/** @file
*
*  Copyright (c) 2014, ARM Limited. All rights reserved.
*
*  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.
*
**/

#include <Library/ArmLib.h>
#include <Library/ArmGicLib.h>

ARM_GIC_ARCH_REVISION
EFIAPI
ArmGicGetSupportedArchRevision (
  VOID
  )
{
  // Ideally we would like to use the GICC IIDR Architecture version here, but
  // this does not seem to be very reliable as the implementation could easily
  // get it wrong. It is more reliable to check if the GICv3 System Register
  // feature is implemented on the CPU. This is also convenient as our GICv3
  // driver requires SRE. If only Memory mapped access is available we try to
  // drive the GIC as a v2.
  if (ArmReadIdPfr0 () & AARCH64_PFR0_GIC) {
    return ARM_GIC_ARCH_REVISION_3;
  }

  return ARM_GIC_ARCH_REVISION_2;
}