audk/ArmPkg/Drivers/ArmGic/AArch64/ArmGicArchLib.c

36 lines
1.2 KiB
C

/** @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;
}