MdePkg/Library/DxeIoLibCpuIo2/IoLib.c - third_party/edk2 - Git at Google

 /** @file
   I/O Library instance based on EFI_CPU_IO2_PROTOCOL.

   Copyright (c) 2010 - 2018, Intel Corporation. All rights reserved.<BR>
   Copyright (c) 2017, AMD Incorporated. 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 "DxeCpuIo2LibInternal.h"

 //
 // Globle varible to cache pointer to CpuIo2 protocol.
 //
 EFI_CPU_IO2_PROTOCOL  *mCpuIo = NULL;

 /**
   The constructor function caches the pointer to CpuIo2 protocol.

   The constructor function locates CpuIo2 protocol from protocol database.
   It will ASSERT() if that operation fails and it will always return EFI_SUCCESS.

   @param  ImageHandle   The firmware allocated handle for the EFI image.
   @param  SystemTable   A pointer to the EFI System Table.

   @retval EFI_SUCCESS   The constructor always returns EFI_SUCCESS.

 **/
 EFI_STATUS
 EFIAPI
 IoLibConstructor (
   IN      EFI_HANDLE                ImageHandle,
   IN      EFI_SYSTEM_TABLE          *SystemTable
   )
 {
   EFI_STATUS  Status;

   Status = gBS->LocateProtocol (&gEfiCpuIo2ProtocolGuid, NULL, (VOID **) &mCpuIo);
   ASSERT_EFI_ERROR (Status);

   return Status;
 }

 /**
   Reads registers in the EFI CPU I/O space.

   Reads the I/O port specified by Port with registers width specified by Width.
   The read value is returned.

   This function must guarantee that all I/O read and write operations are serialized.
   If such operations are not supported, then ASSERT().

   @param  Port          The base address of the I/O operation.
                         The caller is responsible for aligning the Address if required.
   @param  Width         The width of the I/O operation.

   @return Data read from registers in the EFI CPU I/O space.

 **/
 UINT64
 EFIAPI
 IoReadWorker (
   IN      UINTN                      Port,
   IN      EFI_CPU_IO_PROTOCOL_WIDTH  Width
   )
 {
   EFI_STATUS  Status;
   UINT64      Data;

   Status = mCpuIo->Io.Read (mCpuIo, Width, Port, 1, &Data);
   ASSERT_EFI_ERROR (Status);

   return Data;
 }

 /**
   Writes registers in the EFI CPU I/O space.

   Writes the I/O port specified by Port with registers width and value specified by Width
   and Data respectively. Data is returned.

   This function must guarantee that all I/O read and write operations are serialized.
   If such operations are not supported, then ASSERT().

   @param  Port          The base address of the I/O operation.
                         The caller is responsible for aligning the Address if required.
   @param  Width         The width of the I/O operation.
   @param  Data          The value to write to the I/O port.

   @return The parameter of Data.

 **/
 UINT64
 EFIAPI
 IoWriteWorker (
   IN      UINTN                      Port,
   IN      EFI_CPU_IO_PROTOCOL_WIDTH  Width,
   IN      UINT64                     Data
   )
 {
   EFI_STATUS  Status;

   Status = mCpuIo->Io.Write (mCpuIo, Width, Port, 1, &Data);
   ASSERT_EFI_ERROR (Status);

   return Data;
 }

 /**
   Reads registers in the EFI CPU I/O space.

   Reads the I/O port specified by Port with registers width specified by Width.
   The port is read Count times, and the read data is stored in the provided Buffer.

   This function must guarantee that all I/O read and write operations are serialized.
   If such operations are not supported, then ASSERT().

   @param  Port          The base address of the I/O operation.
                         The caller is responsible for aligning the Address if required.
   @param  Width         The width of the I/O operation.
   @param  Count         The number of times to read I/O port.
   @param  Buffer        The buffer to store the read data into.

 **/
 VOID
 EFIAPI
 IoReadFifoWorker (
   IN      UINTN                      Port,
   IN      EFI_CPU_IO_PROTOCOL_WIDTH  Width,
   IN      UINTN                      Count,
   IN      VOID                       *Buffer
   )
 {
   EFI_STATUS  Status;

   Status = mCpuIo->Io.Read (mCpuIo, Width, Port, Count, Buffer);
   ASSERT_EFI_ERROR (Status);
 }

 /**
   Writes registers in the EFI CPU I/O space.

   Writes the I/O port specified by Port with registers width specified by Width.
   The port is written Count times, and the write data is retrieved from the provided Buffer.

   This function must guarantee that all I/O read and write operations are serialized.
   If such operations are not supported, then ASSERT().

   @param  Port          The base address of the I/O operation.
                         The caller is responsible for aligning the Address if required.
   @param  Width         The width of the I/O operation.
   @param  Count         The number of times to write I/O port.
   @param  Buffer        The buffer to store the read data into.

 **/
 VOID
 EFIAPI
 IoWriteFifoWorker (
   IN      UINTN                      Port,
   IN      EFI_CPU_IO_PROTOCOL_WIDTH  Width,
   IN      UINTN                      Count,
   IN      VOID                       *Buffer
   )
 {
   EFI_STATUS  Status;

   Status = mCpuIo->Io.Write (mCpuIo, Width, Port, Count, Buffer);
   ASSERT_EFI_ERROR (Status);
 }

 /**
   Reads memory-mapped registers in the EFI system memory space.

   Reads the MMIO registers specified by Address with registers width specified by Width.
   The read value is returned. If such operations are not supported, then ASSERT().
   This function must guarantee that all MMIO read and write operations are serialized.

   @param  Address       The MMIO register to read.
                         The caller is responsible for aligning the Address if required.
   @param  Width         The width of the I/O operation.

   @return Data read from registers in the EFI system memory space.

