From mboxrd@z Thu Jan 1 00:00:00 1970 From: robherring2@gmail.com (Rob Herring) Date: Sun, 28 Jul 2013 16:14:08 -0500 Subject: [PATCH v2] ARM: Add check for Cortex-A15 errata 798181 ECO Message-ID: <1375046048-25853-1-git-send-email-robherring2@gmail.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org From: Rob Herring The work-around for A15 errata 798181 is not needed if appropriate ECO fixes have been applied to r3p2 and earlier core revisions. This can be checked by reading REVIDR register bits 4 and 9. If only bit 4 is set, then the IPI broadcast can be skipped. Signed-off-by: Rob Herring --- v2: - Determine the work-around needed and save in a static varible instead of re-reading the ID registers. arch/arm/include/asm/cputype.h | 1 + arch/arm/kernel/smp_tlb.c | 31 +++++++++++++++++++++++-------- 2 files changed, 24 insertions(+), 8 deletions(-) diff --git a/arch/arm/include/asm/cputype.h b/arch/arm/include/asm/cputype.h index 8c25dc4..e5952b7 100644 --- a/arch/arm/include/asm/cputype.h +++ b/arch/arm/include/asm/cputype.h @@ -10,6 +10,7 @@ #define CPUID_TLBTYPE 3 #define CPUID_MPUIR 4 #define CPUID_MPIDR 5 +#define CPUID_REVIDR 6 #ifdef CONFIG_CPU_V7M #define CPUID_EXT_PFR0 0x40 diff --git a/arch/arm/kernel/smp_tlb.c b/arch/arm/kernel/smp_tlb.c index a98b62d..da20db1 100644 --- a/arch/arm/kernel/smp_tlb.c +++ b/arch/arm/kernel/smp_tlb.c @@ -73,12 +73,29 @@ static inline void ipi_flush_bp_all(void *ignored) #ifdef CONFIG_ARM_ERRATA_798181 static int erratum_a15_798181(void) { - unsigned int midr = read_cpuid_id(); - - /* Cortex-A15 r0p0..r3p2 affected */ - if ((midr & 0xff0ffff0) != 0x410fc0f0 || midr > 0x413fc0f2) - return 0; - return 1; + static int errata_fix_needed = -1; + + if (unlikely(errata_fix_needed == -1)) { + unsigned int midr = read_cpuid_id(); + unsigned int revidr = read_cpuid(CPUID_REVIDR); + + /* Cortex-A15 r0p0..r3p2 w/o ECO fix affected */ + if ((midr & 0xff0ffff0) != 0x410fc0f0 || midr > 0x413fc0f2 || + (revidr & 0x210) == 0x210) { + errata_fix_needed = 0; /* No work-around needed */ + return 0; + } + if (revidr & 0x10) + errata_fix_needed = 1; /* Only TLB flush needed */ + else + errata_fix_needed = 2; /* IPI broadcast needed */ + } + + if (errata_fix_needed) + dummy_flush_tlb_a15_erratum(); + + /* Return 1 if IPI broadcast to other cores is needed */ + return (errata_fix_needed == 2) ? 1: 0; } #else static int erratum_a15_798181(void) @@ -97,7 +114,6 @@ static void broadcast_tlb_a15_erratum(void) if (!erratum_a15_798181()) return; - dummy_flush_tlb_a15_erratum(); smp_call_function(ipi_flush_tlb_a15_erratum, NULL, 1); } @@ -109,7 +125,6 @@ static void broadcast_tlb_mm_a15_erratum(struct mm_struct *mm) if (!erratum_a15_798181()) return; - dummy_flush_tlb_a15_erratum(); this_cpu = get_cpu(); a15_erratum_get_cpumask(this_cpu, mm, &mask); smp_call_function_many(&mask, ipi_flush_tlb_a15_erratum, NULL, 1); -- 1.8.1.2