EmbeddedPkg/Library/NonCoherentDmaLib/NonCoherentDmaLib.c - third_party/edk2 - Git at Google

 /** @file

   Generic non-coherent implementation of DmaLib.h

   Copyright (c) 2008 - 2010, Apple Inc. All rights reserved.<BR>
   Copyright (c) 2015 - 2017, Linaro, Ltd. All rights reserved.<BR>

   This program and the accompanying materials are licensed and made
   available under the terms and conditions of the BSD License which
   accompanies this distribution.  The full text of the license may be
   found at http://opensource.org/licenses/bsd-license.php

   THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
   WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR
   IMPLIED.

 **/

 #include <PiDxe.h>
 #include <Library/BaseLib.h>
 #include <Library/DebugLib.h>
 #include <Library/DmaLib.h>
 #include <Library/DxeServicesTableLib.h>
 #include <Library/MemoryAllocationLib.h>
 #include <Library/UefiBootServicesTableLib.h>
 #include <Library/IoLib.h>
 #include <Library/BaseMemoryLib.h>

 #include <Protocol/Cpu.h>

 typedef struct {
   EFI_PHYSICAL_ADDRESS      HostAddress;
   VOID                      *BufferAddress;
   UINTN                     NumberOfBytes;
   DMA_MAP_OPERATION         Operation;
   BOOLEAN                   DoubleBuffer;
 } MAP_INFO_INSTANCE;


 typedef struct {
   LIST_ENTRY          Link;
   VOID                *HostAddress;
   UINTN               NumPages;
   UINT64              Attributes;
 } UNCACHED_ALLOCATION;

 STATIC EFI_CPU_ARCH_PROTOCOL      *mCpu;
 STATIC LIST_ENTRY                 UncachedAllocationList;

 STATIC
 PHYSICAL_ADDRESS
 HostToDeviceAddress (
   IN  VOID      *Address
   )
 {
   return (PHYSICAL_ADDRESS)(UINTN)Address + PcdGet64 (PcdDmaDeviceOffset);
 }

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

   Operation is relative to the DMA bus master.

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

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

 **/
 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                      Status;
   MAP_INFO_INSTANCE               *Map;
   VOID                            *Buffer;
   EFI_GCD_MEMORY_SPACE_DESCRIPTOR GcdDescriptor;
   UINTN                           AllocSize;

   if (HostAddress == NULL ||
       NumberOfBytes == NULL ||
       DeviceAddress == NULL ||
       Mapping == NULL ) {
     return EFI_INVALID_PARAMETER;
   }

   if (Operation >= MapOperationMaximum) {
     return EFI_INVALID_PARAMETER;
   }

   *DeviceAddress = HostToDeviceAddress (HostAddress);

   // Remember range so we can flush on the other side
   Map = AllocatePool (sizeof (MAP_INFO_INSTANCE));
   if (Map == NULL) {
     return  EFI_OUT_OF_RESOURCES;
   }

   if (Operation != MapOperationBusMasterRead &&
       ((((UINTN)HostAddress & (mCpu->DmaBufferAlignment - 1)) != 0) ||
        ((*NumberOfBytes & (mCpu->DmaBufferAlignment - 1)) != 0))) {

     // Get the cacheability of the region
     Status = gDS->GetMemorySpaceDescriptor ((UINTN)HostAddress, &GcdDescriptor);
     if (EFI_ERROR(Status)) {
       goto FreeMapInfo;
     }

     // If the mapped buffer is not an uncached buffer
     if ((GcdDescriptor.Attributes & (EFI_MEMORY_WB | EFI_MEMORY_WT)) != 0) {
       //
       // Operations of type MapOperationBusMasterCommonBuffer are only allowed
       // on uncached buffers.
       //
       if (Operation == MapOperationBusMasterCommonBuffer) {
         DEBUG ((DEBUG_ERROR,
           "%a: Operation type 'MapOperationBusMasterCommonBuffer' is only "
           "supported\non memory regions that were allocated using "
           "DmaAllocateBuffer ()\n", __FUNCTION__));
         Status = EFI_UNSUPPORTED;
         goto FreeMapInfo;
       }

