ixp4xx_wdt.c

Go to the documentation of this file.

/*
 * drivers/char/watchdog/ixp4xx_wdt.c
 *
 * Watchdog driver for Intel IXP4xx network processors
 *
 * Author: Deepak Saxena <[email protected]>
 *
 * Copyright 2004 (c) MontaVista, Software, Inc.
 * Based on sa1100 driver, Copyright (C) 2000 Oleg Drokin <[email protected]>
 *
 * This file is licensed under  the terms of the GNU General Public
 * License version 2. This program is licensed "as is" without any
 * warranty of any kind, whether express or implied.
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/init.h>
#include <linux/bitops.h>
#include <linux/uaccess.h>
#include <mach/hardware.h>

static bool nowayout = WATCHDOG_NOWAYOUT;
static int heartbeat = 60;  /* (secs) Default is 1 minute */
static unsigned long wdt_status;
static unsigned long boot_status;
static DEFINE_SPINLOCK(wdt_lock);

#define WDT_TICK_RATE (IXP4XX_PERIPHERAL_BUS_CLOCK * 1000000UL)

#define WDT_IN_USE      0
#define WDT_OK_TO_CLOSE     1

static void wdt_enable(void)
{
    spin_lock(&wdt_lock);
    *IXP4XX_OSWK = IXP4XX_WDT_KEY;
    *IXP4XX_OSWE = 0;
    *IXP4XX_OSWT = WDT_TICK_RATE * heartbeat;
    *IXP4XX_OSWE = IXP4XX_WDT_COUNT_ENABLE | IXP4XX_WDT_RESET_ENABLE;
    *IXP4XX_OSWK = 0;
    spin_unlock(&wdt_lock);
}

static void wdt_disable(void)
{
    spin_lock(&wdt_lock);
    *IXP4XX_OSWK = IXP4XX_WDT_KEY;
    *IXP4XX_OSWE = 0;
    *IXP4XX_OSWK = 0;
    spin_unlock(&wdt_lock);
}

static int ixp4xx_wdt_open(struct inode *inode, struct file *file)
{
    if (test_and_set_bit(WDT_IN_USE, &wdt_status))
        return -EBUSY;

    clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
    wdt_enable();
    return nonseekable_open(inode, file);
}

static ssize_t
ixp4xx_wdt_write(struct file *file, const char *data, size_t len, loff_t *ppos)
{
    if (len) {
        if (!nowayout) {
            size_t i;

            clear_bit(WDT_OK_TO_CLOSE, &wdt_status);

            for (i = 0; i != len; i++) {
                char c;

                if (get_user(c, data + i))
                    return -EFAULT;
                if (c == 'V')
                    set_bit(WDT_OK_TO_CLOSE, &wdt_status);
            }
        }
        wdt_enable();
    }
    return len;
}

static const struct watchdog_info ident = {
    .options    = WDIOF_CARDRESET | WDIOF_MAGICCLOSE |
              WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
    .identity   = "IXP4xx Watchdog",
};


static long ixp4xx_wdt_ioctl(struct file *file, unsigned int cmd,
                            unsigned long arg)
{
    int ret = -ENOTTY;
    int time;

    switch (cmd) {
    case WDIOC_GETSUPPORT:
        ret = copy_to_user((struct watchdog_info *)arg, &ident,
                   sizeof(ident)) ? -EFAULT : 0;
        break;

    case WDIOC_GETSTATUS:
        ret = put_user(0, (int *)arg);
        break;

    case WDIOC_GETBOOTSTATUS:
        ret = put_user(boot_status, (int *)arg);
        break;

    case WDIOC_KEEPALIVE:
        wdt_enable();
        ret = 0;
        break;

    case WDIOC_SETTIMEOUT:
        ret = get_user(time, (int *)arg);
        if (ret)
            break;

        if (time <= 0 || time > 60) {
            ret = -EINVAL;
            break;
        }

        heartbeat = time;
        wdt_enable();
        /* Fall through */

    case WDIOC_GETTIMEOUT:
        ret = put_user(heartbeat, (int *)arg);
        break;
    }
    return ret;
}

static int ixp4xx_wdt_release(struct inode *inode, struct file *file)
{
    if (test_bit(WDT_OK_TO_CLOSE, &wdt_status))
        wdt_disable();
    else
        pr_crit("Device closed unexpectedly - timer will not stop\n");
    clear_bit(WDT_IN_USE, &wdt_status);
    clear_bit(WDT_OK_TO_CLOSE, &wdt_status);

    return 0;
}


static const struct file_operations ixp4xx_wdt_fops = {
    .owner      = THIS_MODULE,
    .llseek     = no_llseek,
    .write      = ixp4xx_wdt_write,
    .unlocked_ioctl = ixp4xx_wdt_ioctl,
    .open       = ixp4xx_wdt_open,
    .release    = ixp4xx_wdt_release,
};

static struct miscdevice ixp4xx_wdt_miscdev = {
    .minor      = WATCHDOG_MINOR,
    .name       = "watchdog",
    .fops       = &ixp4xx_wdt_fops,
};

static int __init ixp4xx_wdt_init(void)
{
    int ret;

    if (!(read_cpuid_id() & 0xf) && !cpu_is_ixp46x()) {
        pr_err("Rev. A0 IXP42x CPU detected - watchdog disabled\n");

        return -ENODEV;
    }
    boot_status = (*IXP4XX_OSST & IXP4XX_OSST_TIMER_WARM_RESET) ?
            WDIOF_CARDRESET : 0;
    ret = misc_register(&ixp4xx_wdt_miscdev);
    if (ret == 0)
        pr_info("timer heartbeat %d sec\n", heartbeat);
    return ret;
}

static void __exit ixp4xx_wdt_exit(void)
{
    misc_deregister(&ixp4xx_wdt_miscdev);
}


module_init(ixp4xx_wdt_init);
module_exit(ixp4xx_wdt_exit);

MODULE_AUTHOR("Deepak Saxena <[email protected]>");
MODULE_DESCRIPTION("IXP4xx Network Processor Watchdog");

module_param(heartbeat, int, 0);
MODULE_PARM_DESC(heartbeat, "Watchdog heartbeat in seconds (default 60s)");

module_param(nowayout, bool, 0);
MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");

MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);