dog Timer, a read from I/O port 443h must

 *      be performed. This will enable and activate the countdown timer

 *      which will eventually time out and either reset the CPU or cause

 *      an NMI depending on the setting of a jumper. To ensure that this

 *      reset condition does not occur, the Watch-Dog Timer must be

 *      periodically refreshed by reading the same I/O port 443h.

 *      The Watch-Dog Timer is disabled by reading I/O port 043h.

 *

 *      The Watch-Dog Timer Time-Out Period is set via jumpers.

 *      It can be 1, 2, 10, 20, 110 or 220 seconds.

 */

​

/*

 *  Includes, defines, variables, module parameters, ...

 */

​

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

​

/* Includes */

#include <linux/module.h>       /* For module specific items */

#include <linux/moduleparam.h>      /* For new moduleparam's */

#include <linux/types.h>        /* For standard types (like size_t) */

#include <linux/errno.h>        /* For the -ENODEV/... values */

#include <linux/kernel.h>       /* For printk/panic/... */

#include <linux/miscdevice.h>       /* For struct miscdevice */

#include <linux/watchdog.h>     /* For the watchdog specific items */

#include <linux/fs.h>           /* For file operations */

#include <linux/ioport.h>       /* For io-port access */

#include <linux/platform_device.h>  /* For platform_driver framework */

#include <linux/init.h>         /* For __init/__exit/... */

#include <linux/uaccess.h>      /* For copy_to_user/put_user/... */

#include <linux/io.h>           /* For inb/outb/... */

​

/* Module information */

#define DRV_NAME "acquirewdt"

#define WATCHDOG_NAME "Acquire WDT"

/* There is no way to see what the correct time-out period is */

#define WATCHDOG_HEARTBEAT 0

​

/* internal variables */

/* the watchdog platform device */

static struct platform_device *acq_platform_device;

static unsigned long acq_is_open;

static char expect_close;

​

/* module parameters */

/* You must set this - there is no sane way to probe for this board. */

static int wdt_stop = 0x43;

module_param(wdt_stop, int, 0);

MODULE_PARM_DESC(wdt_stop, "Acquire WDT 'stop' io port (default 0x43)");

​

/* You must set this - there is no sane way to probe for this board. */

static int wdt_start = 0x443;

module_param(wdt_start, int, 0);