 **/
 UINT64
 EFIAPI
 MmioReadWorker (
   IN      UINTN                      Address,
   IN      EFI_CPU_IO_PROTOCOL_WIDTH  Width
   )
 {
   EFI_STATUS  Status;
   UINT64      Data;

   Status = mCpuIo->Mem.Read (mCpuIo, Width, Address, 1, &Data);
   ASSERT_EFI_ERROR (Status);

   return Data;
 }

 /**
   Writes memory-mapped registers in the EFI system memory space.

   Writes the MMIO registers specified by Address with registers width and value specified by Width
   and Data respectively. Data is returned. If such operations are not supported, then ASSERT().
   This function must guarantee that all MMIO read and write operations are serialized.

   @param  Address       The MMIO register to read.
                         The caller is responsible for aligning the Address if required.
   @param  Width         The width of the I/O operation.
   @param  Data          The value to write to the I/O port.

   @return Data read from registers in the EFI system memory space.

 **/
 UINT64
 EFIAPI
 MmioWriteWorker (
   IN      UINTN                      Address,
   IN      EFI_CPU_IO_PROTOCOL_WIDTH  Width,
   IN      UINT64                     Data
   )
 {
   EFI_STATUS  Status;

   Status = mCpuIo->Mem.Write (mCpuIo, Width, Address, 1, &Data);
   ASSERT_EFI_ERROR (Status);

   return Data;
 }

 /**
   Reads an 8-bit I/O port.

   Reads the 8-bit I/O port specified by Port. The 8-bit read value is returned.
   This function must guarantee that all I/O read and write operations are
   serialized.

   If 8-bit I/O port operations are not supported, then ASSERT().

   @param  Port  The I/O port to read.

   @return The value read.

 **/
 UINT8
 EFIAPI
 IoRead8 (
   IN      UINTN                     Port
   )
 {
   return (UINT8)IoReadWorker (Port, EfiCpuIoWidthUint8);
 }

 /**
   Writes an 8-bit I/O port.

   Writes the 8-bit I/O port specified by Port with the value specified by Value
   and returns Value. This function must guarantee that all I/O read and write
   operations are serialized.

   If 8-bit I/O port operations are not supported, then ASSERT().

   @param  Port  The I/O port to write.
   @param  Value The value to write to the I/O port.

   @return The value written the I/O port.

 **/
 UINT8
 EFIAPI
 IoWrite8 (
   IN      UINTN                     Port,
   IN      UINT8                     Value
   )
 {
   return (UINT8)IoWriteWorker (Port, EfiCpuIoWidthUint8, Value);
 }

 /**
   Reads a 16-bit I/O port.

   Reads the 16-bit I/O port specified by Port. The 16-bit read value is returned.
   This function must guarantee that all I/O read and write operations are
   serialized.

   If Port is not aligned on a 16-bit boundary, then ASSERT().

   If 16-bit I/O port operations are not supported, then ASSERT().

   @param  Port  The I/O port to read.

   @return The value read.

 **/
 UINT16
 EFIAPI
 IoRead16 (
   IN      UINTN                     Port
   )
 {
   //
   // Make sure Port is aligned on a 16-bit boundary.
   //
   ASSERT ((Port & 1) == 0);
   return (UINT16)IoReadWorker (Port, EfiCpuIoWidthUint16);
 }

 /**
   Writes a 16-bit I/O port.

   Writes the 16-bit I/O port specified by Port with the value specified by Value
   and returns Value. This function must guarantee that all I/O read and write
   operations are serialized.

   If Port is not aligned on a 16-bit boundary, then ASSERT().

   If 16-bit I/O port operations are not supported, then ASSERT().

   @param  Port  The I/O port to write.
   @param  Value The value to write to the I/O port.

   @return The value written the I/O port.

 **/
 UINT16
 EFIAPI
 IoWrite16 (
   IN      UINTN                     Port,
   IN      UINT16                    Value
   )
 {
   //
   // Make sure Port is aligned on a 16-bit boundary.
   //
   ASSERT ((Port & 1) == 0);
   return (UINT16)IoWriteWorker (Port, EfiCpuIoWidthUint16, Value);
 }

 /**
   Reads a 32-bit I/O port.

   Reads the 32-bit I/O port specified by Port. The 32-bit read value is returned.
   This function must guarantee that all I/O read and write operations are
   serialized.

   If Port is not aligned on a 32-bit boundary, then ASSERT().

   If 32-bit I/O port operations are not supported, then ASSERT().

   @param  Port  The I/O port to read.

   @return The value read.

 **/
 UINT32
 EFIAPI
 IoRead32 (
   IN      UINTN                     Port
   )
 {
   //
   // Make sure Port is aligned on a 32-bit boundary.
   //
   ASSERT ((Port & 3) == 0);
   return (UINT32)IoReadWorker (Port, EfiCpuIoWidthUint32);
 }

 /**
   Writes a 32-bit I/O port.

   Writes the 32-bit I/O port specified by Port with the value specified by Value
   and returns Value. This function must guarantee that all I/O read and write
   operations are serialized.

   If Port is not aligned on a 32-bit boundary, then ASSERT().

   If 32-bit I/O port operations are not supported, then ASSERT().

   @param  Port  The I/O port to write.
   @param  Value The value to write to the I/O port.

   @return The value written the I/O port.

 **/
 UINT32
 EFIAPI
 IoWrite32 (
   IN      UINTN                     Port,
   IN      UINT32                    Value
   )
 {
   //
   // Make sure Port is aligned on a 32-bit boundary.
   //
   ASSERT ((Port & 3) == 0);
   return (UINT32)IoWriteWorker (Port, EfiCpuIoWidthUint32, Value);
 }

 /**
   Reads a 64-bit I/O port.

   Reads the 64-bit I/O port specified by Port. The 64-bit read value is returned.
   This function must guarantee that all I/O read and write operations are
   serialized.

   If Port is not aligned on a 64-bit boundary, then ASSERT().

   If 64-bit I/O port operations are not supported, then ASSERT().

   @param  Port  The I/O port to read.

   @return The value read.

