mixcomwd.c

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/*
 * MixCom Watchdog: A Simple Hardware Watchdog Device
 * Based on Softdog driver by Alan Cox and PC Watchdog driver by Ken Hollis
 *
 * Author: Gergely Madarasz <[email protected]>
 *
 * Copyright (c) 1999 ITConsult-Pro Co. <[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.
 *
 * Version 0.1 (99/04/15):
 *      - first version
 *
 * Version 0.2 (99/06/16):
 *      - added kernel timer watchdog ping after close
 *        since the hardware does not support watchdog shutdown
 *
 * Version 0.3 (99/06/21):
 *      - added WDIOC_GETSTATUS and WDIOC_GETSUPPORT ioctl calls
 *
 * Version 0.3.1 (99/06/22):
 *      - allow module removal while internal timer is active,
 *        print warning about probable reset
 *
 * Version 0.4 (99/11/15):
 *      - support for one more type board
 *
 * Version 0.5 (2001/12/14) Matt Domsch <[email protected]>
 *      - added nowayout module option to override
 *        CONFIG_WATCHDOG_NOWAYOUT
 *
 * Version 0.6 (2002/04/12): Rob Radez <[email protected]>
 *      - make mixcomwd_opened unsigned,
 *        removed lock_kernel/unlock_kernel from mixcomwd_release,
 *        modified ioctl a bit to conform to API
 *
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#define VERSION "0.6"
#define WATCHDOG_NAME "mixcomwd"

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

/*
 * We have two types of cards that can be probed:
 * 1) The Mixcom cards: these cards can be found at addresses
 *    0x180, 0x280, 0x380 with an additional offset of 0xc10.
 *    (Or 0xd90, 0xe90, 0xf90).
 * 2) The FlashCOM cards: these cards can be set up at
 *    0x300 -> 0x378, in 0x8 jumps with an offset of 0x04.
 *    (Or 0x304 -> 0x37c in 0x8 jumps).
 *    Each card has it's own ID.
 */
#define MIXCOM_ID 0x11
#define FLASHCOM_ID 0x18
static struct {
    int ioport;
    int id;
} mixcomwd_io_info[] __devinitdata = {
    /* The Mixcom cards */
    {0x0d90, MIXCOM_ID},
    {0x0e90, MIXCOM_ID},
    {0x0f90, MIXCOM_ID},
    /* The FlashCOM cards */
    {0x0304, FLASHCOM_ID},
    {0x030c, FLASHCOM_ID},
    {0x0314, FLASHCOM_ID},
    {0x031c, FLASHCOM_ID},
    {0x0324, FLASHCOM_ID},
    {0x032c, FLASHCOM_ID},
    {0x0334, FLASHCOM_ID},
    {0x033c, FLASHCOM_ID},
    {0x0344, FLASHCOM_ID},
    {0x034c, FLASHCOM_ID},
    {0x0354, FLASHCOM_ID},
    {0x035c, FLASHCOM_ID},
    {0x0364, FLASHCOM_ID},
    {0x036c, FLASHCOM_ID},
    {0x0374, FLASHCOM_ID},
    {0x037c, FLASHCOM_ID},
    /* The end of the list */
    {0x0000, 0},
};

static void mixcomwd_timerfun(unsigned long d);

static unsigned long mixcomwd_opened; /* long req'd for setbit --RR */

static int watchdog_port;
static int mixcomwd_timer_alive;
static DEFINE_TIMER(mixcomwd_timer, mixcomwd_timerfun, 0, 0);
static char expect_close;

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 mixcomwd_ping(void)
{
    outb_p(55, watchdog_port);
    return;
}

static void mixcomwd_timerfun(unsigned long d)
{
    mixcomwd_ping();
    mod_timer(&mixcomwd_timer, jiffies + 5 * HZ);
}

