From mboxrd@z Thu Jan 1 00:00:00 1970 From: james.morse@arm.com (James Morse) Date: Tue, 21 Jul 2015 13:23:29 +0100 Subject: [PATCH v3 4/6] arm64: kernel: Add min_field_value and use '>=' for feature detection In-Reply-To: <1437481411-1595-1-git-send-email-james.morse@arm.com> References: <1437481411-1595-1-git-send-email-james.morse@arm.com> Message-ID: <1437481411-1595-5-git-send-email-james.morse@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org When a new cpu feature is available, the cpu feature bits will have some initial value, which is incremented when the feature is updated. This patch changes 'register_value' to be 'min_field_value', and checks the feature bits value (interpreted as a signed int) is greater than this minimum. Signed-off-by: James Morse Cc: Catalin Marinas Cc: Will Deacon --- arch/arm64/include/asm/cpufeature.h | 4 ++-- arch/arm64/kernel/cpufeature.c | 14 +++++++++++--- 2 files changed, 13 insertions(+), 5 deletions(-) diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h index 484fa9425314..f595f7ddd43b 100644 --- a/arch/arm64/include/asm/cpufeature.h +++ b/arch/arm64/include/asm/cpufeature.h @@ -42,8 +42,8 @@ struct arm64_cpu_capabilities { }; struct { /* Feature register checking */ - u64 register_mask; - u64 register_value; + int field_pos; + int min_field_value; }; }; }; diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index 650ffc28bedc..74fd0f74b065 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -23,12 +23,20 @@ #include static bool +feature_matches(u64 reg, const struct arm64_cpu_capabilities *entry) +{ + int val = cpuid_feature_extract_field(reg, entry->field_pos); + + return val >= entry->min_field_value; +} + +static bool has_id_aa64pfr0_feature(const struct arm64_cpu_capabilities *entry) { u64 val; val = read_cpuid(id_aa64pfr0_el1); - return (val & entry->register_mask) == entry->register_value; + return feature_matches(val, entry); } static const struct arm64_cpu_capabilities arm64_features[] = { @@ -36,8 +44,8 @@ static const struct arm64_cpu_capabilities arm64_features[] = { .desc = "GIC system register CPU interface", .capability = ARM64_HAS_SYSREG_GIC_CPUIF, .matches = has_id_aa64pfr0_feature, - .register_mask = (0xf << 24), - .register_value = (1 << 24), + .field_pos = 24, + .min_field_value = 1, }, {}, }; -- 2.1.4