 **/
 UINT64
 EFIAPI
 IoRead64 (
   IN      UINTN                     Port
   )
 {
   //
   // Make sure Port is aligned on a 64-bit boundary.
   //
   ASSERT ((Port & 7) == 0);
   return IoReadWorker (Port, EfiCpuIoWidthUint64);
 }

 /**
   Writes a 64-bit I/O port.

   Writes the 64-bit I/O port specified by Port with the value specified by Value
   and returns Value. This function must guarantee that all I/O read and write
   operations are serialized.

   If Port is not aligned on a 64-bit boundary, then ASSERT().

   If 64-bit I/O port operations are not supported, then ASSERT().

   @param  Port  The I/O port to write.
   @param  Value The value to write to the I/O port.

   @return The value written the I/O port.

 **/
 UINT64
 EFIAPI
 IoWrite64 (
   IN      UINTN                     Port,
   IN      UINT64                    Value
   )
 {
   //
   // Make sure Port is aligned on a 64-bit boundary.
   //
   ASSERT ((Port & 7) == 0);
   return IoWriteWorker (Port, EfiCpuIoWidthUint64, Value);
 }

 /**
   Reads an 8-bit I/O port fifo into a block of memory.

   Reads the 8-bit I/O fifo port specified by Port.
   The port is read Count times, and the read data is
   stored in the provided Buffer.

   This function must guarantee that all I/O read and write operations are
   serialized.

   If 8-bit I/O port operations are not supported, then ASSERT().

   @param  Port    The I/O port to read.
   @param  Count   The number of times to read I/O port.
   @param  Buffer  The buffer to store the read data into.

 **/
 VOID
 EFIAPI
 IoReadFifo8 (
   IN      UINTN                     Port,
   IN      UINTN                     Count,
   OUT     VOID                      *Buffer
   )
 {
   IoReadFifoWorker (Port, EfiCpuIoWidthFifoUint8, Count, Buffer);
 }

 /**
   Writes a block of memory into an 8-bit I/O port fifo.

   Writes the 8-bit I/O fifo port specified by Port.
   The port is written Count times, and the write data is
   retrieved from the provided Buffer.

   This function must guarantee that all I/O write and write operations are
   serialized.

   If 8-bit I/O port operations are not supported, then ASSERT().

   @param  Port    The I/O port to write.
   @param  Count   The number of times to write I/O port.
   @param  Buffer  The buffer to retrieve the write data from.

 **/
 VOID
 EFIAPI
 IoWriteFifo8 (
   IN      UINTN                     Port,
   IN      UINTN                     Count,
   IN      VOID                      *Buffer
   )
 {
   IoWriteFifoWorker (Port, EfiCpuIoWidthFifoUint8, Count, Buffer);
 }

 /**
   Reads a 16-bit I/O port fifo into a block of memory.

   Reads the 16-bit I/O fifo port specified by Port.
   The port is read Count times, and the read data is
   stored in the provided Buffer.

   This function must guarantee that all I/O read and write operations are
   serialized.

   If 16-bit I/O port operations are not supported, then ASSERT().

   @param  Port    The I/O port to read.
   @param  Count   The number of times to read I/O port.
   @param  Buffer  The buffer to store the read data into.

 **/
 VOID
 EFIAPI
 IoReadFifo16 (
   IN      UINTN                     Port,
   IN      UINTN                     Count,
   OUT     VOID                      *Buffer
   )
 {
   //
   // Make sure Port is aligned on a 16-bit boundary.
   //
   ASSERT ((Port & 1) == 0);
   IoReadFifoWorker (Port, EfiCpuIoWidthFifoUint16, Count, Buffer);
 }

 /**
   Writes a block of memory into a 16-bit I/O port fifo.

   Writes the 16-bit I/O fifo port specified by Port.
   The port is written Count times, and the write data is
   retrieved from the provided Buffer.

   This function must guarantee that all I/O write and write operations are
   serialized.

   If 16-bit I/O port operations are not supported, then ASSERT().

   @param  Port    The I/O port to write.
   @param  Count   The number of times to write I/O port.
   @param  Buffer  The buffer to retrieve the write data from.

 **/
 VOID
 EFIAPI
 IoWriteFifo16 (
   IN      UINTN                     Port,
   IN      UINTN                     Count,
   IN      VOID                      *Buffer
   )
 {
   //
   // Make sure Port is aligned on a 16-bit boundary.
   //
   ASSERT ((Port & 1) == 0);
   IoWriteFifoWorker (Port, EfiCpuIoWidthFifoUint16, Count, Buffer);
 }

 /**
   Reads a 32-bit I/O port fifo into a block of memory.

   Reads the 32-bit I/O fifo port specified by Port.
   The port is read Count times, and the read data is
   stored in the provided Buffer.

   This function must guarantee that all I/O read and write operations are
   serialized.

   If 32-bit I/O port operations are not supported, then ASSERT().

   @param  Port    The I/O port to read.
   @param  Count   The number of times to read I/O port.
   @param  Buffer  The buffer to store the read data into.

 **/
 VOID
 EFIAPI
 IoReadFifo32 (
   IN      UINTN                     Port,
   IN      UINTN                     Count,
   OUT     VOID                      *Buffer
   )
 {
   //
   // Make sure Port is aligned on a 32-bit boundary.
   //
   ASSERT ((Port & 3) == 0);
   IoReadFifoWorker (Port, EfiCpuIoWidthFifoUint32, Count, Buffer);
 }

 /**
   Writes a block of memory into a 32-bit I/O port fifo.

   Writes the 32-bit I/O fifo port specified by Port.
   The port is written Count times, and the write data is
   retrieved from the provided Buffer.

   This function must guarantee that all I/O write and write operations are
   serialized.

   If 32-bit I/O port operations are not supported, then ASSERT().

   @param  Port    The I/O port to write.
   @param  Count   The number of times to write I/O port.
   @param  Buffer  The buffer to retrieve the write data from.