       //
       // If the buffer does not fill entire cache lines we must double buffer
       // into a suitably aligned allocation that allows us to invalidate the
       // cache without running the risk of corrupting adjacent unrelated data.
       // Note that pool allocations are guaranteed to be 8 byte aligned, so
       // we only have to add (alignment - 8) worth of padding.
       //
       Map->DoubleBuffer = TRUE;
       AllocSize = ALIGN_VALUE (*NumberOfBytes, mCpu->DmaBufferAlignment) +
                   (mCpu->DmaBufferAlignment - 8);
       Map->BufferAddress = AllocatePool (AllocSize);
       if (Map->BufferAddress == NULL) {
         Status = EFI_OUT_OF_RESOURCES;
         goto FreeMapInfo;
       }

       Buffer = ALIGN_POINTER (Map->BufferAddress, mCpu->DmaBufferAlignment);
       *DeviceAddress = HostToDeviceAddress (Buffer);

       //
       // Get rid of any dirty cachelines covering the double buffer. This
       // prevents them from being written back unexpectedly, potentially
       // overwriting the data we receive from the device.
       //
       mCpu->FlushDataCache (mCpu, (UINTN)Buffer, *NumberOfBytes,
               EfiCpuFlushTypeWriteBack);
     } else {
       Map->DoubleBuffer  = FALSE;
     }
   } else {
     Map->DoubleBuffer  = FALSE;

     DEBUG_CODE_BEGIN ();

     //
     // The operation type check above only executes if the buffer happens to be
     // misaligned with respect to CWG, but even if it is aligned, we should not
     // allow arbitrary buffers to be used for creating consistent mappings.
     // So duplicate the check here when running in DEBUG mode, just to assert
     // that we are not trying to create a consistent mapping for cached memory.
     //
     Status = gDS->GetMemorySpaceDescriptor ((UINTN)HostAddress, &GcdDescriptor);
     ASSERT_EFI_ERROR(Status);

     ASSERT (Operation != MapOperationBusMasterCommonBuffer ||
             (GcdDescriptor.Attributes & (EFI_MEMORY_WB | EFI_MEMORY_WT)) == 0);

     DEBUG_CODE_END ();

     // Flush the Data Cache (should not have any effect if the memory region is
     // uncached)
     mCpu->FlushDataCache (mCpu, (UINTN)HostAddress, *NumberOfBytes,
             EfiCpuFlushTypeWriteBackInvalidate);
   }

   Map->HostAddress   = (UINTN)HostAddress;
   Map->NumberOfBytes = *NumberOfBytes;
   Map->Operation     = Operation;

   *Mapping = Map;

   return EFI_SUCCESS;

 FreeMapInfo:
   FreePool (Map);

   return Status;
 }


 /**
   Completes the DmaMapBusMasterRead(), DmaMapBusMasterWrite(), or
   DmaMapBusMasterCommonBuffer() operation and releases any corresponding
   resources.

   @param  Mapping               The mapping value returned from DmaMap*().

   @retval EFI_SUCCESS           The range was unmapped.
   @retval EFI_DEVICE_ERROR      The data was not committed to the target system
                                 memory.
   @retval EFI_INVALID_PARAMETER An inconsistency was detected between the
                                 mapping type and the DoubleBuffer field

 **/
 EFI_STATUS
 EFIAPI
 DmaUnmap (
   IN  VOID                         *Mapping
   )
 {
   MAP_INFO_INSTANCE *Map;
   EFI_STATUS        Status;
   VOID              *Buffer;

   if (Mapping == NULL) {
     ASSERT (FALSE);
     return EFI_INVALID_PARAMETER;
   }

   Map = (MAP_INFO_INSTANCE *)Mapping;

   Status = EFI_SUCCESS;
   if (Map->DoubleBuffer) {
     ASSERT (Map->Operation == MapOperationBusMasterWrite);

     if (Map->Operation != MapOperationBusMasterWrite) {
       Status = EFI_INVALID_PARAMETER;
     } else {
       Buffer = ALIGN_POINTER (Map->BufferAddress, mCpu->DmaBufferAlignment);

       mCpu->FlushDataCache (mCpu, (UINTN)Buffer, Map->NumberOfBytes,
               EfiCpuFlushTypeInvalidate);

