sbc8360.c

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/*
 *  SBC8360 Watchdog driver
 *
 *  (c) Copyright 2005 Webcon, Inc.
 *
 *  Based on ib700wdt.c, which is based on advantechwdt.c which is based
 *  on acquirewdt.c which is based on wdt.c.
 *
 *  (c) Copyright 2001 Charles Howes <[email protected]>
 *
 *  Based on advantechwdt.c which is based on acquirewdt.c which
 *  is based on wdt.c.
 *
 *  (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
 *       Added timeout module option to override default
 *
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

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


static unsigned long sbc8360_is_open;
static char expect_close;

/*
 *
 * Watchdog Timer Configuration
 *
 * The function of the watchdog timer is to reset the system automatically
 * and is defined at I/O port 0120H and 0121H.  To enable the watchdog timer
 * and allow the system to reset, write appropriate values from the table
 * below to I/O port 0120H and 0121H.  To disable the timer, write a zero
 * value to I/O port 0121H for the system to stop the watchdog function.
 *
 * The following describes how the timer should be programmed (according to
 * the vendor documentation)
 *
 * Enabling Watchdog:
 * MOV AX,000AH (enable, phase I)
 * MOV DX,0120H
 * OUT DX,AX
 * MOV AX,000BH (enable, phase II)
 * MOV DX,0120H
 * OUT DX,AX
 * MOV AX,000nH (set multiplier n, from 1-4)
 * MOV DX,0120H
 * OUT DX,AX
 * MOV AX,000mH (set base timer m, from 0-F)
 * MOV DX,0121H
 * OUT DX,AX
 *
 * Reset timer:
 * MOV AX,000mH (same as set base timer, above)
 * MOV DX,0121H
 * OUT DX,AX
 *
 * Disabling Watchdog:
 * MOV AX,0000H (a zero value)
 * MOV DX,0120H
 * OUT DX,AX
 *
 * Watchdog timeout configuration values:
 *      N
 *  M | 1   2   3   4
 *  --|----------------------------------
 *  0 | 0.5s    5s  50s 100s
 *  1 | 1s  10s 100s    200s
 *  2 | 1.5s    15s 150s    300s
 *  3 | 2s  20s 200s    400s
 *  4 | 2.5s    25s 250s    500s
 *  5 | 3s  30s 300s    600s
 *  6 | 3.5s    35s 350s    700s
 *  7 | 4s  40s 400s    800s
 *  8 | 4.5s    45s 450s    900s
 *  9 | 5s  50s 500s    1000s
 *  A | 5.5s    55s 550s    1100s
 *  B | 6s  60s 600s    1200s
 *  C | 6.5s    65s 650s    1300s
 *  D | 7s  70s 700s    1400s
 *  E | 7.5s    75s 750s    1500s
 *  F | 8s  80s 800s    1600s
 *
 * Another way to say the same things is:
 *  For N=1, Timeout = (M+1) * 0.5s
 *  For N=2, Timeout = (M+1) * 5s
 *  For N=3, Timeout = (M+1) * 50s
 *  For N=4, Timeout = (M+1) * 100s
 *
 */