 **/
 VOID
 EFIAPI
 IoWriteFifo32 (
   IN      UINTN                     Port,
   IN      UINTN                     Count,
   IN      VOID                      *Buffer
   )
 {
   //
   // Make sure Port is aligned on a 32-bit boundary.
   //
   ASSERT ((Port & 3) == 0);
   IoWriteFifoWorker (Port, EfiCpuIoWidthFifoUint32, Count, Buffer);
 }

 /**
   Reads an 8-bit MMIO register.

   Reads the 8-bit MMIO register specified by Address. The 8-bit read value is
   returned. This function must guarantee that all MMIO read and write
   operations are serialized.

   If 8-bit MMIO register operations are not supported, then ASSERT().

   @param  Address The MMIO register to read.

   @return The value read.

 **/
 UINT8
 EFIAPI
 MmioRead8 (
   IN      UINTN                     Address
   )
 {
   return (UINT8)MmioReadWorker (Address, EfiCpuIoWidthUint8);
 }

 /**
   Writes an 8-bit MMIO register.

   Writes the 8-bit MMIO register specified by Address with the value specified
   by Value and returns Value. This function must guarantee that all MMIO read
   and write operations are serialized.

   If 8-bit MMIO register operations are not supported, then ASSERT().

   @param  Address The MMIO register to write.
   @param  Value   The value to write to the MMIO register.

 **/
 UINT8
 EFIAPI
 MmioWrite8 (
   IN      UINTN                     Address,
   IN      UINT8                     Value
   )
 {
   return (UINT8)MmioWriteWorker (Address, EfiCpuIoWidthUint8, Value);
 }

 /**
   Reads a 16-bit MMIO register.

   Reads the 16-bit MMIO register specified by Address. The 16-bit read value is
   returned. This function must guarantee that all MMIO read and write
   operations are serialized.

   If Address is not aligned on a 16-bit boundary, then ASSERT().

   If 16-bit MMIO register operations are not supported, then ASSERT().

   @param  Address The MMIO register to read.

   @return The value read.

 **/
 UINT16
 EFIAPI
 MmioRead16 (
   IN      UINTN                     Address
   )
 {
   //
   // Make sure Address is aligned on a 16-bit boundary.
   //
   ASSERT ((Address & 1) == 0);
   return (UINT16)MmioReadWorker (Address, EfiCpuIoWidthUint16);
 }

 /**
   Writes a 16-bit MMIO register.

   Writes the 16-bit MMIO register specified by Address with the value specified
   by Value and returns Value. This function must guarantee that all MMIO read
   and write operations are serialized.

   If Address is not aligned on a 16-bit boundary, then ASSERT().

   If 16-bit MMIO register operations are not supported, then ASSERT().

   @param  Address The MMIO register to write.
   @param  Value   The value to write to the MMIO register.

 **/
 UINT16
 EFIAPI
 MmioWrite16 (
   IN      UINTN                     Address,
   IN      UINT16                    Value
   )
 {
   //
   // Make sure Address is aligned on a 16-bit boundary.
   //
   ASSERT ((Address & 1) == 0);
   return (UINT16)MmioWriteWorker (Address, EfiCpuIoWidthUint16, Value);
 }

 /**
   Reads a 32-bit MMIO register.

   Reads the 32-bit MMIO register specified by Address. The 32-bit read value is
   returned. This function must guarantee that all MMIO read and write
   operations are serialized.

   If Address is not aligned on a 32-bit boundary, then ASSERT().

   If 32-bit MMIO register operations are not supported, then ASSERT().

   @param  Address The MMIO register to read.

   @return The value read.

 **/
 UINT32
 EFIAPI
 MmioRead32 (
   IN      UINTN                     Address
   )
 {
   //
   // Make sure Address is aligned on a 32-bit boundary.
   //
   ASSERT ((Address & 3) == 0);
   return (UINT32)MmioReadWorker (Address, EfiCpuIoWidthUint32);
 }

 /**
   Writes a 32-bit MMIO register.

   Writes the 32-bit MMIO register specified by Address with the value specified
   by Value and returns Value. This function must guarantee that all MMIO read
   and write operations are serialized.

   If Address is not aligned on a 32-bit boundary, then ASSERT().

   If 32-bit MMIO register operations are not supported, then ASSERT().

   @param  Address The MMIO register to write.
   @param  Value   The value to write to the MMIO register.

 **/
 UINT32
 EFIAPI
 MmioWrite32 (
   IN      UINTN                     Address,
   IN      UINT32                    Value
   )
 {
   //
   // Make sure Address is aligned on a 32-bit boundary.
   //
   ASSERT ((Address & 3) == 0);
   return (UINT32)MmioWriteWorker (Address, EfiCpuIoWidthUint32, Value);
 }

 /**
   Reads a 64-bit MMIO register.

   Reads the 64-bit MMIO register specified by Address. The 64-bit read value is
   returned. This function must guarantee that all MMIO read and write
   operations are serialized.

   If Address is not aligned on a 64-bit boundary, then ASSERT().

   If 64-bit MMIO register operations are not supported, then ASSERT().

   @param  Address The MMIO register to read.

   @return The value read.

 **/
 UINT64
 EFIAPI
 MmioRead64 (
   IN      UINTN                     Address
   )
 {
   //
   // Make sure Address is aligned on a 64-bit boundary.
   //
   ASSERT ((Address & 7) == 0);
   return (UINT64)MmioReadWorker (Address, EfiCpuIoWidthUint64);
 }

 /**
   Writes a 64-bit MMIO register.

   Writes the 64-bit MMIO register specified by Address with the value specified
   by Value and returns Value. This function must guarantee that all MMIO read
   and write operations are serialized.

   If Address is not aligned on a 64-bit boundary, then ASSERT().

   If 64-bit MMIO register operations are not supported, then ASSERT().

   @param  Address The MMIO register to write.
   @param  Value   The value to write to the MMIO register.

