From 5cc25cff5de191583f3ecb2d9a7e9a13baa70071 Mon Sep 17 00:00:00 2001
From: Leif Lindholm <leif@nuviainc.com>
Date: Fri, 18 Dec 2020 11:55:52 +0000
Subject: ArmPkg/ArmLib: add ArmHasGicSystemRegisters () helper function

Create a helper function to eliminate direct feature register reading,
which gets messy in code shared between ARM/AArch64.

Returns BOOLEAN True if the CPU implements the GIC System Register
Interface (any version), otherwise returns BOOL False.

Cc: Ard Biesheuvel <ard.biesheuvel@arm.com>
Signed-off-by: Leif Lindholm <leif@nuviainc.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@arm.com>
---
 ArmPkg/Include/Library/ArmLib.h            | 18 ++++++++++++++++++
 ArmPkg/Library/ArmLib/AArch64/AArch64Lib.c | 16 ++++++++++++++++
 ArmPkg/Library/ArmLib/Arm/ArmV7Lib.c       | 16 ++++++++++++++++
 3 files changed, 50 insertions(+)

diff --git a/ArmPkg/Include/Library/ArmLib.h b/ArmPkg/Include/Library/ArmLib.h
index 5a27b7c..8a364f2 100644
--- a/ArmPkg/Include/Library/ArmLib.h
+++ b/ArmPkg/Include/Library/ArmLib.h
@@ -2,6 +2,7 @@
 
   Copyright (c) 2008 - 2009, Apple Inc. All rights reserved.<BR>
   Copyright (c) 2011 - 2016, ARM Ltd. All rights reserved.<BR>
+  Copyright (c) 2020, NUVIA Inc. All rights reserved.<BR>
 
   SPDX-License-Identifier: BSD-2-Clause-Patent
 
@@ -715,4 +716,21 @@ ArmGetPhysicalAddressBits (
   VOID
   );
 
+
+///
+///  ID Register Helper functions
+///
+
+/**
+  Check whether the CPU supports the GIC system register interface (any version)
+
+  @return   Whether GIC System Register Interface is supported
+
+**/
+BOOLEAN
+EFIAPI
+ArmHasGicSystemRegisters (
+  VOID
+  );
+
 #endif // __ARM_LIB__
diff --git a/ArmPkg/Library/ArmLib/AArch64/AArch64Lib.c b/ArmPkg/Library/ArmLib/AArch64/AArch64Lib.c
index 3fbd591..5b10eb3 100644
--- a/ArmPkg/Library/ArmLib/AArch64/AArch64Lib.c
+++ b/ArmPkg/Library/ArmLib/AArch64/AArch64Lib.c
@@ -2,6 +2,7 @@
 
   Copyright (c) 2008 - 2009, Apple Inc. All rights reserved.<BR>
   Portions copyright (c) 2011 - 2014, ARM Ltd. All rights reserved.<BR>
+  Copyright (c) 2020, NUVIA Inc. All rights reserved.<BR>
 
   SPDX-License-Identifier: BSD-2-Clause-Patent
 
@@ -71,3 +72,18 @@ ArmCleanDataCache (
   ArmDataSynchronizationBarrier ();
   AArch64DataCacheOperation (ArmCleanDataCacheEntryBySetWay);
 }
+
+/**
+  Check whether the CPU supports the GIC system register interface (any version)
+
+  @return   Whether GIC System Register Interface is supported
+
+**/
+BOOLEAN
+EFIAPI
+ArmHasGicSystemRegisters (
+  VOID
+  )
+{
+  return ((ArmReadIdPfr0 () & AARCH64_PFR0_GIC) != 0);
+}
diff --git a/ArmPkg/Library/ArmLib/Arm/ArmV7Lib.c b/ArmPkg/Library/ArmLib/Arm/ArmV7Lib.c
index 2c4a23e..3faada3 100644
--- a/ArmPkg/Library/ArmLib/Arm/ArmV7Lib.c
+++ b/ArmPkg/Library/ArmLib/Arm/ArmV7Lib.c
@@ -2,6 +2,7 @@
 
   Copyright (c) 2008 - 2009, Apple Inc. All rights reserved.<BR>
   Copyright (c) 2011 - 2014, ARM Limited. All rights reserved.
+  Copyright (c) 2020, NUVIA Inc. All rights reserved.<BR>
 
   SPDX-License-Identifier: BSD-2-Clause-Patent
 
@@ -71,3 +72,18 @@ ArmCleanDataCache (
   ArmDataSynchronizationBarrier ();
   ArmV7DataCacheOperation (ArmCleanDataCacheEntryBySetWay);
 }
+
+/**
+  Check whether the CPU supports the GIC system register interface (any version)
+
+  @return   Whether GIC System Register Interface is supported
+
+**/
+BOOLEAN
+EFIAPI
+ArmHasGicSystemRegisters (
+  VOID
+  )
+{
+  return ((ArmReadIdPfr1 () & ARM_PFR1_GIC) != 0);
+}
-- 
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