This is xnu-8019. See this file in:
/*
 * Copyright (c) 1998-2016 Apple 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@
 */

#ifndef __IOKIT_IOMAPPER_H
#define __IOKIT_IOMAPPER_H

#include <sys/cdefs.h>

__BEGIN_DECLS
#include <IOKit/IOTypes.h>
#include <mach/vm_types.h>

// These are C accessors to the system mapper for non-IOKit clients
ppnum_t IOMapperIOVMAlloc(unsigned pages);
void IOMapperIOVMFree(ppnum_t addr, unsigned pages);
ppnum_t IOMapperInsertPage(ppnum_t addr, unsigned offset, ppnum_t page);

__END_DECLS

#if __cplusplus

#include <IOKit/IOService.h>
#include <IOKit/IOMemoryDescriptor.h>
#include <IOKit/IODMACommand.h>
#include <libkern/c++/OSPtr.h>

class OSData;

extern const OSSymbol * gIOMapperIDKey;

class IOMapper : public IOService
{
	OSDeclareAbstractStructors(IOMapper);

// Give the platform expert access to setMapperRequired();
	friend class IOPlatformExpert;
	friend class IOMemoryDescriptor;
	friend class IOGeneralMemoryDescriptor;

private:
	enum SystemMapperState {
		kNoMapper  = 0,
		kUnknown   = 1,
		kHasMapper = 2, // Any other value is pointer to a live mapper
		kWaitMask  = 3,
	};
protected:
#ifdef XNU_KERNEL_PRIVATE
	uint64_t   __reservedA[6];
	kern_allocation_name_t fAllocName;
	uint32_t   __reservedB;
	uint32_t   fPageSize;
#else
	uint64_t __reserved[8];
#endif
	bool fIsSystem;

	static void setMapperRequired(bool hasMapper);
	static void waitForSystemMapper();

	virtual bool initHardware(IOService *provider) = 0;

public:
	virtual bool start(IOService *provider) APPLE_KEXT_OVERRIDE;
	virtual void free() APPLE_KEXT_OVERRIDE;

// To get access to the system mapper IOMapper::gSystem
	static IOMapper *gSystem;

	static void
	checkForSystemMapper()
	{
		if ((uintptr_t) gSystem & kWaitMask) {
			waitForSystemMapper();
		}
	}

	static OSPtr<IOMapper>  copyMapperForDevice(IOService * device);
	static OSPtr<IOMapper>  copyMapperForDeviceWithIndex(IOService * device, unsigned int index);

// { subclasses

	virtual uint64_t getPageSize(void) const = 0;

	virtual IOReturn iovmMapMemory(IOMemoryDescriptor          * memory,
	    uint64_t                      descriptorOffset,
	    uint64_t                      length,
	    uint32_t                      mapOptions,
	    const IODMAMapSpecification * mapSpecification,
	    IODMACommand                * dmaCommand,
	    const IODMAMapPageList      * pageList,
	    uint64_t                    * mapAddress,
	    uint64_t                    * mapLength) = 0;

	virtual IOReturn iovmUnmapMemory(IOMemoryDescriptor * memory,
	    IODMACommand       * dmaCommand,
	    uint64_t             mapAddress,
	    uint64_t             mapLength) = 0;

	virtual IOReturn iovmInsert(uint32_t options,
	    uint64_t mapAddress,
	    uint64_t offset,
	    uint64_t physicalAddress,
	    uint64_t length) = 0;

	virtual uint64_t mapToPhysicalAddress(uint64_t mappedAddress) = 0;

// }

private:
	OSMetaClassDeclareReservedUnused(IOMapper, 0);
	OSMetaClassDeclareReservedUnused(IOMapper, 1);
	OSMetaClassDeclareReservedUnused(IOMapper, 2);
	OSMetaClassDeclareReservedUnused(IOMapper, 3);
	OSMetaClassDeclareReservedUnused(IOMapper, 4);
	OSMetaClassDeclareReservedUnused(IOMapper, 5);
	OSMetaClassDeclareReservedUnused(IOMapper, 6);
	OSMetaClassDeclareReservedUnused(IOMapper, 7);
	OSMetaClassDeclareReservedUnused(IOMapper, 8);
	OSMetaClassDeclareReservedUnused(IOMapper, 9);
	OSMetaClassDeclareReservedUnused(IOMapper, 10);
	OSMetaClassDeclareReservedUnused(IOMapper, 11);
	OSMetaClassDeclareReservedUnused(IOMapper, 12);
	OSMetaClassDeclareReservedUnused(IOMapper, 13);
	OSMetaClassDeclareReservedUnused(IOMapper, 14);
	OSMetaClassDeclareReservedUnused(IOMapper, 15);
};

#endif /* __cplusplus */

#endif /* !__IOKIT_IOMAPPER_H */