 **/
 UINT64
 EFIAPI
 MmioWrite64 (
   IN      UINTN                     Address,
   IN      UINT64                    Value
   )
 {
   //
   // Make sure Address is aligned on a 64-bit boundary.
   //
   ASSERT ((Address & 7) == 0);
   return (UINT64)MmioWriteWorker (Address, EfiCpuIoWidthUint64, Value);
 }
	/** @file
	I/O Library instance based on EFI_CPU_IO2_PROTOCOL.

	Copyright (c) 2010 - 2018, Intel Corporation. All rights reserved.<BR>
	Copyright (c) 2017, AMD Incorporated. 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 "DxeCpuIo2LibInternal.h"

	//
	// Globle varible to cache pointer to CpuIo2 protocol.
	//
	EFI_CPU_IO2_PROTOCOL *mCpuIo = NULL;

	/**
	The constructor function caches the pointer to CpuIo2 protocol.

	The constructor function locates CpuIo2 protocol from protocol database.
	It will ASSERT() if that operation fails and it will always return EFI_SUCCESS.

	@param ImageHandle The firmware allocated handle for the EFI image.
	@param SystemTable A pointer to the EFI System Table.

	@retval EFI_SUCCESS The constructor always returns EFI_SUCCESS.

	**/
	EFI_STATUS
	EFIAPI
	IoLibConstructor (
	IN EFI_HANDLE ImageHandle,
	IN EFI_SYSTEM_TABLE *SystemTable
	)
	{
	EFI_STATUS Status;

	Status = gBS->LocateProtocol (&gEfiCpuIo2ProtocolGuid, NULL, (VOID **) &mCpuIo);
	ASSERT_EFI_ERROR (Status);

	return Status;
	}

	/**
	Reads registers in the EFI CPU I/O space.

	Reads the I/O port specified by Port with registers width specified by Width.
	The read value is returned.

	This function must guarantee that all I/O read and write operations are serialized.
	If such operations are not supported, then ASSERT().

	@param Port The base address of the I/O operation.
	The caller is responsible for aligning the Address if required.
	@param Width The width of the I/O operation.

	@return Data read from registers in the EFI CPU I/O space.

	**/
	UINT64
	EFIAPI
	IoReadWorker (
	IN UINTN Port,
	IN EFI_CPU_IO_PROTOCOL_WIDTH Width
	)
	{
	EFI_STATUS Status;
	UINT64 Data;

	Status = mCpuIo->Io.Read (mCpuIo, Width, Port, 1, &Data);
	ASSERT_EFI_ERROR (Status);

	return Data;
	}

	/**
	Writes registers in the EFI CPU I/O space.

	Writes the I/O port specified by Port with registers width and value specified by Width
	and Data respectively. Data is returned.

	This function must guarantee that all I/O read and write operations are serialized.
	If such operations are not supported, then ASSERT().

	@param Port The base address of the I/O operation.
	The caller is responsible for aligning the Address if required.
	@param Width The width of the I/O operation.
	@param Data The value to write to the I/O port.

	@return The parameter of Data.

	**/
	UINT64
	EFIAPI
	IoWriteWorker (
	IN UINTN Port,
	IN EFI_CPU_IO_PROTOCOL_WIDTH Width,
	IN UINT64 Data
	)
	{
	EFI_STATUS Status;

	Status = mCpuIo->Io.Write (mCpuIo, Width, Port, 1, &Data);
	ASSERT_EFI_ERROR (Status);

	return Data;
	}

	/**
	Reads registers in the EFI CPU I/O space.

	Reads the I/O port specified by Port with registers width specified by Width.
	The port is read Count times, and the read data is stored in the provided Buffer.

	This function must guarantee that all I/O read and write operations are serialized.
	If such operations are not supported, then ASSERT().

	@param Port The base address of the I/O operation.
	The caller is responsible for aligning the Address if required.
	@param Width The width of the I/O operation.
	@param Count The number of times to read I/O port.
	@param Buffer The buffer to store the read data into.

	**/
	VOID
	EFIAPI
	IoReadFifoWorker (
	IN UINTN Port,
	IN EFI_CPU_IO_PROTOCOL_WIDTH Width,
	IN UINTN Count,
	IN VOID *Buffer
	)
	{
	EFI_STATUS Status;

	Status = mCpuIo->Io.Read (mCpuIo, Width, Port, Count, Buffer);
	ASSERT_EFI_ERROR (Status);
	}

	/**
	Writes registers in the EFI CPU I/O space.

	Writes the I/O port specified by Port with registers width specified by Width.
	The port is written Count times, and the write data is retrieved from the provided Buffer.

	This function must guarantee that all I/O read and write operations are serialized.
	If such operations are not supported, then ASSERT().

	@param Port The base address of the I/O operation.
	The caller is responsible for aligning the Address if required.
	@param Width The width of the I/O operation.
	@param Count The number of times to write I/O port.
	@param Buffer The buffer to store the read data into.

	**/
	VOID
	EFIAPI
	IoWriteFifoWorker (
	IN UINTN Port,
	IN EFI_CPU_IO_PROTOCOL_WIDTH Width,
	IN UINTN Count,
	IN VOID *Buffer
	)
	{
	EFI_STATUS Status;

	Status = mCpuIo->Io.Write (mCpuIo, Width, Port, Count, Buffer);
	ASSERT_EFI_ERROR (Status);
	}

	/**
	Reads memory-mapped registers in the EFI system memory space.

	Reads the MMIO registers specified by Address with registers width specified by Width.
	The read value is returned. If such operations are not supported, then ASSERT().
	This function must guarantee that all MMIO read and write operations are serialized.

	@param Address The MMIO register to read.
	The caller is responsible for aligning the Address if required.
	@param Width The width of the I/O operation.

	@return Data read from registers in the EFI system memory space.