static int wd_times[64][2] = {
    {0, 1},         /* 0  = 0.5s */
    {1, 1},         /* 1  = 1s   */
    {2, 1},         /* 2  = 1.5s */
    {3, 1},         /* 3  = 2s   */
    {4, 1},         /* 4  = 2.5s */
    {5, 1},         /* 5  = 3s   */
    {6, 1},         /* 6  = 3.5s */
    {7, 1},         /* 7  = 4s   */
    {8, 1},         /* 8  = 4.5s */
    {9, 1},         /* 9  = 5s   */
    {0xA, 1},       /* 10 = 5.5s */
    {0xB, 1},       /* 11 = 6s   */
    {0xC, 1},       /* 12 = 6.5s */
    {0xD, 1},       /* 13 = 7s   */
    {0xE, 1},       /* 14 = 7.5s */
    {0xF, 1},       /* 15 = 8s   */
    {0, 2},         /* 16 = 5s  */
    {1, 2},         /* 17 = 10s */
    {2, 2},         /* 18 = 15s */
    {3, 2},         /* 19 = 20s */
    {4, 2},         /* 20 = 25s */
    {5, 2},         /* 21 = 30s */
    {6, 2},         /* 22 = 35s */
    {7, 2},         /* 23 = 40s */
    {8, 2},         /* 24 = 45s */
    {9, 2},         /* 25 = 50s */
    {0xA, 2},       /* 26 = 55s */
    {0xB, 2},       /* 27 = 60s */
    {0xC, 2},       /* 28 = 65s */
    {0xD, 2},       /* 29 = 70s */
    {0xE, 2},       /* 30 = 75s */
    {0xF, 2},       /* 31 = 80s */
    {0, 3},         /* 32 = 50s  */
    {1, 3},         /* 33 = 100s */
    {2, 3},         /* 34 = 150s */
    {3, 3},         /* 35 = 200s */
    {4, 3},         /* 36 = 250s */
    {5, 3},         /* 37 = 300s */
    {6, 3},         /* 38 = 350s */
    {7, 3},         /* 39 = 400s */
    {8, 3},         /* 40 = 450s */
    {9, 3},         /* 41 = 500s */
    {0xA, 3},       /* 42 = 550s */
    {0xB, 3},       /* 43 = 600s */
    {0xC, 3},       /* 44 = 650s */
    {0xD, 3},       /* 45 = 700s */
    {0xE, 3},       /* 46 = 750s */
    {0xF, 3},       /* 47 = 800s */
    {0, 4},         /* 48 = 100s */
    {1, 4},         /* 49 = 200s */
    {2, 4},         /* 50 = 300s */
    {3, 4},         /* 51 = 400s */
    {4, 4},         /* 52 = 500s */
    {5, 4},         /* 53 = 600s */
    {6, 4},         /* 54 = 700s */
    {7, 4},         /* 55 = 800s */
    {8, 4},         /* 56 = 900s */
    {9, 4},         /* 57 = 1000s */
    {0xA, 4},       /* 58 = 1100s */
    {0xB, 4},       /* 59 = 1200s */
    {0xC, 4},       /* 60 = 1300s */
    {0xD, 4},       /* 61 = 1400s */
    {0xE, 4},       /* 62 = 1500s */
    {0xF, 4}        /* 63 = 1600s */
};

#define SBC8360_ENABLE 0x120
#define SBC8360_BASETIME 0x121

static int timeout = 27;
static int wd_margin = 0xB;
static int wd_multiplier = 2;
static bool nowayout = WATCHDOG_NOWAYOUT;

module_param(timeout, int, 0);
MODULE_PARM_DESC(timeout, "Index into timeout table (0-63) (default=27 (60s))");
module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout,
         "Watchdog cannot be stopped once started (default="
                __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");

/*
 *  Kernel methods.
 */

/* Activate and pre-configure watchdog */
static void sbc8360_activate(void)
{
    /* Enable the watchdog */
    outb(0x0A, SBC8360_ENABLE);
    msleep_interruptible(100);
    outb(0x0B, SBC8360_ENABLE);
    msleep_interruptible(100);
    /* Set timeout multiplier */
    outb(wd_multiplier, SBC8360_ENABLE);
    msleep_interruptible(100);
    /* Nothing happens until first sbc8360_ping() */
}

/* Kernel pings watchdog */
static void sbc8360_ping(void)
{
    /* Write the base timer register */
    outb(wd_margin, SBC8360_BASETIME);
}

/* stop watchdog */
static void sbc8360_stop(void)
{
    /* De-activate the watchdog */
    outb(0, SBC8360_ENABLE);
}

/* Userspace pings kernel driver, or requests clean close */
static ssize_t sbc8360_write(struct file *file, const char __user *buf,
                 size_t count, loff_t *ppos)
{
    if (count) {
        if (!nowayout) {
            size_t i;

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

            for (i = 0; i != count; i++) {
                char c;
                if (get_user(c, buf + i))
                    return -EFAULT;
                if (c == 'V')
                    expect_close = 42;
            }
        }
        sbc8360_ping();
    }
    return count;
}

static int sbc8360_open(struct inode *inode, struct file *file)
{
    if (test_and_set_bit(0, &sbc8360_is_open))
        return -EBUSY;
    if (nowayout)
        __module_get(THIS_MODULE);

