This is xnu-11215.1.10. See this file in: 
/*
 * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 *
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 *
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 *
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */

#include <IOKit/IOUserClient.h>
#include <IOKit/IOMessage.h>
#include <IOKit/system_management/IOWatchDogTimer.h>
#include <IOKit/pwr_mgt/RootDomain.h>


static IOReturn IOWatchDogTimerSleepHandler(void *target, void *refCon,
    UInt32 messageType,
    IOService *provider,
    void *messageArgument,
    vm_size_t argSize);


#define kWatchDogEnabledProperty     "IOWatchDogEnabled"


#define super IOService

OSDefineMetaClassAndAbstractStructors(IOWatchDogTimer, IOService);

OSMetaClassDefineReservedUnused(IOWatchDogTimer, 0);
OSMetaClassDefineReservedUnused(IOWatchDogTimer, 1);
OSMetaClassDefineReservedUnused(IOWatchDogTimer, 2);
OSMetaClassDefineReservedUnused(IOWatchDogTimer, 3);

bool
IOWatchDogTimer::start(IOService *provider)
{
	if (!super::start(provider)) {
		return false;
	}

	notifier = registerSleepWakeInterest(IOWatchDogTimerSleepHandler, this);
	if (notifier == NULL) {
		return false;
	}

	setProperty(kWatchDogEnabledProperty, kOSBooleanFalse);
	setWatchDogTimer(0);

	registerService();

	return true;
}

void
IOWatchDogTimer::stop(IOService *provider)
{
	setWatchDogTimer(0);
	notifier->remove();
}

IOReturn
IOWatchDogTimer::setProperties(OSObject *properties)
{
	OSNumber *theNumber;
	UInt32   theValue;
	IOReturn result;

	result = IOUserClient::clientHasPrivilege(current_task(),
	    kIOClientPrivilegeAdministrator);
	if (result != kIOReturnSuccess) {
		return kIOReturnNotPrivileged;
	}

	theNumber = OSDynamicCast(OSNumber, properties);
	if (theNumber == NULL) {
		return kIOReturnBadArgument;
	}

	theValue = theNumber->unsigned32BitValue();
	if (theValue == 0) {
		setProperty(kWatchDogEnabledProperty, kOSBooleanFalse);
	} else {
		setProperty(kWatchDogEnabledProperty, kOSBooleanTrue);
	}

	setWatchDogTimer(theValue);

	return kIOReturnSuccess;
}

static IOReturn
IOWatchDogTimerSleepHandler(void *target, void */*refCon*/,
    UInt32 messageType,
    IOService */*provider*/,
    void *messageArgument,
    vm_size_t /*argSize*/)
{
	IOWatchDogTimer *watchDogTimer = (IOWatchDogTimer *)target;
	sleepWakeNote *swNote = (sleepWakeNote *)messageArgument;

	if (messageType != kIOMessageSystemWillSleep) {
		return kIOReturnUnsupported;
	}

	watchDogTimer->setProperty(kWatchDogEnabledProperty, kOSBooleanFalse);
	watchDogTimer->setWatchDogTimer(0);

	swNote->returnValue = 0;
	acknowledgeSleepWakeNotification(swNote->powerRef);

	return kIOReturnSuccess;
}