EmbeddedPkg/AcpiLib: Add more helper functions

This adds more helper functions that assist in calculating the checksum,
locating an ACPI table by signature, and updating an AML integer object.

Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
Cc: Daniel Schaefer <daniel.schaefer@hpe.com>
Signed-off-by: Nhi Pham <nhi@os.amperecomputing.com>
Acked-by: Leif Lindholm <leif@nuviainc.com>
Reviewed-by: Abner Chang <abner.chang@hpe.com>

EmbeddedPkg/Include/Library/AcpiLib.h

@@ -2,6 +2,7 @@
   Helper Library for ACPI
 
   Copyright (c) 2014-2016, ARM Ltd. All rights reserved.
+  Copyright (c) 2021, Ampere Computing LLC. All rights reserved.
 
   SPDX-License-Identifier: BSD-2-Clause-Patent
 
@@ -13,6 +14,7 @@
 #include <Uefi.h>
 
 #include <IndustryStandard/Acpi10.h>
+#include <Protocol/AcpiSystemDescriptionTable.h>
 
 //
 // Macros for the Generic Address Space
@@ -128,4 +130,73 @@ LocateAndInstallAcpiFromFv (
   IN CONST EFI_GUID  *AcpiFile
   );
 
+/**
+  This function calculates and updates a UINT8 checksum
+  in an ACPI description table header.
+
+  @param  Buffer          Pointer to buffer to checksum
+  @param  Size            Number of bytes to checksum
+
+  @retval EFI_SUCCESS             The function completed successfully.
+  @retval EFI_INVALID_PARAMETER   Invalid parameter.
+
+**/
+EFI_STATUS
+EFIAPI
+AcpiUpdateChecksum (
+  IN OUT  UINT8      *Buffer,
+  IN      UINTN      Size
+  );
+
+/**
+  This function uses the ACPI SDT protocol to search an ACPI table
+  with a given signature.
+
+  @param  AcpiTableSdtProtocol    Pointer to ACPI SDT protocol.
+  @param  TableSignature          ACPI table signature.
+  @param  Index                   The zero-based index of the table where to search the table.
+                                  The index will be updated to the next instance if the table
+                                  is found with the matched TableSignature.
+  @param  Table                   Pointer to the table.
+  @param  TableKey                Pointer to the table key.
+
+  @return EFI_SUCCESS             The function completed successfully.
+  @return EFI_INVALID_PARAMETER   At least one of parameters is invalid.
+  @retval EFI_NOT_FOUND           The requested index is too large and a table was not found.
+
+**/
+EFI_STATUS
+EFIAPI
+AcpiLocateTableBySignature (
+  IN      EFI_ACPI_SDT_PROTOCOL           *AcpiSdtProtocol,
+  IN      UINT32                          TableSignature,
+  IN OUT  UINTN                           *Index,
+  OUT     EFI_ACPI_DESCRIPTION_HEADER     **Table,
+  OUT     UINTN                           *TableKey
+  );
+
+/**
+  This function updates the integer value of an AML Object.
+
+  @param  AcpiTableSdtProtocol    Pointer to ACPI SDT protocol.
+  @param  TableHandle             Points to the table representing the starting point
+                                  for the object path search.
+  @param  AsciiObjectPath         Pointer to the ACPI path of the object being updated.
+  @param  Value                   New value to write to the object.
+
+  @return EFI_SUCCESS             The function completed successfully.
+  @return EFI_INVALID_PARAMETER   At least one of parameters is invalid or the data type
+                                  of the ACPI object is not an integer value.
+  @retval EFI_NOT_FOUND           The object is not found with the given path.
+
+**/
+EFI_STATUS
+EFIAPI
+AcpiAmlObjectUpdateInteger (
+  IN  EFI_ACPI_SDT_PROTOCOL           *AcpiSdtProtocol,
+  IN  EFI_ACPI_HANDLE                 TableHandle,
+  IN  CHAR8                           *AsciiObjectPath,
+  IN  UINTN                           Value
+  );
+
 #endif // __ACPI_LIB_H__