iop_wdt.c

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/*
 * drivers/char/watchdog/iop_wdt.c
 *
 * WDT driver for Intel I/O Processors
 * Copyright (C) 2005, Intel Corporation.
 *
 * Based on ixp4xx driver, Copyright 2004 (c) MontaVista, Software, Inc.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope 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., 59 Temple
 * Place - Suite 330, Boston, MA 02111-1307 USA.
 *
 *  Curt E Bruns <[email protected]>
 *  Peter Milne <[email protected]>
 *  Dan Williams <[email protected]>
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

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

static bool nowayout = WATCHDOG_NOWAYOUT;
static unsigned long wdt_status;
static unsigned long boot_status;
static DEFINE_SPINLOCK(wdt_lock);

#define WDT_IN_USE      0
#define WDT_OK_TO_CLOSE     1
#define WDT_ENABLED     2

static unsigned long iop_watchdog_timeout(void)
{
    return (0xffffffffUL / get_iop_tick_rate());
}

static int wdt_supports_disable(void)
{
    int can_disable;

    if (IOP_WDTCR_EN_ARM != IOP_WDTCR_DIS_ARM)
        can_disable = 1;
    else
        can_disable = 0;

    return can_disable;
}

static void wdt_enable(void)
{
    /* Arm and enable the Timer to starting counting down from 0xFFFF.FFFF
     * Takes approx. 10.7s to timeout
     */
    spin_lock(&wdt_lock);
    write_wdtcr(IOP_WDTCR_EN_ARM);
    write_wdtcr(IOP_WDTCR_EN);
    spin_unlock(&wdt_lock);
}

/* returns 0 if the timer was successfully disabled */
static int wdt_disable(void)
{
    /* Stop Counting */
    if (wdt_supports_disable()) {
        spin_lock(&wdt_lock);
        write_wdtcr(IOP_WDTCR_DIS_ARM);
        write_wdtcr(IOP_WDTCR_DIS);
        clear_bit(WDT_ENABLED, &wdt_status);
        spin_unlock(&wdt_lock);
        pr_info("Disabled\n");
        return 0;
    } else
        return 1;
}

static int iop_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();
    set_bit(WDT_ENABLED, &wdt_status);
    return nonseekable_open(inode, file);
}

static ssize_t iop_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_KEEPALIVEPING,
    .identity = "iop watchdog",
};

static long iop_wdt_ioctl(struct file *file,
                unsigned int cmd, unsigned long arg)
{
    int options;
    int ret = -ENOTTY;
    int __user *argp = (int __user *)arg;

    switch (cmd) {
    case WDIOC_GETSUPPORT:
        if (copy_to_user(argp, &ident, sizeof(ident)))
            ret = -EFAULT;
        else
            ret = 0;
        break;

    case WDIOC_GETSTATUS:
        ret = put_user(0, argp);
        break;

    case WDIOC_GETBOOTSTATUS:
        ret = put_user(boot_status, argp);
        break;

    case WDIOC_SETOPTIONS:
        if (get_user(options, (int *)arg))
            return -EFAULT;

        if (options & WDIOS_DISABLECARD) {
            if (!nowayout) {
                if (wdt_disable() == 0) {
                    set_bit(WDT_OK_TO_CLOSE, &wdt_status);
                    ret = 0;
                } else
                    ret = -ENXIO;
            } else
                ret = 0;
        }
        if (options & WDIOS_ENABLECARD) {
            wdt_enable();
            ret = 0;
        }
        break;

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

    case WDIOC_GETTIMEOUT:
        ret = put_user(iop_watchdog_timeout(), argp);
        break;
    }
    return ret;
}

static int iop_wdt_release(struct inode *inode, struct file *file)
{
    int state = 1;
    if (test_bit(WDT_OK_TO_CLOSE, &wdt_status))
        if (test_bit(WDT_ENABLED, &wdt_status))
            state = wdt_disable();

    /* if the timer is not disabled reload and notify that we are still
     * going down
     */
    if (state != 0) {
        wdt_enable();
        pr_crit("Device closed unexpectedly - reset in %lu seconds\n",
            iop_watchdog_timeout());
    }

    clear_bit(WDT_IN_USE, &wdt_status);
    clear_bit(WDT_OK_TO_CLOSE, &wdt_status);

    return 0;
}

static const struct file_operations iop_wdt_fops = {
    .owner = THIS_MODULE,
    .llseek = no_llseek,
    .write = iop_wdt_write,
    .unlocked_ioctl = iop_wdt_ioctl,
    .open = iop_wdt_open,
    .release = iop_wdt_release,
};

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

static int __init iop_wdt_init(void)
{
    int ret;

    /* check if the reset was caused by the watchdog timer */
    boot_status = (read_rcsr() & IOP_RCSR_WDT) ? WDIOF_CARDRESET : 0;

    /* Configure Watchdog Timeout to cause an Internal Bus (IB) Reset
     * NOTE: An IB Reset will Reset both cores in the IOP342
     */
    write_wdtsr(IOP13XX_WDTCR_IB_RESET);

    /* Register after we have the device set up so we cannot race
       with an open */
    ret = misc_register(&iop_wdt_miscdev);
    if (ret == 0)
        pr_info("timeout %lu sec\n", iop_watchdog_timeout());

    return ret;
}

static void __exit iop_wdt_exit(void)
{
    misc_deregister(&iop_wdt_miscdev);
}

module_init(iop_wdt_init);
module_exit(iop_wdt_exit);

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

MODULE_AUTHOR("Curt E Bruns <[email protected]>");
MODULE_DESCRIPTION("iop watchdog timer driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);