[PATCH 1/2] OvmfPkg/BaseCachingPciExpressLib: Clone ArmVirtPkg BaseCachingPciExpressLib

["Abner Chang" <abner.chang@hpe.com>]

Clone BaseCachingPciExpressLib library from ArmVirtPkg to under OvmfPkg.
RISC-V Virt platform can leverage the same library to access PCI Express
registers through PCI Express base address set in PcdPciExpressBaseAddress
and cached in a global variable.

Signed-off-by: Abner Chang <abner.chang@hpe.com>
Cc: Daniel Schaefer <daniel.schaefer@hpe.com>
Cc: Sunil V L <sunilvl@ventanamicro.com>
Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Leif Lindholm <leif@nuviainc.com>
Cc: Sami Mujawar <sami.mujawar@arm.com>
---
 .../BaseCachingPciExpressLib.inf              |   44 +
 .../BaseCachingPciExpressLib/PciExpressLib.c  | 1420 +++++++++++++++++
 2 files changed, 1464 insertions(+)
 create mode 100644 OvmfPkg/Library/BaseCachingPciExpressLib/BaseCachingPciExpressLib.inf
 create mode 100644 OvmfPkg/Library/BaseCachingPciExpressLib/PciExpressLib.c

diff --git a/OvmfPkg/Library/BaseCachingPciExpressLib/BaseCachingPciExpressLib.inf b/OvmfPkg/Library/BaseCachingPciExpressLib/BaseCachingPciExpressLib.inf
new file mode 100644
index 0000000000..a95a35e0a5
--- /dev/null
+++ b/OvmfPkg/Library/BaseCachingPciExpressLib/BaseCachingPciExpressLib.inf
@@ -0,0 +1,44 @@
+## @file
+#  Instance of PCI Express Library using the 256 MB PCI Express MMIO window
+#  with caching PcdPciExpressBaseAddress as the global variable.
+#
+#  PCI Express Library that uses the 256 MB PCI Express MMIO window to perform
+#  PCI Configuration cycles. Layers on top of an I/O Library instance.
+#
+#  Copyright (c) 2007 - 2014, Intel Corporation. All rights reserved.<BR>
+#
+#  SPDX-License-Identifier: BSD-2-Clause-Patent
+#
+#
+##
+
+[Defines]
+  INF_VERSION                    = 0x00010005
+  BASE_NAME                      = BaseCachingPciExpressLib
+  FILE_GUID                      = 3f3ffd80-04dc-4a2b-9d25-ecca55c2e520
+  MODULE_TYPE                    = BASE
+  VERSION_STRING                 = 1.0
+  LIBRARY_CLASS                  = PciExpressLib|DXE_DRIVER UEFI_DRIVER UEFI_APPLICATION
+  CONSTRUCTOR                    = PciExpressLibInitialize
+
+#
+#  VALID_ARCHITECTURES           = ARM AARCH64
+#
+
+[Sources]
+  PciExpressLib.c
+
+[Packages]
+  MdePkg/MdePkg.dec
+  OvmfPkg/OvmfPkg.dec
+
+[LibraryClasses]
+  BaseLib
+  PcdLib
+  DebugLib
+  IoLib
+  PciPcdProducerLib
+
+[Pcd]
+  gEfiMdePkgTokenSpaceGuid.PcdPciExpressBaseAddress  ## CONSUMES
+
diff --git a/OvmfPkg/Library/BaseCachingPciExpressLib/PciExpressLib.c b/OvmfPkg/Library/BaseCachingPciExpressLib/PciExpressLib.c
new file mode 100644
index 0000000000..2474128697
--- /dev/null
+++ b/OvmfPkg/Library/BaseCachingPciExpressLib/PciExpressLib.c
@@ -0,0 +1,1420 @@
+/** @file
+  Functions in this library instance make use of MMIO functions in IoLib to
+  access memory mapped PCI configuration space.
+
+  All assertions for I/O operations are handled in MMIO functions in the IoLib
+  Library.
+
+  Copyright (c) 2006 - 2012, Intel Corporation. All rights reserved.<BR>
+  SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+
+#include <Base.h>
+
+#include <Library/BaseLib.h>
+#include <Library/PciExpressLib.h>
+#include <Library/IoLib.h>
+#include <Library/DebugLib.h>
+#include <Library/PcdLib.h>
+
+/**
+  Assert the validity of a PCI address. A valid PCI address should contain 1's
+  only in the low 28 bits.
+
+  @param  A The address to validate.
+
+**/
+#define ASSERT_INVALID_PCI_ADDRESS(A) \
+  ASSERT (((A) & ~0xfffffff) == 0)
+
+/**
+  Registers a PCI device so PCI configuration registers may be accessed after
+  SetVirtualAddressMap().
+
+  Registers the PCI device specified by Address so all the PCI configuration
+  registers associated with that PCI device may be accessed after SetVirtualAddressMap()
+  is called.
+
+  If Address > 0x0FFFFFFF, then ASSERT().
+
+  @param  Address The address that encodes the PCI Bus, Device, Function and
+                  Register.
+
+  @retval RETURN_SUCCESS           The PCI device was registered for runtime access.
+  @retval RETURN_UNSUPPORTED       An attempt was made to call this function
+                                   after ExitBootServices().
+  @retval RETURN_UNSUPPORTED       The resources required to access the PCI device
+                                   at runtime could not be mapped.
+  @retval RETURN_OUT_OF_RESOURCES  There are not enough resources available to
+                                   complete the registration.
+
+**/
+RETURN_STATUS
+EFIAPI
+PciExpressRegisterForRuntimeAccess (
+  IN UINTN  Address
+  )
+{
+  ASSERT_INVALID_PCI_ADDRESS (Address);
+  return RETURN_UNSUPPORTED;
+}
+
+STATIC UINT64  mPciExpressBaseAddress;
+
+RETURN_STATUS
+EFIAPI
+PciExpressLibInitialize (
+  VOID
+  )
+{
+  mPciExpressBaseAddress = PcdGet64 (PcdPciExpressBaseAddress);
+  return RETURN_SUCCESS;
+}
+
+/**
+  Gets the base address of PCI Express.
+
+  @return The base address of PCI Express.
+
+**/
+VOID *
+GetPciExpressBaseAddress (
+  VOID
+  )
+{
+  return (VOID *)(UINTN)mPciExpressBaseAddress;
+}
+
+/**
+  Reads an 8-bit PCI configuration register.
+
+  Reads and returns the 8-bit PCI configuration register specified by Address.
+  This function must guarantee that all PCI read and write operations are
+  serialized.
+
+  If Address > 0x0FFFFFFF, then ASSERT().
+
+  @param  Address The address that encodes the PCI Bus, Device, Function and
+                  Register.
+
+  @return The read value from the PCI configuration register.
