[PATCH v7 1/3] arm64: cpufeature: introduce helper cpu_has_hw_af()

Jia He
2019-09-20T13:55:03Z

We unconditionally set the HW_AFDBM capability and only enable it on
CPUs which really have the feature. But sometimes we need to know
whether this cpu has the capability of HW AF. So decouple AF from
DBM by new helper cpu_has_hw_af().

Reported-by: kbuild test robot <lkp@intel.com>
Suggested-by: Suzuki Poulose <Suzuki.Poulose@arm.com>
Signed-off-by: Jia He <justin.he@arm.com>
---
arch/arm64/include/asm/cpufeature.h | 10 ++++++++++
1 file changed, 10 insertions(+)

diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index c96ffa4722d3..46caf934ba4e 100644
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -667,6 +667,16 @@ static inline u32 id_aa64mmfr0_parange_to_phys_shift(int parange)
default: return CONFIG_ARM64_PA_BITS;
}
}
+
+/* Decouple AF from AFDBM. */
+static inline bool cpu_has_hw_af(void)
+{
+ if (IS_ENABLED(CONFIG_ARM64_HW_AFDBM))
+ return read_cpuid(ID_AA64MMFR1_EL1) & 0xf;
+
+ return false;
+}
+
#endif /* __ASSEMBLY__ */

#endif
--
2.17.1