From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752874AbdCVUTU (ORCPT ); Wed, 22 Mar 2017 16:19:20 -0400 Received: from aserp1040.oracle.com ([141.146.126.69]:44538 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752796AbdCVUSx (ORCPT ); Wed, 22 Mar 2017 16:18:53 -0400 From: Pavel Tatashin To: x86@kernel.org, linux-kernel@vger.kernel.org, mingo@redhat.com, peterz@infradead.org, tglx@linutronix.de, hpa@zytor.com Subject: [v1 7/9] x86/tsc: use cpuid to determine CPU frequency Date: Wed, 22 Mar 2017 16:24:23 -0400 Message-Id: <1490214265-899964-8-git-send-email-pasha.tatashin@oracle.com> X-Mailer: git-send-email 1.7.1 In-Reply-To: <1490214265-899964-1-git-send-email-pasha.tatashin@oracle.com> References: <1490214265-899964-1-git-send-email-pasha.tatashin@oracle.com> X-Source-IP: aserv0021.oracle.com [141.146.126.233] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Newer processors implement cpuid extension to determine CPU frequency from cpuid. This patch adds a function that can do this early in boot. Signed-off-by: Pavel Tatashin --- arch/x86/kernel/tsc.c | 10 ++++++---- 1 files changed, 6 insertions(+), 4 deletions(-) diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c index 1c9fc23..58bd575 100644 --- a/arch/x86/kernel/tsc.c +++ b/arch/x86/kernel/tsc.c @@ -743,14 +743,14 @@ unsigned long native_calibrate_tsc(void) return tsc_khz; } -static unsigned long cpu_khz_from_cpuid(void) +static unsigned long cpu_khz_from_cpuid_early(int vendor, int cpuid_level) { unsigned int eax_base_mhz, ebx_max_mhz, ecx_bus_mhz, edx; - if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL) + if (vendor != X86_VENDOR_INTEL) return 0; - if (boot_cpu_data.cpuid_level < 0x16) + if (cpuid_level < 0x16) return 0; eax_base_mhz = ebx_max_mhz = ecx_bus_mhz = edx = 0; @@ -770,7 +770,9 @@ unsigned long native_calibrate_cpu(void) unsigned long flags, latch, ms, fast_calibrate; int hpet = is_hpet_enabled(), i, loopmin; - fast_calibrate = cpu_khz_from_cpuid(); + fast_calibrate = cpu_khz_from_cpuid_early(boot_cpu_data.x86_vendor, + boot_cpu_data.cpuid_level); + if (fast_calibrate) return fast_calibrate; -- 1.7.1