cpu5wdt.c

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/*
 * sma cpu5 watchdog driver
 *
 * Copyright (C) 2003 Heiko Ronsdorf <[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.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#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/io.h>
#include <linux/uaccess.h>
#include <linux/watchdog.h>

/* adjustable parameters */

static int verbose;
static int port = 0x91;
static int ticks = 10000;
static DEFINE_SPINLOCK(cpu5wdt_lock);

#define PFX         "cpu5wdt: "

#define CPU5WDT_EXTENT          0x0A

#define CPU5WDT_STATUS_REG      0x00
#define CPU5WDT_TIME_A_REG      0x02
#define CPU5WDT_TIME_B_REG      0x03
#define CPU5WDT_MODE_REG        0x04
#define CPU5WDT_TRIGGER_REG     0x07
#define CPU5WDT_ENABLE_REG      0x08
#define CPU5WDT_RESET_REG       0x09

#define CPU5WDT_INTERVAL    (HZ/10+1)

/* some device data */

static struct {
    struct completion stop;
    int running;
    struct timer_list timer;
    int queue;
    int default_ticks;
    unsigned long inuse;
} cpu5wdt_device;

/* generic helper functions */

static void cpu5wdt_trigger(unsigned long unused)
{
    if (verbose > 2)
        pr_debug("trigger at %i ticks\n", ticks);

    if (cpu5wdt_device.running)
        ticks--;

    spin_lock(&cpu5wdt_lock);
    /* keep watchdog alive */
    outb(1, port + CPU5WDT_TRIGGER_REG);

    /* requeue?? */
    if (cpu5wdt_device.queue && ticks)
        mod_timer(&cpu5wdt_device.timer, jiffies + CPU5WDT_INTERVAL);
    else {
        /* ticks doesn't matter anyway */
        complete(&cpu5wdt_device.stop);
    }
    spin_unlock(&cpu5wdt_lock);

}

static void cpu5wdt_reset(void)
{
    ticks = cpu5wdt_device.default_ticks;

    if (verbose)
        pr_debug("reset (%i ticks)\n", (int) ticks);

}

static void cpu5wdt_start(void)
{
    unsigned long flags;

    spin_lock_irqsave(&cpu5wdt_lock, flags);
    if (!cpu5wdt_device.queue) {
        cpu5wdt_device.queue = 1;
        outb(0, port + CPU5WDT_TIME_A_REG);
        outb(0, port + CPU5WDT_TIME_B_REG);
        outb(1, port + CPU5WDT_MODE_REG);
        outb(0, port + CPU5WDT_RESET_REG);
        outb(0, port + CPU5WDT_ENABLE_REG);
        mod_timer(&cpu5wdt_device.timer, jiffies + CPU5WDT_INTERVAL);
    }
    /* if process dies, counter is not decremented */
    cpu5wdt_device.running++;
    spin_unlock_irqrestore(&cpu5wdt_lock, flags);
}

static int cpu5wdt_stop(void)
{
    unsigned long flags;

    spin_lock_irqsave(&cpu5wdt_lock, flags);
    if (cpu5wdt_device.running)
        cpu5wdt_device.running = 0;
    ticks = cpu5wdt_device.default_ticks;
    spin_unlock_irqrestore(&cpu5wdt_lock, flags);
    if (verbose)
        pr_crit("stop not possible\n");
    return -EIO;
}

/* filesystem operations */

static int cpu5wdt_open(struct inode *inode, struct file *file)
{
    if (test_and_set_bit(0, &cpu5wdt_device.inuse))
        return -EBUSY;
    return nonseekable_open(inode, file);
}

static int cpu5wdt_release(struct inode *inode, struct file *file)
{
    clear_bit(0, &cpu5wdt_device.inuse);
    return 0;
}

static long cpu5wdt_ioctl(struct file *file, unsigned int cmd,
                        unsigned long arg)
{
    void __user *argp = (void __user *)arg;
    int __user *p = argp;
    unsigned int value;
    static const struct watchdog_info ident = {
        .options = WDIOF_CARDRESET,
        .identity = "CPU5 WDT",
    };

