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

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Message-Id: <1445261101-22344-11-git-send-email-suzuki.poulose@arm.com>
Date:	Mon, 19 Oct 2015 14:24:47 +0100
From:	"Suzuki K. Poulose" <suzuki.poulose@....com>
To:	linux-arm-kernel@...ts.infradead.org
Cc:	linux-kernel@...r.kernel.org, catalin.marinas@....com,
	will.deacon@....com, mark.rutland@....com,
	christoffer.dall@...aro.org, steve.capper@...aro.org,
	Vladimir.Murzin@....com, james.morse@....com,
	andre.przywara@....com, ryan.arnold@...aro.org, aph@...hat.com,
	edward.nevill@...aro.org, dave.martin@....com,
	ard.biesheuvel@...aro.org, marc.zyngier@....com,
	"Suzuki K. Poulose" <suzuki.poulose@....com>
Subject: [PATCHv4 10/24] arm64: Read system wide CPUID value

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

Signed-off-by: Suzuki K. Poulose <suzuki.poulose@....com>
---
 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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