Re: [edk2-devel] [PATCH v2 RESEND 2/4] Platform/AMD/PlatformPkg: Adds PciHotPlug init protocol implementation

["Leif Lindholm" <quic_llindhol@quicinc.com>]

On Fri, Mar 17, 2023 at 12:20:05 +0530, Abdul Lateef Attar via groups.io wrote:
> Adds PCI hotplug init protocol implementation.

What are some notable aspects of this initial implementation?
What groups of platforms is it intended to cover?

> Signed-off-by: Abdul Lateef Attar <abdattar@amd.com>
> Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
> Cc: Leif Lindholm <quic_llindhol@quicinc.com>
> Cc: Abner Chang <abner.chang@amd.com>
> Cc: Michael D Kinney <michael.d.kinney@intel.com>
> ---
>  Platform/AMD/PlatformPkg/PlatformPkg.dec      |  16 +
>  Platform/AMD/PlatformPkg/PlatformPkg.dsc      |  23 ++
>  .../PlatformPkg/PciHotPlug/PciHotPlugInit.inf |  41 +++
>  .../PlatformPkg/PciHotPlug/PciHotPlugInit.c   | 340 ++++++++++++++++++
>  4 files changed, 420 insertions(+)
>  create mode 100644 Platform/AMD/PlatformPkg/PciHotPlug/PciHotPlugInit.inf
>  create mode 100644 Platform/AMD/PlatformPkg/PciHotPlug/PciHotPlugInit.c
> 
> diff --git a/Platform/AMD/PlatformPkg/PlatformPkg.dec b/Platform/AMD/PlatformPkg/PlatformPkg.dec
> index 6155860979cb..1bc38d6025c3 100644
> --- a/Platform/AMD/PlatformPkg/PlatformPkg.dec
> +++ b/Platform/AMD/PlatformPkg/PlatformPkg.dec
> @@ -13,3 +13,19 @@ [Defines]
>    PACKAGE_NAME                   = PlatformPkg
>    PACKAGE_GUID                   = 38FBA311-E2AA-4620-9A90-9A23753D1878
>    PACKAGE_VERSION                = 0.1
> +
> +[Guids]
> +  gPlatformPkgTokenSpaceGuid     = { 0x95ECA58D, 0x09B6, 0x4420, { 0xB4, 0xE7, 0x01, 0x7F, 0x6A, 0x5B, 0x26, 0x0F }}
> +
> +[PcdsDynamic, PcdsDynamicEx]
> +  #
> +  # PCI HotPlug Resource Padding
> +  #
> +  # IO Resource padding in bytes, default 4KB
> +  gPlatformPkgTokenSpaceGuid.PcdPciHotPlugResourcePadIO|0x00001000|UINT64|0x10000000
> +  # PreFetch Memory padding in bytes, default 2MB
> +  gPlatformPkgTokenSpaceGuid.PcdPciHotPlugResourcePadPMem|0x00200000|UINT64|0x10000001
> +  # Non-PreFetch Memory padding in bytes, default 1MB
> +  gPlatformPkgTokenSpaceGuid.PcdPciHotPlugResourcePadMem|0x00100000|UINT64|0x10000002
> +  # PCI bus padding, number of bus to reserve, default 2 bus
> +  gPlatformPkgTokenSpaceGuid.PcdPciHotPlugResourcePadBus|2|UINT8|0x10000003
> diff --git a/Platform/AMD/PlatformPkg/PlatformPkg.dsc b/Platform/AMD/PlatformPkg/PlatformPkg.dsc
> index 704566b9ea73..9a693070ab3f 100644
> --- a/Platform/AMD/PlatformPkg/PlatformPkg.dsc
> +++ b/Platform/AMD/PlatformPkg/PlatformPkg.dsc
> @@ -16,5 +16,28 @@ [Defines]
>    BUILD_TARGETS               = DEBUG | RELEASE | NOOPT
>    SUPPORTED_ARCHITECTURES     = IA32 | X64
>  
> +

Please don't add spurious whitespaces.

>  [Packages]
>    PlatformPkg/PlatformPkg.dec
> +  MdeModulePkg/MdeModulePkg.dec
> +  MdePkg/MdePkg.dec

I won't be maintaining this code, but I generally advocate sorting
these types of enumerations alphabetically in order to speed up reading.

(That's not really possible for the block below.)

