ArmPlatformPkg/ArmPlatformLib: Added support for ArmPlatformIsPrimaryCore()

Checking if a core if the primary/boot core used to be done with the macro
IS_PRIMARY_CORE().
Some platforms exposes configuration registers to change the primary core.
Replacing the macro IS_PRIMARY_CORE() by ArmPlatformIsPrimaryCore() allows
some flexibility in the way to check the primary core.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Olivier Martin <olivier.martin@arm.com>
Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>
Acked-by: Ryan Harkin <ryan.harkin@linaro.org>


git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@14344 6f19259b-4bc3-4df7-8a09-765794883524

ArmPlatformPkg/Include/Library/ArmPlatformLib.h

@@ -40,11 +40,35 @@ typedef struct {
   UINT64                       NumberOfBytes;
 } ARM_SYSTEM_MEMORY_REGION_DESCRIPTOR;
 
+/**
+  Return the core position from the value of its MpId register
+
+  This function returns the core position from the position 0 in the processor.
+  This function might be called from assembler before any stack is set.
+
+  @return   Return the core position
+
+**/
 UINTN
 ArmPlatformGetCorePosition (
   IN UINTN MpId
   );
 
+/**
+  Return a non-zero value if the callee is the primary core
+
+  This function returns a non-zero value if the callee is the primary core.
+  The primary core is the core responsible to initialize the hardware and run UEFI.
+  This function might be called from assembler before any stack is set.
+
+  @return   Return a non-zero value if the callee is the primary core.
+
+**/
+UINTN
+ArmPlatformIsPrimaryCore (
+  IN UINTN MpId
+  );
+
 /**
   Return the current Boot Mode