core: arm: add helper for reading isar5

Add helper function for reading ID_ISAR register on both
aarch32/aarch64.

Signed-off-by: Igor Opaniuk <igor.opaniuk@foundries.io>

core/arch/arm/include/arm32.h

@@ -276,6 +276,14 @@ static __always_inline __noprof uint32_t read_r7(void)
 	return val;
 }
 
+static __always_inline __noprof uint32_t read_isar5(void)
+{
+	uint32_t isar_reg;
+
+	asm volatile("mrc p15, 0, %0, c0, c2, 5" : "=r"(isar_reg));
+	return isar_reg;
+}
+
 #endif /*__ASSEMBLER__*/
 
 #endif /*__ARM32_H*/

core/arch/arm/include/arm64.h

@@ -366,6 +366,14 @@ static inline __noprof void tlbi_vale1is(uint64_t va)
 	asm volatile ("tlbi	vale1is, %0" : : "r" (va));
 }
 
+static inline __noprof uint32_t read_isar5(void)
+{
+	uint64_t isar_reg;
+
+	asm volatile("mrs %0, ID_ISAR5_EL1" : "=r"(isar_reg));
+	return (uint32_t)isar_reg;
+}
+
 static inline void write_64bit_pair(uint64_t dst, uint64_t hi, uint64_t lo)
 {
 	/* 128bits should be written to hardware at one time */