+
+**/
+UINT8
+EFIAPI
+PciExpressRead8 (
+  IN      UINTN  Address
+  )
+{
+  ASSERT_INVALID_PCI_ADDRESS (Address);
+  return MmioRead8 ((UINTN)GetPciExpressBaseAddress () + Address);
+}
+
+/**
+  Writes an 8-bit PCI configuration register.
+
+  Writes the 8-bit PCI configuration register specified by Address with the
+  value specified by Value. Value is returned. This function must guarantee
+  that all PCI read and write operations are serialized.
+
+  If Address > 0x0FFFFFFF, then ASSERT().
+
+  @param  Address The address that encodes the PCI Bus, Device, Function and
+                  Register.
+  @param  Value   The value to write.
+
+  @return The value written to the PCI configuration register.
+
+**/
+UINT8
+EFIAPI
+PciExpressWrite8 (
+  IN      UINTN  Address,
+  IN      UINT8  Value
+  )
+{
+  ASSERT_INVALID_PCI_ADDRESS (Address);
+  return MmioWrite8 ((UINTN)GetPciExpressBaseAddress () + Address, Value);
+}
+
+/**
+  Performs a bitwise OR of an 8-bit PCI configuration register with
+  an 8-bit value.
+
+  Reads the 8-bit PCI configuration register specified by Address, performs a
+  bitwise OR between the read result and the value specified by
+  OrData, and writes the result to the 8-bit PCI configuration register
+  specified by Address. The value written to the PCI configuration register is
+  returned. This function must guarantee that all PCI read and write operations
+  are serialized.
+
+  If Address > 0x0FFFFFFF, then ASSERT().
+
+  @param  Address The address that encodes the PCI Bus, Device, Function and
+                  Register.
+  @param  OrData  The value to OR with the PCI configuration register.
+
+  @return The value written back to the PCI configuration register.
+
+**/
+UINT8
+EFIAPI
+PciExpressOr8 (
+  IN      UINTN  Address,
+  IN      UINT8  OrData
+  )
+{
+  ASSERT_INVALID_PCI_ADDRESS (Address);
+  return MmioOr8 ((UINTN)GetPciExpressBaseAddress () + Address, OrData);
+}
+
+/**
+  Performs a bitwise AND of an 8-bit PCI configuration register with an 8-bit
+  value.
+
+  Reads the 8-bit PCI configuration register specified by Address, performs a
+  bitwise AND between the read result and the value specified by AndData, and
+  writes the result to the 8-bit PCI configuration register specified by
+  Address. The value written to the PCI configuration register is returned.
+  This function must guarantee that all PCI read and write operations are
+  serialized.
+
+  If Address > 0x0FFFFFFF, then ASSERT().
+
+  @param  Address The address that encodes the PCI Bus, Device, Function and
+                  Register.
+  @param  AndData The value to AND with the PCI configuration register.
+
+  @return The value written back to the PCI configuration register.
+
+**/
+UINT8
+EFIAPI
+PciExpressAnd8 (
+  IN      UINTN  Address,
+  IN      UINT8  AndData
+  )
+{
+  ASSERT_INVALID_PCI_ADDRESS (Address);
+  return MmioAnd8 ((UINTN)GetPciExpressBaseAddress () + Address, AndData);
+}
+
+/**
+  Performs a bitwise AND of an 8-bit PCI configuration register with an 8-bit
+  value, followed a  bitwise OR with another 8-bit value.
+
+  Reads the 8-bit PCI configuration register specified by Address, performs a
+  bitwise AND between the read result and the value specified by AndData,
+  performs a bitwise OR between the result of the AND operation and
+  the value specified by OrData, and writes the result to the 8-bit PCI
+  configuration register specified by Address. The value written to the PCI
+  configuration register is returned. This function must guarantee that all PCI
+  read and write operations are serialized.
+
+  If Address > 0x0FFFFFFF, then ASSERT().
+
+  @param  Address The address that encodes the PCI Bus, Device, Function and
+                  Register.
+  @param  AndData The value to AND with the PCI configuration register.
+  @param  OrData  The value to OR with the result of the AND operation.
+
+  @return The value written back to the PCI configuration register.
+
+**/
+UINT8
+EFIAPI
+PciExpressAndThenOr8 (
+  IN      UINTN  Address,
+  IN      UINT8  AndData,
+  IN      UINT8  OrData
+  )
+{
+  ASSERT_INVALID_PCI_ADDRESS (Address);
+  return MmioAndThenOr8 (
+           (UINTN)GetPciExpressBaseAddress () + Address,
+           AndData,
+           OrData
+           );
+}
+
+/**
+  Reads a bit field of a PCI configuration register.
+
+  Reads the bit field in an 8-bit PCI configuration register. The bit field is
+  specified by the StartBit and the EndBit. The value of the bit field is
+  returned.
+
+  If Address > 0x0FFFFFFF, then ASSERT().
+  If StartBit is greater than 7, then ASSERT().
+  If EndBit is greater than 7, then ASSERT().
+  If EndBit is less than StartBit, then ASSERT().
+
+  @param  Address   The PCI configuration register to read.
+  @param  StartBit  The ordinal of the least significant bit in the bit field.
+                    Range 0..7.
+  @param  EndBit    The ordinal of the most significant bit in the bit field.
+                    Range 0..7.
+
+  @return The value of the bit field read from the PCI configuration register.
+
+**/
+UINT8
+EFIAPI
+PciExpressBitFieldRead8 (
+  IN      UINTN  Address,
+  IN      UINTN  StartBit,
+  IN      UINTN  EndBit
+  )
+{
+  ASSERT_INVALID_PCI_ADDRESS (Address);
+  return MmioBitFieldRead8 (
+           (UINTN)GetPciExpressBaseAddress () + Address,
+           StartBit,
+           EndBit
+           );
+}
+
+/**
+  Writes a bit field to a PCI configuration register.
+
+  Writes Value to the bit field of the PCI configuration register. The bit
+  field is specified by the StartBit and the EndBit. All other bits in the
+  destination PCI configuration register are preserved. The new value of the
+  8-bit register is returned.
+
+  If Address > 0x0FFFFFFF, then ASSERT().
+  If StartBit is greater than 7, then ASSERT().
+  If EndBit is greater than 7, then ASSERT().
+  If EndBit is less than StartBit, then ASSERT().
+  If Value is larger than the bitmask value range specified by StartBit and EndBit, then ASSERT().
+
+  @param  Address   The PCI configuration register to write.
+  @param  StartBit  The ordinal of the least significant bit in the bit field.
+                    Range 0..7.
+  @param  EndBit    The ordinal of the most significant bit in the bit field.
+                    Range 0..7.
+  @param  Value     The new value of the bit field.
+
+  @return The value written back to the PCI configuration register.
