[PATCH v4 05/10] ArmPkg: Add helper function to read the Memory Model Feature Register 4

["Rebecca Cran" <rebecca@nuviainc.com>]

In AARCH32, CCIDX support is indicated in the MMFR4 register - unlike
under AARCH64 where it's in MMFR2. Add a helper function to read it.

Signed-off-by: Rebecca Cran <rebecca@nuviainc.com>
---
 ArmPkg/Library/ArmLib/Arm/ArmV7Lib.h          | 6 ++++++
 ArmPkg/Library/ArmLib/Arm/ArmLibSupportV7.S   | 4 ++++
 ArmPkg/Library/ArmLib/Arm/ArmLibSupportV7.asm | 4 ++++
 3 files changed, 14 insertions(+)

diff --git a/ArmPkg/Library/ArmLib/Arm/ArmV7Lib.h b/ArmPkg/Library/ArmLib/Arm/ArmV7Lib.h
index 93183e67230e..3b331a3b2088 100644
--- a/ArmPkg/Library/ArmLib/Arm/ArmV7Lib.h
+++ b/ArmPkg/Library/ArmLib/Arm/ArmV7Lib.h
@@ -48,5 +48,11 @@ ArmCleanInvalidateDataCacheEntryBySetWay (
   IN  UINTN   SetWayFormat
   );
 
+UINT32
+EFIAPI
+ArmReadIdMmfr4 (
+  VOID
+  );
+
 #endif // __ARM_V7_LIB_H__
 
diff --git a/ArmPkg/Library/ArmLib/Arm/ArmLibSupportV7.S b/ArmPkg/Library/ArmLib/Arm/ArmLibSupportV7.S
index 01c91b10fcb7..a60a2f634132 100644
--- a/ArmPkg/Library/ArmLib/Arm/ArmLibSupportV7.S
+++ b/ArmPkg/Library/ArmLib/Arm/ArmLibSupportV7.S
@@ -60,6 +60,10 @@ ASM_FUNC(ArmDisableInterrupts)
   isb
   bx      LR
 
+ASM_FUNC(ArmReadIdMmfr4)
+  mrc    p15,0,r0,c0,c2,6     @ Read ID_MMFR4 Register
+  bx     lr
+
 // UINT32
 // ReadCCSIDR (
 //   IN UINT32 CSSELR
diff --git a/ArmPkg/Library/ArmLib/Arm/ArmLibSupportV7.asm b/ArmPkg/Library/ArmLib/Arm/ArmLibSupportV7.asm
index 26ffa331b929..1679b09b797a 100644
--- a/ArmPkg/Library/ArmLib/Arm/ArmLibSupportV7.asm
+++ b/ArmPkg/Library/ArmLib/Arm/ArmLibSupportV7.asm
@@ -64,6 +64,10 @@
   isb
   bx      LR
 
+ RVCT_ASM_EXPORT ArmReadIdMmfr4
+  mrc    p15,0,r0,c0,c2,6     ; Read ID_MMFR4 Register
+  bx     LR
+
 // UINT32
 // ReadCCSIDR (
 //   IN UINT32 CSSELR
-- 
2.26.2