       CopyMem ((VOID *)(UINTN)Map->HostAddress, Buffer, Map->NumberOfBytes);

       FreePool (Map->BufferAddress);
     }
   } else {
     if (Map->Operation == MapOperationBusMasterWrite) {
       //
       // Make sure we read buffer from uncached memory and not the cache
       //
       mCpu->FlushDataCache (mCpu, Map->HostAddress, Map->NumberOfBytes,
               EfiCpuFlushTypeInvalidate);
     }
   }

   FreePool (Map);

   return Status;
 }

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

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

   @retval EFI_SUCCESS           The requested memory pages were allocated.
   @retval EFI_INVALID_PARAMETER One or more parameters are invalid.
   @retval 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
   )
 {
   return DmaAllocateAlignedBuffer (MemoryType, Pages, 0, HostAddress);
 }

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

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

   @retval EFI_SUCCESS           The requested memory pages were allocated.
   @retval EFI_INVALID_PARAMETER One or more parameters are invalid.
   @retval EFI_OUT_OF_RESOURCES  The memory pages could not be allocated.

 **/
 EFI_STATUS
 EFIAPI
 DmaAllocateAlignedBuffer (
   IN  EFI_MEMORY_TYPE              MemoryType,
   IN  UINTN                        Pages,
   IN  UINTN                        Alignment,
   OUT VOID                         **HostAddress
   )
 {
   EFI_GCD_MEMORY_SPACE_DESCRIPTOR   GcdDescriptor;
   VOID                              *Allocation;
   UINT64                            MemType;
   UNCACHED_ALLOCATION               *Alloc;
   EFI_STATUS                        Status;

   if (Alignment == 0) {
     Alignment = EFI_PAGE_SIZE;
   }

   if (HostAddress == NULL ||
       (Alignment & (Alignment - 1)) != 0) {
     return EFI_INVALID_PARAMETER;
   }

   if (MemoryType == EfiBootServicesData) {
     Allocation = AllocateAlignedPages (Pages, Alignment);
   } else if (MemoryType == EfiRuntimeServicesData) {
     Allocation = AllocateAlignedRuntimePages (Pages, Alignment);
   } else {
     return EFI_INVALID_PARAMETER;
   }

   if (Allocation == NULL) {
     return EFI_OUT_OF_RESOURCES;
   }

   // Get the cacheability of the region
   Status = gDS->GetMemorySpaceDescriptor ((UINTN)Allocation, &GcdDescriptor);
   if (EFI_ERROR(Status)) {
     goto FreeBuffer;
   }

   // Choose a suitable uncached memory type that is supported by the region
   if (GcdDescriptor.Capabilities & EFI_MEMORY_WC) {
     MemType = EFI_MEMORY_WC;
   } else if (GcdDescriptor.Capabilities & EFI_MEMORY_UC) {
     MemType = EFI_MEMORY_UC;
   } else {
     Status = EFI_UNSUPPORTED;
     goto FreeBuffer;
   }

   Alloc = AllocatePool (sizeof *Alloc);
   if (Alloc == NULL) {
     goto FreeBuffer;
   }

   Alloc->HostAddress = Allocation;
   Alloc->NumPages = Pages;
   Alloc->Attributes = GcdDescriptor.Attributes;

   InsertHeadList (&UncachedAllocationList, &Alloc->Link);

   // Remap the region with the new attributes
   Status = gDS->SetMemorySpaceAttributes ((PHYSICAL_ADDRESS)(UINTN)Allocation,
                                           EFI_PAGES_TO_SIZE (Pages),
                                           MemType);
   if (EFI_ERROR (Status)) {
     goto FreeAlloc;
   }

   Status = mCpu->FlushDataCache (mCpu,
                                  (PHYSICAL_ADDRESS)(UINTN)Allocation,
                                  EFI_PAGES_TO_SIZE (Pages),
                                  EfiCpuFlushTypeInvalidate);
   if (EFI_ERROR (Status)) {
     goto FreeAlloc;
   }

   *HostAddress = Allocation;

   return EFI_SUCCESS;

 FreeAlloc:
   RemoveEntryList (&Alloc->Link);
   FreePool (Alloc);

 FreeBuffer:
   FreePages (Allocation, Pages);
   return Status;
 }


 /**
   Frees memory that was allocated with DmaAllocateBuffer().