+
+**/
+UINT8
+EFIAPI
+PciExpressBitFieldWrite8 (
+  IN      UINTN  Address,
+  IN      UINTN  StartBit,
+  IN      UINTN  EndBit,
+  IN      UINT8  Value
+  )
+{
+  ASSERT_INVALID_PCI_ADDRESS (Address);
+  return MmioBitFieldWrite8 (
+           (UINTN)GetPciExpressBaseAddress () + Address,
+           StartBit,
+           EndBit,
+           Value
+           );
+}
+
+/**
+  Reads a bit field in an 8-bit PCI configuration, performs a bitwise OR, and
+  writes the result back to the bit field in the 8-bit port.
+
+  Reads the 8-bit PCI configuration register specified by Address, performs a
+  bitwise OR between the read result and the value specified by
+  OrData, and writes the result to the 8-bit PCI configuration register
+  specified by Address. The value written to the PCI configuration register is
+  returned. This function must guarantee that all PCI read and write operations
+  are serialized. Extra left bits in OrData are stripped.
+
+  If Address > 0x0FFFFFFF, then ASSERT().
+  If StartBit is greater than 7, then ASSERT().
+  If EndBit is greater than 7, then ASSERT().
+  If EndBit is less than StartBit, then ASSERT().
+  If OrData is larger than the bitmask value range specified by StartBit and EndBit, then ASSERT().
+
+  @param  Address   The PCI configuration register to write.
+  @param  StartBit  The ordinal of the least significant bit in the bit field.
+                    Range 0..7.
+  @param  EndBit    The ordinal of the most significant bit in the bit field.
+                    Range 0..7.
+  @param  OrData    The value to OR with the PCI configuration register.
+
+  @return The value written back to the PCI configuration register.
+
+**/
+UINT8
+EFIAPI
+PciExpressBitFieldOr8 (
+  IN      UINTN  Address,
+  IN      UINTN  StartBit,
+  IN      UINTN  EndBit,
+  IN      UINT8  OrData
+  )
+{
+  ASSERT_INVALID_PCI_ADDRESS (Address);
+  return MmioBitFieldOr8 (
+           (UINTN)GetPciExpressBaseAddress () + Address,
+           StartBit,
+           EndBit,
+           OrData
+           );
+}
+
+/**
+  Reads a bit field in an 8-bit PCI configuration register, performs a bitwise
+  AND, and writes the result back to the bit field in the 8-bit register.
+
+  Reads the 8-bit PCI configuration register specified by Address, performs a
+  bitwise AND between the read result and the value specified by AndData, and
+  writes the result to the 8-bit PCI configuration register specified by
+  Address. The value written to the PCI configuration register is returned.
+  This function must guarantee that all PCI read and write operations are
+  serialized. Extra left bits in AndData are stripped.
+
+  If Address > 0x0FFFFFFF, then ASSERT().
+  If StartBit is greater than 7, then ASSERT().
+  If EndBit is greater than 7, then ASSERT().
+  If EndBit is less than StartBit, then ASSERT().
+  If AndData is larger than the bitmask value range specified by StartBit and EndBit, then ASSERT().
+
+  @param  Address   The PCI configuration register to write.
+  @param  StartBit  The ordinal of the least significant bit in the bit field.
+                    Range 0..7.
+  @param  EndBit    The ordinal of the most significant bit in the bit field.
+                    Range 0..7.
+  @param  AndData   The value to AND with the PCI configuration register.
+
+  @return The value written back to the PCI configuration register.
+
+**/
+UINT8
+EFIAPI
+PciExpressBitFieldAnd8 (
+  IN      UINTN  Address,
+  IN      UINTN  StartBit,
+  IN      UINTN  EndBit,
+  IN      UINT8  AndData
+  )
+{
+  ASSERT_INVALID_PCI_ADDRESS (Address);
+  return MmioBitFieldAnd8 (
+           (UINTN)GetPciExpressBaseAddress () + Address,
+           StartBit,
+           EndBit,
+           AndData
+           );
+}
+
+/**
+  Reads a bit field in an 8-bit port, performs a bitwise AND followed by a
+  bitwise OR, and writes the result back to the bit field in the
+  8-bit port.
+
+  Reads the 8-bit PCI configuration register specified by Address, performs a
+  bitwise AND followed by a bitwise OR between the read result and
+  the value specified by AndData, and writes the result to the 8-bit PCI
+  configuration register specified by Address. The value written to the PCI
+  configuration register is returned. This function must guarantee that all PCI
+  read and write operations are serialized. Extra left bits in both AndData and
+  OrData are stripped.
+
+  If Address > 0x0FFFFFFF, then ASSERT().
+  If StartBit is greater than 7, then ASSERT().
+  If EndBit is greater than 7, then ASSERT().
+  If EndBit is less than StartBit, then ASSERT().
+  If AndData is larger than the bitmask value range specified by StartBit and EndBit, then ASSERT().
+  If OrData is larger than the bitmask value range specified by StartBit and EndBit, then ASSERT().
+
+  @param  Address   The PCI configuration register to write.
+  @param  StartBit  The ordinal of the least significant bit in the bit field.
+                    Range 0..7.
+  @param  EndBit    The ordinal of the most significant bit in the bit field.
+                    Range 0..7.
+  @param  AndData   The value to AND with the PCI configuration register.
+  @param  OrData    The value to OR with the result of the AND operation.
+
+  @return The value written back to the PCI configuration register.
+
+**/
+UINT8
+EFIAPI
+PciExpressBitFieldAndThenOr8 (
+  IN      UINTN  Address,
+  IN      UINTN  StartBit,
+  IN      UINTN  EndBit,
+  IN      UINT8  AndData,
+  IN      UINT8  OrData
+  )
+{
+  ASSERT_INVALID_PCI_ADDRESS (Address);
+  return MmioBitFieldAndThenOr8 (
+           (UINTN)GetPciExpressBaseAddress () + Address,
+           StartBit,
+           EndBit,
+           AndData,
+           OrData
+           );
+}
+
+/**
+  Reads a 16-bit PCI configuration register.
+
+  Reads and returns the 16-bit PCI configuration register specified by Address.
+  This function must guarantee that all PCI read and write operations are
+  serialized.
+
+  If Address > 0x0FFFFFFF, then ASSERT().
+  If Address is not aligned on a 16-bit boundary, then ASSERT().
+
+  @param  Address The address that encodes the PCI Bus, Device, Function and
+                  Register.
+
+  @return The read value from the PCI configuration register.
+
+**/
+UINT16
+EFIAPI
+PciExpressRead16 (
+  IN      UINTN  Address
+  )
+{
+  ASSERT_INVALID_PCI_ADDRESS (Address);
+  return MmioRead16 ((UINTN)GetPciExpressBaseAddress () + Address);
+}
+
+/**
+  Writes a 16-bit PCI configuration register.
