/*++
Copyright (c) 2006 - 2012, Intel Corporation. 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.
Module Name:
DeviceIo.c
Abstract:
EFI PC-AT PCI Device IO driver
--*/
#include "PcatPciRootBridge.h"
#include "DeviceIo.h"
EFI_STATUS
DeviceIoConstructor (
IN EFI_HANDLE Handle,
IN EFI_PCI_ROOT_BRIDGE_IO_PROTOCOL *PciRootBridgeIo,
IN EFI_DEVICE_PATH_PROTOCOL *DevicePath,
IN UINT16 PrimaryBus,
IN UINT16 SubordinateBus
)
/*++
Routine Description:
Initialize and install a Device IO protocol on a empty device path handle.
Arguments:
Handle - Handle of PCI RootBridge IO instance
PciRootBridgeIo - PCI RootBridge IO instance
DevicePath - Device Path of PCI RootBridge IO instance
PrimaryBus - Primary Bus
SubordinateBus - Subordinate Bus
Returns:
EFI_SUCCESS - This driver is added to ControllerHandle.
EFI_ALREADY_STARTED - This driver is already running on ControllerHandle.
Others - This driver does not support this device.
--*/
{
EFI_STATUS Status;
DEVICE_IO_PRIVATE_DATA *Private;
//
// Initialize the Device IO device instance.
//
Private = AllocateZeroPool (sizeof (DEVICE_IO_PRIVATE_DATA));
if (Private == NULL) {
return EFI_OUT_OF_RESOURCES;
}
Private->Signature = DEVICE_IO_PRIVATE_DATA_SIGNATURE;
Private->Handle = Handle;
Private->PciRootBridgeIo = PciRootBridgeIo;
Private->DevicePath = DevicePath;
Private->PrimaryBus = PrimaryBus;
Private->SubordinateBus = SubordinateBus;
Private->DeviceIo.Mem.Read = DeviceIoMemRead;
Private->DeviceIo.Mem.Write = DeviceIoMemWrite;
Private->DeviceIo.Io.Read = DeviceIoIoRead;
Private->DeviceIo.Io.Write = DeviceIoIoWrite;
Private->DeviceIo.Pci.Read = DeviceIoPciRead;
Private->DeviceIo.Pci.Write = DeviceIoPciWrite;
Private->DeviceIo.PciDevicePath = DeviceIoPciDevicePath;
Private->DeviceIo.Map = DeviceIoMap;
Private->DeviceIo.Unmap = DeviceIoUnmap;
Private->DeviceIo.AllocateBuffer = DeviceIoAllocateBuffer;
Private->DeviceIo.Flush = DeviceIoFlush;
Private->DeviceIo.FreeBuffer = DeviceIoFreeBuffer;
//
// Install protocol interfaces for the Device IO device.
//
Status = gBS->InstallMultipleProtocolInterfaces (
&Private->Handle,
&gEfiDeviceIoProtocolGuid,
&Private->DeviceIo,
NULL
);
ASSERT_EFI_ERROR (Status);
return Status;
}
EFI_STATUS
EFIAPI
DeviceIoMemRead (
IN EFI_DEVICE_IO_PROTOCOL *This,
IN EFI_IO_WIDTH Width,
IN UINT64 Address,
IN UINTN Count,
IN OUT VOID *Buffer
)
/*++
Routine Description:
Perform reading memory mapped I/O space of device.
Arguments:
This - A pointer to EFI_DEVICE_IO protocol instance.
Width - Width of I/O operations.
Address - The base address of I/O operations.
Count - The number of I/O operations to perform.
Bytes moves is Width size * Count, starting at Address.
Buffer - The destination buffer to store results.
Returns:
EFI_SUCCESS - The data was read from the device.
EFI_INVALID_PARAMETER - Width is invalid.
EFI_OUT_OF_RESOURCES - The request could not be completed due to lack of resources.