> +
> +[LibraryClasses.Common]
> +  UefiDriverEntryPoint|MdePkg/Library/UefiDriverEntryPoint/UefiDriverEntryPoint.inf
> +  UefiBootServicesTableLib|MdePkg/Library/UefiBootServicesTableLib/UefiBootServicesTableLib.inf
> +  DebugLib|MdePkg/Library/BaseDebugLibSerialPort/BaseDebugLibSerialPort.inf
> +  MemoryAllocationLib|MdePkg/Library/UefiMemoryAllocationLib/UefiMemoryAllocationLib.inf
> +  BaseMemoryLib|MdePkg/Library/BaseMemoryLib/BaseMemoryLib.inf
> +  BaseLib|MdePkg/Library/BaseLib/BaseLib.inf
> +  PcdLib|MdePkg/Library/DxePcdLib/DxePcdLib.inf
> +  RegisterFilterLib|MdePkg/Library/RegisterFilterLibNull/RegisterFilterLibNull.inf
> +  SerialPortLib|MdeModulePkg/Library/BaseSerialPortLib16550/BaseSerialPortLib16550.inf
> +  PrintLib|MdePkg/Library/BasePrintLib/BasePrintLib.inf
> +  DebugPrintErrorLevelLib|MdePkg/Library/BaseDebugPrintErrorLevelLib/BaseDebugPrintErrorLevelLib.inf
> +  IoLib|MdePkg/Library/BaseIoLibIntrinsic/BaseIoLibIntrinsic.inf
> +  PlatformHookLib|MdeModulePkg/Library/BasePlatformHookLibNull/BasePlatformHookLibNull.inf
> +  PciLib|MdePkg/Library/BasePciLibPciExpress/BasePciLibPciExpress.inf
> +  PciExpressLib|MdePkg/Library/BasePciExpressLib/BasePciExpressLib.inf
> +
> +[Components.X64]
> +  PlatformPkg/PciHotPlug/PciHotPlugInit.inf
> diff --git a/Platform/AMD/PlatformPkg/PciHotPlug/PciHotPlugInit.inf b/Platform/AMD/PlatformPkg/PciHotPlug/PciHotPlugInit.inf
> new file mode 100644
> index 000000000000..0079c4acf14e
> --- /dev/null
> +++ b/Platform/AMD/PlatformPkg/PciHotPlug/PciHotPlugInit.inf
> @@ -0,0 +1,41 @@
> +## @file
> +# This driver implements EFI_PCI_HOT_PLUG_INIT_PROTOCOL.
> +# Adds resource padding information, for PCIe hotplug purposes.
> +#
> +# Copyright (C) 2023 Advanced Micro Devices, Inc. All rights reserved
> +# SPDX-License-Identifier: BSD-2-Clause-Patent
> +##
> +
> +[Defines]
> +  INF_VERSION                    = 1.29
> +  BASE_NAME                      = PciHotPlugInit
> +  FILE_GUID                      = 8B67D95F-78B7-484F-8F16-5F22AB388B0C
> +  MODULE_TYPE                    = DXE_DRIVER
> +  VERSION_STRING                 = 0.1
> +  ENTRY_POINT                    = PciHotPlugInitialize
> +
> +[Sources]
> +  PciHotPlugInit.c
> +
> +[Packages]
> +  MdeModulePkg/MdeModulePkg.dec
> +  MdePkg/MdePkg.dec
> +  PlatformPkg/PlatformPkg.dec

But these would benefit from sorting

> +
> +[LibraryClasses]
> +  UefiDriverEntryPoint
> +  UefiBootServicesTableLib
> +  DebugLib
> +  MemoryAllocationLib