+
+  Writes the 16-bit PCI configuration register specified by Address with the
+  value specified by Value. Value is returned. This function must guarantee
+  that all PCI read and write operations are serialized.
+
+  If Address > 0x0FFFFFFF, then ASSERT().
+  If Address is not aligned on a 16-bit boundary, then ASSERT().
+
+  @param  Address The address that encodes the PCI Bus, Device, Function and
+                  Register.
+  @param  Value   The value to write.
+
+  @return The value written to the PCI configuration register.
+
+**/
+UINT16
+EFIAPI
+PciExpressWrite16 (
+  IN      UINTN   Address,
+  IN      UINT16  Value
+  )
+{
+  ASSERT_INVALID_PCI_ADDRESS (Address);
+  return MmioWrite16 ((UINTN)GetPciExpressBaseAddress () + Address, Value);
+}
+
+/**
+  Performs a bitwise OR of a 16-bit PCI configuration register with
+  a 16-bit value.
+
+  Reads the 16-bit PCI configuration register specified by Address, performs a
+  bitwise OR between the read result and the value specified by
+  OrData, and writes the result to the 16-bit PCI configuration register
+  specified by Address. The value written to the PCI configuration register is
+  returned. This function must guarantee that all PCI read and write operations
+  are serialized.
+
+  If Address > 0x0FFFFFFF, then ASSERT().
+  If Address is not aligned on a 16-bit boundary, then ASSERT().
+
+  @param  Address The address that encodes the PCI Bus, Device, Function and
+                  Register.
+  @param  OrData  The value to OR with the PCI configuration register.
+
+  @return The value written back to the PCI configuration register.
+
+**/
+UINT16
+EFIAPI
+PciExpressOr16 (
+  IN      UINTN   Address,
+  IN      UINT16  OrData
+  )
+{
+  ASSERT_INVALID_PCI_ADDRESS (Address);
+  return MmioOr16 ((UINTN)GetPciExpressBaseAddress () + Address, OrData);
+}
+
+/**
+  Performs a bitwise AND of a 16-bit PCI configuration register with a 16-bit
+  value.
+
+  Reads the 16-bit PCI configuration register specified by Address, performs a
+  bitwise AND between the read result and the value specified by AndData, and
+  writes the result to the 16-bit PCI configuration register specified by
+  Address. The value written to the PCI configuration register is returned.
+  This function must guarantee that all PCI read and write operations are
+  serialized.
+
+  If Address > 0x0FFFFFFF, then ASSERT().
+  If Address is not aligned on a 16-bit boundary, then ASSERT().
+
+  @param  Address The address that encodes the PCI Bus, Device, Function and
+                  Register.
+  @param  AndData The value to AND with the PCI configuration register.
+
+  @return The value written back to the PCI configuration register.
+
+**/
+UINT16
+EFIAPI
+PciExpressAnd16 (
+  IN      UINTN   Address,
+  IN      UINT16  AndData
+  )
+{
+  ASSERT_INVALID_PCI_ADDRESS (Address);
+  return MmioAnd16 ((UINTN)GetPciExpressBaseAddress () + Address, AndData);
+}
+
+/**
+  Performs a bitwise AND of a 16-bit PCI configuration register with a 16-bit
+  value, followed a  bitwise OR with another 16-bit value.
+
+  Reads the 16-bit PCI configuration register specified by Address, performs a
+  bitwise AND between the read result and the value specified by AndData,
+  performs a bitwise OR between the result of the AND operation and
+  the value specified by OrData, and writes the result to the 16-bit PCI
+  configuration register specified by Address. The value written to the PCI
+  configuration register is returned. This function must guarantee that all PCI
+  read and write operations are serialized.
+
+  If Address > 0x0FFFFFFF, then ASSERT().
+  If Address is not aligned on a 16-bit boundary, then ASSERT().
+
+  @param  Address The address that encodes the PCI Bus, Device, Function and
+                  Register.
+  @param  AndData The value to AND with the PCI configuration register.
+  @param  OrData  The value to OR with the result of the AND operation.
+
+  @return The value written back to the PCI configuration register.
+
+**/
+UINT16
+EFIAPI
+PciExpressAndThenOr16 (
+  IN      UINTN   Address,
+  IN      UINT16  AndData,
+  IN      UINT16  OrData
+  )
+{
+  ASSERT_INVALID_PCI_ADDRESS (Address);
+  return MmioAndThenOr16 (
+           (UINTN)GetPciExpressBaseAddress () + Address,
+           AndData,
+           OrData
+           );
+}
+
+/**
+  Reads a bit field of a PCI configuration register.
+
+  Reads the bit field in a 16-bit PCI configuration register. The bit field is
+  specified by the StartBit and the EndBit. The value of the bit field is
+  returned.
+
+  If Address > 0x0FFFFFFF, then ASSERT().
+  If Address is not aligned on a 16-bit boundary, then ASSERT().
+  If StartBit is greater than 15, then ASSERT().
+  If EndBit is greater than 15, then ASSERT().
+  If EndBit is less than StartBit, then ASSERT().
+
+  @param  Address   The PCI configuration register to read.
+  @param  StartBit  The ordinal of the least significant bit in the bit field.
+                    Range 0..15.
+  @param  EndBit    The ordinal of the most significant bit in the bit field.
+                    Range 0..15.
+
+  @return The value of the bit field read from the PCI configuration register.
+
+**/
+UINT16
+EFIAPI
+PciExpressBitFieldRead16 (
+  IN      UINTN  Address,
+  IN      UINTN  StartBit,
+  IN      UINTN  EndBit
+  )
+{
+  ASSERT_INVALID_PCI_ADDRESS (Address);
+  return MmioBitFieldRead16 (
+           (UINTN)GetPciExpressBaseAddress () + Address,
+           StartBit,
+           EndBit
+           );
+}
+
+/**
+  Writes a bit field to a PCI configuration register.
+
+  Writes Value to the bit field of the PCI configuration register. The bit
+  field is specified by the StartBit and the EndBit. All other bits in the
+  destination PCI configuration register are preserved. The new value of the
+  16-bit register is returned.
+
+  If Address > 0x0FFFFFFF, then ASSERT().
+  If Address is not aligned on a 16-bit boundary, then ASSERT().
+  If StartBit is greater than 15, then ASSERT().
+  If EndBit is greater than 15, then ASSERT().
+  If EndBit is less than StartBit, then ASSERT().
+  If Value is larger than the bitmask value range specified by StartBit and EndBit, then ASSERT().
+
+  @param  Address   The PCI configuration register to write.
+  @param  StartBit  The ordinal of the least significant bit in the bit field.
+                    Range 0..15.
+  @param  EndBit    The ordinal of the most significant bit in the bit field.
+                    Range 0..15.
+  @param  Value     The new value of the bit field.
+
+  @return The value written back to the PCI configuration register.