	**/
	UINT64
	EFIAPI
	MmioReadWorker (
	IN UINTN Address,
	IN EFI_CPU_IO_PROTOCOL_WIDTH Width
	)
	{
	EFI_STATUS Status;
	UINT64 Data;

	Status = mCpuIo->Mem.Read (mCpuIo, Width, Address, 1, &Data);
	ASSERT_EFI_ERROR (Status);

	return Data;
	}

	/**
	Writes memory-mapped registers in the EFI system memory space.

	Writes the MMIO registers specified by Address with registers width and value specified by Width
	and Data respectively. Data is returned. If such operations are not supported, then ASSERT().
	This function must guarantee that all MMIO read and write operations are serialized.

	@param Address The MMIO register to read.
	The caller is responsible for aligning the Address if required.
	@param Width The width of the I/O operation.
	@param Data The value to write to the I/O port.

	@return Data read from registers in the EFI system memory space.

	**/
	UINT64
	EFIAPI
	MmioWriteWorker (
	IN UINTN Address,
	IN EFI_CPU_IO_PROTOCOL_WIDTH Width,
	IN UINT64 Data
	)
	{
	EFI_STATUS Status;

	Status = mCpuIo->Mem.Write (mCpuIo, Width, Address, 1, &Data);
	ASSERT_EFI_ERROR (Status);

	return Data;
	}

	/**
	Reads an 8-bit I/O port.

	Reads the 8-bit I/O port specified by Port. The 8-bit read value is returned.
	This function must guarantee that all I/O read and write operations are
	serialized.

	If 8-bit I/O port operations are not supported, then ASSERT().

	@param Port The I/O port to read.

	@return The value read.

	**/
	UINT8
	EFIAPI
	IoRead8 (
	IN UINTN Port
	)
	{
	return (UINT8)IoReadWorker (Port, EfiCpuIoWidthUint8);
	}

	/**
	Writes an 8-bit I/O port.

	Writes the 8-bit I/O port specified by Port with the value specified by Value
	and returns Value. This function must guarantee that all I/O read and write
	operations are serialized.

	If 8-bit I/O port operations are not supported, then ASSERT().

	@param Port The I/O port to write.
	@param Value The value to write to the I/O port.

	@return The value written the I/O port.

	**/
	UINT8
	EFIAPI
	IoWrite8 (
	IN UINTN Port,
	IN UINT8 Value
	)
	{
	return (UINT8)IoWriteWorker (Port, EfiCpuIoWidthUint8, Value);
	}

	/**
	Reads a 16-bit I/O port.

	Reads the 16-bit I/O port specified by Port. The 16-bit read value is returned.
	This function must guarantee that all I/O read and write operations are
	serialized.

	If Port is not aligned on a 16-bit boundary, then ASSERT().

	If 16-bit I/O port operations are not supported, then ASSERT().

	@param Port The I/O port to read.

	@return The value read.

	**/
	UINT16
	EFIAPI
	IoRead16 (
	IN UINTN Port
	)
	{
	//
	// Make sure Port is aligned on a 16-bit boundary.
	//
	ASSERT ((Port & 1) == 0);
	return (UINT16)IoReadWorker (Port, EfiCpuIoWidthUint16);
	}

	/**
	Writes a 16-bit I/O port.

	Writes the 16-bit I/O port specified by Port with the value specified by Value
	and returns Value. This function must guarantee that all I/O read and write
	operations are serialized.

	If Port is not aligned on a 16-bit boundary, then ASSERT().

	If 16-bit I/O port operations are not supported, then ASSERT().

	@param Port The I/O port to write.
	@param Value The value to write to the I/O port.

	@return The value written the I/O port.

	**/
	UINT16
	EFIAPI
	IoWrite16 (
	IN UINTN Port,
	IN UINT16 Value
	)
	{
	//
	// Make sure Port is aligned on a 16-bit boundary.
	//
	ASSERT ((Port & 1) == 0);
	return (UINT16)IoWriteWorker (Port, EfiCpuIoWidthUint16, Value);
	}

	/**
	Reads a 32-bit I/O port.

	Reads the 32-bit I/O port specified by Port. The 32-bit read value is returned.
	This function must guarantee that all I/O read and write operations are
	serialized.

	If Port is not aligned on a 32-bit boundary, then ASSERT().

	If 32-bit I/O port operations are not supported, then ASSERT().

	@param Port The I/O port to read.

	@return The value read.

	**/
	UINT32
	EFIAPI
	IoRead32 (
	IN UINTN Port
	)
	{
	//
	// Make sure Port is aligned on a 32-bit boundary.
	//
	ASSERT ((Port & 3) == 0);
	return (UINT32)IoReadWorker (Port, EfiCpuIoWidthUint32);
	}

	/**
	Writes a 32-bit I/O port.

	Writes the 32-bit I/O port specified by Port with the value specified by Value
	and returns Value. This function must guarantee that all I/O read and write
	operations are serialized.

	If Port is not aligned on a 32-bit boundary, then ASSERT().

	If 32-bit I/O port operations are not supported, then ASSERT().

	@param Port The I/O port to write.
	@param Value The value to write to the I/O port.

	@return The value written the I/O port.

	**/
	UINT32
	EFIAPI
	IoWrite32 (
	IN UINTN Port,
	IN UINT32 Value
	)
	{
	//
	// Make sure Port is aligned on a 32-bit boundary.
	//
	ASSERT ((Port & 3) == 0);
	return (UINT32)IoWriteWorker (Port, EfiCpuIoWidthUint32, Value);
	}

	/**
	Reads a 64-bit I/O port.

	Reads the 64-bit I/O port specified by Port. The 64-bit read value is returned.
	This function must guarantee that all I/O read and write operations are
	serialized.

	If Port is not aligned on a 64-bit boundary, then ASSERT().

	If 64-bit I/O port operations are not supported, then ASSERT().

	@param Port The I/O port to read.

	@return The value read.

