ArmPkg: Add helper to read the CCSIDR2 register

Add helper function to read the CCSIDR2 register.
This is used when CCIDX is supported in AARCH32 mode.

Signed-off-by: Rebecca Cran <rebecca@nuviainc.com>
Reviewed-by: Leif Lindholm <leif@nuviainc.com>

ArmPkg/Library/ArmLib/Arm/ArmLibSupportV7.S

@@ -74,6 +74,16 @@ ASM_FUNC(ReadCCSIDR)
   mrc p15,1,r0,c0,c0,0   @ Read current CP15 Cache Size ID Register (CCSIDR)
   bx  lr
 
+// UINT32
+// ReadCCSIDR2 (
+//   IN UINT32 CSSELR
+//   )
+ASM_FUNC(ReadCCSIDR2)
+  mcr p15,2,r0,c0,c0,0   @ Write Cache Size Selection Register (CSSELR)
+  isb
+  mrc p15,1,r0,c0,c0,2   @ Read current CP15 Cache Size ID Register (CCSIDR2)
+  bx  lr
+
 // UINT32
 // ReadCLIDR (
 //   IN UINT32 CSSELR

ArmPkg/Library/ArmLib/Arm/ArmLibSupportV7.asm

@@ -78,6 +78,16 @@
   mrc p15,1,r0,c0,c0,0 ; Read current CP15 Cache Size ID Register (CCSIDR)
   bx  lr
 
+// UINT32
+// ReadCCSIDR2 (
+//   IN UINT32 CSSELR
+//   )
+ RVCT_ASM_EXPORT ReadCCSIDR2
+  mcr p15,2,r0,c0,c0,0 ; Write Cache Size Selection Register (CSSELR)
+  isb
+  mrc p15,1,r0,c0,c0,2 ; Read current CP15 Cache Size ID Register (CCSIDR2)
+  bx  lr
+
 // UINT32
 // ReadCLIDR (
 //   IN UINT32 CSSELR

ArmPkg/Library/ArmLib/ArmLibPrivate.h

@@ -170,6 +170,17 @@ ReadCCSIDR (
   IN UINT32 CSSELR
   );
 
+/** Reads the CCSIDR2 for the specified cache.
+
+  @param CSSELR The CSSELR cache selection register value
+
+  @return The contents of the CCSIDR2 register for the specified cache.
+**/
+UINT32
+ReadCCSIDR2 (
+  IN UINT32 CSSELR
+  );
+
 UINT32
 ReadCLIDR (
   VOID