--*/
{
EFI_STATUS Status;
DEVICE_IO_PRIVATE_DATA *Private;
Private = DEVICE_IO_PRIVATE_DATA_FROM_THIS (This);
if (Width > MMIO_COPY_UINT64) {
return EFI_INVALID_PARAMETER;
}
if (Width >= MMIO_COPY_UINT8) {
Width = (EFI_IO_WIDTH) (Width - MMIO_COPY_UINT8);
Status = Private->PciRootBridgeIo->CopyMem (
Private->PciRootBridgeIo,
(EFI_PCI_ROOT_BRIDGE_IO_PROTOCOL_WIDTH) Width,
(UINT64)(UINTN) Buffer,
Address,
Count
);
} else {
Status = Private->PciRootBridgeIo->Mem.Read (
Private->PciRootBridgeIo,
(EFI_PCI_ROOT_BRIDGE_IO_PROTOCOL_WIDTH) Width,
Address,
Count,
Buffer
);
}
return Status;
}
EFI_STATUS
EFIAPI
DeviceIoMemWrite (
IN EFI_DEVICE_IO_PROTOCOL *This,
IN EFI_IO_WIDTH Width,
IN UINT64 Address,
IN UINTN Count,
IN OUT VOID *Buffer
)
/*++
Routine Description:
Perform writing memory mapped I/O space of device.
Arguments:
This - A pointer to EFI_DEVICE_IO protocol instance.
Width - Width of I/O operations.
Address - The base address of I/O operations.
Count - The number of I/O operations to perform.
Bytes moves is Width size * Count, starting at Address.
Buffer - The source buffer of data to be written.
Returns:
EFI_SUCCESS - The data was written to the device.
EFI_INVALID_PARAMETER - Width is invalid.
EFI_OUT_OF_RESOURCES - The request could not be completed due to lack of resources.
--*/
{
EFI_STATUS Status;
DEVICE_IO_PRIVATE_DATA *Private;
Private = DEVICE_IO_PRIVATE_DATA_FROM_THIS (This);
if (Width > MMIO_COPY_UINT64) {
return EFI_INVALID_PARAMETER;
}
if (Width >= MMIO_COPY_UINT8) {
Width = (EFI_IO_WIDTH) (Width - MMIO_COPY_UINT8);
Status = Private->PciRootBridgeIo->CopyMem (
Private->PciRootBridgeIo,
(EFI_PCI_ROOT_BRIDGE_IO_PROTOCOL_WIDTH) Width,
Address,
(UINT64)(UINTN) Buffer,
Count
);
} else {
Status = Private->PciRootBridgeIo->Mem.Write (
Private->PciRootBridgeIo,
(EFI_PCI_ROOT_BRIDGE_IO_PROTOCOL_WIDTH) Width,
Address,
Count,
Buffer
);
}
return Status;
}
EFI_STATUS
EFIAPI
DeviceIoIoRead (
IN EFI_DEVICE_IO_PROTOCOL *This,
IN EFI_IO_WIDTH Width,
IN UINT64 Address,
IN UINTN Count,
IN OUT VOID *Buffer
)
/*++
Routine Description:
Perform reading I/O space of device.
Arguments:
This - A pointer to EFI_DEVICE_IO protocol instance.
Width - Width of I/O operations.
Address - The base address of I/O operations.
Count - The number of I/O operations to perform.
Bytes moves is Width size * Count, starting at Address.
Buffer - The destination buffer to store results.
Returns:
EFI_SUCCESS - The data was read from the device.
EFI_INVALID_PARAMETER - Width is invalid.
EFI_OUT_OF_RESOURCES - The request could not be completed due to lack of resources.
--*/
{
EFI_STATUS Status;
DEVICE_IO_PRIVATE_DATA *Private;
Private = DEVICE_IO_PRIVATE_DATA_FROM_THIS (This);
if (Width >= MMIO_COPY_UINT8) {
return EFI_INVALID_PARAMETER;
}
Status = Private->PciRootBridgeIo->Io.Read (
Private->PciRootBridgeIo,
(EFI_PCI_ROOT_BRIDGE_IO_PROTOCOL_WIDTH) Width,
Address,
Count,
Buffer
);
return Status;
}
EFI_STATUS
EFIAPI
DeviceIoIoWrite (
IN EFI_DEVICE_IO_PROTOCOL *This,
IN EFI_IO_WIDTH Width,
IN UINT64 Address,
IN UINTN Count,
IN OUT VOID *Buffer
)
/*++
Routine Description:
Perform writing I/O space of device.
