Re: [edk2-platforms][PATCH v1 3/3] ClevoOpenBoardPkg/N1xxWU: Write PEI debug messages to SPI flash

["Kubacki, Michael A" <michael.a.kubacki@intel.com>]

1. I agree. Due to the total debug message length in PEI, I thought this could be added as a future enhancement. I will come back to it soon.
2. Not at the moment. There is an increasing need for a "common board package". PeiSerialPortLibSpiFlash is abstracted with the PCH_SPI_PPI and SpiLib in a way it could be used across generations. If such a package is made this could be moved there.

> -----Original Message-----
> From: Desimone, Nathaniel L
> Sent: Sunday, March 31, 2019 10:54 PM
> To: Kubacki, Michael A <michael.a.kubacki@intel.com>; edk2-
> devel@lists.01.org
> Cc: Sinha, Ankit <ankit.sinha@intel.com>; Chiu, Chasel
> <chasel.chiu@intel.com>; Gao, Liming <liming.gao@intel.com>; Kinney,
> Michael D <michael.d.kinney@intel.com>
> Subject: RE: [edk2-platforms][PATCH v1 3/3] ClevoOpenBoardPkg/N1xxWU:
> Write PEI debug messages to SPI flash
> 
> Look's good. I have a couple of comments, but they are not blocking:
> 
> 1. It would be nice if this library worked more like a circular buffer when
> erasing previous debug messages from flash. Basically, instead of clearing the
> entire debug region, only clear 4KB blocks at a time as they are needed. That
> way you will always have at least NvMessageAreaSize - 4KB worth of debug
> message to look back when trying to debug issues.
> 
> 2. It seems like this library would also be useful for other Kaby Lake boards
> (KabylakeOpenBoardPkg for example) is there any "shared Kaby Lake package"
> that we could put this in where both could use it?
> 
> Reviewed-by: Nate DeSimone <nathaniel.l.desimone@intel.com>
> 
> -----Original Message-----
> From: Kubacki, Michael A
> Sent: Sunday, March 31, 2019 4:28 PM
> To: edk2-devel@lists.01.org
> Cc: Sinha, Ankit <ankit.sinha@intel.com>; Desimone, Nathaniel L
> <nathaniel.l.desimone@intel.com>; Chiu, Chasel <chasel.chiu@intel.com>;
> Gao, Liming <liming.gao@intel.com>; Kinney, Michael D
> <michael.d.kinney@intel.com>
> Subject: [edk2-platforms][PATCH v1 3/3] ClevoOpenBoardPkg/N1xxWU: Write
> PEI debug messages to SPI flash
> 
> Adds a new SerialPortLib instance to the ClevoOpenBoardPkg to support
> writing debug messages to a dedicated area on SPI flash. This is to enable
> closed chassis debug support on the system.
> 
> DXE and later phases after memory initialization are expected to use USB
> debug.
> 
> Cc: Ankit Sinha <mailto:ankit.sinha@intel.com>
> Cc: Nate DeSimone <mailto:nathaniel.l.desimone@intel.com>
> Cc: Chasel Chiu <mailto:chasel.chiu@intel.com>
> Cc: Liming Gao <mailto:liming.gao@intel.com>
> Cc: Michael D Kinney <mailto:michael.d.kinney@intel.com>
> Contributed-under: TianoCore Contribution Agreement 1.0
> Signed-off-by: Michael Kubacki <mailto:michael.a.kubacki@intel.com>