And these

> +
> +[Protocols]
> +  gEfiPciHotPlugInitProtocolGuid
> +
> +[Pcd]
> +  gPlatformPkgTokenSpaceGuid.PcdPciHotPlugResourcePadIO
> +  gPlatformPkgTokenSpaceGuid.PcdPciHotPlugResourcePadPMem
> +  gPlatformPkgTokenSpaceGuid.PcdPciHotPlugResourcePadMem
> +  gPlatformPkgTokenSpaceGuid.PcdPciHotPlugResourcePadBus
> +
> +[Depex]
> +  TRUE
> diff --git a/Platform/AMD/PlatformPkg/PciHotPlug/PciHotPlugInit.c b/Platform/AMD/PlatformPkg/PciHotPlug/PciHotPlugInit.c
> new file mode 100644
> index 000000000000..b977406bbcae
> --- /dev/null
> +++ b/Platform/AMD/PlatformPkg/PciHotPlug/PciHotPlugInit.c
> @@ -0,0 +1,340 @@
> +/** @file
> +  This file declares EFI PCI Hot Plug Init Protocol.
> +
> +  This protocol provides the necessary functionality to initialize the Hot Plug
> +  Controllers (HPCs) and the buses that they control. This protocol also provides
> +  information regarding resource padding.
> +
> +  @par Note:
> +    This source has the reference of OVMF PciHotPluginit.c and Intel platform PciHotPlug.c.
> +
> +    This protocol is required only on platforms that support one or more PCI Hot
> +    Plug* slots or CardBus sockets.
> +
> +  The EFI_PCI_HOT_PLUG_INIT_PROTOCOL provides a mechanism for the PCI bus enumerator
> +  to properly initialize the HPCs and CardBus sockets that require initialization.
> +  The HPC initialization takes place before the PCI enumeration process is complete.
> +  There cannot be more than one instance of this protocol in a system. This protocol
> +  is installed on its own separate handle.
> +
> +  Because the system may include multiple HPCs, one instance of this protocol
> +  should represent all of them. The protocol functions use the device path of
> +  the HPC to identify the HPC. When the PCI bus enumerator finds a root HPC, it
> +  will call EFI_PCI_HOT_PLUG_INIT_PROTOCOL.InitializeRootHpc(). If InitializeRootHpc()
> +  is unable to initialize a root HPC, the PCI enumerator will ignore that root HPC
> +  and continue the enumeration process. If the HPC is not initialized, the devices
> +  that it controls may not be initialized, and no resource padding will be provided.
> +
> +  From the standpoint of the PCI bus enumerator, HPCs are divided into the following
> +  two classes:
> +
> +    - Root HPC:
> +        These HPCs must be initialized by calling InitializeRootHpc() during the
> +        enumeration process. These HPCs will also require resource padding. The
> +        platform code must have a priori knowledge of these devices and must know
> +        how to initialize them. There may not be any way to access their PCI
> +        configuration space before the PCI enumerator programs all the upstream
> +        bridges and thus enables the path to these devices. The PCI bus enumerator
> +        is responsible for determining the PCI bus address of the HPC before it
> +        calls InitializeRootHpc().
> +    - Nonroot HPC:
> +        These HPCs will not need explicit initialization during enumeration process.
> +        These HPCs will require resource padding. The platform code does not have
> +        to have a priori knowledge of these devices.
> +
> +  Copyright (c) 2007 - 2018, Intel Corporation. All rights reserved.<BR>
> +  Copyright (C) 2016, Red Hat, Inc.<BR>
> +  Copyright (C) 2023 Advanced Micro Devices, Inc. All rights reserved.<BR>
> +  SPDX-License-Identifier: BSD-2-Clause-Patent
> +
> +  @par Revision Reference:
> +  This Protocol is defined in UEFI Platform Initialization Specification 1.2

I know you say above that this is based on existing code, but 1.2 is
ancient. Latest version is 1.7 - is there anything missing from being
compliant with that version?

> +  Volume 5: Standards
> +
> +**/
> +
> +#include <Uefi/UefiBaseType.h>
> +#include <Uefi/UefiSpec.h>
> +#include <Library/UefiBootServicesTableLib.h>
> +#include <Library/DebugLib.h>
> +#include <Library/MemoryAllocationLib.h>

I (personally) also like to sort include files within each
Uefi/Library/Protocol group alphabetically.

