arm64: kernel: add MPIDR_EL1 accessors macros

In order to simplify access to different affinity levels within the
MPIDR_EL1 register values, this patch implements some preprocessor
macros that allow to retrieve the MPIDR_EL1 affinity level value according
to the level passed as input parameter.
Reviewed-by: NWill Deacon <will.deacon@arm.com>
Signed-off-by: NLorenzo Pieralisi <lorenzo.pieralisi@arm.com>

arch/arm64/include/asm/cputype.h

@@ -30,6 +30,16 @@
 
 #define MPIDR_HWID_BITMASK	0xff00ffffff
 
+#define MPIDR_LEVEL_BITS_SHIFT	3
+#define MPIDR_LEVEL_BITS	(1 << MPIDR_LEVEL_BITS_SHIFT)
+#define MPIDR_LEVEL_MASK	((1 << MPIDR_LEVEL_BITS) - 1)
+
+#define MPIDR_LEVEL_SHIFT(level) \
+	(((1 << level) >> 1) << MPIDR_LEVEL_BITS_SHIFT)
+
+#define MPIDR_AFFINITY_LEVEL(mpidr, level) \
+	((mpidr >> MPIDR_LEVEL_SHIFT(level)) & MPIDR_LEVEL_MASK)
+
 #define read_cpuid(reg) ({						\
 	u64 __val;							\
 	asm("mrs	%0, " reg : "=r" (__val));			\