Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753370AbbHVBxZ (ORCPT ); Fri, 21 Aug 2015 21:53:25 -0400 Received: from mga01.intel.com ([192.55.52.88]:46598 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752383AbbHVBwv (ORCPT ); Fri, 21 Aug 2015 21:52:51 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.15,726,1432623600"; d="scan'208";a="753236158" From: "Christopher S. Hall" To: jeffrey.t.kirsher@intel.com, hpa@zytor.com, mingo@redhat.com, tglx@linutronix.de, john.stultz@linaro.org Cc: richardcochran@gmail.com, x86@kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, intel-wired-lan@lists.osuosl.org, peterz@infradead.org, "Christopher S. Hall" Subject: [PATCH v3 2/4] Added ART correlated clocksource and ART CPU feature Date: Fri, 21 Aug 2015 11:52:06 -0700 Message-Id: <1440183128-1384-3-git-send-email-christopher.s.hall@intel.com> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1440183128-1384-1-git-send-email-christopher.s.hall@intel.com> References: <1440183128-1384-1-git-send-email-christopher.s.hall@intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4718 Lines: 140 Add detect_art() call to early TSC initialization which reads ART->TSC numerator/denominator and sets CPU feature if present Add convert_art_to_tsc() function performing conversion ART to TSC Add art_timestamp referencing art_to_tsc() and clocksource_tsc enabling driver conversion of ART to TSC Signed-off-by: Christopher S. Hall --- arch/x86/include/asm/cpufeature.h | 3 ++- arch/x86/include/asm/tsc.h | 2 ++ arch/x86/kernel/tsc.c | 54 +++++++++++++++++++++++++++++++++++++++ 3 files changed, 58 insertions(+), 1 deletion(-) diff --git a/arch/x86/include/asm/cpufeature.h b/arch/x86/include/asm/cpufeature.h index 3d6606f..a9322e5 100644 --- a/arch/x86/include/asm/cpufeature.h +++ b/arch/x86/include/asm/cpufeature.h @@ -85,7 +85,7 @@ #define X86_FEATURE_P4 ( 3*32+ 7) /* "" P4 */ #define X86_FEATURE_CONSTANT_TSC ( 3*32+ 8) /* TSC ticks at a constant rate */ #define X86_FEATURE_UP ( 3*32+ 9) /* smp kernel running on up */ -/* free, was #define X86_FEATURE_FXSAVE_LEAK ( 3*32+10) * "" FXSAVE leaks FOP/FIP/FOP */ +#define X86_FEATURE_ART (3*32+10) /* Platform has always running timer (ART) */ #define X86_FEATURE_ARCH_PERFMON ( 3*32+11) /* Intel Architectural PerfMon */ #define X86_FEATURE_PEBS ( 3*32+12) /* Precise-Event Based Sampling */ #define X86_FEATURE_BTS ( 3*32+13) /* Branch Trace Store */ @@ -352,6 +352,7 @@ extern const char * const x86_bug_flags[NBUGINTS*32]; #define cpu_has_de boot_cpu_has(X86_FEATURE_DE) #define cpu_has_pse boot_cpu_has(X86_FEATURE_PSE) #define cpu_has_tsc boot_cpu_has(X86_FEATURE_TSC) +#define cpu_has_art boot_cpu_has(X86_FEATURE_ART) #define cpu_has_pge boot_cpu_has(X86_FEATURE_PGE) #define cpu_has_apic boot_cpu_has(X86_FEATURE_APIC) #define cpu_has_sep boot_cpu_has(X86_FEATURE_SEP) diff --git a/arch/x86/include/asm/tsc.h b/arch/x86/include/asm/tsc.h index 94605c0..8d52d91 100644 --- a/arch/x86/include/asm/tsc.h +++ b/arch/x86/include/asm/tsc.h @@ -45,6 +45,8 @@ static __always_inline cycles_t vget_cycles(void) return (cycles_t)__native_read_tsc(); } +extern struct correlated_cs art_timestamper; + extern void tsc_init(void); extern void mark_tsc_unstable(char *reason); extern int unsynchronized_tsc(void); diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c index 7437b41..13f12e0 100644 --- a/arch/x86/kernel/tsc.c +++ b/arch/x86/kernel/tsc.c @@ -939,10 +939,36 @@ static struct notifier_block time_cpufreq_notifier_block = { .notifier_call = time_cpufreq_notifier }; +#define ART_CPUID_LEAF (0x15) +#define ART_MIN_DENOMINATOR (2) + +static u32 art_to_tsc_numerator; +static u32 art_to_tsc_denominator; + +/* + * If ART is present detect the numberator:denominator to convert to TSC + */ +void detect_art(void) +{ + unsigned int unused[2]; + + if (boot_cpu_data.cpuid_level >= ART_CPUID_LEAF) { + cpuid(ART_CPUID_LEAF, &art_to_tsc_denominator, + &art_to_tsc_numerator, unused, unused+1); + + if (art_to_tsc_denominator >= ART_MIN_DENOMINATOR) { + set_cpu_cap(&boot_cpu_data, X86_FEATURE_ART); + } + } +} + static int __init cpufreq_tsc(void) { if (!cpu_has_tsc) return 0; + + detect_art(); + if (boot_cpu_has(X86_FEATURE_CONSTANT_TSC)) return 0; cpufreq_register_notifier(&time_cpufreq_notifier_block, @@ -1059,6 +1085,32 @@ int unsynchronized_tsc(void) return 0; } +/* + * Convert ART to TSC given numerator/denominator found in detect_art() + */ +static u64 convert_art_to_tsc(struct correlated_cs *cs, u64 cycles) +{ + u64 tmp, res; + + switch (art_to_tsc_denominator) { + default: + res = (cycles / art_to_tsc_denominator) * art_to_tsc_numerator; + tmp = (cycles % art_to_tsc_denominator) * art_to_tsc_numerator; + res += tmp / art_to_tsc_denominator; + break; + case 2: + res = (cycles >> 1) * art_to_tsc_numerator; + tmp = (cycles & 0x1) * art_to_tsc_numerator; + res += tmp >> 1; + break; + } + return res; +} + +struct correlated_cs art_timestamper = { + .convert = convert_art_to_tsc, +}; +EXPORT_SYMBOL(art_timestamper); static void tsc_refine_calibration_work(struct work_struct *work); static DECLARE_DELAYED_WORK(tsc_irqwork, tsc_refine_calibration_work); @@ -1130,6 +1182,8 @@ static void tsc_refine_calibration_work(struct work_struct *work) (unsigned long)tsc_khz % 1000); out: + if (cpu_has_art) + art_timestamper.related_cs = &clocksource_tsc; clocksource_register_khz(&clocksource_tsc, tsc_khz); } -- 2.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/