Arguments:
This - A pointer to EFI_DEVICE_IO protocol instance.
Width - Width of I/O operations.
Address - The base address of I/O operations.
Count - The number of I/O operations to perform.
Bytes moves is Width size * Count, starting at Address.
Buffer - The source buffer of data to be written.
Returns:
EFI_SUCCESS - The data was written to the device.
EFI_INVALID_PARAMETER - Width is invalid.
EFI_OUT_OF_RESOURCES - The request could not be completed due to lack of resources.
--*/
{
EFI_STATUS Status;
DEVICE_IO_PRIVATE_DATA *Private;
Private = DEVICE_IO_PRIVATE_DATA_FROM_THIS (This);
if (Width >= MMIO_COPY_UINT8) {
return EFI_INVALID_PARAMETER;
}
Status = Private->PciRootBridgeIo->Io.Write (
Private->PciRootBridgeIo,
(EFI_PCI_ROOT_BRIDGE_IO_PROTOCOL_WIDTH) Width,
Address,
Count,
Buffer
);
return Status;
}
EFI_STATUS
EFIAPI
DeviceIoPciRead (
IN EFI_DEVICE_IO_PROTOCOL *This,
IN EFI_IO_WIDTH Width,
IN UINT64 Address,
IN UINTN Count,
IN OUT VOID *Buffer
)
/*++
Routine Description:
Perform reading PCI configuration space of device
Arguments:
This - A pointer to EFI_DEVICE_IO protocol instance.
Width - Width of I/O operations.
Address - The base address of I/O operations.
Count - The number of I/O operations to perform.
Bytes moves is Width size * Count, starting at Address.
Buffer - The destination buffer to store results.
Returns:
EFI_SUCCESS - The data was read from the device.
EFI_INVALID_PARAMETER - Width is invalid.
EFI_OUT_OF_RESOURCES - The request could not be completed due to lack of resources.
--*/
{
EFI_STATUS Status;
DEVICE_IO_PRIVATE_DATA *Private;
Private = DEVICE_IO_PRIVATE_DATA_FROM_THIS (This);
if ((UINT32)Width >= MMIO_COPY_UINT8) {
return EFI_INVALID_PARAMETER;
}
Status = Private->PciRootBridgeIo->Pci.Read (
Private->PciRootBridgeIo,
(EFI_PCI_ROOT_BRIDGE_IO_PROTOCOL_WIDTH) Width,
Address,
Count,
Buffer
);
return Status;
}
EFI_STATUS
EFIAPI
DeviceIoPciWrite (
IN EFI_DEVICE_IO_PROTOCOL *This,
IN EFI_IO_WIDTH Width,
IN UINT64 Address,
IN UINTN Count,
IN OUT VOID *Buffer
)
/*++
Routine Description:
Perform writing PCI configuration space of device.
Arguments:
This - A pointer to EFI_DEVICE_IO protocol instance.
Width - Width of I/O operations.
Address - The base address of I/O operations.
Count - The number of I/O operations to perform.
Bytes moves is Width size * Count, starting at Address.
Buffer - The source buffer of data to be written.
Returns:
EFI_SUCCESS - The data was written to the device.
EFI_INVALID_PARAMETER - Width is invalid.
EFI_OUT_OF_RESOURCES - The request could not be completed due to lack of resources.
--*/
{
EFI_STATUS Status;
DEVICE_IO_PRIVATE_DATA *Private;
Private = DEVICE_IO_PRIVATE_DATA_FROM_THIS (This);
if ((UINT32)Width >= MMIO_COPY_UINT8) {
return EFI_INVALID_PARAMETER;
}
Status = Private->PciRootBridgeIo->Pci.Write (
Private->PciRootBridgeIo,
(EFI_PCI_ROOT_BRIDGE_IO_PROTOCOL_WIDTH) Width,
Address,
Count,
Buffer
);
return Status;
}
EFI_DEVICE_PATH_PROTOCOL *
AppendPciDevicePath (
IN DEVICE_IO_PRIVATE_DATA *Private,
IN UINT8 Bus,
IN UINT8 Device,
IN UINT8 Function,
IN EFI_DEVICE_PATH_PROTOCOL *DevicePath,
IN OUT UINT16 *BridgePrimaryBus,
IN OUT UINT16 *BridgeSubordinateBus
)
/*++
Routine Description:
Append a PCI device path node to another device path.
