From c653fc2a91a946ea249e5d6161bca84f6c824f09 Mon Sep 17 00:00:00 2001
From: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Date: Mon, 9 Nov 2015 13:28:17 +0000
Subject: [PATCH] ArmPkg/ArmLib: add accessor function for Cache Writeback
 Granule

Add a function to ArmLib that provides access to the Cache Writeback
Granule (CWG) field in CTR_EL0. This information is required when
performing non-coherent DMA.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18758 6f19259b-4bc3-4df7-8a09-765794883524
---
 ArmPkg/Include/Library/ArmLib.h       |  6 ++++++
 ArmPkg/Library/ArmLib/Common/ArmLib.c | 17 +++++++++++++++++
 2 files changed, 23 insertions(+)

diff --git a/ArmPkg/Include/Library/ArmLib.h b/ArmPkg/Include/Library/ArmLib.h
index 2059a67bbf..a328146b69 100644
--- a/ArmPkg/Include/Library/ArmLib.h
+++ b/ArmPkg/Include/Library/ArmLib.h
@@ -114,6 +114,12 @@ ArmInstructionCacheLineLength (
   VOID
   );
 
+UINTN
+EFIAPI
+ArmCacheWritebackGranule (
+  VOID
+  );
+
 UINTN
 EFIAPI
 ArmIsArchTimerImplemented (
diff --git a/ArmPkg/Library/ArmLib/Common/ArmLib.c b/ArmPkg/Library/ArmLib/Common/ArmLib.c
index ad0a265e9f..7e227936fa 100644
--- a/ArmPkg/Library/ArmLib/Common/ArmLib.c
+++ b/ArmPkg/Library/ArmLib/Common/ArmLib.c
@@ -88,3 +88,20 @@ ArmInstructionCacheLineLength (
 {
   return 4 << (ArmCacheInfo () & 0xf); // CTR_EL0.IminLine
 }
+
+UINTN
+EFIAPI
+ArmCacheWritebackGranule (
+  VOID
+  )
+{
+  UINTN   CWG;
+
+  CWG = (ArmCacheInfo () >> 24) & 0xf; // CTR_EL0.CWG
+
+  if (CWG == 0) {
+    return SIZE_2KB;
+  }
+
+  return 4 << CWG;
+}