+
+**/
+UINT16
+EFIAPI
+PciExpressBitFieldWrite16 (
+  IN      UINTN   Address,
+  IN      UINTN   StartBit,
+  IN      UINTN   EndBit,
+  IN      UINT16  Value
+  )
+{
+  ASSERT_INVALID_PCI_ADDRESS (Address);
+  return MmioBitFieldWrite16 (
+           (UINTN)GetPciExpressBaseAddress () + Address,
+           StartBit,
+           EndBit,
+           Value
+           );
+}
+
+/**
+  Reads a bit field in a 16-bit PCI configuration, performs a bitwise OR, and
+  writes the result back to the bit field in the 16-bit port.
+
+  Reads the 16-bit PCI configuration register specified by Address, performs a
+  bitwise OR between the read result and the value specified by
+  OrData, and writes the result to the 16-bit PCI configuration register
+  specified by Address. The value written to the PCI configuration register is
+  returned. This function must guarantee that all PCI read and write operations
+  are serialized. Extra left bits in OrData are stripped.
+
+  If Address > 0x0FFFFFFF, then ASSERT().
+  If Address is not aligned on a 16-bit boundary, then ASSERT().
+  If StartBit is greater than 15, then ASSERT().
+  If EndBit is greater than 15, then ASSERT().
+  If EndBit is less than StartBit, then ASSERT().
+  If OrData is larger than the bitmask value range specified by StartBit and EndBit, then ASSERT().
+
+  @param  Address   The PCI configuration register to write.
+  @param  StartBit  The ordinal of the least significant bit in the bit field.
+                    Range 0..15.
+  @param  EndBit    The ordinal of the most significant bit in the bit field.
+                    Range 0..15.
+  @param  OrData    The value to OR with the PCI configuration register.
+
+  @return The value written back to the PCI configuration register.
+
+**/
+UINT16
+EFIAPI
+PciExpressBitFieldOr16 (
+  IN      UINTN   Address,
+  IN      UINTN   StartBit,
+  IN      UINTN   EndBit,
+  IN      UINT16  OrData
+  )
+{
+  ASSERT_INVALID_PCI_ADDRESS (Address);
+  return MmioBitFieldOr16 (
+           (UINTN)GetPciExpressBaseAddress () + Address,
+           StartBit,
+           EndBit,
+           OrData
+           );
+}
+
+/**
+  Reads a bit field in a 16-bit PCI configuration register, performs a bitwise
+  AND, and writes the result back to the bit field in the 16-bit register.
+
+  Reads the 16-bit PCI configuration register specified by Address, performs a
+  bitwise AND between the read result and the value specified by AndData, and
+  writes the result to the 16-bit PCI configuration register specified by
+  Address. The value written to the PCI configuration register is returned.
+  This function must guarantee that all PCI read and write operations are
+  serialized. Extra left bits in AndData are stripped.
+
+  If Address > 0x0FFFFFFF, then ASSERT().
+  If Address is not aligned on a 16-bit boundary, then ASSERT().
+  If StartBit is greater than 15, then ASSERT().
+  If EndBit is greater than 15, then ASSERT().
+  If EndBit is less than StartBit, then ASSERT().
+  If AndData is larger than the bitmask value range specified by StartBit and EndBit, then ASSERT().
+
+  @param  Address   The PCI configuration register to write.
+  @param  StartBit  The ordinal of the least significant bit in the bit field.
+                    Range 0..15.
+  @param  EndBit    The ordinal of the most significant bit in the bit field.
+                    Range 0..15.
+  @param  AndData   The value to AND with the PCI configuration register.
+
+  @return The value written back to the PCI configuration register.
+
+**/
+UINT16
+EFIAPI
+PciExpressBitFieldAnd16 (
+  IN      UINTN   Address,
+  IN      UINTN   StartBit,
+  IN      UINTN   EndBit,
+  IN      UINT16  AndData
+  )
+{
+  ASSERT_INVALID_PCI_ADDRESS (Address);
+  return MmioBitFieldAnd16 (
+           (UINTN)GetPciExpressBaseAddress () + Address,
+           StartBit,
+           EndBit,
+           AndData
+           );
+}
+
+/**
+  Reads a bit field in a 16-bit port, performs a bitwise AND followed by a
+  bitwise OR, and writes the result back to the bit field in the
+  16-bit port.
+
+  Reads the 16-bit PCI configuration register specified by Address, performs a
+  bitwise AND followed by a bitwise OR between the read result and
+  the value specified by AndData, and writes the result to the 16-bit PCI
+  configuration register specified by Address. The value written to the PCI
+  configuration register is returned. This function must guarantee that all PCI
+  read and write operations are serialized. Extra left bits in both AndData and
+  OrData are stripped.
+
+  If Address > 0x0FFFFFFF, then ASSERT().
+  If Address is not aligned on a 16-bit boundary, then ASSERT().
+  If StartBit is greater than 15, then ASSERT().
+  If EndBit is greater than 15, then ASSERT().
+  If EndBit is less than StartBit, then ASSERT().
+  If AndData is larger than the bitmask value range specified by StartBit and EndBit, then ASSERT().
+  If OrData is larger than the bitmask value range specified by StartBit and EndBit, then ASSERT().
+
+  @param  Address   The PCI configuration register to write.
+  @param  StartBit  The ordinal of the least significant bit in the bit field.
+                    Range 0..15.
+  @param  EndBit    The ordinal of the most significant bit in the bit field.
+                    Range 0..15.
+  @param  AndData   The value to AND with the PCI configuration register.
+  @param  OrData    The value to OR with the result of the AND operation.
+
+  @return The value written back to the PCI configuration register.
+
+**/
+UINT16
+EFIAPI
+PciExpressBitFieldAndThenOr16 (
+  IN      UINTN   Address,
+  IN      UINTN   StartBit,
+  IN      UINTN   EndBit,
+  IN      UINT16  AndData,
+  IN      UINT16  OrData
+  )
+{
+  ASSERT_INVALID_PCI_ADDRESS (Address);
+  return MmioBitFieldAndThenOr16 (
+           (UINTN)GetPciExpressBaseAddress () + Address,
+           StartBit,
+           EndBit,
+           AndData,
+           OrData
+           );
+}
+
+/**
+  Reads a 32-bit PCI configuration register.
+
+  Reads and returns the 32-bit PCI configuration register specified by Address.
+  This function must guarantee that all PCI read and write operations are
+  serialized.
+
+  If Address > 0x0FFFFFFF, then ASSERT().
+  If Address is not aligned on a 32-bit boundary, then ASSERT().
+
+  @param  Address The address that encodes the PCI Bus, Device, Function and
+                  Register.
+
+  @return The read value from the PCI configuration register.