Arguments:
Private - A pointer to DEVICE_IO_PRIVATE_DATA instance.
Bus - PCI bus number of the device.
Device - PCI device number of the device.
Function - PCI function number of the device.
DevicePath - Original device path which will be appended a PCI device path node.
BridgePrimaryBus - Primary bus number of the bridge.
BridgeSubordinateBus - Subordinate bus number of the bridge.
Returns:
Pointer to the appended PCI device path.
--*/
{
UINT16 ThisBus;
UINT8 ThisDevice;
UINT8 ThisFunc;
UINT64 Address;
PCI_TYPE01 PciBridge;
PCI_TYPE01 *PciPtr;
EFI_DEVICE_PATH_PROTOCOL *ReturnDevicePath;
PCI_DEVICE_PATH PciNode;
PciPtr = &PciBridge;
for (ThisBus = *BridgePrimaryBus; ThisBus <= *BridgeSubordinateBus; ThisBus++) {
for (ThisDevice = 0; ThisDevice <= PCI_MAX_DEVICE; ThisDevice++) {
for (ThisFunc = 0; ThisFunc <= PCI_MAX_FUNC; ThisFunc++) {
Address = EFI_PCI_ADDRESS (ThisBus, ThisDevice, ThisFunc, 0);
ZeroMem (PciPtr, sizeof (PCI_TYPE01));
Private->DeviceIo.Pci.Read (
&Private->DeviceIo,
IO_UINT32,
Address,
1,
&(PciPtr->Hdr.VendorId)
);
if ((PciPtr->Hdr.VendorId == 0xffff) && (ThisFunc == 0)) {
break;
}
if (PciPtr->Hdr.VendorId == 0xffff) {
continue;
}
Private->DeviceIo.Pci.Read (
&Private->DeviceIo,
IO_UINT32,
Address,
sizeof (PCI_TYPE01) / sizeof (UINT32),
PciPtr
);
if (IS_PCI_BRIDGE (PciPtr)) {
if (Bus >= PciPtr->Bridge.SecondaryBus && Bus <= PciPtr->Bridge.SubordinateBus) {
PciNode.Header.Type = HARDWARE_DEVICE_PATH;
PciNode.Header.SubType = HW_PCI_DP;
SetDevicePathNodeLength (&PciNode.Header, sizeof (PciNode));
PciNode.Device = ThisDevice;
PciNode.Function = ThisFunc;
ReturnDevicePath = AppendDevicePathNode (DevicePath, &PciNode.Header);
*BridgePrimaryBus = PciPtr->Bridge.SecondaryBus;
*BridgeSubordinateBus = PciPtr->Bridge.SubordinateBus;
return ReturnDevicePath;
}
}
if ((ThisFunc == 0) && ((PciPtr->Hdr.HeaderType & HEADER_TYPE_MULTI_FUNCTION) == 0x0)) {
//
// Skip sub functions, this is not a multi function device
//
break;
}
}
}
}
ZeroMem (&PciNode, sizeof (PciNode));
PciNode.Header.Type = HARDWARE_DEVICE_PATH;
PciNode.Header.SubType = HW_PCI_DP;
SetDevicePathNodeLength (&PciNode.Header, sizeof (PciNode));
PciNode.Device = Device;
PciNode.Function = Function;
ReturnDevicePath = AppendDevicePathNode (DevicePath, &PciNode.Header);
*BridgePrimaryBus = 0xffff;
*BridgeSubordinateBus = 0xffff;
return ReturnDevicePath;
}
EFI_STATUS
EFIAPI
DeviceIoPciDevicePath (
IN EFI_DEVICE_IO_PROTOCOL *This,
IN UINT64 Address,
IN OUT EFI_DEVICE_PATH_PROTOCOL **PciDevicePath
)
/*++
Routine Description:
Provides an EFI Device Path for a PCI device with the given PCI configuration space address.
Arguments:
This - A pointer to the EFI_DEVICE_IO_INTERFACE instance.
Address - The PCI configuration space address of the device whose Device Path
is going to be returned.
