advantechwdt.c

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/*
 *  Advantech Single Board Computer WDT driver
 *
 *  (c) Copyright 2000-2001 Marek Michalkiewicz <[email protected]>
 *
 *  Based on acquirewdt.c which is based on wdt.c.
 *  Original copyright messages:
 *
 *  (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.
 *
 *  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 <[email protected]>
 *
 *  14-Dec-2001 Matt Domsch <[email protected]>
 *      Added nowayout module option to override CONFIG_WATCHDOG_NOWAYOUT
 *
 *  16-Oct-2002 Rob Radez <[email protected]>
 *      Clean up ioctls, clean up init + exit, add expect close support,
 *      add wdt_start and wdt_stop as parameters.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/types.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/fs.h>
#include <linux/ioport.h>
#include <linux/platform_device.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/uaccess.h>


#define DRV_NAME "advantechwdt"
#define WATCHDOG_NAME "Advantech WDT"
#define WATCHDOG_TIMEOUT 60     /* 60 sec default timeout */

/* the watchdog platform device */
static struct platform_device *advwdt_platform_device;
static unsigned long advwdt_is_open;
static char adv_expect_close;

/*
 *  You must set these - there is no sane way to probe for this board.
 *
 *  To enable or restart, write the timeout value in seconds (1 to 63)
 *  to I/O port wdt_start.  To disable, read I/O port wdt_stop.
 *  Both are 0x443 for most boards (tested on a PCA-6276VE-00B1), but
 *  check your manual (at least the PCA-6159 seems to be different -
 *  the manual says wdt_stop is 0x43, not 0x443).
 *  (0x43 is also a write-only control register for the 8254 timer!)
 */

static int wdt_stop = 0x443;
module_param(wdt_stop, int, 0);
MODULE_PARM_DESC(wdt_stop, "Advantech WDT 'stop' io port (default 0x443)");

static int wdt_start = 0x443;
module_param(wdt_start, int, 0);
MODULE_PARM_DESC(wdt_start, "Advantech WDT 'start' io port (default 0x443)");

static int timeout = WATCHDOG_TIMEOUT;  /* in seconds */
module_param(timeout, int, 0);
MODULE_PARM_DESC(timeout,
    "Watchdog timeout in seconds. 1<= timeout <=63, default="
        __MODULE_STRING(WATCHDOG_TIMEOUT) ".");

static bool nowayout = WATCHDOG_NOWAYOUT;
module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout,
    "Watchdog cannot be stopped once started (default="
        __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");

/*
 *  Watchdog Operations
 */

static void advwdt_ping(void)
{
    /* Write a watchdog value */
    outb_p(timeout, wdt_start);
}

static void advwdt_disable(void)
{
    inb_p(wdt_stop);
}

static int advwdt_set_heartbeat(int t)
{
    if (t < 1 || t > 63)
        return -EINVAL;
    timeout = t;
    return 0;
}

/*
 *  /dev/watchdog handling
 */

static ssize_t advwdt_write(struct file *file, const char __user *buf,
                        size_t count, loff_t *ppos)
{
    if (count) {
        if (!nowayout) {
            size_t i;

            adv_expect_close = 0;

            for (i = 0; i != count; i++) {
                char c;
                if (get_user(c, buf + i))
                    return -EFAULT;
                if (c == 'V')
                    adv_expect_close = 42;
            }
        }
        advwdt_ping();
    }
    return count;
}

static long advwdt_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
    int new_timeout;
    void __user *argp = (void __user *)arg;
    int __user *p = argp;
    static const struct watchdog_info ident = {
        .options = WDIOF_KEEPALIVEPING |
               WDIOF_SETTIMEOUT |
               WDIOF_MAGICCLOSE,
        .firmware_version = 1,
        .identity = WATCHDOG_NAME,
    };

    switch (cmd) {
    case WDIOC_GETSUPPORT:
        if (copy_to_user(argp, &ident, sizeof(ident)))
            return -EFAULT;
        break;

    case WDIOC_GETSTATUS:
    case WDIOC_GETBOOTSTATUS:
        return put_user(0, p);

    case WDIOC_SETOPTIONS:
    {
        int options, retval = -EINVAL;

        if (get_user(options, p))
            return -EFAULT;
        if (options & WDIOS_DISABLECARD) {
            advwdt_disable();
            retval = 0;
        }
        if (options & WDIOS_ENABLECARD) {
            advwdt_ping();
            retval = 0;
        }
        return retval;
    }
    case WDIOC_KEEPALIVE:
        advwdt_ping();
        break;