	**/
	UINT64
	EFIAPI
	IoRead64 (
	IN UINTN Port
	)
	{
	//
	// Make sure Port is aligned on a 64-bit boundary.
	//
	ASSERT ((Port & 7) == 0);
	return IoReadWorker (Port, EfiCpuIoWidthUint64);
	}

	/**
	Writes a 64-bit I/O port.

	Writes the 64-bit I/O port specified by Port with the value specified by Value
	and returns Value. This function must guarantee that all I/O read and write
	operations are serialized.

	If Port is not aligned on a 64-bit boundary, then ASSERT().

	If 64-bit I/O port operations are not supported, then ASSERT().

	@param Port The I/O port to write.
	@param Value The value to write to the I/O port.

	@return The value written the I/O port.

	**/
	UINT64
	EFIAPI
	IoWrite64 (
	IN UINTN Port,
	IN UINT64 Value
	)
	{
	//
	// Make sure Port is aligned on a 64-bit boundary.
	//
	ASSERT ((Port & 7) == 0);
	return IoWriteWorker (Port, EfiCpuIoWidthUint64, Value);
	}

	/**
	Reads an 8-bit I/O port fifo into a block of memory.

	Reads the 8-bit I/O fifo port specified by Port.
	The port is read Count times, and the read data is
	stored in the provided Buffer.

	This function must guarantee that all I/O read and write operations are
	serialized.

	If 8-bit I/O port operations are not supported, then ASSERT().

	@param Port The I/O port to read.
	@param Count The number of times to read I/O port.
	@param Buffer The buffer to store the read data into.

	**/
	VOID
	EFIAPI
	IoReadFifo8 (
	IN UINTN Port,
	IN UINTN Count,
	OUT VOID *Buffer
	)
	{
	IoReadFifoWorker (Port, EfiCpuIoWidthFifoUint8, Count, Buffer);
	}

	/**
	Writes a block of memory into an 8-bit I/O port fifo.

	Writes the 8-bit I/O fifo port specified by Port.
	The port is written Count times, and the write data is
	retrieved from the provided Buffer.

	This function must guarantee that all I/O write and write operations are
	serialized.

	If 8-bit I/O port operations are not supported, then ASSERT().

	@param Port The I/O port to write.
	@param Count The number of times to write I/O port.
	@param Buffer The buffer to retrieve the write data from.

	**/
	VOID
	EFIAPI
	IoWriteFifo8 (
	IN UINTN Port,
	IN UINTN Count,
	IN VOID *Buffer
	)
	{
	IoWriteFifoWorker (Port, EfiCpuIoWidthFifoUint8, Count, Buffer);
	}

	/**
	Reads a 16-bit I/O port fifo into a block of memory.

	Reads the 16-bit I/O fifo port specified by Port.
	The port is read Count times, and the read data is
	stored in the provided Buffer.

	This function must guarantee that all I/O read and write operations are
	serialized.

	If 16-bit I/O port operations are not supported, then ASSERT().

	@param Port The I/O port to read.
	@param Count The number of times to read I/O port.
	@param Buffer The buffer to store the read data into.

	**/
	VOID
	EFIAPI
	IoReadFifo16 (
	IN UINTN Port,
	IN UINTN Count,
	OUT VOID *Buffer
	)
	{
	//
	// Make sure Port is aligned on a 16-bit boundary.
	//
	ASSERT ((Port & 1) == 0);
	IoReadFifoWorker (Port, EfiCpuIoWidthFifoUint16, Count, Buffer);
	}

	/**
	Writes a block of memory into a 16-bit I/O port fifo.

	Writes the 16-bit I/O fifo port specified by Port.
	The port is written Count times, and the write data is
	retrieved from the provided Buffer.

	This function must guarantee that all I/O write and write operations are
	serialized.

	If 16-bit I/O port operations are not supported, then ASSERT().

	@param Port The I/O port to write.
	@param Count The number of times to write I/O port.
	@param Buffer The buffer to retrieve the write data from.

	**/
	VOID
	EFIAPI
	IoWriteFifo16 (
	IN UINTN Port,
	IN UINTN Count,
	IN VOID *Buffer
	)
	{
	//
	// Make sure Port is aligned on a 16-bit boundary.
	//
	ASSERT ((Port & 1) == 0);
	IoWriteFifoWorker (Port, EfiCpuIoWidthFifoUint16, Count, Buffer);
	}

	/**
	Reads a 32-bit I/O port fifo into a block of memory.

	Reads the 32-bit I/O fifo port specified by Port.
	The port is read Count times, and the read data is
	stored in the provided Buffer.

	This function must guarantee that all I/O read and write operations are
	serialized.

	If 32-bit I/O port operations are not supported, then ASSERT().

	@param Port The I/O port to read.
	@param Count The number of times to read I/O port.
	@param Buffer The buffer to store the read data into.

	**/
	VOID
	EFIAPI
	IoReadFifo32 (
	IN UINTN Port,
	IN UINTN Count,
	OUT VOID *Buffer
	)
	{
	//
	// Make sure Port is aligned on a 32-bit boundary.
	//
	ASSERT ((Port & 3) == 0);
	IoReadFifoWorker (Port, EfiCpuIoWidthFifoUint32, Count, Buffer);
	}

	/**
	Writes a block of memory into a 32-bit I/O port fifo.

	Writes the 32-bit I/O fifo port specified by Port.
	The port is written Count times, and the write data is
	retrieved from the provided Buffer.

	This function must guarantee that all I/O write and write operations are
	serialized.

	If 32-bit I/O port operations are not supported, then ASSERT().

	@param Port The I/O port to write.
	@param Count The number of times to write I/O port.
	@param Buffer The buffer to retrieve the write data from.

	**/
	VOID
	EFIAPI
	IoWriteFifo32 (
	IN UINTN Port,
	IN UINTN Count,
	IN VOID *Buffer
	)
	{
	//
	// Make sure Port is aligned on a 32-bit boundary.
	//
	ASSERT ((Port & 3) == 0);
	IoWriteFifoWorker (Port, EfiCpuIoWidthFifoUint32, Count, Buffer);
	}

	/**
	Reads an 8-bit MMIO register.