+
+**/
+UINT32
+EFIAPI
+PciExpressRead32 (
+  IN      UINTN  Address
+  )
+{
+  ASSERT_INVALID_PCI_ADDRESS (Address);
+  return MmioRead32 ((UINTN)GetPciExpressBaseAddress () + Address);
+}
+
+/**
+  Writes a 32-bit PCI configuration register.
+
+  Writes the 32-bit PCI configuration register specified by Address with the
+  value specified by Value. Value is returned. This function must guarantee
+  that all PCI read and write operations are serialized.
+
+  If Address > 0x0FFFFFFF, then ASSERT().
+  If Address is not aligned on a 32-bit boundary, then ASSERT().
+
+  @param  Address The address that encodes the PCI Bus, Device, Function and
+                  Register.
+  @param  Value   The value to write.
+
+  @return The value written to the PCI configuration register.
+
+**/
+UINT32
+EFIAPI
+PciExpressWrite32 (
+  IN      UINTN   Address,
+  IN      UINT32  Value
+  )
+{
+  ASSERT_INVALID_PCI_ADDRESS (Address);
+  return MmioWrite32 ((UINTN)GetPciExpressBaseAddress () + Address, Value);
+}
+
+/**
+  Performs a bitwise OR of a 32-bit PCI configuration register with
+  a 32-bit value.
+
+  Reads the 32-bit PCI configuration register specified by Address, performs a
+  bitwise OR between the read result and the value specified by
+  OrData, and writes the result to the 32-bit PCI configuration register
+  specified by Address. The value written to the PCI configuration register is
+  returned. This function must guarantee that all PCI read and write operations
+  are serialized.
+
+  If Address > 0x0FFFFFFF, then ASSERT().
+  If Address is not aligned on a 32-bit boundary, then ASSERT().
+
+  @param  Address The address that encodes the PCI Bus, Device, Function and
+                  Register.
+  @param  OrData  The value to OR with the PCI configuration register.
+
+  @return The value written back to the PCI configuration register.
+
+**/
+UINT32
+EFIAPI
+PciExpressOr32 (
+  IN      UINTN   Address,
+  IN      UINT32  OrData
+  )
+{
+  ASSERT_INVALID_PCI_ADDRESS (Address);
+  return MmioOr32 ((UINTN)GetPciExpressBaseAddress () + Address, OrData);
+}
+
+/**
+  Performs a bitwise AND of a 32-bit PCI configuration register with a 32-bit
+  value.
+
+  Reads the 32-bit PCI configuration register specified by Address, performs a
+  bitwise AND between the read result and the value specified by AndData, and
+  writes the result to the 32-bit PCI configuration register specified by
+  Address. The value written to the PCI configuration register is returned.
+  This function must guarantee that all PCI read and write operations are
+  serialized.
+
+  If Address > 0x0FFFFFFF, then ASSERT().
+  If Address is not aligned on a 32-bit boundary, then ASSERT().
+
+  @param  Address The address that encodes the PCI Bus, Device, Function and
+                  Register.
+  @param  AndData The value to AND with the PCI configuration register.
+
+  @return The value written back to the PCI configuration register.
+
+**/
+UINT32
+EFIAPI
+PciExpressAnd32 (
+  IN      UINTN   Address,
+  IN      UINT32  AndData
+  )
+{
+  ASSERT_INVALID_PCI_ADDRESS (Address);
+  return MmioAnd32 ((UINTN)GetPciExpressBaseAddress () + Address, AndData);
+}
+
+/**
+  Performs a bitwise AND of a 32-bit PCI configuration register with a 32-bit
+  value, followed a  bitwise OR with another 32-bit value.
+
+  Reads the 32-bit PCI configuration register specified by Address, performs a
+  bitwise AND between the read result and the value specified by AndData,
+  performs a bitwise OR between the result of the AND operation and
+  the value specified by OrData, and writes the result to the 32-bit PCI
+  configuration register specified by Address. The value written to the PCI
+  configuration register is returned. This function must guarantee that all PCI
+  read and write operations are serialized.
+
+  If Address > 0x0FFFFFFF, then ASSERT().
+  If Address is not aligned on a 32-bit boundary, then ASSERT().
+
+  @param  Address The address that encodes the PCI Bus, Device, Function and
+                  Register.
+  @param  AndData The value to AND with the PCI configuration register.
+  @param  OrData  The value to OR with the result of the AND operation.
+
+  @return The value written back to the PCI configuration register.
+
+**/
+UINT32
+EFIAPI
+PciExpressAndThenOr32 (
+  IN      UINTN   Address,
+  IN      UINT32  AndData,
+  IN      UINT32  OrData
+  )
+{
+  ASSERT_INVALID_PCI_ADDRESS (Address);
+  return MmioAndThenOr32 (
+           (UINTN)GetPciExpressBaseAddress () + Address,
+           AndData,
+           OrData
+           );
+}
+
+/**
+  Reads a bit field of a PCI configuration register.
+
+  Reads the bit field in a 32-bit PCI configuration register. The bit field is
+  specified by the StartBit and the EndBit. The value of the bit field is
+  returned.
+
+  If Address > 0x0FFFFFFF, then ASSERT().
+  If Address is not aligned on a 32-bit boundary, then ASSERT().
+  If StartBit is greater than 31, then ASSERT().
+  If EndBit is greater than 31, then ASSERT().
+  If EndBit is less than StartBit, then ASSERT().
+
+  @param  Address   The PCI configuration register to read.
+  @param  StartBit  The ordinal of the least significant bit in the bit field.
+                    Range 0..31.
+  @param  EndBit    The ordinal of the most significant bit in the bit field.
+                    Range 0..31.
+
+  @return The value of the bit field read from the PCI configuration register.
+
+**/
+UINT32
+EFIAPI
+PciExpressBitFieldRead32 (
+  IN      UINTN  Address,
+  IN      UINTN  StartBit,
+  IN      UINTN  EndBit
+  )
+{
+  ASSERT_INVALID_PCI_ADDRESS (Address);
+  return MmioBitFieldRead32 (
+           (UINTN)GetPciExpressBaseAddress () + Address,
+           StartBit,
+           EndBit
+           );
+}
+
+/**
+  Writes a bit field to a PCI configuration register.
+
+  Writes Value to the bit field of the PCI configuration register. The bit
+  field is specified by the StartBit and the EndBit. All other bits in the
+  destination PCI configuration register are preserved. The new value of the
+  32-bit register is returned.
+
+  If Address > 0x0FFFFFFF, then ASSERT().
+  If Address is not aligned on a 32-bit boundary, then ASSERT().
+  If StartBit is greater than 31, then ASSERT().
+  If EndBit is greater than 31, then ASSERT().
+  If EndBit is less than StartBit, then ASSERT().
+  If Value is larger than the bitmask value range specified by StartBit and EndBit, then ASSERT().
+
+  @param  Address   The PCI configuration register to write.
