Apple ARM SoCs (A11 and newer) have some interrupt sources hard-wired to the FIQ line. Introduce a cpufeature that can be used to enable FIQ handling via alternatives. This is currently enabled for all Apple CPUs. If/when support is implemented for older (pre-A11) iPhone/iPad SoCs which do not need FIQs, or if newer SoCs are released without the FIQ requirement, we can revisit the condition. Signed-off-by: Hector Martin <marcan@xxxxxxxxx> --- arch/arm64/Kconfig | 11 +++++++++++ arch/arm64/include/asm/cpucaps.h | 3 ++- arch/arm64/kernel/cpufeature.c | 14 ++++++++++++++ 3 files changed, 27 insertions(+), 1 deletion(-) diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index f39568b28ec1..fbc02af404b6 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -1756,6 +1756,17 @@ config ARM64_DEBUG_PRIORITY_MASKING If unsure, say N endif +config ARM64_FIQ_SUPPORT + bool "Support for FIQ interrupts" + help + Adds support for handling FIQ interrupts as normal IRQs. + This is required on Apple platforms where some IRQ sources are + hardwired to the FIQ interrupt line. + + This option only affects platforms that require FIQ handling. + On all other platforms, unexpected FIQs will continue to + trigger a kernel panic. + config RELOCATABLE bool "Build a relocatable kernel image" if EXPERT select ARCH_HAS_RELR diff --git a/arch/arm64/include/asm/cpucaps.h b/arch/arm64/include/asm/cpucaps.h index b77d997b173b..c36d926ad801 100644 --- a/arch/arm64/include/asm/cpucaps.h +++ b/arch/arm64/include/asm/cpucaps.h @@ -66,7 +66,8 @@ #define ARM64_WORKAROUND_1508412 58 #define ARM64_HAS_LDAPR 59 #define ARM64_KVM_PROTECTED_MODE 60 +#define ARM64_NEEDS_FIQ 61 -#define ARM64_NCAPS 61 +#define ARM64_NCAPS 62 #endif /* __ASM_CPUCAPS_H */ diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index e99eddec0a46..9fde84beabf1 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -1237,6 +1237,12 @@ static bool has_cache_idc(const struct arm64_cpu_capabilities *entry, return ctr & BIT(CTR_IDC_SHIFT); } +static bool needs_fiq(const struct arm64_cpu_capabilities *entry, int __unused) +{ + /* All supported Apple cores need this */ + return read_cpuid_implementor() == ARM_CPU_IMP_APPLE; +} + static void cpu_emulate_effective_ctr(const struct arm64_cpu_capabilities *__unused) { /* @@ -2154,6 +2160,14 @@ static const struct arm64_cpu_capabilities arm64_features[] = { .matches = has_cpuid_feature, .min_field_value = 1, }, +#ifdef CONFIG_ARM64_FIQ_SUPPORT + { + .desc = "FIQs", + .capability = ARM64_NEEDS_FIQ, + .type = ARM64_CPUCAP_BOOT_CPU_FEATURE, + .matches = needs_fiq, + }, +#endif {}, }; -- 2.30.0