    /* Activate and ping once to start the countdown */
    sbc8360_activate();
    sbc8360_ping();
    return nonseekable_open(inode, file);
}

static int sbc8360_close(struct inode *inode, struct file *file)
{
    if (expect_close == 42)
        sbc8360_stop();
    else
        pr_crit("SBC8360 device closed unexpectedly.  SBC8360 will not stop!\n");

    clear_bit(0, &sbc8360_is_open);
    expect_close = 0;
    return 0;
}

/*
 *  Notifier for system down
 */

static int sbc8360_notify_sys(struct notifier_block *this, unsigned long code,
                  void *unused)
{
    if (code == SYS_DOWN || code == SYS_HALT)
        sbc8360_stop(); /* Disable the SBC8360 Watchdog */

    return NOTIFY_DONE;
}

/*
 *  Kernel Interfaces
 */

static const struct file_operations sbc8360_fops = {
    .owner = THIS_MODULE,
    .llseek = no_llseek,
    .write = sbc8360_write,
    .open = sbc8360_open,
    .release = sbc8360_close,
};

static struct miscdevice sbc8360_miscdev = {
    .minor = WATCHDOG_MINOR,
    .name = "watchdog",
    .fops = &sbc8360_fops,
};

/*
 *  The SBC8360 needs to learn about soft shutdowns in order to
 *  turn the timebomb registers off.
 */

static struct notifier_block sbc8360_notifier = {
    .notifier_call = sbc8360_notify_sys,
};

static int __init sbc8360_init(void)
{
    int res;
    unsigned long int mseconds = 60000;

    if (timeout < 0 || timeout > 63) {
        pr_err("Invalid timeout index (must be 0-63)\n");
        res = -EINVAL;
        goto out;
    }

    if (!request_region(SBC8360_ENABLE, 1, "SBC8360")) {
        pr_err("ENABLE method I/O %X is not available\n",
               SBC8360_ENABLE);
        res = -EIO;
        goto out;
    }
    if (!request_region(SBC8360_BASETIME, 1, "SBC8360")) {
        pr_err("BASETIME method I/O %X is not available\n",
               SBC8360_BASETIME);
        res = -EIO;
        goto out_nobasetimereg;
    }

    res = register_reboot_notifier(&sbc8360_notifier);
    if (res) {
        pr_err("Failed to register reboot notifier\n");
        goto out_noreboot;
    }

    res = misc_register(&sbc8360_miscdev);
    if (res) {
        pr_err("failed to register misc device\n");
        goto out_nomisc;
    }

    wd_margin = wd_times[timeout][0];
    wd_multiplier = wd_times[timeout][1];

    if (wd_multiplier == 1)
        mseconds = (wd_margin + 1) * 500;
    else if (wd_multiplier == 2)
        mseconds = (wd_margin + 1) * 5000;
    else if (wd_multiplier == 3)
        mseconds = (wd_margin + 1) * 50000;
    else if (wd_multiplier == 4)
        mseconds = (wd_margin + 1) * 100000;

    /* My kingdom for the ability to print "0.5 seconds" in the kernel! */
    pr_info("Timeout set at %ld ms\n", mseconds);

    return 0;

out_nomisc:
    unregister_reboot_notifier(&sbc8360_notifier);
out_noreboot:
    release_region(SBC8360_BASETIME, 1);
out_nobasetimereg:
    release_region(SBC8360_ENABLE, 1);
out:
    return res;
}

static void __exit sbc8360_exit(void)
{
    misc_deregister(&sbc8360_miscdev);
    unregister_reboot_notifier(&sbc8360_notifier);
    release_region(SBC8360_ENABLE, 1);
    release_region(SBC8360_BASETIME, 1);
}

module_init(sbc8360_init);
module_exit(sbc8360_exit);

MODULE_AUTHOR("Ian E. Morgan <[email protected]>");
MODULE_DESCRIPTION("SBC8360 watchdog driver");
MODULE_LICENSE("GPL");
MODULE_VERSION("1.01");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);

/* end of sbc8360.c */