> ---
>  Platform/Intel/ClevoOpenBoardPkg/OpenBoardPkg.dec  |   5 +
>  .../ClevoOpenBoardPkg/N1xxWU/OpenBoardPkg.dsc      |  20 +-
>  .../ClevoOpenBoardPkg/N1xxWU/OpenBoardPkg.fdf      |   4 +
>  .../PeiSerialPortLibSpiFlash.inf                   |  56 ++++
>  .../PeiSerialPortLibSpiFlash.c                     | 326 +++++++++++++++++++++
>  5 files changed, 407 insertions(+), 4 deletions(-)  create mode 100644
> Platform/Intel/ClevoOpenBoardPkg/Library/PeiSerialPortLibSpiFlash/PeiSerialP
> ortLibSpiFlash.inf
>  create mode 100644
> Platform/Intel/ClevoOpenBoardPkg/Library/PeiSerialPortLibSpiFlash/PeiSerialP
> ortLibSpiFlash.c
> 
> diff --git a/Platform/Intel/ClevoOpenBoardPkg/OpenBoardPkg.dec
> b/Platform/Intel/ClevoOpenBoardPkg/OpenBoardPkg.dec
> index 87bbfb2240..aa457e64db 100644
> --- a/Platform/Intel/ClevoOpenBoardPkg/OpenBoardPkg.dec
> +++ b/Platform/Intel/ClevoOpenBoardPkg/OpenBoardPkg.dec
> @@ -30,6 +30,7 @@ Features\Tbt\Include
>  [Guids]
>  gBoardModuleTokenSpaceGuid            =  {0x72d1fff7, 0xa42a, 0x4219, {0xb9,
> 0x95, 0x5a, 0x67, 0x53, 0x6e, 0xa4, 0x2a}}
>  gTianoLogoGuid                        =  {0x7BB28B99, 0x61BB, 0x11D5, {0x9A, 0x5D,
> 0x00, 0x90, 0x27, 0x3F, 0xC1, 0x4D}}
> +gSpiFlashDebugHobGuid                 =  {0xcaaaf418, 0x38a5, 0x4d49, {0xbe,
> 0x74, 0xe6, 0x06, 0xe4, 0x02, 0x6d, 0x25}}
>  gTbtInfoHobGuid                       =  {0x74a81eaa, 0x033c, 0x4783, {0xbe, 0x2b,
> 0x84, 0x85, 0x74, 0xa6, 0x97, 0xb7}}
>  gPlatformModuleTokenSpaceGuid         =  {0x69d13bf0, 0xaf91, 0x4d96, {0xaa,
> 0x9f, 0x21, 0x84, 0xc5, 0xce, 0x3b, 0xc0}}
> 
> @@ -64,6 +65,10 @@
> gBoardModuleTokenSpaceGuid.PcdSwSmiDTbtEnumerate|0xF7|UINT8|0x000
> 000110
> 
> 
> gBoardModuleTokenSpaceGuid.PcdSmcExtSmiBitPosition|0x01|UINT8|0x9000
> 0015
> 
> +gBoardModuleTokenSpaceGuid.PcdFlashNvDebugMessageBase|0x00000000|
> UINT32
> +|0x90000030
> +gBoardModuleTokenSpaceGuid.PcdFlashNvDebugMessageSize|0x00000000|
> UINT32
> +|0x90000031
> +gBoardModuleTokenSpaceGuid.PcdFlashNvDebugMessageOffset|0x00000000
> |UINT
> +32|0x90000032
> +
>  [PcdsDynamic]
> 
>  # Board GPIO Table
> diff --git a/Platform/Intel/ClevoOpenBoardPkg/N1xxWU/OpenBoardPkg.dsc
> b/Platform/Intel/ClevoOpenBoardPkg/N1xxWU/OpenBoardPkg.dsc
> index 2116c48fc0..c43a30de34 100644
> --- a/Platform/Intel/ClevoOpenBoardPkg/N1xxWU/OpenBoardPkg.dsc
> +++ b/Platform/Intel/ClevoOpenBoardPkg/N1xxWU/OpenBoardPkg.dsc
> @@ -116,10 +116,18 @@
>  #
>  !include $(PLATFORM_SI_PACKAGE)/SiPkgCommonLib.dsc
> 
> +[LibraryClasses.IA32.SEC]
> +
> +SerialPortLib|MdePkg/Library/BaseSerialPortLibNull/BaseSerialPortLibNul
> +l.inf
> +  DebugLib|MdePkg/Library/BaseDebugLibNull/BaseDebugLibNull.inf
> +
> +TestPointCheckLib|$(PLATFORM_PACKAGE)/Test/Library/TestPointCheckLib/S
> e
> +cTestPointCheckLib.inf
> +
> +SecBoardInitLib|$(PLATFORM_PACKAGE)/PlatformInit/Library/SecBoardInitLi