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

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

 **/
 EFI_STATUS
 EFIAPI
 DmaFreeBuffer (
   IN  UINTN                        Pages,
   IN  VOID                         *HostAddress
   )
 {
   LIST_ENTRY                       *Link;
   UNCACHED_ALLOCATION              *Alloc;
   BOOLEAN                          Found;
   EFI_STATUS                       Status;

   if (HostAddress == NULL) {
      return EFI_INVALID_PARAMETER;
   }

   for (Link = GetFirstNode (&UncachedAllocationList), Found = FALSE;
        !IsNull (&UncachedAllocationList, Link);
        Link = GetNextNode (&UncachedAllocationList, Link)) {

     Alloc = BASE_CR (Link, UNCACHED_ALLOCATION, Link);
     if (Alloc->HostAddress == HostAddress && Alloc->NumPages == Pages) {
       Found = TRUE;
       break;
     }
   }

   if (!Found) {
     ASSERT (FALSE);
     return EFI_INVALID_PARAMETER;
   }

   RemoveEntryList (&Alloc->Link);

   Status = gDS->SetMemorySpaceAttributes ((PHYSICAL_ADDRESS)(UINTN)HostAddress,
                                           EFI_PAGES_TO_SIZE (Pages),
                                           Alloc->Attributes);
   if (EFI_ERROR (Status)) {
     goto FreeAlloc;
   }

   //
   // If we fail to restore the original attributes, it is better to leak the
   // memory than to return it to the heap
   //
   FreePages (HostAddress, Pages);

 FreeAlloc:
   FreePool (Alloc);
   return Status;
 }


 EFI_STATUS
 EFIAPI
 NonCoherentDmaLibConstructor (
   IN EFI_HANDLE       ImageHandle,
   IN EFI_SYSTEM_TABLE *SystemTable
   )
 {
   InitializeListHead (&UncachedAllocationList);

   // Get the Cpu protocol for later use
   return gBS->LocateProtocol (&gEfiCpuArchProtocolGuid, NULL, (VOID **)&mCpu);
 }
	/** @file

	Generic non-coherent implementation of DmaLib.h

	Copyright (c) 2008 - 2010, Apple Inc. All rights reserved.<BR>
	Copyright (c) 2015 - 2017, Linaro, Ltd. All rights reserved.<BR>

	This program and the accompanying materials are licensed and made
	available under the terms and conditions of the BSD License which
	accompanies this distribution. The full text of the license may be
	found at http://opensource.org/licenses/bsd-license.php

	THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
	WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR
	IMPLIED.

	**/

	#include <PiDxe.h>
	#include <Library/BaseLib.h>
	#include <Library/DebugLib.h>
	#include <Library/DmaLib.h>
	#include <Library/DxeServicesTableLib.h>
	#include <Library/MemoryAllocationLib.h>
	#include <Library/UefiBootServicesTableLib.h>
	#include <Library/IoLib.h>
	#include <Library/BaseMemoryLib.h>

	#include <Protocol/Cpu.h>

	typedef struct {
	EFI_PHYSICAL_ADDRESS HostAddress;
	VOID *BufferAddress;
	UINTN NumberOfBytes;
	DMA_MAP_OPERATION Operation;
	BOOLEAN DoubleBuffer;
	} MAP_INFO_INSTANCE;


	typedef struct {
	LIST_ENTRY Link;
	VOID *HostAddress;
	UINTN NumPages;
	UINT64 Attributes;
	} UNCACHED_ALLOCATION;

	STATIC EFI_CPU_ARCH_PROTOCOL *mCpu;
	STATIC LIST_ENTRY UncachedAllocationList;

	STATIC
	PHYSICAL_ADDRESS
	HostToDeviceAddress (
	IN VOID *Address
	)
	{
	return (PHYSICAL_ADDRESS)(UINTN)Address + PcdGet64 (PcdDmaDeviceOffset);
	}

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

	Operation is relative to the DMA bus master.