    switch (cmd) {
    case WDIOC_GETSUPPORT:
        if (copy_to_user(argp, &ident, sizeof(ident)))
            return -EFAULT;
        break;
    case WDIOC_GETSTATUS:
        value = inb(port + CPU5WDT_STATUS_REG);
        value = (value >> 2) & 1;
        return put_user(value, p);
    case WDIOC_GETBOOTSTATUS:
        return put_user(0, p);
    case WDIOC_SETOPTIONS:
        if (get_user(value, p))
            return -EFAULT;
        if (value & WDIOS_ENABLECARD)
            cpu5wdt_start();
        if (value & WDIOS_DISABLECARD)
            cpu5wdt_stop();
        break;
    case WDIOC_KEEPALIVE:
        cpu5wdt_reset();
        break;
    default:
        return -ENOTTY;
    }
    return 0;
}

static ssize_t cpu5wdt_write(struct file *file, const char __user *buf,
                        size_t count, loff_t *ppos)
{
    if (!count)
        return -EIO;
    cpu5wdt_reset();
    return count;
}

static const struct file_operations cpu5wdt_fops = {
    .owner      = THIS_MODULE,
    .llseek     = no_llseek,
    .unlocked_ioctl = cpu5wdt_ioctl,
    .open       = cpu5wdt_open,
    .write      = cpu5wdt_write,
    .release    = cpu5wdt_release,
};

static struct miscdevice cpu5wdt_misc = {
    .minor  = WATCHDOG_MINOR,
    .name   = "watchdog",
    .fops   = &cpu5wdt_fops,
};

/* init/exit function */

static int __devinit cpu5wdt_init(void)
{
    unsigned int val;
    int err;

    if (verbose)
        pr_debug("port=0x%x, verbose=%i\n", port, verbose);

    init_completion(&cpu5wdt_device.stop);
    cpu5wdt_device.queue = 0;
    setup_timer(&cpu5wdt_device.timer, cpu5wdt_trigger, 0);
    cpu5wdt_device.default_ticks = ticks;

    if (!request_region(port, CPU5WDT_EXTENT, PFX)) {
        pr_err("request_region failed\n");
        err = -EBUSY;
        goto no_port;
    }

    /* watchdog reboot? */
    val = inb(port + CPU5WDT_STATUS_REG);
    val = (val >> 2) & 1;
    if (!val)
        pr_info("sorry, was my fault\n");

    err = misc_register(&cpu5wdt_misc);
    if (err < 0) {
        pr_err("misc_register failed\n");
        goto no_misc;
    }


    pr_info("init success\n");
    return 0;

no_misc:
    release_region(port, CPU5WDT_EXTENT);
no_port:
    return err;
}

static int __devinit cpu5wdt_init_module(void)
{
    return cpu5wdt_init();
}

static void __devexit cpu5wdt_exit(void)
{
    if (cpu5wdt_device.queue) {
        cpu5wdt_device.queue = 0;
        wait_for_completion(&cpu5wdt_device.stop);
    }

    misc_deregister(&cpu5wdt_misc);

    release_region(port, CPU5WDT_EXTENT);

}

static void __devexit cpu5wdt_exit_module(void)
{
    cpu5wdt_exit();
}

/* module entry points */

module_init(cpu5wdt_init_module);
module_exit(cpu5wdt_exit_module);

MODULE_AUTHOR("Heiko Ronsdorf <[email protected]>");
MODULE_DESCRIPTION("sma cpu5 watchdog driver");
MODULE_SUPPORTED_DEVICE("sma cpu5 watchdog");
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);

module_param(port, int, 0);
MODULE_PARM_DESC(port, "base address of watchdog card, default is 0x91");

module_param(verbose, int, 0);
MODULE_PARM_DESC(verbose, "be verbose, default is 0 (no)");

module_param(ticks, int, 0);
MODULE_PARM_DESC(ticks, "count down ticks, default is 10000");