> +bNull/SecBoardInitLibNull.inf
> +
>  [LibraryClasses.IA32]
>    #
>    # PEI phase common
>    #
> +
> + SerialPortLib|$(PLATFORM_BOARD_PACKAGE)/Library/PeiSerialPortLibSpiFla
> + sh/PeiSerialPortLibSpiFlash.inf
> +
> DebugLib|MdeModulePkg/Library/PeiDxeDebugLibReportStatusCode/PeiDxeD
> eb
> + ugLibReportStatusCode.inf
> 
> FspWrapperPlatformLib|$(PLATFORM_PACKAGE)/FspWrapper/Library/PeiFsp
> WrapperPlatformLib/PeiFspWrapperPlatformLib.inf
>  !if $(TARGET) == DEBUG
> 
> TestPointCheckLib|$(PLATFORM_PACKAGE)/Test/Library/TestPointCheckLib/P
> eiTestPointCheckLib.inf
> @@ -138,10 +146,6 @@
>  #
>  !include $(PLATFORM_SI_PACKAGE)/SiPkgPeiLib.dsc
> 
> -[LibraryClasses.IA32.SEC]
> -
> TestPointCheckLib|$(PLATFORM_PACKAGE)/Test/Library/TestPointCheckLib/Se
> cTestPointCheckLib.inf
> -
> SecBoardInitLib|$(PLATFORM_PACKAGE)/PlatformInit/Library/SecBoardInitLib
> Null/SecBoardInitLibNull.inf
> -
>  [LibraryClasses.X64]
>    #
>    # DXE phase common
> @@ -185,6 +189,14 @@
>  #
>  !include $(PLATFORM_PACKAGE)/Include/Dsc/CorePeiInclude.dsc
> 
> +  #
> +  # Core
> +  #
> +
> MdeModulePkg/Universal/StatusCodeHandler/Pei/StatusCodeHandlerPei.inf {
> +    <LibraryClasses>
> +      DebugLib|MdePkg/Library/BaseDebugLibNull/BaseDebugLibNull.inf
> +  }
> +
>    #
>    # FSP wrapper SEC Core
>    #
> diff --git a/Platform/Intel/ClevoOpenBoardPkg/N1xxWU/OpenBoardPkg.fdf
> b/Platform/Intel/ClevoOpenBoardPkg/N1xxWU/OpenBoardPkg.fdf
> index 95c1758ff3..7f3e965c75 100644
> --- a/Platform/Intel/ClevoOpenBoardPkg/N1xxWU/OpenBoardPkg.fdf
> +++ b/Platform/Intel/ClevoOpenBoardPkg/N1xxWU/OpenBoardPkg.fdf
> @@ -136,6 +136,10 @@
> gMinPlatformPkgTokenSpaceGuid.PcdFlashNvStorageFtwSpareOffset|gEfiMde
> ModulePkgTo
> 
> gEfiMdeModulePkgTokenSpaceGuid.PcdFlashNvStorageFtwSpareBase|gEfiMde
> ModulePkgTokenSpaceGuid.PcdFlashNvStorageFtwSpareSize
>  #NV_FTW_SPARE
> 
> +gBoardModuleTokenSpaceGuid.PcdFlashNvDebugMessageOffset|gBoardMod
> uleTok
> +enSpaceGuid.PcdFlashNvDebugMessageSize
> +gBoardModuleTokenSpaceGuid.PcdFlashNvDebugMessageBase|gBoardModu
> leToken
> +SpaceGuid.PcdFlashNvDebugMessageSize
> +#DEBUG_MESSAGE_AREA
> +
> 
> gMinPlatformPkgTokenSpaceGuid.PcdFlashFvAdvancedOffset|gMinPlatformPk
> gTokenSpaceGuid.PcdFlashFvAdvancedSize
> 
> gMinPlatformPkgTokenSpaceGuid.PcdFlashFvAdvancedBase|gMinPlatformPkg
> TokenSpaceGuid.PcdFlashFvAdvancedSize
>  FV = FvAdvanced
> diff --git
> a/Platform/Intel/ClevoOpenBoardPkg/Library/PeiSerialPortLibSpiFlash/PeiSeri
> alPortLibSpiFlash.inf
> b/Platform/Intel/ClevoOpenBoardPkg/Library/PeiSerialPortLibSpiFlash/PeiSeri
> alPortLibSpiFlash.inf
> new file mode 100644
> index 0000000000..c22201e033
> --- /dev/null
> +++ b/Platform/Intel/ClevoOpenBoardPkg/Library/PeiSerialPortLibSpiFlash/
> +++ PeiSerialPortLibSpiFlash.inf
> @@ -0,0 +1,56 @@
> +### @file
> +# Component description file for Serial I/O Port library to write to SPI flash.
