Re: [edk2-platforms][PATCH v2 2/3] Platform/RPi: Add PlatformPcdLib to set the Genet MAC address

["Ard Biesheuvel" <ard.biesheuvel@linaro.org>]

On Fri, 24 Jan 2020 at 12:54, Pete Batard <pete@akeo.ie> wrote:
>
> The Genet driver stub used by the Raspberry Pi 4 platform is
> designed to set the MAC address according to a PCD.
>
> To be able to set that PCD at runtime, by using the Raspberry
> Pi firmware interface, that has a dedicated call to retrieve
> the MAC address, and satisfy driver dependencies in a generic
> manner, we create a new PlatformPcdLib that can be referenced
> by the Genet driver, to set the MAC PCD before use there.
>
> While it is currently only tailored around MAC PCD population
> for Genet, we do expect this PCD library to be extended in the
> future, to provide additional PCD facilities for other drivers.
>
> Signed-off-by: Pete Batard <pete@akeo.ie>
> ---
>  Platform/RaspberryPi/Library/PlatformPcdLib/PlatformPcdLib.c   | 51 ++++++++++++++++++++
>  Platform/RaspberryPi/Library/PlatformPcdLib/PlatformPcdLib.inf | 43 +++++++++++++++++
>  2 files changed, 94 insertions(+)
>
> diff --git a/Platform/RaspberryPi/Library/PlatformPcdLib/PlatformPcdLib.c b/Platform/RaspberryPi/Library/PlatformPcdLib/PlatformPcdLib.c
> new file mode 100644
> index 000000000000..792073a903e9
> --- /dev/null
> +++ b/Platform/RaspberryPi/Library/PlatformPcdLib/PlatformPcdLib.c
> @@ -0,0 +1,51 @@
> +/** @file
> + *
> + *  Copyright (c) 2020, Pete Batard <pete@akeo.ie>
> + *
> + *  SPDX-License-Identifier: BSD-2-Clause-Patent
> + *
> + **/
> +
> +#include <Library/DebugLib.h>
> +#include <Library/PcdLib.h>
> +#include <Library/PrintLib.h>
> +#include <Library/UefiBootServicesTableLib.h>
> +#include <Library/UefiLib.h>
> +#include <Library/UefiRuntimeServicesTableLib.h>
> +#include <Protocol/RpiFirmware.h>
> +
> +EFI_STATUS
> +EFIAPI
> +PlatformPcdLibConstructor (
> +  IN EFI_HANDLE ImageHandle,
> +  IN EFI_SYSTEM_TABLE *SystemTable
> +  )
> +{
> +
> +  //
> +  // If Genet is in use and a MAC address PCD has not been set, do it here.
> +  //
> +#if (FixedPcdGet64 (PcdBcmGenetRegistersAddress) != 0)

I still don't see why we need this conditional. This is a fixed PCD,
so it must be set in the .DSC. If you are going to set it in the .DSC,
why include this driver in the first place?

> +  EFI_STATUS                       Status;
> +  UINT64                           MacAddr;
> +  RASPBERRY_PI_FIRMWARE_PROTOCOL   *mFwProtocol;
> +
> +  if (PcdGet64 (PcdBcmGenetMacAddress) == 0) {
> +    Status = gBS->LocateProtocol (&gRaspberryPiFirmwareProtocolGuid, NULL,
> +                    (VOID**)&mFwProtocol);
> +    ASSERT_EFI_ERROR(Status);
> +
> +    //
> +    // Get the MAC address from the firmware
> +    //
> +    Status = mFwProtocol->GetMacAddress ((UINT8*) &MacAddr);
> +    if (EFI_ERROR (Status)) {
> +      DEBUG ((DEBUG_WARN, "%a: failed to retrieve MAC address\n", __FUNCTION__));
> +    } else {
> +      PcdSet64S (PcdBcmGenetMacAddress, MacAddr);
> +    }
> +  }
> +#endif
> +
> +  return EFI_SUCCESS;
> +}
> diff --git a/Platform/RaspberryPi/Library/PlatformPcdLib/PlatformPcdLib.inf b/Platform/RaspberryPi/Library/PlatformPcdLib/PlatformPcdLib.inf
> new file mode 100644
> index 000000000000..2a207d2b3e54
> --- /dev/null
> +++ b/Platform/RaspberryPi/Library/PlatformPcdLib/PlatformPcdLib.inf
> @@ -0,0 +1,43 @@
> +#/** @file
> +#
> +#  Copyright (c) 2020, Pete Batard <pete@akeo.ie>
> +#
> +#  SPDX-License-Identifier: BSD-2-Clause-Patent
> +#
> +#**/
> +
> +[Defines]
> +  INF_VERSION                    = 0x0001001A
> +  BASE_NAME                      = PlatformPcdLib
> +  FILE_GUID                      = 3B8409D7-D3C7-4006-823B-BFB184435363
> +  MODULE_TYPE                    = DXE_DRIVER
> +  VERSION_STRING                 = 1.0
> +  LIBRARY_CLASS                  = NULL|DXE_DRIVER UEFI_APPLICATION
> +  CONSTRUCTOR                    = PlatformPcdLibConstructor
> +
> +[Sources]
> +  PlatformPcdLib.c
> +
> +[Packages]
> +  MdePkg/MdePkg.dec
> +  MdeModulePkg/MdeModulePkg.dec
> +  Platform/RaspberryPi/RaspberryPi.dec
> +  Silicon/Broadcom/Drivers/Net/BcmNet.dec
> +
> +[LibraryClasses]
> +  DebugLib
> +  PcdLib
> +  UefiLib
> +  PrintLib
> +
> +[Protocols]
> +  gRaspberryPiFirmwareProtocolGuid              ## CONSUMES
> +
> +[Pcd]
> +  gBcmNetTokenSpaceGuid.PcdBcmGenetMacAddress   ## SOMETIMES_PRODUCES
> +
> +[FixedPcd]
> +  gBcmNetTokenSpaceGuid.PcdBcmGenetRegistersAddress
> +
> +[Depex]
> +  gRaspberryPiFirmwareProtocolGuid
> --
> 2.21.0.windows.1
>