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

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

	**/
	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 Status;
	MAP_INFO_INSTANCE *Map;
	VOID *Buffer;
	EFI_GCD_MEMORY_SPACE_DESCRIPTOR GcdDescriptor;
	UINTN AllocSize;

	if (HostAddress == NULL \|\|
	NumberOfBytes == NULL \|\|
	DeviceAddress == NULL \|\|
	Mapping == NULL ) {
	return EFI_INVALID_PARAMETER;
	}

	if (Operation >= MapOperationMaximum) {
	return EFI_INVALID_PARAMETER;
	}

	*DeviceAddress = HostToDeviceAddress (HostAddress);

	// Remember range so we can flush on the other side
	Map = AllocatePool (sizeof (MAP_INFO_INSTANCE));
	if (Map == NULL) {
	return EFI_OUT_OF_RESOURCES;
	}

	if (Operation != MapOperationBusMasterRead &&
	((((UINTN)HostAddress & (mCpu->DmaBufferAlignment - 1)) != 0) \|\|
	((*NumberOfBytes & (mCpu->DmaBufferAlignment - 1)) != 0))) {

	// Get the cacheability of the region
	Status = gDS->GetMemorySpaceDescriptor ((UINTN)HostAddress, &GcdDescriptor);
	if (EFI_ERROR(Status)) {
	goto FreeMapInfo;
	}

	// If the mapped buffer is not an uncached buffer
	if ((GcdDescriptor.Attributes & (EFI_MEMORY_WB \| EFI_MEMORY_WT)) != 0) {
	//
	// Operations of type MapOperationBusMasterCommonBuffer are only allowed
	// on uncached buffers.
	//
	if (Operation == MapOperationBusMasterCommonBuffer) {
	DEBUG ((DEBUG_ERROR,
	"%a: Operation type 'MapOperationBusMasterCommonBuffer' is only "
	"supported\non memory regions that were allocated using "
	"DmaAllocateBuffer ()\n", __FUNCTION__));
	Status = EFI_UNSUPPORTED;
	goto FreeMapInfo;
	}

	//
	// If the buffer does not fill entire cache lines we must double buffer
	// into a suitably aligned allocation that allows us to invalidate the
	// cache without running the risk of corrupting adjacent unrelated data.
	// Note that pool allocations are guaranteed to be 8 byte aligned, so
	// we only have to add (alignment - 8) worth of padding.
	//
	Map->DoubleBuffer = TRUE;
	AllocSize = ALIGN_VALUE (*NumberOfBytes, mCpu->DmaBufferAlignment) +
	(mCpu->DmaBufferAlignment - 8);
	Map->BufferAddress = AllocatePool (AllocSize);
	if (Map->BufferAddress == NULL) {
	Status = EFI_OUT_OF_RESOURCES;
	goto FreeMapInfo;
	}

	Buffer = ALIGN_POINTER (Map->BufferAddress, mCpu->DmaBufferAlignment);
	*DeviceAddress = HostToDeviceAddress (Buffer);

	//
	// Get rid of any dirty cachelines covering the double buffer. This
	// prevents them from being written back unexpectedly, potentially
	// overwriting the data we receive from the device.
	//
	mCpu->FlushDataCache (mCpu, (UINTN)Buffer, *NumberOfBytes,
	EfiCpuFlushTypeWriteBack);
	} else {
	Map->DoubleBuffer = FALSE;
	}
	} else {
	Map->DoubleBuffer = FALSE;

	DEBUG_CODE_BEGIN ();

	//
	// The operation type check above only executes if the buffer happens to be
	// misaligned with respect to CWG, but even if it is aligned, we should not
	// allow arbitrary buffers to be used for creating consistent mappings.
	// So duplicate the check here when running in DEBUG mode, just to assert
	// that we are not trying to create a consistent mapping for cached memory.
	//
	Status = gDS->GetMemorySpaceDescriptor ((UINTN)HostAddress, &GcdDescriptor);
	ASSERT_EFI_ERROR(Status);

	ASSERT (Operation != MapOperationBusMasterCommonBuffer \|\|
	(GcdDescriptor.Attributes & (EFI_MEMORY_WB \| EFI_MEMORY_WT)) == 0);