> +#
> +# Copyright (c) 2019, Intel Corporation. All rights reserved.<BR> # #
> +This program and the accompanying materials are licensed and made
> +available under # the terms and conditions of the BSD License which
> accompanies this distribution.
> +# The full text of the license may be found at #
> +http://opensource.org/licenses/bsd-license.php
> +#
> +# THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS"
> BASIS,
> +# WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER
> EXPRESS OR IMPLIED.
> +#
> +##
> +
> +[Defines]
> +  INF_VERSION                    = 0x00010005
> +  BASE_NAME                      = PeiSerialPortLibFlash
> +  FILE_GUID                      = 35A3BA89-04BE-409C-A3CA-DEF6B510F80F
> +  VERSION_STRING                 = 1.1
> +  MODULE_TYPE                    = PEIM
> +  LIBRARY_CLASS                  = SerialPortLib|PEIM PEI_CORE
> +#
> +# The following information is for reference only and not required by the
> build tools.
> +#
> +# VALID_ARCHITECTURES = IA32 X64 IPF
> +#
> +
> +[LibraryClasses]
> +  BaseLib
> +  BaseMemoryLib
> +  HobLib
> +  PcdLib
> +  PeiServicesLib
> +  SpiLib
> +
> +[Packages]
> +  MdePkg/MdePkg.dec
> +  MdeModulePkg/MdeModulePkg.dec
> +  MinPlatformPkg/MinPlatformPkg.dec
> +  KabylakeSiliconPkg/SiPkg.dec
> +  ClevoOpenBoardPkg/OpenBoardPkg.dec
> +
> +[Sources]
> +  PeiSerialPortLibSpiFlash.c
> +
> +[Ppis]
> +  gPchSpiPpiGuid
> +
> +[Guids]
> +  gSpiFlashDebugHobGuid
> +
> +[Pcd]
> +  gMinPlatformPkgTokenSpaceGuid.PcdFlashAreaBaseAddress           ##
> CONSUMES
> +  gBoardModuleTokenSpaceGuid.PcdFlashNvDebugMessageBase           ##
> CONSUMES
> +  gBoardModuleTokenSpaceGuid.PcdFlashNvDebugMessageSize           ##
> CONSUMES
> diff --git
> a/Platform/Intel/ClevoOpenBoardPkg/Library/PeiSerialPortLibSpiFlash/PeiSeri
> alPortLibSpiFlash.c
> b/Platform/Intel/ClevoOpenBoardPkg/Library/PeiSerialPortLibSpiFlash/PeiSeri
> alPortLibSpiFlash.c
> new file mode 100644
> index 0000000000..e36ff8bff8
> --- /dev/null
> +++ b/Platform/Intel/ClevoOpenBoardPkg/Library/PeiSerialPortLibSpiFlash/
> +++ PeiSerialPortLibSpiFlash.c
> @@ -0,0 +1,326 @@
> +/** @file
> +  Serial I/O Port library implementation for output to SPI flash
> +
> +Copyright (c) 2019, Intel Corporation. All rights reserved.<BR> This
> +program and the accompanying materials are licensed and made available
> +under the terms and conditions of the BSD License that 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 <Base.h>
> +#include <Ppi/Spi.h>
> +#include <Library/BaseLib.h>
> +#include <Library/BaseMemoryLib.h>
> +#include <Library/HobLib.h>
> +#include <Library/PcdLib.h>
> +#include <Library/PeiServicesLib.h>
> +#include <Library/SerialPortLib.h>
> +#include <Library/SpiLib.h>
> +
> +typedef struct {
> +  PCH_SPI_PPI           *PchSpiPpi;
> +  UINT32                CurrentWriteOffset;
> +} SPI_FLASH_DEBUG_CONTEXT;
> +
> +/**
> +  Update reference to the most recent PCH SPI PPI installed
> +
> +  @param PeiServices       An indirect pointer to the EFI_PEI_SERVICES table
> published by the PEI Foundation
> +  @param NotifyDescriptor  Address of the notification descriptor data
> structure.
