wdt285.c

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/*
 *  Intel 21285 watchdog driver
 *  Copyright (c) Phil Blundell <[email protected]>, 1998
 *
 *  based on
 *
 *  SoftDog 0.05:   A Software Watchdog Device
 *
 *  (c) Copyright 1996 Alan Cox <[email protected]>,
 *                      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.
 *
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/reboot.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/uaccess.h>
#include <linux/irq.h>
#include <mach/hardware.h>

#include <asm/mach-types.h>
#include <asm/system_info.h>
#include <asm/hardware/dec21285.h>

/*
 * Define this to stop the watchdog actually rebooting the machine.
 */
#undef ONLY_TESTING

static unsigned int soft_margin = 60;       /* in seconds */
static unsigned int reload;
static unsigned long timer_alive;

#ifdef ONLY_TESTING
/*
 *  If the timer expires..
 */
static void watchdog_fire(int irq, void *dev_id)
{
    pr_crit("Would Reboot\n");
    *CSR_TIMER4_CNTL = 0;
    *CSR_TIMER4_CLR = 0;
}
#endif

/*
 *  Refresh the timer.
 */
static void watchdog_ping(void)
{
    *CSR_TIMER4_LOAD = reload;
}

/*
 *  Allow only one person to hold it open
 */
static int watchdog_open(struct inode *inode, struct file *file)
{
    int ret;

    if (*CSR_SA110_CNTL & (1 << 13))
        return -EBUSY;

    if (test_and_set_bit(1, &timer_alive))
        return -EBUSY;

    reload = soft_margin * (mem_fclk_21285 / 256);

    *CSR_TIMER4_CLR = 0;
    watchdog_ping();
    *CSR_TIMER4_CNTL = TIMER_CNTL_ENABLE | TIMER_CNTL_AUTORELOAD
        | TIMER_CNTL_DIV256;

#ifdef ONLY_TESTING
    ret = request_irq(IRQ_TIMER4, watchdog_fire, 0, "watchdog", NULL);
    if (ret) {
        *CSR_TIMER4_CNTL = 0;
        clear_bit(1, &timer_alive);
    }
#else
    /*
     * Setting this bit is irreversible; once enabled, there is
     * no way to disable the watchdog.
     */
    *CSR_SA110_CNTL |= 1 << 13;

    ret = 0;
#endif
    nonseekable_open(inode, file);
    return ret;
}

/*
 *  Shut off the timer.
 *  Note: if we really have enabled the watchdog, there
 *  is no way to turn off.
 */
static int watchdog_release(struct inode *inode, struct file *file)
{
#ifdef ONLY_TESTING
    free_irq(IRQ_TIMER4, NULL);
    clear_bit(1, &timer_alive);
#endif
    return 0;
}

static ssize_t watchdog_write(struct file *file, const char __user *data,
                  size_t len, loff_t *ppos)
{
    /*
     *  Refresh the timer.
     */
    if (len)
        watchdog_ping();

    return len;
}

static const struct watchdog_info ident = {
    .options    = WDIOF_SETTIMEOUT,
    .identity   = "Footbridge Watchdog",
};

static long watchdog_ioctl(struct file *file, unsigned int cmd,
               unsigned long arg)
{
    unsigned int new_margin;
    int __user *int_arg = (int __user *)arg;
    int ret = -ENOTTY;

    switch (cmd) {
    case WDIOC_GETSUPPORT:
        ret = 0;
        if (copy_to_user((void __user *)arg, &ident, sizeof(ident)))
            ret = -EFAULT;
        break;

    case WDIOC_GETSTATUS:
    case WDIOC_GETBOOTSTATUS:
        ret = put_user(0, int_arg);
        break;

    case WDIOC_KEEPALIVE:
        watchdog_ping();
        ret = 0;
        break;

    case WDIOC_SETTIMEOUT:
        ret = get_user(new_margin, int_arg);
        if (ret)
            break;

        /* Arbitrary, can't find the card's limits */
        if (new_margin < 0 || new_margin > 60) {
            ret = -EINVAL;
            break;
        }

        soft_margin = new_margin;
        reload = soft_margin * (mem_fclk_21285 / 256);
        watchdog_ping();
        /* Fall */
    case WDIOC_GETTIMEOUT:
        ret = put_user(soft_margin, int_arg);
        break;
    }
    return ret;
}

static const struct file_operations watchdog_fops = {
    .owner      = THIS_MODULE,
    .llseek     = no_llseek,
    .write      = watchdog_write,
    .unlocked_ioctl = watchdog_ioctl,
    .open       = watchdog_open,
    .release    = watchdog_release,
};

static struct miscdevice watchdog_miscdev = {
    .minor      = WATCHDOG_MINOR,
    .name       = "watchdog",
    .fops       = &watchdog_fops,
};

static int __init footbridge_watchdog_init(void)
{
    int retval;

    if (machine_is_netwinder())
        return -ENODEV;

    retval = misc_register(&watchdog_miscdev);
    if (retval < 0)
        return retval;

    pr_info("Footbridge Watchdog Timer: 0.01, timer margin: %d sec\n",
        soft_margin);

    if (machine_is_cats())
        pr_warn("Warning: Watchdog reset may not work on this machine\n");
    return 0;
}

static void __exit footbridge_watchdog_exit(void)
{
    misc_deregister(&watchdog_miscdev);
}

MODULE_AUTHOR("Phil Blundell <[email protected]>");
MODULE_DESCRIPTION("Footbridge watchdog driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);

module_param(soft_margin, int, 0);
MODULE_PARM_DESC(soft_margin, "Watchdog timeout in seconds");

module_init(footbridge_watchdog_init);
module_exit(footbridge_watchdog_exit);