	DEBUG_CODE_END ();

	// Flush the Data Cache (should not have any effect if the memory region is
	// uncached)
	mCpu->FlushDataCache (mCpu, (UINTN)HostAddress, *NumberOfBytes,
	EfiCpuFlushTypeWriteBackInvalidate);
	}

	Map->HostAddress = (UINTN)HostAddress;
	Map->NumberOfBytes = *NumberOfBytes;
	Map->Operation = Operation;

	*Mapping = Map;

	return EFI_SUCCESS;

	FreeMapInfo:
	FreePool (Map);

	return Status;
	}


	/**
	Completes the DmaMapBusMasterRead(), DmaMapBusMasterWrite(), or
	DmaMapBusMasterCommonBuffer() operation and releases any corresponding
	resources.

	@param Mapping The mapping value returned from DmaMap*().

	@retval EFI_SUCCESS The range was unmapped.
	@retval EFI_DEVICE_ERROR The data was not committed to the target system
	memory.
	@retval EFI_INVALID_PARAMETER An inconsistency was detected between the
	mapping type and the DoubleBuffer field

	**/
	EFI_STATUS
	EFIAPI
	DmaUnmap (
	IN VOID *Mapping
	)
	{
	MAP_INFO_INSTANCE *Map;
	EFI_STATUS Status;
	VOID *Buffer;

	if (Mapping == NULL) {
	ASSERT (FALSE);
	return EFI_INVALID_PARAMETER;
	}

	Map = (MAP_INFO_INSTANCE *)Mapping;

	Status = EFI_SUCCESS;
	if (Map->DoubleBuffer) {
	ASSERT (Map->Operation == MapOperationBusMasterWrite);

	if (Map->Operation != MapOperationBusMasterWrite) {
	Status = EFI_INVALID_PARAMETER;
	} else {
	Buffer = ALIGN_POINTER (Map->BufferAddress, mCpu->DmaBufferAlignment);

	mCpu->FlushDataCache (mCpu, (UINTN)Buffer, Map->NumberOfBytes,
	EfiCpuFlushTypeInvalidate);

	CopyMem ((VOID *)(UINTN)Map->HostAddress, Buffer, Map->NumberOfBytes);

	FreePool (Map->BufferAddress);
	}
	} else {
	if (Map->Operation == MapOperationBusMasterWrite) {
	//
	// Make sure we read buffer from uncached memory and not the cache
	//
	mCpu->FlushDataCache (mCpu, Map->HostAddress, Map->NumberOfBytes,
	EfiCpuFlushTypeInvalidate);
	}
	}

	FreePool (Map);

	return Status;
	}

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

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

	@retval EFI_SUCCESS The requested memory pages were allocated.
	@retval EFI_INVALID_PARAMETER One or more parameters are invalid.
	@retval 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
	)
	{
	return DmaAllocateAlignedBuffer (MemoryType, Pages, 0, HostAddress);
	}

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

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

	@retval EFI_SUCCESS The requested memory pages were allocated.
	@retval EFI_INVALID_PARAMETER One or more parameters are invalid.
	@retval EFI_OUT_OF_RESOURCES The memory pages could not be allocated.

	**/
	EFI_STATUS
	EFIAPI
	DmaAllocateAlignedBuffer (
	IN EFI_MEMORY_TYPE MemoryType,
	IN UINTN Pages,
	IN UINTN Alignment,
	OUT VOID **HostAddress
	)
	{
	EFI_GCD_MEMORY_SPACE_DESCRIPTOR GcdDescriptor;
	VOID *Allocation;
	UINT64 MemType;
	UNCACHED_ALLOCATION *Alloc;
	EFI_STATUS Status;

	if (Alignment == 0) {
	Alignment = EFI_PAGE_SIZE;
	}

	if (HostAddress == NULL \|\|
	(Alignment & (Alignment - 1)) != 0) {
	return EFI_INVALID_PARAMETER;
	}

	if (MemoryType == EfiBootServicesData) {
	Allocation = AllocateAlignedPages (Pages, Alignment);
	} else if (MemoryType == EfiRuntimeServicesData) {
	Allocation = AllocateAlignedRuntimePages (Pages, Alignment);
	} else {
	return EFI_INVALID_PARAMETER;
	}

	if (Allocation == NULL) {
	return EFI_OUT_OF_RESOURCES;
	}

	// Get the cacheability of the region
	Status = gDS->GetMemorySpaceDescriptor ((UINTN)Allocation, &GcdDescriptor);
	if (EFI_ERROR(Status)) {
	goto FreeBuffer;
	}