> +  @param Ppi               Address of the PPI that was installed.
> +
> +  @retval EFI_SUCCESS      Successfully update the PCH SPI PPI reference
> +  @retval EFI_NOT_FOUND    An error occurred locating a required interface
> +  @retval EFI_NOT_SUPPORTED
> +
> +**/
> +EFI_STATUS
> +EFIAPI
> +SpiPpiNotifyCallback (
> +  IN EFI_PEI_SERVICES           **PeiServices,
> +  IN EFI_PEI_NOTIFY_DESCRIPTOR  *NotifyDescriptor,
> +  IN VOID                       *Ppi
> +  )
> +{
> +  EFI_STATUS                Status;
> +  EFI_HOB_GUID_TYPE         *GuidHob;
> +  PCH_SPI_PPI               *PchSpiPpi;
> +  SPI_FLASH_DEBUG_CONTEXT   *Context;
> +
> +  GuidHob = GetFirstGuidHob (&gSpiFlashDebugHobGuid);  if (GuidHob ==
> + NULL) {
> +    return EFI_NOT_FOUND;
> +  }
> +  Context = GET_GUID_HOB_DATA (GuidHob);
> +
> +  Status =  PeiServicesLocatePpi (
> +              &gPchSpiPpiGuid,
> +              0,
> +              NULL,
> +              (VOID **) &PchSpiPpi
> +              );
> +  if (EFI_ERROR (Status)) {
> +    return EFI_NOT_FOUND;
> +  }
> +
> +  Context->PchSpiPpi = PchSpiPpi;
> +
> +  return EFI_SUCCESS;
> +}
> +
> +EFI_PEI_NOTIFY_DESCRIPTOR mSpiPpiNotifyList[] = {
> +  {
> +    (EFI_PEI_PPI_DESCRIPTOR_NOTIFY_CALLBACK |
> EFI_PEI_PPI_DESCRIPTOR_TERMINATE_LIST),
> +    &gPchSpiPpiGuid,
> +    SpiPpiNotifyCallback
> +  }
> +};
> +
> +/**
> +  Common function to write trace data to a chosen debug interface like
> +  UART Serial device, USB Serial device or Trace Hub device
> +
> +  @param  Buffer           Point of data buffer which need to be writed.
> +  @param  NumberOfBytes    Number of output bytes which are cached in
> Buffer.
> +
> +**/
> +UINTN
> +EFIAPI
> +SerialPortWrite (
> +  IN UINT8     *Buffer,
> +  IN UINTN     NumberOfBytes
> +  )
> +{
> +  EFI_STATUS                Status;
> +  EFI_HOB_GUID_TYPE         *GuidHob;
> +  SPI_FLASH_DEBUG_CONTEXT   *Context;
> +  UINT32                    BytesWritten;
> +  UINT32                    SourceBufferOffset;
> +  UINT32                    NvMessageAreaSize;
> +  UINT32                    LinearOffset;
> +
> +  BytesWritten       = NumberOfBytes;
> +  SourceBufferOffset = 0;
> +
> +  NvMessageAreaSize = (UINT32) FixedPcdGet32
> + (PcdFlashNvDebugMessageSize);
> +
> +  if (NumberOfBytes == 0 || NvMessageAreaSize == 0) {
> +    return 0;
> +  }
> +  GuidHob = GetFirstGuidHob (&gSpiFlashDebugHobGuid);  if (GuidHob ==
> + NULL) {
> +    return 0;
> +  }
> +  Context = GET_GUID_HOB_DATA (GuidHob);  if (Context == NULL ||
> + Context->PchSpiPpi == NULL || Context->CurrentWriteOffset >=
> + Context->NvMessageAreaSize) {
> +    return 0;
> +  }
> +
> +  if ((Context->CurrentWriteOffset + NumberOfBytes) / NvMessageAreaSize >
> 0) {
> +    LinearOffset = (UINT32) (FixedPcdGet32 (PcdFlashNvDebugMessageBase) -
> FixedPcdGet32 (PcdFlashAreaBaseAddress));
> +    Status =  Context->PchSpiPpi->FlashErase (
> +                                    Context->PchSpiPpi,
> +                                    FlashRegionBios,
> +                                    LinearOffset,
> +                                    NvMessageAreaSize
> +                                    );
