mtx-1_wdt.c

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/*
 *      Driver for the MTX-1 Watchdog.
 *
 *      (C) Copyright 2005 4G Systems <[email protected]>,
 *                          All Rights Reserved.
 *                              http://www.4g-systems.biz
 *
 *  (C) Copyright 2007 OpenWrt.org, Florian Fainelli <[email protected]>
 *
 *      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 Michael Stickel nor 4G Systems admit liability nor provide
 *      warranty for any of this software. This material is provided
 *      "AS-IS" and at no charge.
 *
 *      (c) Copyright 2005    4G Systems <[email protected]>
 *
 *      Release 0.01.
 *      Author: Michael Stickel  [email protected]
 *
 *      Release 0.02.
 *  Author: Florian Fainelli [email protected]
 *      use the Linux watchdog/timer APIs
 *
 *      The Watchdog is configured to reset the MTX-1
 *      if it is not triggered for 100 seconds.
 *      It should not be triggered more often than 1.6 seconds.
 *
 *      A timer triggers the watchdog every 5 seconds, until
 *      it is opened for the first time. After the first open
 *      it MUST be triggered every 2..95 seconds.
 */

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/miscdevice.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/ioport.h>
#include <linux/timer.h>
#include <linux/completion.h>
#include <linux/jiffies.h>
#include <linux/watchdog.h>
#include <linux/platform_device.h>
#include <linux/io.h>
#include <linux/uaccess.h>
#include <linux/gpio.h>

#include <asm/mach-au1x00/au1000.h>

#define MTX1_WDT_INTERVAL   (5 * HZ)

static int ticks = 100 * HZ;

static struct {
    struct completion stop;
    spinlock_t lock;
    int running;
    struct timer_list timer;
    int queue;
    int default_ticks;
    unsigned long inuse;
    unsigned gpio;
    unsigned int gstate;
} mtx1_wdt_device;

static void mtx1_wdt_trigger(unsigned long unused)
{
    spin_lock(&mtx1_wdt_device.lock);
    if (mtx1_wdt_device.running)
        ticks--;

    /* toggle wdt gpio */
    mtx1_wdt_device.gstate = !mtx1_wdt_device.gstate;
    gpio_set_value(mtx1_wdt_device.gpio, mtx1_wdt_device.gstate);

    if (mtx1_wdt_device.queue && ticks)
        mod_timer(&mtx1_wdt_device.timer, jiffies + MTX1_WDT_INTERVAL);
    else
        complete(&mtx1_wdt_device.stop);
    spin_unlock(&mtx1_wdt_device.lock);
}

static void mtx1_wdt_reset(void)
{
    ticks = mtx1_wdt_device.default_ticks;
}


static void mtx1_wdt_start(void)
{
    unsigned long flags;

    spin_lock_irqsave(&mtx1_wdt_device.lock, flags);
    if (!mtx1_wdt_device.queue) {
        mtx1_wdt_device.queue = 1;
        mtx1_wdt_device.gstate = 1;
        gpio_set_value(mtx1_wdt_device.gpio, 1);
        mod_timer(&mtx1_wdt_device.timer, jiffies + MTX1_WDT_INTERVAL);
    }
    mtx1_wdt_device.running++;
    spin_unlock_irqrestore(&mtx1_wdt_device.lock, flags);
}

static int mtx1_wdt_stop(void)
{
    unsigned long flags;

    spin_lock_irqsave(&mtx1_wdt_device.lock, flags);
    if (mtx1_wdt_device.queue) {
        mtx1_wdt_device.queue = 0;
        mtx1_wdt_device.gstate = 0;
        gpio_set_value(mtx1_wdt_device.gpio, 0);
    }
    ticks = mtx1_wdt_device.default_ticks;
    spin_unlock_irqrestore(&mtx1_wdt_device.lock, flags);
    return 0;
}