+  @param  StartBit  The ordinal of the least significant bit in the bit field.
+                    Range 0..31.
+  @param  EndBit    The ordinal of the most significant bit in the bit field.
+                    Range 0..31.
+  @param  Value     The new value of the bit field.
+
+  @return The value written back to the PCI configuration register.
+
+**/
+UINT32
+EFIAPI
+PciExpressBitFieldWrite32 (
+  IN      UINTN   Address,
+  IN      UINTN   StartBit,
+  IN      UINTN   EndBit,
+  IN      UINT32  Value
+  )
+{
+  ASSERT_INVALID_PCI_ADDRESS (Address);
+  return MmioBitFieldWrite32 (
+           (UINTN)GetPciExpressBaseAddress () + Address,
+           StartBit,
+           EndBit,
+           Value
+           );
+}
+
+/**
+  Reads a bit field in a 32-bit PCI configuration, performs a bitwise OR, and
+  writes the result back to the bit field in the 32-bit port.
+
+  Reads the 32-bit PCI configuration register specified by Address, performs a
+  bitwise OR between the read result and the value specified by
+  OrData, and writes the result to the 32-bit PCI configuration register
+  specified by Address. The value written to the PCI configuration register is
+  returned. This function must guarantee that all PCI read and write operations
+  are serialized. Extra left bits in OrData are stripped.
+
+  If Address > 0x0FFFFFFF, then ASSERT().
+  If Address is not aligned on a 32-bit boundary, then ASSERT().
+  If StartBit is greater than 31, then ASSERT().
+  If EndBit is greater than 31, then ASSERT().
+  If EndBit is less than StartBit, then ASSERT().
+  If OrData is larger than the bitmask value range specified by StartBit and EndBit, then ASSERT().
+
+  @param  Address   The PCI configuration register to write.
+  @param  StartBit  The ordinal of the least significant bit in the bit field.
+                    Range 0..31.
+  @param  EndBit    The ordinal of the most significant bit in the bit field.
+                    Range 0..31.
+  @param  OrData    The value to OR with the PCI configuration register.
+
+  @return The value written back to the PCI configuration register.
+
+**/
+UINT32
+EFIAPI
+PciExpressBitFieldOr32 (
+  IN      UINTN   Address,
+  IN      UINTN   StartBit,
+  IN      UINTN   EndBit,
+  IN      UINT32  OrData
+  )
+{
+  ASSERT_INVALID_PCI_ADDRESS (Address);
+  return MmioBitFieldOr32 (
+           (UINTN)GetPciExpressBaseAddress () + Address,
+           StartBit,
+           EndBit,
+           OrData
+           );
+}
+
+/**
+  Reads a bit field in a 32-bit PCI configuration register, performs a bitwise
+  AND, and writes the result back to the bit field in the 32-bit register.
+
+  Reads the 32-bit PCI configuration register specified by Address, performs a
+  bitwise AND between the read result and the value specified by AndData, and
+  writes the result to the 32-bit PCI configuration register specified by
+  Address. The value written to the PCI configuration register is returned.
+  This function must guarantee that all PCI read and write operations are
+  serialized. Extra left bits in AndData are stripped.
+
+  If Address > 0x0FFFFFFF, then ASSERT().
+  If Address is not aligned on a 32-bit boundary, then ASSERT().
+  If StartBit is greater than 31, then ASSERT().
+  If EndBit is greater than 31, then ASSERT().
+  If EndBit is less than StartBit, then ASSERT().
+  If AndData is larger than the bitmask value range specified by StartBit and EndBit, then ASSERT().
+
+  @param  Address   The PCI configuration register to write.
+  @param  StartBit  The ordinal of the least significant bit in the bit field.
+                    Range 0..31.
+  @param  EndBit    The ordinal of the most significant bit in the bit field.
+                    Range 0..31.
+  @param  AndData   The value to AND with the PCI configuration register.
+
+  @return The value written back to the PCI configuration register.
+
+**/
+UINT32
+EFIAPI
+PciExpressBitFieldAnd32 (
+  IN      UINTN   Address,
+  IN      UINTN   StartBit,
+  IN      UINTN   EndBit,
+  IN      UINT32  AndData
+  )
+{
+  ASSERT_INVALID_PCI_ADDRESS (Address);
+  return MmioBitFieldAnd32 (
+           (UINTN)GetPciExpressBaseAddress () + Address,
+           StartBit,
+           EndBit,
+           AndData
+           );
+}
+
+/**
+  Reads a bit field in a 32-bit port, performs a bitwise AND followed by a
+  bitwise OR, and writes the result back to the bit field in the
+  32-bit port.
+
+  Reads the 32-bit PCI configuration register specified by Address, performs a
+  bitwise AND followed by a bitwise OR between the read result and
+  the value specified by AndData, and writes the result to the 32-bit PCI
+  configuration register specified by Address. The value written to the PCI
+  configuration register is returned. This function must guarantee that all PCI
+  read and write operations are serialized. Extra left bits in both AndData and
+  OrData are stripped.
+
+  If Address > 0x0FFFFFFF, then ASSERT().
+  If Address is not aligned on a 32-bit boundary, then ASSERT().
+  If StartBit is greater than 31, then ASSERT().
+  If EndBit is greater than 31, then ASSERT().
+  If EndBit is less than StartBit, then ASSERT().
+  If AndData is larger than the bitmask value range specified by StartBit and EndBit, then ASSERT().
+  If OrData is larger than the bitmask value range specified by StartBit and EndBit, then ASSERT().
+
+  @param  Address   The PCI configuration register to write.
+  @param  StartBit  The ordinal of the least significant bit in the bit field.
+                    Range 0..31.
+  @param  EndBit    The ordinal of the most significant bit in the bit field.
+                    Range 0..31.
+  @param  AndData   The value to AND with the PCI configuration register.
+  @param  OrData    The value to OR with the result of the AND operation.
+
+  @return The value written back to the PCI configuration register.
+
+**/
+UINT32
+EFIAPI
+PciExpressBitFieldAndThenOr32 (
+  IN      UINTN   Address,
+  IN      UINTN   StartBit,
+  IN      UINTN   EndBit,
+  IN      UINT32  AndData,
+  IN      UINT32  OrData
+  )
+{
+  ASSERT_INVALID_PCI_ADDRESS (Address);
+  return MmioBitFieldAndThenOr32 (
+           (UINTN)GetPciExpressBaseAddress () + Address,
+           StartBit,
+           EndBit,
+           AndData,
+           OrData
+           );
+}
+
+/**
+  Reads a range of PCI configuration registers into a caller supplied buffer.
