From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753163AbbJEREL (ORCPT ); Mon, 5 Oct 2015 13:04:11 -0400 Received: from eu-smtp-delivery-143.mimecast.com ([207.82.80.143]:11010 "EHLO eu-smtp-delivery-143.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752441AbbJERDC (ORCPT ); Mon, 5 Oct 2015 13:03:02 -0400 From: "Suzuki K. Poulose" To: linux-arm-kernel@lists.infradead.org Cc: marc.zyngier@arm.com, will.deacon@arm.com, mark.rutland@arm.com, catalin.marinas@arm.com, steve.capper@linaro.org, linux-kernel@vger.kernel.org, andre.przywara@arm.com, dave.martin@arm.com, Vladimir.Murzin@arm.com, james.morse@arm.com, ard.biesheuvel@linaro.org, edward.nevill@linaro.org, aph@redhat.com, "Suzuki K. Poulose" Subject: [PATCH v2 21/22] arm64: cpuinfo: Expose MIDR_EL1 and REVIDR_EL1 to sysfs Date: Mon, 5 Oct 2015 18:02:10 +0100 Message-Id: <1444064531-25607-22-git-send-email-suzuki.poulose@arm.com> X-Mailer: git-send-email 1.7.9.5 In-Reply-To: <1444064531-25607-1-git-send-email-suzuki.poulose@arm.com> References: <1444064531-25607-1-git-send-email-suzuki.poulose@arm.com> X-OriginalArrivalTime: 05 Oct 2015 17:02:34.0146 (UTC) FILETIME=[A111F820:01D0FF8F] X-MC-Unique: 75XNncm2Qdyv1augPblnhA-11 Content-Type: text/plain; charset=WINDOWS-1252 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by mail.home.local id t95H4H1X008830 From: Steve Capper It can be useful for JIT software to be aware of MIDR_EL1 and REVIDR_EL1 to ascertain the presence of any core errata that could affect codegen. This patch exposes these registers through sysfs: /sys/devices/system/cpu/cpu$ID/identification/midr /sys/devices/system/cpu/cpu$ID/identification/revidr where $ID is the cpu number. For big.LITTLE systems, one can have a mixture of cores (e.g. Cortex A53 and Cortex A57), thus all CPUs need to be enumerated. If the kernel does not have valid information to populate these entries with, an empty string is returned to userspace. Signed-off-by: Steve Capper Signed-off-by: Suzuki K. Poulose --- arch/arm64/include/asm/cpu.h | 1 + arch/arm64/kernel/cpuinfo.c | 48 ++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 49 insertions(+) diff --git a/arch/arm64/include/asm/cpu.h b/arch/arm64/include/asm/cpu.h index b5e9cee..bb1b0cf 100644 --- a/arch/arm64/include/asm/cpu.h +++ b/arch/arm64/include/asm/cpu.h @@ -29,6 +29,7 @@ struct cpuinfo_arm64 { u32 reg_cntfrq; u32 reg_dczid; u32 reg_midr; + u32 reg_revidr; u64 reg_id_aa64dfr0; u64 reg_id_aa64dfr1; diff --git a/arch/arm64/kernel/cpuinfo.c b/arch/arm64/kernel/cpuinfo.c index 52331ff..93e0488 100644 --- a/arch/arm64/kernel/cpuinfo.c +++ b/arch/arm64/kernel/cpuinfo.c @@ -199,6 +199,7 @@ static void __cpuinfo_store_cpu(struct cpuinfo_arm64 *info) info->reg_ctr = read_cpuid_cachetype(); info->reg_dczid = read_cpuid(DCZID_EL0); info->reg_midr = read_cpuid_id(); + info->reg_revidr = read_cpuid(REVIDR_EL1); info->reg_id_aa64dfr0 = read_cpuid(ID_AA64DFR0_EL1); info->reg_id_aa64dfr1 = read_cpuid(ID_AA64DFR1_EL1); @@ -247,3 +248,50 @@ void __init cpuinfo_store_boot_cpu(void) boot_cpu_data = *info; init_cpu_features(&boot_cpu_data); } + +#define CPUINFO_ATTR_RO(_name) \ + static ssize_t show_##_name (struct device *dev, \ + struct device_attribute *attr, char *buf) \ + { \ + struct cpuinfo_arm64 *info = &per_cpu(cpu_data, dev->id); \ + \ + if (info->reg_midr) \ + return sprintf(buf, "0x%016x\n", info->reg_##_name); \ + else \ + return 0; \ + } \ + static DEVICE_ATTR(_name, 0444, show_##_name, NULL) + +CPUINFO_ATTR_RO(midr); +CPUINFO_ATTR_RO(revidr); + +static struct attribute *cpuregs_attrs[] = { + &dev_attr_midr.attr, + &dev_attr_revidr.attr, + NULL +}; + +static struct attribute_group cpuregs_attr_group = { + .attrs = cpuregs_attrs, + .name = "identification" +}; + +static int __init cpuinfo_regs_init(void) +{ + int cpu, ret; + + for_each_present_cpu(cpu) { + struct device *dev = get_cpu_device(cpu); + + if (!dev) + return -1; + + ret = sysfs_create_group(&dev->kobj, &cpuregs_attr_group); + if (ret) + return ret; + } + + return 0; +} + +device_initcall(cpuinfo_regs_init); -- 1.7.9.5