[RFC PATCH 09/10] arm64: Read system wide CPUID value

From: Suzuki K. Poulose
Date: Fri Jul 24 2015 - 05:46:06 EST


From: "Suzuki K. Poulose" <suzuki.poulose@xxxxxxx>

Add an API for reading a safe CPUID value across the system

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

diff --git a/arch/arm64/include/asm/cpu.h b/arch/arm64/include/asm/cpu.h
index cb25cb9..17a871d 100644
--- a/arch/arm64/include/asm/cpu.h
+++ b/arch/arm64/include/asm/cpu.h
@@ -177,6 +177,7 @@ struct arm64_ftr_reg {
.ftr_bits = &((ftr_table)[0]), \
}

+#define read_system_cpuid(id) read_system_reg(SYS_##id)
/*
* Records attributes of an individual CPU.
*/
@@ -226,4 +227,5 @@ static inline u64 arm64_ftr_value(struct arm64_ftr_bits *ftrp, u64 reg)
return ((reg >> ftrp->shift) & ftrp->mask);
}

+u64 read_system_reg(enum sys_id id);
#endif /* __ASM_CPU_H */
diff --git a/arch/arm64/kernel/cpuinfo.c b/arch/arm64/kernel/cpuinfo.c
index 9145eef..7d140f7 100644
--- a/arch/arm64/kernel/cpuinfo.c
+++ b/arch/arm64/kernel/cpuinfo.c
@@ -310,6 +310,15 @@ static struct arm64_ftr_reg* get_arm64_sys_reg(enum sys_id sys_id)
return NULL;
}

+u64 read_system_reg(enum sys_id id)
+{
+ struct arm64_ftr_reg *regp = get_arm64_sys_reg(id);
+
+ /* We shouldn't get a request for an unsupported register */
+ BUG_ON(!regp);
+ return regp->sys_val;
+}
+
static u64 arm64_ftr_set_value(struct arm64_ftr_bits *ftrp, u64 reg, u64 ftr_val)
{
u64 mask = ftrp->mask << ftrp->shift;
--
1.7.9.5

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