DmaLib.h File Reference

Enumerations
enum	DMA_MAP_OPERATION { MapOperationBusMasterRead, MapOperationBusMasterWrite, MapOperationBusMasterCommonBuffer, MapOperationMaximum }

Functions
EFI_STATUS EFIAPI	DmaMap (IN DMA_MAP_OPERATION Operation, IN VOID *HostAddress, IN OUT UINTN *NumberOfBytes, OUT PHYSICAL_ADDRESS *DeviceAddress, OUT VOID **Mapping)
EFI_STATUS EFIAPI	DmaUnmap (IN VOID *Mapping)
EFI_STATUS EFIAPI	DmaAllocateBuffer (IN EFI_MEMORY_TYPE MemoryType, IN UINTN Pages, OUT VOID **HostAddress)
EFI_STATUS EFIAPI	DmaFreeBuffer (IN UINTN Pages, IN VOID *HostAddress)
EFI_STATUS EFIAPI	DmaAllocateAlignedBuffer (IN EFI_MEMORY_TYPE MemoryType, IN UINTN Pages, IN UINTN Alignment, OUT VOID **HostAddress)

Detailed Description

DMA abstraction library APIs. Based on UEFI PCI IO protocol DMA abstractions. At some point these functions will probably end up in a non PCI protocol for embedded systems.

DMA Bus Master Read Operation: Call DmaMap() for MapOperationBusMasterRead. Program the DMA Bus Master with the DeviceAddress returned by DmaMap(). Start the DMA Bus Master. Wait for DMA Bus Master to complete the read operation. Call DmaUnmap().

DMA Bus Master Write Operation: Call DmaMap() for MapOperationBusMasterWrite. Program the DMA Bus Master with the DeviceAddress returned by DmaMap(). Start the DMA Bus Master. Wait for DMA Bus Master to complete the write operation. Call DmaUnmap().

DMA Bus Master Common Buffer Operation: Call DmaAllocateBuffer() to allocate a common buffer. Call DmaMap() for MapOperationBusMasterCommonBuffer. Program the DMA Bus Master with the DeviceAddress returned by DmaMap(). The common buffer can now be accessed equally by the processor and the DMA bus master. Call DmaUnmap(). Call DmaFreeBuffer().

Copyright (c) 2008 - 2010, Apple Inc. All rights reserved.

SPDX-License-Identifier: BSD-2-Clause-Patent

Enumeration Type Documentation

enum DMA_MAP_OPERATION

Enumerator
MapOperationBusMasterRead	A read operation from system memory by a bus master.
MapOperationBusMasterWrite	A write operation from system memory by a bus master.
MapOperationBusMasterCommonBuffer	Provides both read and write access to system memory by both the processor and a bus master. The buffer is coherent from both the processor's and the bus master's point of view.
MapOperationMaximum

Function Documentation

EFI_STATUS EFIAPI DmaAllocateAlignedBuffer	(	IN EFI_MEMORY_TYPE	MemoryType,
		IN UINTN	Pages,
		IN UINTN	Alignment,
		OUT VOID **	HostAddress
	)

Allocates pages that are suitable for an DmaMap() of type MapOperationBusMasterCommonBuffer mapping, at the requested alignment.

Parameters

MemoryType	The type of memory to allocate, EfiBootServicesData or EfiRuntimeServicesData.
Pages	The number of pages to allocate.
Alignment	Alignment in bytes of the base of the returned buffer (must be a power of 2)
HostAddress	A pointer to store the base system memory address of the allocated range.

Return values

EFI_SUCCESS	The requested memory pages were allocated.
EFI_UNSUPPORTED	Attributes is unsupported. The only legal attribute bits are MEMORY_WRITE_COMBINE and MEMORY_CACHED.
EFI_INVALID_PARAMETER	One or more parameters are invalid.
EFI_OUT_OF_RESOURCES	The memory pages could not be allocated.

EFI_STATUS EFIAPI DmaAllocateBuffer	(	IN EFI_MEMORY_TYPE	MemoryType,
		IN UINTN	Pages,
		OUT VOID **	HostAddress
	)

Allocates pages that are suitable for an DmaMap() of type MapOperationBusMasterCommonBuffer. mapping.

Parameters

MemoryType	The type of memory to allocate, EfiBootServicesData or EfiRuntimeServicesData.
Pages	The number of pages to allocate.
HostAddress	A pointer to store the base system memory address of the allocated range.

Return values

EFI_SUCCESS	The requested memory pages were allocated.
EFI_UNSUPPORTED	Attributes is unsupported. The only legal attribute bits are MEMORY_WRITE_COMBINE and MEMORY_CACHED.
EFI_INVALID_PARAMETER	One or more parameters are invalid.
EFI_OUT_OF_RESOURCES	The memory pages could not be allocated.

EFI_STATUS EFIAPI DmaFreeBuffer	(	IN UINTN	Pages,
		IN VOID *	HostAddress
	)

Frees memory that was allocated with DmaAllocateBuffer().

Parameters

Pages	The number of pages to free.
HostAddress	The base system memory address of the allocated range.

Return values

EFI_SUCCESS	The requested memory pages were freed.
EFI_INVALID_PARAMETER	The memory range specified by HostAddress and Pages was not allocated with DmaAllocateBuffer().

EFI_STATUS EFIAPI DmaMap	(	IN DMA_MAP_OPERATION	Operation,
		IN VOID *	HostAddress,
		IN OUT UINTN *	NumberOfBytes,
		OUT PHYSICAL_ADDRESS *	DeviceAddress,
		OUT VOID **	Mapping
	)

Provides the DMA controller-specific addresses needed to access system memory.

Operation is relative to the DMA bus master.

Parameters

Operation	Indicates if the bus master is going to read or write to system memory.
HostAddress	The system memory address to map to the DMA controller.
NumberOfBytes	On input the number of bytes to map. On output the number of bytes that were mapped.
DeviceAddress	The resulting map address for the bus master controller to use to access the hosts HostAddress.
Mapping	A resulting value to pass to DmaUnmap().

Return values

EFI_SUCCESS	The range was mapped for the returned NumberOfBytes.
EFI_UNSUPPORTED	The HostAddress cannot be mapped as a common buffer.
EFI_INVALID_PARAMETER	One or more parameters are invalid.
EFI_OUT_OF_RESOURCES	The request could not be completed due to a lack of resources.
EFI_DEVICE_ERROR	The system hardware could not map the requested address.

EFI_STATUS EFIAPI DmaUnmap

(

IN VOID *

Mapping

)

Completes the DmaMapBusMasterRead, DmaMapBusMasterWrite, or DmaMapBusMasterCommonBuffer operation and releases any corresponding resources.

Parameters

Mapping

The mapping value returned from DmaMap().

Return values

EFI_SUCCESS	The range was unmapped.
EFI_DEVICE_ERROR	The data was not committed to the target system memory.