PciDevicePath - A pointer to the pointer for the EFI Device Path for PciAddress.
Memory for the Device Path is allocated from the pool.
Returns:
EFI_SUCCESS - The PciDevicePath returns a pointer to a valid EFI Device Path.
EFI_UNSUPPORTED - The PciAddress does not map to a valid EFI Device Path.
EFI_OUT_OF_RESOURCES - The request could not be completed due to a lack of resources.
--*/
{
DEVICE_IO_PRIVATE_DATA *Private;
UINT16 PrimaryBus;
UINT16 SubordinateBus;
UINT8 Bus;
UINT8 Device;
UINT8 Func;
Private = DEVICE_IO_PRIVATE_DATA_FROM_THIS (This);
Bus = (UINT8) (((UINT32) Address >> 24) & 0xff);
Device = (UINT8) (((UINT32) Address >> 16) & 0xff);
Func = (UINT8) (((UINT32) Address >> 8) & 0xff);
if (Bus < Private->PrimaryBus || Bus > Private->SubordinateBus) {
return EFI_UNSUPPORTED;
}
*PciDevicePath = Private->DevicePath;
PrimaryBus = Private->PrimaryBus;
SubordinateBus = Private->SubordinateBus;
do {
*PciDevicePath = AppendPciDevicePath (
Private,
Bus,
Device,
Func,
*PciDevicePath,
&PrimaryBus,
&SubordinateBus
);
if (*PciDevicePath == NULL) {
return EFI_OUT_OF_RESOURCES;
}
} while (PrimaryBus != 0xffff);
return EFI_SUCCESS;
}
EFI_STATUS
EFIAPI
DeviceIoMap (
IN EFI_DEVICE_IO_PROTOCOL *This,
IN EFI_IO_OPERATION_TYPE Operation,
IN EFI_PHYSICAL_ADDRESS *HostAddress,
IN OUT UINTN *NumberOfBytes,
OUT EFI_PHYSICAL_ADDRESS *DeviceAddress,
OUT VOID **Mapping
)
/*++
Routine Description:
Provides the device-specific addresses needed to access system memory.
Arguments:
This - A pointer to the EFI_DEVICE_IO_INTERFACE instance.
Operation - Indicates if the bus master is going to read or write to system memory.
HostAddress - The system memory address to map to the device.
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 device to use to access the
hosts HostAddress.
Mapping - A resulting value to pass to Unmap().
Returns:
EFI_SUCCESS - The range was mapped for the returned NumberOfBytes.
EFI_INVALID_PARAMETER - The Operation or HostAddress is undefined.
EFI_UNSUPPORTED - The HostAddress cannot be mapped as a common buffer.
EFI_DEVICE_ERROR - The system hardware could not map the requested address.
EFI_OUT_OF_RESOURCES - The request could not be completed due to a lack of resources.
--*/
{
EFI_STATUS Status;
DEVICE_IO_PRIVATE_DATA *Private;
Private = DEVICE_IO_PRIVATE_DATA_FROM_THIS (This);
if ((UINT32)Operation > EfiBusMasterCommonBuffer) {
return EFI_INVALID_PARAMETER;
}
if (((UINTN) (*HostAddress) != (*HostAddress)) && Operation == EfiBusMasterCommonBuffer) {
return EFI_UNSUPPORTED;
}
Status = Private->PciRootBridgeIo->Map (
Private->PciRootBridgeIo,
(EFI_PCI_ROOT_BRIDGE_IO_PROTOCOL_OPERATION) Operation,
(VOID *) (UINTN) (*HostAddress),
NumberOfBytes,
DeviceAddress,
Mapping
);
return Status;
}
EFI_STATUS
EFIAPI
DeviceIoUnmap (
IN EFI_DEVICE_IO_PROTOCOL *This,
IN VOID *Mapping
)
/*++
Routine Description:
Completes the Map() operation and releases any corresponding resources.
Arguments:
This - A pointer to the EFI_DEVICE_IO_INTERFACE instance.
Mapping - The mapping value returned from Map().
Returns:
EFI_SUCCESS - The range was unmapped.
EFI_DEVICE_ERROR - The data was not committed to the target system memory.