/
    Leif

> +#include <Protocol/PciHotPlugInit.h>
> +
> +//
> +// The protocol interface this driver produces.
> +//
> +STATIC EFI_PCI_HOT_PLUG_INIT_PROTOCOL  mPciHotPlugInit;
> +
> +/**
> +  Returns a list of root Hot Plug Controllers (HPCs) that require initialization
> +  during the boot process.
> +
> +  This procedure returns a list of root HPCs. The PCI bus driver must initialize
> +  these controllers during the boot process. The PCI bus driver may or may not be
> +  able to detect these HPCs. If the platform includes a PCI-to-CardBus bridge, it
> +  can be included in this list if it requires initialization.  The HpcList must be
> +  self consistent. An HPC cannot control any of its parent buses. Only one HPC can
> +  control a PCI bus. Because this list includes only root HPCs, no HPC in the list
> +  can be a child of another HPC. This policy must be enforced by the
> +  EFI_PCI_HOT_PLUG_INIT_PROTOCOL.   The PCI bus driver may not check for such
> +  invalid conditions.  The callee allocates the buffer HpcList
> +
> +  @param[in]  This       Pointer to the EFI_PCI_HOT_PLUG_INIT_PROTOCOL instance.
> +  @param[out] HpcCount   The number of root HPCs that were returned.
> +  @param[out] HpcList    The list of root HPCs. HpcCount defines the number of
> +                         elements in this list.
> +
> +  @retval EFI_SUCCESS             HpcList was returned.
> +  @retval EFI_OUT_OF_RESOURCES    HpcList was not returned due to insufficient
> +                                  resources.
> +  @retval EFI_INVALID_PARAMETER   HpcCount is NULL or HpcList is NULL.
> +
> +**/
> +EFI_STATUS
> +EFIAPI
> +GetRootHpcList (
> +  IN  EFI_PCI_HOT_PLUG_INIT_PROTOCOL  *This,
> +  OUT UINTN                           *HpcCount,
> +  OUT EFI_HPC_LOCATION                **HpcList
> +  )
> +{
> +  if ((HpcCount == NULL) || (HpcList == NULL)) {
> +    return EFI_INVALID_PARAMETER;
> +  }
> +
> +  //
> +  // Platform BIOS not doing any extra/special HPC initialization
> +  // Hence returning the HpcCount as zero and HpcList as NULL
> +  //
> +  *HpcCount = 0;
> +  *HpcList  = NULL;
> +
> +  return EFI_SUCCESS;
> +}
> +
> +/**
> +  Initializes one root Hot Plug Controller (HPC). This process may causes
> +  initialization of its subordinate buses.
> +
> +  This function initializes the specified HPC. At the end of initialization,
> +  the hot-plug slots or sockets (controlled by this HPC) are powered and are
> +  connected to the bus. All the necessary registers in the HPC are set up. For
> +  a Standard (PCI) Hot Plug Controller (SHPC), the registers that must be set
> +  up are defined in the PCI Standard Hot Plug Controller and Subsystem
> +  Specification.
> +
> +  @param[in]  This            Pointer to the EFI_PCI_HOT_PLUG_INIT_PROTOCOL instance.
> +  @param[in]  HpcDevicePath   The device path to the HPC that is being initialized.
> +  @param[in]  HpcPciAddress   The address of the HPC function on the PCI bus.
> +  @param[in]  Event           The event that should be signaled when the HPC
> +                              initialization is complete.  Set to NULL if the
> +                              caller wants to wait until the entire initialization
> +                              process is complete.
> +  @param[out] HpcState        The state of the HPC hardware. The state is
> +                              EFI_HPC_STATE_INITIALIZED or EFI_HPC_STATE_ENABLED.
> +
> +  @retval EFI_SUCCESS             If Event is NULL, the specific HPC was successfully
> +                                  initialized. If Event is not NULL, Event will be
> +                                  signaled at a later time when initialization is complete.
> +  @retval EFI_UNSUPPORTED         This instance of EFI_PCI_HOT_PLUG_INIT_PROTOCOL
> +                                  does not support the specified HPC.
> +  @retval EFI_OUT_OF_RESOURCES    Initialization failed due to insufficient
> +                                  resources.
> +  @retval EFI_INVALID_PARAMETER   HpcState is NULL.
> +
> +**/
> +EFI_STATUS
> +EFIAPI