	// Choose a suitable uncached memory type that is supported by the region
	if (GcdDescriptor.Capabilities & EFI_MEMORY_WC) {
	MemType = EFI_MEMORY_WC;
	} else if (GcdDescriptor.Capabilities & EFI_MEMORY_UC) {
	MemType = EFI_MEMORY_UC;
	} else {
	Status = EFI_UNSUPPORTED;
	goto FreeBuffer;
	}

	Alloc = AllocatePool (sizeof *Alloc);
	if (Alloc == NULL) {
	goto FreeBuffer;
	}

	Alloc->HostAddress = Allocation;
	Alloc->NumPages = Pages;
	Alloc->Attributes = GcdDescriptor.Attributes;

	InsertHeadList (&UncachedAllocationList, &Alloc->Link);

	// Remap the region with the new attributes
	Status = gDS->SetMemorySpaceAttributes ((PHYSICAL_ADDRESS)(UINTN)Allocation,
	EFI_PAGES_TO_SIZE (Pages),
	MemType);
	if (EFI_ERROR (Status)) {
	goto FreeAlloc;
	}

	Status = mCpu->FlushDataCache (mCpu,
	(PHYSICAL_ADDRESS)(UINTN)Allocation,
	EFI_PAGES_TO_SIZE (Pages),
	EfiCpuFlushTypeInvalidate);
	if (EFI_ERROR (Status)) {
	goto FreeAlloc;
	}

	*HostAddress = Allocation;

	return EFI_SUCCESS;

	FreeAlloc:
	RemoveEntryList (&Alloc->Link);
	FreePool (Alloc);

	FreeBuffer:
	FreePages (Allocation, Pages);
	return Status;
	}


	/**
	Frees memory that was allocated with DmaAllocateBuffer().

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

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

	**/
	EFI_STATUS
	EFIAPI
	DmaFreeBuffer (
	IN UINTN Pages,
	IN VOID *HostAddress
	)
	{
	LIST_ENTRY *Link;
	UNCACHED_ALLOCATION *Alloc;
	BOOLEAN Found;
	EFI_STATUS Status;

	if (HostAddress == NULL) {
	return EFI_INVALID_PARAMETER;
	}

	for (Link = GetFirstNode (&UncachedAllocationList), Found = FALSE;
	!IsNull (&UncachedAllocationList, Link);
	Link = GetNextNode (&UncachedAllocationList, Link)) {

	Alloc = BASE_CR (Link, UNCACHED_ALLOCATION, Link);
	if (Alloc->HostAddress == HostAddress && Alloc->NumPages == Pages) {
	Found = TRUE;
	break;
	}
	}

	if (!Found) {
	ASSERT (FALSE);
	return EFI_INVALID_PARAMETER;
	}

	RemoveEntryList (&Alloc->Link);

	Status = gDS->SetMemorySpaceAttributes ((PHYSICAL_ADDRESS)(UINTN)HostAddress,
	EFI_PAGES_TO_SIZE (Pages),
	Alloc->Attributes);
	if (EFI_ERROR (Status)) {
	goto FreeAlloc;
	}

	//
	// If we fail to restore the original attributes, it is better to leak the
	// memory than to return it to the heap
	//
	FreePages (HostAddress, Pages);

	FreeAlloc:
	FreePool (Alloc);
	return Status;
	}


	EFI_STATUS
	EFIAPI
	NonCoherentDmaLibConstructor (
	IN EFI_HANDLE ImageHandle,
	IN EFI_SYSTEM_TABLE *SystemTable
	)
	{
	InitializeListHead (&UncachedAllocationList);

	// Get the Cpu protocol for later use
	return gBS->LocateProtocol (&gEfiCpuArchProtocolGuid, NULL, (VOID **)&mCpu);
	}