wafer5823wdt.c

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/*
 *  ICP Wafer 5823 Single Board Computer WDT driver
 *  http://www.icpamerica.com/wafer_5823.php
 *  May also work on other similar models
 *
 *  (c) Copyright 2002 Justin Cormack <[email protected]>
 *
 *  Release 0.02
 *
 *  Based on advantechwdt.c which is based on wdt.c.
 *  Original copyright messages:
 *
 *  (c) Copyright 1996-1997 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]>
 *
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/fs.h>
#include <linux/ioport.h>
#include <linux/notifier.h>
#include <linux/reboot.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/io.h>
#include <linux/uaccess.h>

#define WATCHDOG_NAME "Wafer 5823 WDT"
#define PFX WATCHDOG_NAME ": "
#define WD_TIMO 60          /* 60 sec default timeout */

static unsigned long wafwdt_is_open;
static char expect_close;
static DEFINE_SPINLOCK(wafwdt_lock);

/*
 *  You must set these - there is no sane way to probe for this board.
 *
 *  To enable, write the timeout value in seconds (1 to 255) to I/O
 *  port WDT_START, then read the port to start the watchdog. To pat
 *  the dog, read port WDT_STOP to stop the timer, then read WDT_START
 *  to restart it again.
 */

static int wdt_stop = 0x843;
static int wdt_start = 0x443;

static int timeout = WD_TIMO;  /* in seconds */
module_param(timeout, int, 0);
MODULE_PARM_DESC(timeout,
        "Watchdog timeout in seconds. 1 <= timeout <= 255, default="
                __MODULE_STRING(WD_TIMO) ".");

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) ")");

static void wafwdt_ping(void)
{
    /* pat watchdog */
    spin_lock(&wafwdt_lock);
    inb_p(wdt_stop);
    inb_p(wdt_start);
    spin_unlock(&wafwdt_lock);
}

static void wafwdt_start(void)
{
    /* start up watchdog */
    outb_p(timeout, wdt_start);
    inb_p(wdt_start);
}

static void wafwdt_stop(void)
{
    /* stop watchdog */
    inb_p(wdt_stop);
}

static ssize_t wafwdt_write(struct file *file, const char __user *buf,
                        size_t count, loff_t *ppos)
{
    /* See if we got the magic character 'V' and reload the timer */
    if (count) {
        if (!nowayout) {
            size_t i;

            /* In case it was set long ago */
            expect_close = 0;

            /* scan to see whether or not we got the magic
               character */
            for (i = 0; i != count; i++) {
                char c;
                if (get_user(c, buf + i))
                    return -EFAULT;
                if (c == 'V')
                    expect_close = 42;
            }
        }
        /* Well, anyhow someone wrote to us, we should
           return that favour */
        wafwdt_ping();
    }
    return count;
}

static long wafwdt_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 = "Wafer 5823 WDT",
    };

    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) {
            wafwdt_stop();
            retval = 0;
        }

        if (options & WDIOS_ENABLECARD) {
            wafwdt_start();
            retval = 0;
        }

        return retval;
    }

    case WDIOC_KEEPALIVE:
        wafwdt_ping();
        break;

    case WDIOC_SETTIMEOUT:
        if (get_user(new_timeout, p))
            return -EFAULT;
        if ((new_timeout < 1) || (new_timeout > 255))
            return -EINVAL;
        timeout = new_timeout;
        wafwdt_stop();
        wafwdt_start();
        /* Fall */
    case WDIOC_GETTIMEOUT:
        return put_user(timeout, p);

    default:
        return -ENOTTY;
    }
    return 0;
}

static int wafwdt_open(struct inode *inode, struct file *file)
{
    if (test_and_set_bit(0, &wafwdt_is_open))
        return -EBUSY;

    /*
     *      Activate
     */
    wafwdt_start();
    return nonseekable_open(inode, file);
}

static int wafwdt_close(struct inode *inode, struct file *file)
{
    if (expect_close == 42)
        wafwdt_stop();
    else {
        pr_crit("WDT device closed unexpectedly.  WDT will not stop!\n");
        wafwdt_ping();
    }
    clear_bit(0, &wafwdt_is_open);
    expect_close = 0;
    return 0;
}

/*
 *  Notifier for system down
 */

static int wafwdt_notify_sys(struct notifier_block *this, unsigned long code,
                                void *unused)
{
    if (code == SYS_DOWN || code == SYS_HALT)
        wafwdt_stop();
    return NOTIFY_DONE;
}

/*
 *  Kernel Interfaces
 */

static const struct file_operations wafwdt_fops = {
    .owner      = THIS_MODULE,
    .llseek     = no_llseek,
    .write      = wafwdt_write,
    .unlocked_ioctl = wafwdt_ioctl,
    .open       = wafwdt_open,
    .release    = wafwdt_close,
};

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

/*
 *  The WDT needs to learn about soft shutdowns in order to
 *  turn the timebomb registers off.
 */

static struct notifier_block wafwdt_notifier = {
    .notifier_call = wafwdt_notify_sys,
};

static int __init wafwdt_init(void)
{
    int ret;

    pr_info("WDT driver for Wafer 5823 single board computer initialising\n");

    if (timeout < 1 || timeout > 255) {
        timeout = WD_TIMO;
        pr_info("timeout value must be 1 <= x <= 255, using %d\n",
            timeout);
    }

    if (wdt_stop != wdt_start) {
        if (!request_region(wdt_stop, 1, "Wafer 5823 WDT")) {
            pr_err("I/O address 0x%04x already in use\n", wdt_stop);
            ret = -EIO;
            goto error;
        }
    }

    if (!request_region(wdt_start, 1, "Wafer 5823 WDT")) {
        pr_err("I/O address 0x%04x already in use\n", wdt_start);
        ret = -EIO;
        goto error2;
    }

    ret = register_reboot_notifier(&wafwdt_notifier);
    if (ret != 0) {
        pr_err("cannot register reboot notifier (err=%d)\n", ret);
        goto error3;
    }

    ret = misc_register(&wafwdt_miscdev);
    if (ret != 0) {
        pr_err("cannot register miscdev on minor=%d (err=%d)\n",
               WATCHDOG_MINOR, ret);
        goto error4;
    }

    pr_info("initialized. timeout=%d sec (nowayout=%d)\n",
        timeout, nowayout);

    return ret;
error4:
    unregister_reboot_notifier(&wafwdt_notifier);
error3:
    release_region(wdt_start, 1);
error2:
    if (wdt_stop != wdt_start)
        release_region(wdt_stop, 1);
error:
    return ret;
}

static void __exit wafwdt_exit(void)
{
    misc_deregister(&wafwdt_miscdev);
    unregister_reboot_notifier(&wafwdt_notifier);
    if (wdt_stop != wdt_start)
        release_region(wdt_stop, 1);
    release_region(wdt_start, 1);
}

module_init(wafwdt_init);
module_exit(wafwdt_exit);

MODULE_AUTHOR("Justin Cormack");
MODULE_DESCRIPTION("ICP Wafer 5823 Single Board Computer WDT driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);

/* end of wafer5823wdt.c */