/* Filesystem functions */

static int mtx1_wdt_open(struct inode *inode, struct file *file)
{
    if (test_and_set_bit(0, &mtx1_wdt_device.inuse))
        return -EBUSY;
    return nonseekable_open(inode, file);
}


static int mtx1_wdt_release(struct inode *inode, struct file *file)
{
    clear_bit(0, &mtx1_wdt_device.inuse);
    return 0;
}

static long mtx1_wdt_ioctl(struct file *file, unsigned int cmd,
                            unsigned long arg)
{
    void __user *argp = (void __user *)arg;
    int __user *p = (int __user *)argp;
    unsigned int value;
    static const struct watchdog_info ident = {
        .options = WDIOF_CARDRESET,
        .identity = "MTX-1 WDT",
    };

    switch (cmd) {
    case WDIOC_GETSUPPORT:
        if (copy_to_user(argp, &ident, sizeof(ident)))
            return -EFAULT;
        break;
    case WDIOC_GETSTATUS:
    case WDIOC_GETBOOTSTATUS:
        put_user(0, p);
        break;
    case WDIOC_SETOPTIONS:
        if (get_user(value, p))
            return -EFAULT;
        if (value & WDIOS_ENABLECARD)
            mtx1_wdt_start();
        else if (value & WDIOS_DISABLECARD)
            mtx1_wdt_stop();
        else
            return -EINVAL;
        return 0;
    case WDIOC_KEEPALIVE:
        mtx1_wdt_reset();
        break;
    default:
        return -ENOTTY;
    }
    return 0;
}


static ssize_t mtx1_wdt_write(struct file *file, const char *buf,
                        size_t count, loff_t *ppos)
{
    if (!count)
        return -EIO;
    mtx1_wdt_reset();
    return count;
}

static const struct file_operations mtx1_wdt_fops = {
    .owner      = THIS_MODULE,
    .llseek     = no_llseek,
    .unlocked_ioctl = mtx1_wdt_ioctl,
    .open       = mtx1_wdt_open,
    .write      = mtx1_wdt_write,
    .release    = mtx1_wdt_release,
};


static struct miscdevice mtx1_wdt_misc = {
    .minor  = WATCHDOG_MINOR,
    .name   = "watchdog",
    .fops   = &mtx1_wdt_fops,
};


static int __devinit mtx1_wdt_probe(struct platform_device *pdev)
{
    int ret;

    mtx1_wdt_device.gpio = pdev->resource[0].start;
    ret = gpio_request_one(mtx1_wdt_device.gpio,
                GPIOF_OUT_INIT_HIGH, "mtx1-wdt");
    if (ret < 0) {
        dev_err(&pdev->dev, "failed to request gpio");
        return ret;
    }

    spin_lock_init(&mtx1_wdt_device.lock);
    init_completion(&mtx1_wdt_device.stop);
    mtx1_wdt_device.queue = 0;
    clear_bit(0, &mtx1_wdt_device.inuse);
    setup_timer(&mtx1_wdt_device.timer, mtx1_wdt_trigger, 0L);
    mtx1_wdt_device.default_ticks = ticks;

    ret = misc_register(&mtx1_wdt_misc);
    if (ret < 0) {
        dev_err(&pdev->dev, "failed to register\n");
        return ret;
    }
    mtx1_wdt_start();
    dev_info(&pdev->dev, "MTX-1 Watchdog driver\n");
    return 0;
}

static int __devexit mtx1_wdt_remove(struct platform_device *pdev)
{
    /* FIXME: do we need to lock this test ? */
    if (mtx1_wdt_device.queue) {
        mtx1_wdt_device.queue = 0;
        wait_for_completion(&mtx1_wdt_device.stop);
    }

    gpio_free(mtx1_wdt_device.gpio);
    misc_deregister(&mtx1_wdt_misc);
    return 0;
}

static struct platform_driver mtx1_wdt_driver = {
    .probe = mtx1_wdt_probe,
    .remove = __devexit_p(mtx1_wdt_remove),
    .driver.name = "mtx1-wdt",
    .driver.owner = THIS_MODULE,
};

module_platform_driver(mtx1_wdt_driver);

MODULE_AUTHOR("Michael Stickel, Florian Fainelli");
MODULE_DESCRIPTION("Driver for the MTX-1 watchdog");
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
MODULE_ALIAS("platform:mtx1-wdt");