This is xnu-8019. See this file in:
/*
 * Copyright (c) 2020 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,
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 */

#if !__IIG
#if KERNEL
#include <IOKit/IODMACommand.h>
#endif
#endif

#ifndef _IOKIT_UIODMACOMMMAND_H
#define _IOKIT_UIODMACOMMMAND_H

#include <DriverKit/IOMemoryDescriptor.iig>
#include <DriverKit/IOService.iig>

// IODMACommand Create options
enum {
	kIODMACommandCreateNoOptions = 0,
};

// IODMACommand PrepareForDMA options
enum {
	kIODMACommandPrepareForDMANoOptions = 0,
};

// IODMACommand CompleteDMA options
enum {
	kIODMACommandCompleteDMANoOptions = 0,
};

// IODMACommand PerformOperation options
enum {
	kIODMACommandPerformOperationOptionRead  = 0x00000001,
	kIODMACommandPerformOperationOptionWrite = 0x00000002,
	kIODMACommandPerformOperationOptionZero  = 0x00000004,
};

// IODMACommandSpecification options
enum {
	kIODMACommandSpecificationNoOptions = 0,
};

struct IODMACommandSpecification {
	uint64_t options;
	uint64_t maxAddressBits;
	uint64_t _resv[16];
};

/*!
 * @class IODMACommand
 *
 * @abstract
 * IODMACommand allows a mapping for DMA to be created from an IOMemoryDescriptor. 
 *
 * @discussion
 * IODMACommand allows a mapping for DMA to be created from an IOMemoryDescriptor. 
 * The IODMACommand instance represents the mapping and should be kept prepared for the
 * duration of the I/O, and completed when the I/O is finished.
 * IODMACommand does not perform bounce buffering but allows access to the mapping with
 * the PerformOperation method so that data can moved into and out of the mapping, eg.
 * to/from a driver allocated bounce buffer.
 *
*/

class KERNEL IODMACommand : public OSObject
{
public:

	virtual bool
	init() override;

	virtual void
	free() override;

    /*!
     * @brief       Create an IODMACommand instance.
	 * @param       device The device (typically an IOPCIDevice instance that will be
	 *              generating the I/O.
     * @param       options
	 *              kIODMACommandCreateNoOptions No options needed
     * @param       specification A caller initialized structure describing
     *              the hardware's DMA capaibilities
	 * @param       command Returned IODMACommand object with +1 retain count. 
	 *              It should be retained until the map is no longer required.
     * @return      kIOReturnSuccess on success. See IOReturn.h for error codes.
     */
	static kern_return_t
	Create(
		IOService * device,
		uint64_t options,
		const IODMACommandSpecification * specification,
		IODMACommand ** command);

    /*!
     * @brief       Create a DMA mapping for memory.
     * @param       options
	 *              kIODMACommandPrepareForDMANoOptions No options needed.
	 * @param       memory IOMemoryDescriptor for memory.
	 * @param       offset Start offset of the DMA operation in the descriptor.
	 * @param       length Pass zero to map the entire memory, or a value <= the length of the descriptor.
	 * @param       flags Returned bit mask of flags 
					kIOMemoryDirectionOut the memory is readable
					kIOMemoryDirectionIn the memory is writable
	 * @param       segmentsCount In/out parameter - size of segments array on input,
					and number of valid segments returned
	 * @param       segments Returned DMA physical address and length segments covering the DMA
     * @return      kIOReturnSuccess on success. See IOReturn.h for error codes.
     */
	virtual kern_return_t
	PrepareForDMA(
		uint64_t options,
		IOMemoryDescriptor * memory,
		uint64_t offset,
		uint64_t length,
		uint64_t * flags,
		uint32_t * segmentsCount,
		IOAddressSegment segments[32]);

    /*!
     * @brief       Release a DMA mapping for memory.
     * @param       options
	 *              kIODMACommandCompleteDMANoOptions No options needed.
     * @return      kIOReturnSuccess on success. See IOReturn.h for error codes.
     */
	virtual kern_return_t
	CompleteDMA(
		uint64_t options);

    /*!
     * @brief       Obtain the parameters of a DMA preparation.
     * @param       offset Returned starting offset of the preparation.
     * @param       length Returned length of the preparation.
     * @param       memory Returned IOMemoryDescriptor of the preparation. This should be
     *              released by the caller.
     * @return      kIOReturnSuccess on success. See IOReturn.h for error codes.
     */
	virtual kern_return_t
	GetPreparation(
		uint64_t * offset,
		uint64_t * length,
		IOMemoryDescriptor ** memory);

    /*!
     * @brief       Perform CPU access to the DMA mapping.
	 * @param       options Flags for the operation to be performed
					kIODMACommandPerformOperationOptionRead read from the DMA mapping to
					the memory specified with the data param
					kIODMACommandPerformOperationOptionWrite write to the DMA mapping from
					the memory specified with the data param
					kIODMACommandPerformOperationOptionZero zero the DMA mapping
     * @param       dmaOffset Offset into the DMA mapping for the operation to begin.
     * @param       length Length of the operation.
     * @param       dataffset Offset into the memory specified with the data param
     * @param       data Callers buffer to read into or write from. Pass NULL when 
     *              using kIODMACommandPerformOperationOptionZero.
     * @return      kIOReturnSuccess on success. See IOReturn.h for error codes.
     */
	virtual kern_return_t
	PerformOperation(
		uint64_t options,
		uint64_t dmaOffset,
		uint64_t length,
		uint64_t dataOffset,
		IOMemoryDescriptor * data);
};

#endif /* ! _IOKIT_UIODMACOMMMAND_H */