> +    if (!EFI_ERROR (Status)) {
> +      Context->CurrentWriteOffset = 0;
> +    } else {
> +      return 0;
> +    }
> +  }
> +
> +  if (NumberOfBytes > NvMessageAreaSize) {
> +    BytesWritten = NvMessageAreaSize;
> +    SourceBufferOffset = NumberOfBytes - NvMessageAreaSize;  }
> +
> +  LinearOffset = (FixedPcdGet32 (PcdFlashNvDebugMessageBase) +
> + Context->CurrentWriteOffset) - FixedPcdGet32
> + (PcdFlashAreaBaseAddress);
> +
> +  Status =  Context->PchSpiPpi->FlashWrite (
> +                                  Context->PchSpiPpi,
> +                                  FlashRegionBios,
> +                                  LinearOffset,
> +                                  BytesWritten,
> +                                  (UINT8 *) &Buffer[SourceBufferOffset]
> +                                  );
> +  if (!EFI_ERROR (Status)) {
> +    Context->CurrentWriteOffset += BytesWritten;
> +    return BytesWritten;
> +  }
> +
> +  return 0;
> +}
> +
> +/**
> +  Common function to Read data from UART serial device, USB serial device
> and save the datas in buffer.
> +
> +  @param  Buffer           Point of data buffer which need to be writed.
> +  @param  NumberOfBytes    Number of output bytes which are cached in
> Buffer.
> +
> +  @retval 0                Read data failed, no data is to be read.
> +  @retval >0               Actual number of bytes read from debug device.
> +
> +**/
> +UINTN
> +EFIAPI
> +SerialPortRead (
> +  OUT UINT8     *Buffer,
> +  IN  UINTN     NumberOfBytes
> +)
> +{
> +  return 0;
> +}
> +
> +/**
> +  Polls a serial device to see if there is any data waiting to be read.
> +
> +  Polls a serial device to see if there is any data waiting to be read.
> +  If there is data waiting to be read from the serial device, then TRUE is
> returned.
> +  If there is no data waiting to be read from the serial device, then FALSE is
> returned.
> +
> +  @retval TRUE             Data is waiting to be read from the serial device.
> +  @retval FALSE            There is no data waiting to be read from the serial
> device.
> +
> +**/
> +BOOLEAN
> +EFIAPI
> +SerialPortPoll (
> +  VOID
> +  )
> +{
> +  return FALSE;
> +}
> +
> +/**
> +  Sets the control bits on a serial device.
> +
> +  @param Control                Sets the bits of Control that are settable.
> +
> +  @retval RETURN_SUCCESS        The new control bits were set on the serial
> device.
> +  @retval RETURN_UNSUPPORTED    The serial device does not support this
> operation.
> +  @retval RETURN_DEVICE_ERROR   The serial device is not functioning
> correctly.
> +
> +**/
> +RETURN_STATUS
> +EFIAPI
> +SerialPortSetControl (
> +  IN UINT32 Control
> +  )
> +{
> +  return EFI_UNSUPPORTED;
> +}
> +
> +/**
> +  Retrieve the status of the control bits on a serial device.
> +
> +  @param Control                A pointer to return the current control signals
> from the serial device.
> +
> +  @retval RETURN_SUCCESS        The control bits were read from the serial
> device.
> +  @retval RETURN_UNSUPPORTED    The serial device does not support this
> operation.
> +  @retval RETURN_DEVICE_ERROR   The serial device is not functioning
> correctly.