+
+  Reads the range of PCI configuration registers specified by StartAddress and
+  Size into the buffer specified by Buffer. This function only allows the PCI
+  configuration registers from a single PCI function to be read. Size is
+  returned. When possible 32-bit PCI configuration read cycles are used to read
+  from StartAddress to StartAddress + Size. Due to alignment restrictions, 8-bit
+  and 16-bit PCI configuration read cycles may be used at the beginning and the
+  end of the range.
+
+  If StartAddress > 0x0FFFFFFF, then ASSERT().
+  If ((StartAddress & 0xFFF) + Size) > 0x1000, then ASSERT().
+  If Size > 0 and Buffer is NULL, then ASSERT().
+
+  @param  StartAddress  The starting address that encodes the PCI Bus, Device,
+                        Function and Register.
+  @param  Size          The size in bytes of the transfer.
+  @param  Buffer        The pointer to a buffer receiving the data read.
+
+  @return Size read data from StartAddress.
+
+**/
+UINTN
+EFIAPI
+PciExpressReadBuffer (
+  IN      UINTN  StartAddress,
+  IN      UINTN  Size,
+  OUT     VOID   *Buffer
+  )
+{
+  UINTN  ReturnValue;
+
+  ASSERT_INVALID_PCI_ADDRESS (StartAddress);
+  ASSERT (((StartAddress & 0xFFF) + Size) <= 0x1000);
+
+  if (Size == 0) {
+    return Size;
+  }
+
+  ASSERT (Buffer != NULL);
+
+  //
+  // Save Size for return
+  //
+  ReturnValue = Size;
+
+  if ((StartAddress & 1) != 0) {
+    //
+    // Read a byte if StartAddress is byte aligned
+    //
+    *(volatile UINT8 *)Buffer = PciExpressRead8 (StartAddress);
+    StartAddress             += sizeof (UINT8);
+    Size                     -= sizeof (UINT8);
+    Buffer                    = (UINT8 *)Buffer + 1;
+  }
+
+  if ((Size >= sizeof (UINT16)) && ((StartAddress & 2) != 0)) {
+    //
+    // Read a word if StartAddress is word aligned
+    //
+    WriteUnaligned16 ((UINT16 *)Buffer, (UINT16)PciExpressRead16 (StartAddress));
+
+    StartAddress += sizeof (UINT16);
+    Size         -= sizeof (UINT16);
+    Buffer        = (UINT16 *)Buffer + 1;
+  }
+
+  while (Size >= sizeof (UINT32)) {
+    //
+    // Read as many double words as possible
+    //
+    WriteUnaligned32 ((UINT32 *)Buffer, (UINT32)PciExpressRead32 (StartAddress));
+
+    StartAddress += sizeof (UINT32);
+    Size         -= sizeof (UINT32);
+    Buffer        = (UINT32 *)Buffer + 1;
+  }
+
+  if (Size >= sizeof (UINT16)) {
+    //
+    // Read the last remaining word if exist
+    //
+    WriteUnaligned16 ((UINT16 *)Buffer, (UINT16)PciExpressRead16 (StartAddress));
+    StartAddress += sizeof (UINT16);
+    Size         -= sizeof (UINT16);
+    Buffer        = (UINT16 *)Buffer + 1;
+  }
+
+  if (Size >= sizeof (UINT8)) {
+    //
+    // Read the last remaining byte if exist
+    //
+    *(volatile UINT8 *)Buffer = PciExpressRead8 (StartAddress);
+  }
+
+  return ReturnValue;
+}
+
+/**
+  Copies the data in a caller supplied buffer to a specified range of PCI
+  configuration space.
+
+  Writes the range of PCI configuration registers specified by StartAddress and
+  Size from the buffer specified by Buffer. This function only allows the PCI
+  configuration registers from a single PCI function to be written. Size is
+  returned. When possible 32-bit PCI configuration write cycles are used to
+  write from StartAddress to StartAddress + Size. Due to alignment restrictions,
+  8-bit and 16-bit PCI configuration write cycles may be used at the beginning
+  and the end of the range.
+
+  If StartAddress > 0x0FFFFFFF, then ASSERT().
+  If ((StartAddress & 0xFFF) + Size) > 0x1000, then ASSERT().
+  If Size > 0 and Buffer is NULL, then ASSERT().
+
+  @param  StartAddress  The starting address that encodes the PCI Bus, Device,
+                        Function and Register.
+  @param  Size          The size in bytes of the transfer.
+  @param  Buffer        The pointer to a buffer containing the data to write.
+
+  @return Size written to StartAddress.
+
+**/
+UINTN
+EFIAPI
+PciExpressWriteBuffer (
+  IN      UINTN  StartAddress,
+  IN      UINTN  Size,
+  IN      VOID   *Buffer
+  )
+{
+  UINTN  ReturnValue;
+
+  ASSERT_INVALID_PCI_ADDRESS (StartAddress);
+  ASSERT (((StartAddress & 0xFFF) + Size) <= 0x1000);
+
+  if (Size == 0) {
+    return 0;
+  }
+
+  ASSERT (Buffer != NULL);
+
+  //
+  // Save Size for return
+  //
+  ReturnValue = Size;
+
+  if ((StartAddress & 1) != 0) {
+    //
+    // Write a byte if StartAddress is byte aligned
+    //
+    PciExpressWrite8 (StartAddress, *(UINT8 *)Buffer);
+    StartAddress += sizeof (UINT8);
+    Size         -= sizeof (UINT8);
+    Buffer        = (UINT8 *)Buffer + 1;
+  }
+
+  if ((Size >= sizeof (UINT16)) && ((StartAddress & 2) != 0)) {
+    //
+    // Write a word if StartAddress is word aligned
+    //
+    PciExpressWrite16 (StartAddress, ReadUnaligned16 ((UINT16 *)Buffer));
+    StartAddress += sizeof (UINT16);
+    Size         -= sizeof (UINT16);
+    Buffer        = (UINT16 *)Buffer + 1;
+  }
+
+  while (Size >= sizeof (UINT32)) {
+    //
+    // Write as many double words as possible
+    //
+    PciExpressWrite32 (StartAddress, ReadUnaligned32 ((UINT32 *)Buffer));
+    StartAddress += sizeof (UINT32);
+    Size         -= sizeof (UINT32);
+    Buffer        = (UINT32 *)Buffer + 1;
+  }
+
+  if (Size >= sizeof (UINT16)) {
+    //
+    // Write the last remaining word if exist
+    //
+    PciExpressWrite16 (StartAddress, ReadUnaligned16 ((UINT16 *)Buffer));
+    StartAddress += sizeof (UINT16);
+    Size         -= sizeof (UINT16);
+    Buffer        = (UINT16 *)Buffer + 1;
+  }
+
+  if (Size >= sizeof (UINT8)) {
+    //
+    // Write the last remaining byte if exist
+    //
+    PciExpressWrite8 (StartAddress, *(UINT8 *)Buffer);
+  }
+
+  return ReturnValue;
+}
-- 
2.31.1