MdeModulePkg/Library/ArmFfaLib/ArmFfaStandaloneMmLib.c

/** @file
  Arm Ffa library code for StandaloneMmCore.

  Copyright (c) 2024, Arm Limited. All rights reserved.<BR>
  SPDX-License-Identifier: BSD-2-Clause-Patent

   @par Glossary:
     - FF-A - Firmware Framework for Arm A-profile

   @par Reference(s):
     - Arm Firmware Framework for Arm A-Profile [https://developer.arm.com/documentation/den0077/latest]

**/

#include <PiMm.h>

#include <Library/ArmLib.h>
#include <Library/ArmSmcLib.h>
#include <Library/ArmFfaLib.h>
#include <Library/BaseLib.h>
#include <Library/BaseMemoryLib.h>
#include <Library/DebugLib.h>

#include "ArmFfaCommon.h"

/**
  Get mapped Rx/Tx buffers.

  @param [out]   TxBuffer         Address of TxBuffer
  @param [out]   TxBufferSize     Size of TxBuffer
  @param [out]   RxBuffer         Address of RxBuffer
  @param [out]   RxBufferSize     Size of RxBuffer

  @retval EFI_SUCCESS
  @retval Others             Error.

**/
EFI_STATUS
EFIAPI
ArmFfaLibGetRxTxBuffers (
  OUT VOID    **TxBuffer,
  OUT UINT64  *TxBufferSize,
  OUT VOID    **RxBuffer,
  OUT UINT64  *RxBufferSize
  )
{
  /*
   * StandaloneMm doesn't use Rx/Tx buffer.
   * So, return EFI_UNSUPPORTED.
   */
  return EFI_UNSUPPORTED;
}

/**
  ArmFfaLib Constructor.

  @param  [in]  ImageHandle     The firmware allocated handle for the EFI image
  @param  [in]  MmSystemTable   A pointer to the Management mode System Table

  @retval EFI_SUCCESS            Success
  @retval Others                 Error

**/
EFI_STATUS
EFIAPI
ArmFfaStandaloneMmLibConstructor (
  IN EFI_HANDLE           ImageHandle,
  IN EFI_MM_SYSTEM_TABLE  *MmSystemTable
  )
{
  EFI_STATUS  Status;

  Status = ArmFfaLibCommonInit ();
  if (Status == EFI_UNSUPPORTED) {
    /*
     * EFI_UNSUPPORTED means FF-A interface isn't available.
     * However, for Standalone MM modules, FF-A availability is not required.
     * i.e. Standalone MM could use SpmMm as a legitimate protocol.
     * Thus, returning EFI_SUCCESS here to avoid the entrypoint to assert.
     */
    return EFI_SUCCESS;
  }

  if (EFI_ERROR (Status)) {
    DEBUG ((DEBUG_ERROR, "%a failed. Status = %r\n", __func__, Status));
  }

  return Status;
}