linux-imx

/*

 *  Xen Watchdog Driver

 *

 *  (c) Copyright 2010 Novell, Inc.

 *

 *  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.

 */

​

#define DRV_NAME    "xen_wdt"

​

#include <linux/bug.h>

#include <linux/errno.h>

#include <linux/fs.h>

#include <linux/hrtimer.h>

#include <linux/kernel.h>

#include <linux/ktime.h>

#include <linux/init.h>

#include <linux/module.h>

#include <linux/moduleparam.h>

#include <linux/platform_device.h>

#include <linux/watchdog.h>

#include <xen/xen.h>

#include <asm/xen/hypercall.h>

#include <xen/interface/sched.h>

​

static struct platform_device *platform_device;

static struct sched_watchdog wdt;

static time64_t wdt_expires;

​

#define WATCHDOG_TIMEOUT 60 /* in seconds */

static unsigned int timeout;

module_param(timeout, uint, S_IRUGO);

MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds "

    "(default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ")");

​

static bool nowayout = WATCHDOG_NOWAYOUT;

module_param(nowayout, bool, S_IRUGO);

MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "

    "(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");

​

static inline time64_t set_timeout(struct watchdog_device *wdd)

{

    wdt.timeout = wdd->timeout;

    return ktime_get_seconds() + wdd->timeout;

}

​

static int xen_wdt_start(struct watchdog_device *wdd)

{

    time64_t expires;

    int err;

​

    expires = set_timeout(wdd);

    if (!wdt.id)

        err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);

    else

        err = -EBUSY;

    if (err > 0) {

        wdt.id = err;

        wdt_expires = expires;

        err = 0;

    } else

        BUG_ON(!err);

​

    return err;

}

​

static int xen_wdt_stop(struct watchdog_device *wdd)

{

    int err = 0;

​

    wdt.timeout = 0;

    if (wdt.id)

        err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);

    if (!err)

        wdt.id = 0;

​

    return err;

}

​

static int xen_wdt_kick(struct watchdog_device *wdd)

{

    time64_t expires;

    int err;

​

    expires = set_timeout(wdd);

    if (wdt.id)

        err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);

    else

        err = -ENXIO;