	Reads the 8-bit MMIO register specified by Address. The 8-bit read value is
	returned. This function must guarantee that all MMIO read and write
	operations are serialized.

	If 8-bit MMIO register operations are not supported, then ASSERT().

	@param Address The MMIO register to read.

	@return The value read.

	**/
	UINT8
	EFIAPI
	MmioRead8 (
	IN UINTN Address
	)
	{
	return (UINT8)MmioReadWorker (Address, EfiCpuIoWidthUint8);
	}

	/**
	Writes an 8-bit MMIO register.

	Writes the 8-bit MMIO register specified by Address with the value specified
	by Value and returns Value. This function must guarantee that all MMIO read
	and write operations are serialized.

	If 8-bit MMIO register operations are not supported, then ASSERT().

	@param Address The MMIO register to write.
	@param Value The value to write to the MMIO register.

	**/
	UINT8
	EFIAPI
	MmioWrite8 (
	IN UINTN Address,
	IN UINT8 Value
	)
	{
	return (UINT8)MmioWriteWorker (Address, EfiCpuIoWidthUint8, Value);
	}

	/**
	Reads a 16-bit MMIO register.

	Reads the 16-bit MMIO register specified by Address. The 16-bit read value is
	returned. This function must guarantee that all MMIO read and write
	operations are serialized.

	If Address is not aligned on a 16-bit boundary, then ASSERT().

	If 16-bit MMIO register operations are not supported, then ASSERT().

	@param Address The MMIO register to read.

	@return The value read.

	**/
	UINT16
	EFIAPI
	MmioRead16 (
	IN UINTN Address
	)
	{
	//
	// Make sure Address is aligned on a 16-bit boundary.
	//
	ASSERT ((Address & 1) == 0);
	return (UINT16)MmioReadWorker (Address, EfiCpuIoWidthUint16);
	}

	/**
	Writes a 16-bit MMIO register.

	Writes the 16-bit MMIO register specified by Address with the value specified
	by Value and returns Value. This function must guarantee that all MMIO read
	and write operations are serialized.

	If Address is not aligned on a 16-bit boundary, then ASSERT().

	If 16-bit MMIO register operations are not supported, then ASSERT().

	@param Address The MMIO register to write.
	@param Value The value to write to the MMIO register.

	**/
	UINT16
	EFIAPI
	MmioWrite16 (
	IN UINTN Address,
	IN UINT16 Value
	)
	{
	//
	// Make sure Address is aligned on a 16-bit boundary.
	//
	ASSERT ((Address & 1) == 0);
	return (UINT16)MmioWriteWorker (Address, EfiCpuIoWidthUint16, Value);
	}

	/**
	Reads a 32-bit MMIO register.

	Reads the 32-bit MMIO register specified by Address. The 32-bit read value is
	returned. This function must guarantee that all MMIO read and write
	operations are serialized.

	If Address is not aligned on a 32-bit boundary, then ASSERT().

	If 32-bit MMIO register operations are not supported, then ASSERT().

	@param Address The MMIO register to read.

	@return The value read.

	**/
	UINT32
	EFIAPI
	MmioRead32 (
	IN UINTN Address
	)
	{
	//
	// Make sure Address is aligned on a 32-bit boundary.
	//
	ASSERT ((Address & 3) == 0);
	return (UINT32)MmioReadWorker (Address, EfiCpuIoWidthUint32);
	}

	/**
	Writes a 32-bit MMIO register.

	Writes the 32-bit MMIO register specified by Address with the value specified
	by Value and returns Value. This function must guarantee that all MMIO read
	and write operations are serialized.

	If Address is not aligned on a 32-bit boundary, then ASSERT().

	If 32-bit MMIO register operations are not supported, then ASSERT().

	@param Address The MMIO register to write.
	@param Value The value to write to the MMIO register.

	**/
	UINT32
	EFIAPI
	MmioWrite32 (
	IN UINTN Address,
	IN UINT32 Value
	)
	{
	//
	// Make sure Address is aligned on a 32-bit boundary.
	//
	ASSERT ((Address & 3) == 0);
	return (UINT32)MmioWriteWorker (Address, EfiCpuIoWidthUint32, Value);
	}

	/**
	Reads a 64-bit MMIO register.

	Reads the 64-bit MMIO register specified by Address. The 64-bit read value is
	returned. This function must guarantee that all MMIO read and write
	operations are serialized.

	If Address is not aligned on a 64-bit boundary, then ASSERT().

	If 64-bit MMIO register operations are not supported, then ASSERT().

	@param Address The MMIO register to read.

	@return The value read.

	**/
	UINT64
	EFIAPI
	MmioRead64 (
	IN UINTN Address
	)
	{
	//
	// Make sure Address is aligned on a 64-bit boundary.
	//
	ASSERT ((Address & 7) == 0);
	return (UINT64)MmioReadWorker (Address, EfiCpuIoWidthUint64);
	}

	/**
	Writes a 64-bit MMIO register.

	Writes the 64-bit MMIO register specified by Address with the value specified
	by Value and returns Value. This function must guarantee that all MMIO read
	and write operations are serialized.

	If Address is not aligned on a 64-bit boundary, then ASSERT().

	If 64-bit MMIO register operations are not supported, then ASSERT().

	@param Address The MMIO register to write.
	@param Value The value to write to the MMIO register.

	**/
	UINT64
	EFIAPI
	MmioWrite64 (
	IN UINTN Address,
	IN UINT64 Value
	)
	{
	//
	// Make sure Address is aligned on a 64-bit boundary.
	//
	ASSERT ((Address & 7) == 0);
	return (UINT64)MmioWriteWorker (Address, EfiCpuIoWidthUint64, Value);
	}