> +InitializeRootHpc (
> +  IN  EFI_PCI_HOT_PLUG_INIT_PROTOCOL *This,
> +  IN  EFI_DEVICE_PATH_PROTOCOL *HpcDevicePath,
> +  IN  UINT64 HpcPciAddress,
> +  IN  EFI_EVENT Event, OPTIONAL
> +  OUT EFI_HPC_STATE                   *HpcState
> +  )
> +{
> +  if (HpcState == NULL) {
> +    return EFI_INVALID_PARAMETER;
> +  }
> +
> +  //
> +  // This Platform doesnt have any non-enumerated HPC.
> +  // Hence no extra initialization required from Platform BIOS.
> +  //
> +  return EFI_UNSUPPORTED;
> +}
> +
> +/**
> +  Returns the resource padding that is required by the PCI bus that is controlled
> +  by the specified Hot Plug Controller (HPC).
> +
> +  This function returns the resource padding that is required by the PCI bus that
> +  is controlled by the specified HPC. This member function is called for all the
> +  root HPCs and nonroot HPCs that are detected by the PCI bus enumerator. This
> +  function will be called before PCI resource allocation is completed. This function
> +  must be called after all the root HPCs, with the possible exception of a
> +  PCI-to-CardBus bridge, have completed initialization.
> +
> +  @param[in]  This            Pointer to the EFI_PCI_HOT_PLUG_INIT_PROTOCOL instance.
> +  @param[in]  HpcDevicePath   The device path to the HPC.
> +  @param[in]  HpcPciAddress   The address of the HPC function on the PCI bus.
> +  @param[out] HpcState        The state of the HPC hardware.
> +  @param[out] Padding         The amount of resource padding that is required by the
> +                              PCI bus under the control of the specified HPC.
> +  @param[out] Attributes      Describes how padding is accounted for. The padding
> +                              is returned in the form of ACPI 2.0 resource descriptors.
> +
> +  @retval EFI_SUCCESS             The resource padding was successfully returned.
> +  @retval EFI_UNSUPPORTED         This instance of the EFI_PCI_HOT_PLUG_INIT_PROTOCOL
> +                                  does not support the specified HPC.
> +  @retval EFI_NOT_READY           This function was called before HPC initialization
> +                                  is complete.
> +  @retval EFI_INVALID_PARAMETER   HpcState or Padding or Attributes is NULL.
> +  @retval EFI_OUT_OF_RESOURCES    ACPI 2.0 resource descriptors for Padding
> +                                  cannot be allocated due to insufficient resources.
> +
> +**/
> +EFI_STATUS
> +EFIAPI
> +GetResourcePadding (
> +  IN  EFI_PCI_HOT_PLUG_INIT_PROTOCOL  *This,
> +  IN  EFI_DEVICE_PATH_PROTOCOL        *HpcDevicePath,
> +  IN  UINT64                          HpcPciAddress,
> +  OUT EFI_HPC_STATE                   *HpcState,
> +  OUT VOID                            **Padding,
> +  OUT EFI_HPC_PADDING_ATTRIBUTES      *Attributes
> +  )
> +{
> +  EFI_ACPI_ADDRESS_SPACE_DESCRIPTOR  *PaddingResource;
> +
> +  //
> +  // Need total 5 resources
> +  // 1 - IO resource
> +  // 2 - Mem resource
> +  // 3 - PMem resource
> +  // 4 - Bus resource
> +  // 5 - end tag resource
> +  PaddingResource = AllocateZeroPool (4 * sizeof (EFI_ACPI_ADDRESS_SPACE_DESCRIPTOR) + sizeof (EFI_ACPI_END_TAG_DESCRIPTOR));
> +  if (PaddingResource == NULL) {
> +    return EFI_OUT_OF_RESOURCES;
> +  }
> +
> +  *Padding = (VOID *)PaddingResource;
> +
> +  //
> +  // Padding for bus
> +  //
> +  *Attributes = EfiPaddingPciBus;
> +
> +  PaddingResource->Desc = ACPI_ADDRESS_SPACE_DESCRIPTOR;
> +  PaddingResource->Len  = (UINT16)(
> +                                   sizeof (EFI_ACPI_ADDRESS_SPACE_DESCRIPTOR) -
> +                                   OFFSET_OF (
> +                                     EFI_ACPI_ADDRESS_SPACE_DESCRIPTOR,
> +                                     ResType
> +                                     )
> +                                   );
> +  PaddingResource->ResType      = ACPI_ADDRESS_SPACE_TYPE_BUS;
> +  PaddingResource->GenFlag      = 0x0;
> +  PaddingResource->SpecificFlag = 0;
> +  PaddingResource->AddrRangeMin = 0;
> +  PaddingResource->AddrRangeMax = 0;
> +  PaddingResource->AddrLen      = PcdGet8 (PcdPciHotPlugResourcePadBus);
