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/*
* This file is part of the coreboot project.
*
* Copyright (C) 2017-2019 Intel Corporation.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; version 2 of the License.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*/
#include <arch/cpu.h>
#include <arch/intel-family.h>
#include <cpu/cpu.h>
#include <cpu/x86/msr.h>
#include <cpu/x86/tsc.h>
#include <intelblocks/msr.h>
static int get_processor_model(void)
{
struct cpuinfo_x86 c;
get_fms(&c, cpuid_eax(1));
return c.x86_model;
}
/*
* Nominal TSC frequency = "core crystal clock frequency" * EBX/EAX
*
* Time Stamp Counter
* CPUID Initial EAX value = 0x15
* EAX Bit 31-0 : An unsigned integer which is the denominator of the
* TSC/"core crystal clock" ratio
* EBX Bit 31-0 : An unsigned integer which is the numerator of the
* TSC/"core crystal clock" ratio
* ECX Bit 31-0 : An unsigned integer which is the nominal frequency of the
* core crystal clock in Hz.
* EDX Bit 31-0 : Reserved = 0
*
* Refer to Intel SDM Jan 2019 Vol 3B Section 18.7.3
*/
unsigned long tsc_freq_mhz(void)
{
unsigned int core_crystal_nominal_freq_khz;
struct cpuid_result cpuidr;
/* CPUID 15H TSC/Crystal ratio, plus optionally Crystal Hz */
cpuidr = cpuid(0x15);
if (!cpuidr.ebx || !cpuidr.eax)
return 0;
core_crystal_nominal_freq_khz = cpuidr.ecx / 1000;
if (!core_crystal_nominal_freq_khz) {
switch (get_processor_model()) {
case CPU_MODEL_INTEL_SKYLAKE_MOBILE:
case CPU_MODEL_INTEL_SKYLAKE_DESKTOP:
case CPU_MODEL_INTEL_KABYLAKE_MOBILE:
case CPU_MODEL_INTEL_KABYLAKE_DESKTOP:
case CPU_MODEL_INTEL_CANNONLAKE_MOBILE:
case CPU_MODEL_INTEL_ICELAKE_MOBILE:
core_crystal_nominal_freq_khz = 24000;
break;
case CPU_MODEL_INTEL_ATOM_DENVERTON:
core_crystal_nominal_freq_khz = 25000;
break;
case CPU_MODEL_INTEL_ATOM_GOLDMONT:
case CPU_MODEL_INTEL_ATOM_GEMINI_LAKE:
core_crystal_nominal_freq_khz = 19200;
break;
}
}
return (core_crystal_nominal_freq_khz * cpuidr.ebx / cpuidr.eax) /
1000;
}
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