[PATCHv4 10/24] arm64: Read system wide CPUID value

From: Suzuki K. Poulose
Date: Mon Oct 19 2015 - 09:04:56 EST


Add an API for reading the safe CPUID value across the
system from the new infrastructure.

Signed-off-by: Suzuki K. Poulose <suzuki.poulose@xxxxxxx>
---
arch/arm64/include/asm/cpufeature.h | 2 ++
arch/arm64/kernel/cpufeature.c | 9 +++++++++
2 files changed, 11 insertions(+)

diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index af0c187..c882d46 100644
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -144,6 +144,8 @@ void check_local_cpu_features(void);
bool cpu_supports_mixed_endian_el0(void);
bool system_supports_mixed_endian_el0(void);

+u64 read_system_reg(u32 id);
+
#endif /* __ASSEMBLY__ */

#endif
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index aae1817..b4656ca 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -590,6 +590,15 @@ void update_cpu_features(int cpu,
update_mixed_endian_el0_support(info);
}

+u64 read_system_reg(u32 id)
+{
+ struct arm64_ftr_reg *regp = get_arm64_ftr_reg(id);
+
+ /* We shouldn't get a request for an unsupported register */
+ BUG_ON(!regp);
+ return regp->sys_val;
+}
+
static bool
feature_matches(u64 reg, const struct arm64_cpu_capabilities *entry)
{
--
1.7.9.5

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