> +
> +  //
> +  // Padding for non-prefetchable memory
> +  //
> +  PaddingResource++;
> +  PaddingResource->Desc = ACPI_ADDRESS_SPACE_DESCRIPTOR;
> +  PaddingResource->Len  = (UINT16)(
> +                                   sizeof (EFI_ACPI_ADDRESS_SPACE_DESCRIPTOR) -
> +                                   OFFSET_OF (
> +                                     EFI_ACPI_ADDRESS_SPACE_DESCRIPTOR,
> +                                     ResType
> +                                     )
> +                                   );
> +  PaddingResource->ResType              = ACPI_ADDRESS_SPACE_TYPE_MEM;
> +  PaddingResource->GenFlag              = 0x0;
> +  PaddingResource->AddrSpaceGranularity = 32;
> +  PaddingResource->SpecificFlag         = EFI_ACPI_MEMORY_RESOURCE_SPECIFIC_FLAG_NON_CACHEABLE;
> +  PaddingResource->AddrRangeMin         = 0;
> +  PaddingResource->AddrLen              = PcdGet64 (PcdPciHotPlugResourcePadMem);
> +  PaddingResource->AddrRangeMax         = PaddingResource->AddrLen - 1;
> +
> +  //
> +  // Padding for prefetchable memory
> +  //
> +  PaddingResource++;
> +  PaddingResource->Desc = ACPI_ADDRESS_SPACE_DESCRIPTOR;
> +  PaddingResource->Len  = (UINT16)(
> +                                   sizeof (EFI_ACPI_ADDRESS_SPACE_DESCRIPTOR) -
> +                                   OFFSET_OF (
> +                                     EFI_ACPI_ADDRESS_SPACE_DESCRIPTOR,
> +                                     ResType
> +                                     )
> +                                   );
> +  PaddingResource->ResType              = ACPI_ADDRESS_SPACE_TYPE_MEM;
> +  PaddingResource->GenFlag              = 0x0;
> +  PaddingResource->AddrSpaceGranularity = 32;
> +  PaddingResource->SpecificFlag         = EFI_ACPI_MEMORY_RESOURCE_SPECIFIC_FLAG_CACHEABLE_PREFETCHABLE;
> +  PaddingResource->AddrLen              = PcdGet64 (PcdPciHotPlugResourcePadPMem);
> +  PaddingResource->AddrRangeMax         = PaddingResource->AddrLen - 1;
> +
> +  //
> +  // Padding for I/O
> +  //
> +  PaddingResource++;
> +  PaddingResource->Desc = ACPI_ADDRESS_SPACE_DESCRIPTOR;
> +  PaddingResource->Len  = (UINT16)(
> +                                   sizeof (EFI_ACPI_ADDRESS_SPACE_DESCRIPTOR) -
> +                                   OFFSET_OF (
> +                                     EFI_ACPI_ADDRESS_SPACE_DESCRIPTOR,
> +                                     ResType
> +                                     )
> +                                   );
> +  PaddingResource->ResType      = ACPI_ADDRESS_SPACE_TYPE_IO;
> +  PaddingResource->GenFlag      = 0x0;
> +  PaddingResource->SpecificFlag = 0;
> +  PaddingResource->AddrRangeMin = 0;
> +  PaddingResource->AddrLen      = PcdGet64 (PcdPciHotPlugResourcePadIO);
> +  PaddingResource->AddrRangeMax = PaddingResource->AddrLen - 1;
> +
> +  //
> +  // Terminate the entries.
> +  //
> +  PaddingResource++;
> +  ((EFI_ACPI_END_TAG_DESCRIPTOR *)PaddingResource)->Desc     = ACPI_END_TAG_DESCRIPTOR;
> +  ((EFI_ACPI_END_TAG_DESCRIPTOR *)PaddingResource)->Checksum = 0x0;
> +
> +  *HpcState = EFI_HPC_STATE_INITIALIZED | EFI_HPC_STATE_ENABLED;
> +
> +  return EFI_SUCCESS;
> +}
> +
> +/**
> +  Entry point for this driver.
> +
> +  @param[in] ImageHandle  Image handle of this driver.
> +  @param[in] SystemTable  Pointer to SystemTable.
> +
> +  @retval EFI_SUCESS       Driver has loaded successfully.
> +  @return                  Error codes from lower level functions.
> +
> +**/
> +EFI_STATUS
> +EFIAPI
> +PciHotPlugInitialize (
> +  IN EFI_HANDLE        ImageHandle,
> +  IN EFI_SYSTEM_TABLE  *SystemTable
> +  )
> +{
> +  mPciHotPlugInit.GetRootHpcList     = GetRootHpcList;
> +  mPciHotPlugInit.InitializeRootHpc  = InitializeRootHpc;
> +  mPciHotPlugInit.GetResourcePadding = GetResourcePadding;
> +  return gBS->InstallMultipleProtocolInterfaces (
> +                &ImageHandle,
> +                &gEfiPciHotPlugInitProtocolGuid,
> +                &mPciHotPlugInit,
> +                NULL
> +                );
> +}
> -- 
> 2.25.1
> 
> 
> 
> 
> 
>