    case WDIOC_SETTIMEOUT:
        if (get_user(new_timeout, p))
            return -EFAULT;
        if (advwdt_set_heartbeat(new_timeout))
            return -EINVAL;
        advwdt_ping();
        /* Fall */
    case WDIOC_GETTIMEOUT:
        return put_user(timeout, p);
    default:
        return -ENOTTY;
    }
    return 0;
}

static int advwdt_open(struct inode *inode, struct file *file)
{
    if (test_and_set_bit(0, &advwdt_is_open))
        return -EBUSY;
    /*
     *  Activate
     */

    advwdt_ping();
    return nonseekable_open(inode, file);
}

static int advwdt_close(struct inode *inode, struct file *file)
{
    if (adv_expect_close == 42) {
        advwdt_disable();
    } else {
        pr_crit("Unexpected close, not stopping watchdog!\n");
        advwdt_ping();
    }
    clear_bit(0, &advwdt_is_open);
    adv_expect_close = 0;
    return 0;
}

/*
 *  Kernel Interfaces
 */

static const struct file_operations advwdt_fops = {
    .owner      = THIS_MODULE,
    .llseek     = no_llseek,
    .write      = advwdt_write,
    .unlocked_ioctl = advwdt_ioctl,
    .open       = advwdt_open,
    .release    = advwdt_close,
};

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

/*
 *  Init & exit routines
 */

static int __devinit advwdt_probe(struct platform_device *dev)
{
    int ret;

    if (wdt_stop != wdt_start) {
        if (!request_region(wdt_stop, 1, WATCHDOG_NAME)) {
            pr_err("I/O address 0x%04x already in use\n",
                   wdt_stop);
            ret = -EIO;
            goto out;
        }
    }

    if (!request_region(wdt_start, 1, WATCHDOG_NAME)) {
        pr_err("I/O address 0x%04x already in use\n", wdt_start);
        ret = -EIO;
        goto unreg_stop;
    }

    /* Check that the heartbeat value is within it's range ;
     * if not reset to the default */
    if (advwdt_set_heartbeat(timeout)) {
        advwdt_set_heartbeat(WATCHDOG_TIMEOUT);
        pr_info("timeout value must be 1<=x<=63, using %d\n", timeout);
    }

    ret = misc_register(&advwdt_miscdev);
    if (ret != 0) {
        pr_err("cannot register miscdev on minor=%d (err=%d)\n",
               WATCHDOG_MINOR, ret);
        goto unreg_regions;
    }
    pr_info("initialized. timeout=%d sec (nowayout=%d)\n",
        timeout, nowayout);
out:
    return ret;
unreg_regions:
    release_region(wdt_start, 1);
unreg_stop:
    if (wdt_stop != wdt_start)
        release_region(wdt_stop, 1);
    goto out;
}

static int __devexit advwdt_remove(struct platform_device *dev)
{
    misc_deregister(&advwdt_miscdev);
    release_region(wdt_start, 1);
    if (wdt_stop != wdt_start)
        release_region(wdt_stop, 1);

    return 0;
}

static void advwdt_shutdown(struct platform_device *dev)
{
    /* Turn the WDT off if we have a soft shutdown */
    advwdt_disable();
}

static struct platform_driver advwdt_driver = {
    .probe      = advwdt_probe,
    .remove     = __devexit_p(advwdt_remove),
    .shutdown   = advwdt_shutdown,
    .driver     = {
        .owner  = THIS_MODULE,
        .name   = DRV_NAME,
    },
};

static int __init advwdt_init(void)
{
    int err;

    pr_info("WDT driver for Advantech single board computer initialising\n");

    err = platform_driver_register(&advwdt_driver);
    if (err)
        return err;

    advwdt_platform_device = platform_device_register_simple(DRV_NAME,
                                -1, NULL, 0);
    if (IS_ERR(advwdt_platform_device)) {
        err = PTR_ERR(advwdt_platform_device);
        goto unreg_platform_driver;
    }

    return 0;

unreg_platform_driver:
    platform_driver_unregister(&advwdt_driver);
    return err;
}

static void __exit advwdt_exit(void)
{
    platform_device_unregister(advwdt_platform_device);
    platform_driver_unregister(&advwdt_driver);
    pr_info("Watchdog Module Unloaded\n");
}

module_init(advwdt_init);
module_exit(advwdt_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Marek Michalkiewicz <[email protected]>");
MODULE_DESCRIPTION("Advantech Single Board Computer WDT driver");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);