arm64: Move mixed endian support detection

Move the mixed endian support detection code to cpufeature.c
from cpuinfo.c. This also moves the update_cpu_features()
used by mixed endian detection code, which will get more
functionality.

Also moves the ID register field shifts to asm/sysreg.h,
where all the useful definitions will end up in later patches.

Signed-off-by: Suzuki K. Poulose <suzuki.poulose@arm.com>
Tested-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

arch/arm64/kernel/cpufeature.c

@@ -22,7 +22,9 @@
 #include <asm/cpu.h>
 #include <asm/cpufeature.h>
 #include <asm/processor.h>
+#include <asm/sysreg.h>
 
+static bool mixed_endian_el0 = true;
 unsigned long elf_hwcap __read_mostly;
 EXPORT_SYMBOL_GPL(elf_hwcap);
 
@@ -41,6 +43,26 @@ unsigned int compat_elf_hwcap2 __read_mostly;
 DECLARE_BITMAP(cpu_hwcaps, ARM64_NCAPS);
 
 
+bool cpu_supports_mixed_endian_el0(void)
+{
+	return id_aa64mmfr0_mixed_endian_el0(read_cpuid(ID_AA64MMFR0_EL1));
+}
+
+bool system_supports_mixed_endian_el0(void)
+{
+	return mixed_endian_el0;
+}
+
+static void update_mixed_endian_el0_support(struct cpuinfo_arm64 *info)
+{
+	mixed_endian_el0 &= id_aa64mmfr0_mixed_endian_el0(info->reg_id_aa64mmfr0);
+}
+
+void update_cpu_features(struct cpuinfo_arm64 *info)
+{
+	update_mixed_endian_el0_support(info);
+}
+
 static bool
 feature_matches(u64 reg, const struct arm64_cpu_capabilities *entry)
 {