/*
 *  Allow only one person to hold it open
 */

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

    mixcomwd_ping();

    if (nowayout)
        /*
         * fops_get() code via open() has already done
         * a try_module_get() so it is safe to do the
         * __module_get().
         */
        __module_get(THIS_MODULE);
    else {
        if (mixcomwd_timer_alive) {
            del_timer(&mixcomwd_timer);
            mixcomwd_timer_alive = 0;
        }
    }
    return nonseekable_open(inode, file);
}

static int mixcomwd_release(struct inode *inode, struct file *file)
{
    if (expect_close == 42) {
        if (mixcomwd_timer_alive) {
            pr_err("release called while internal timer alive\n");
            return -EBUSY;
        }
        mixcomwd_timer_alive = 1;
        mod_timer(&mixcomwd_timer, jiffies + 5 * HZ);
    } else
        pr_crit("WDT device closed unexpectedly.  WDT will not stop!\n");

    clear_bit(0, &mixcomwd_opened);
    expect_close = 0;
    return 0;
}


static ssize_t mixcomwd_write(struct file *file, const char __user *data,
                        size_t len, loff_t *ppos)
{
    if (len) {
        if (!nowayout) {
            size_t i;

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

            for (i = 0; i != len; i++) {
                char c;
                if (get_user(c, data + i))
                    return -EFAULT;
                if (c == 'V')
                    expect_close = 42;
            }
        }
        mixcomwd_ping();
    }
    return len;
}

static long mixcomwd_ioctl(struct file *file,
                unsigned int cmd, unsigned long arg)
{
    void __user *argp = (void __user *)arg;
    int __user *p = argp;
    int status;
    static const struct watchdog_info ident = {
        .options = WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
        .firmware_version = 1,
        .identity = "MixCOM watchdog",
    };

    switch (cmd) {
    case WDIOC_GETSUPPORT:
        if (copy_to_user(argp, &ident, sizeof(ident)))
            return -EFAULT;
        break;
    case WDIOC_GETSTATUS:
        status = mixcomwd_opened;
        if (!nowayout)
            status |= mixcomwd_timer_alive;
        return put_user(status, p);
    case WDIOC_GETBOOTSTATUS:
        return put_user(0, p);
    case WDIOC_KEEPALIVE:
        mixcomwd_ping();
        break;
    default:
        return -ENOTTY;
    }
    return 0;
}

static const struct file_operations mixcomwd_fops = {
    .owner      = THIS_MODULE,
    .llseek     = no_llseek,
    .write      = mixcomwd_write,
    .unlocked_ioctl = mixcomwd_ioctl,
    .open       = mixcomwd_open,
    .release    = mixcomwd_release,
};

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

static int __init checkcard(int port, int card_id)
{
    int id;

    if (!request_region(port, 1, "MixCOM watchdog"))
        return 0;

    id = inb_p(port);
    if (card_id == MIXCOM_ID)
        id &= 0x3f;

    if (id != card_id) {
        release_region(port, 1);
        return 0;
    }
    return 1;
}

static int __init mixcomwd_init(void)
{
    int i, ret, found = 0;

    for (i = 0; !found && mixcomwd_io_info[i].ioport != 0; i++) {
        if (checkcard(mixcomwd_io_info[i].ioport,
                  mixcomwd_io_info[i].id)) {
            found = 1;
            watchdog_port = mixcomwd_io_info[i].ioport;
        }
    }

    if (!found) {
        pr_err("No card detected, or port not available\n");
        return -ENODEV;
    }

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

    pr_info("MixCOM watchdog driver v%s, watchdog port at 0x%3x\n",
        VERSION, watchdog_port);

    return 0;

error_misc_register_watchdog:
    release_region(watchdog_port, 1);
    watchdog_port = 0x0000;
    return ret;
}

static void __exit mixcomwd_exit(void)
{
    if (!nowayout) {
        if (mixcomwd_timer_alive) {
            pr_warn("I quit now, hardware will probably reboot!\n");
            del_timer_sync(&mixcomwd_timer);
            mixcomwd_timer_alive = 0;
        }
    }
    misc_deregister(&mixcomwd_miscdev);
    release_region(watchdog_port, 1);
}

module_init(mixcomwd_init);
module_exit(mixcomwd_exit);

MODULE_AUTHOR("Gergely Madarasz <[email protected]>");
MODULE_DESCRIPTION("MixCom Watchdog driver");
MODULE_VERSION(VERSION);
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);