--*/
{
EFI_STATUS Status;
DEVICE_IO_PRIVATE_DATA *Private;
Private = DEVICE_IO_PRIVATE_DATA_FROM_THIS (This);
Status = Private->PciRootBridgeIo->Unmap (
Private->PciRootBridgeIo,
Mapping
);
return Status;
}
EFI_STATUS
EFIAPI
DeviceIoAllocateBuffer (
IN EFI_DEVICE_IO_PROTOCOL *This,
IN EFI_ALLOCATE_TYPE Type,
IN EFI_MEMORY_TYPE MemoryType,
IN UINTN Pages,
IN OUT EFI_PHYSICAL_ADDRESS *PhysicalAddress
)
/*++
Routine Description:
Allocates pages that are suitable for an EFIBusMasterCommonBuffer mapping.
Arguments:
This - A pointer to the EFI_DEVICE_IO_INTERFACE instance.
Type - The type allocation to perform.
MemoryType - The type of memory to allocate, EfiBootServicesData or
EfiRuntimeServicesData.
Pages - The number of pages to allocate.
PhysicalAddress - A pointer to store the base address of the allocated range.
Returns:
EFI_SUCCESS - The requested memory pages were allocated.
EFI_OUT_OF_RESOURCES - The memory pages could not be allocated.
EFI_INVALID_PARAMETER - The requested memory type is invalid.
EFI_UNSUPPORTED - The requested PhysicalAddress is not supported on
this platform.
--*/
{
EFI_STATUS Status;
EFI_PHYSICAL_ADDRESS HostAddress;
HostAddress = *PhysicalAddress;
if ((MemoryType != EfiBootServicesData) && (MemoryType != EfiRuntimeServicesData)) {
return EFI_INVALID_PARAMETER;
}
if ((UINT32)Type >= MaxAllocateType) {
return EFI_INVALID_PARAMETER;
}
if ((Type == AllocateAddress) && (HostAddress + EFI_PAGES_TO_SIZE (Pages) - 1 > MAX_COMMON_BUFFER)) {
return EFI_UNSUPPORTED;
}
if ((AllocateAnyPages == Type) || (AllocateMaxAddress == Type && HostAddress > MAX_COMMON_BUFFER)) {
Type = AllocateMaxAddress;
HostAddress = MAX_COMMON_BUFFER;
}
Status = gBS->AllocatePages (
Type,
MemoryType,
Pages,
&HostAddress
);
if (EFI_ERROR (Status)) {
return Status;
}
*PhysicalAddress = HostAddress;
return EFI_SUCCESS;
}
EFI_STATUS
EFIAPI
DeviceIoFlush (
IN EFI_DEVICE_IO_PROTOCOL *This
)
/*++
Routine Description:
Flushes any posted write data to the device.
Arguments:
This - A pointer to the EFI_DEVICE_IO_INTERFACE instance.
Returns:
EFI_SUCCESS - The buffers were flushed.
EFI_DEVICE_ERROR - The buffers were not flushed due to a hardware error.
--*/
{
EFI_STATUS Status;
DEVICE_IO_PRIVATE_DATA *Private;
Private = DEVICE_IO_PRIVATE_DATA_FROM_THIS (This);
Status = Private->PciRootBridgeIo->Flush (Private->PciRootBridgeIo);
return Status;
}
EFI_STATUS
EFIAPI
DeviceIoFreeBuffer (
IN EFI_DEVICE_IO_PROTOCOL *This,
IN UINTN Pages,
IN EFI_PHYSICAL_ADDRESS HostAddress
)
/*++
Routine Description:
Frees pages that were allocated with AllocateBuffer().
Arguments:
This - A pointer to the EFI_DEVICE_IO_INTERFACE instance.
Pages - The number of pages to free.
HostAddress - The base address of the range to free.
Returns:
EFI_SUCCESS - The requested memory pages were freed.
EFI_NOT_FOUND - The requested memory pages were not allocated with
AllocateBuffer().
EFI_INVALID_PARAMETER - HostAddress is not page aligned or Pages is invalid.
--*/
{
if (((HostAddress & EFI_PAGE_MASK) != 0) || (Pages <= 0)) {
return EFI_INVALID_PARAMETER;
}
return gBS->FreePages (HostAddress, Pages);
}