> +
> +**/
> +RETURN_STATUS
> +EFIAPI
> +SerialPortGetControl (
> +  OUT UINT32 *Control
> +  )
> +{
> +  return EFI_UNSUPPORTED;
> +}
> +
> +/**
> +  Sets the baud rate, receive FIFO depth, transmit/receice time out,
> +parity,
> +  data bits, and stop bits on a serial device.
> +
> +  @param BaudRate           The requested baud rate. A BaudRate value of 0
> will use the
> +                            device's default interface speed.
> +                            On output, the value actually set.
> +  @param ReveiveFifoDepth   The requested depth of the FIFO on the receive
> side of the
> +                            serial interface. A ReceiveFifoDepth value of 0 will use
> +                            the device's default FIFO depth.
> +                            On output, the value actually set.
> +  @param Timeout            The requested time out for a single character in
> microseconds.
> +                            This timeout applies to both the transmit and receive side
> of the
> +                            interface. A Timeout value of 0 will use the device's default
> time
> +                            out value.
> +                            On output, the value actually set.
> +  @param Parity             The type of parity to use on this serial device. A
> Parity value of
> +                            DefaultParity will use the device's default parity value.
> +                            On output, the value actually set.
> +  @param DataBits           The number of data bits to use on the serial device.
> A DataBits
> +                            vaule of 0 will use the device's default data bit setting.
> +                            On output, the value actually set.
> +  @param StopBits           The number of stop bits to use on this serial device.
> A StopBits
> +                            value of DefaultStopBits will use the device's default
> number of
> +                            stop bits.
> +                            On output, the value actually set.
> +
> +  @retval RETURN_SUCCESS            The new attributes were set on the serial
> device.
> +  @retval RETURN_UNSUPPORTED        The serial device does not support
> this operation.
> +  @retval RETURN_INVALID_PARAMETER  One or more of the attributes has
> an unsupported value.
> +  @retval RETURN_DEVICE_ERROR       The serial device is not functioning
> correctly.
> +
> +**/
> +RETURN_STATUS
> +EFIAPI
> +SerialPortSetAttributes (
> +  IN OUT UINT64             *BaudRate,
> +  IN OUT UINT32             *ReceiveFifoDepth,
> +  IN OUT UINT32             *Timeout,
> +  IN OUT EFI_PARITY_TYPE    *Parity,
> +  IN OUT UINT8              *DataBits,
> +  IN OUT EFI_STOP_BITS_TYPE *StopBits
> +  )
> +{
> +  return EFI_UNSUPPORTED;
> +}
> +
> +/**
> +  Initialize the serial device hardware.
> +
> +  If no initialization is required, then return RETURN_SUCCESS.
> +  If the serial device was successfully initialized, then return
> RETURN_SUCCESS.
> +  If the serial device could not be initialized, then return
> RETURN_DEVICE_ERROR.
> +
> +  @retval RETURN_SUCCESS        The serial device was initialized.
> +  @retval RETURN_DEVICE_ERROR   The serial device could not be initialized.
> +
> +**/
> +RETURN_STATUS
> +EFIAPI
> +SerialPortInitialize (
> +  VOID
> +  )
> +{
> +  EFI_STATUS                Status;
> +  SPI_FLASH_DEBUG_CONTEXT   *Context;
> +
> +  Context = (SPI_FLASH_DEBUG_CONTEXT *) BuildGuidHob
> + (&gSpiFlashDebugHobGuid, sizeof (SPI_FLASH_DEBUG_CONTEXT));  if
> (Context == NULL) {
> +    return EFI_DEVICE_ERROR;
> +  }
> +  ZeroMem ((VOID *) Context, sizeof (SPI_FLASH_DEBUG_CONTEXT));
> +
> +  Status = PeiServicesNotifyPpi (&mSpiPpiNotifyList[0]);  if (EFI_ERROR
> + (Status)) {
> +    return EFI_DEVICE_ERROR;
> +  }
> +
> +  //
> +  // Perform silicon specific initialization required to enable write to SPI flash.
> +  //
> +  Status = SpiServiceInit ();
> +  if (EFI_ERROR (Status)) {
> +    Status = EFI_DEVICE_ERROR;
> +  }
> +
> +  return Status;
> +}
> --
> 2.16.2.windows.1