linux/arch/x86/kernel/acpi/cppc.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * cppc.c: CPPC Interface for x86
 * Copyright (c) 2016, Intel Corporation.
 */

#include <acpi/cppc_acpi.h>
#include <asm/msr.h>
#include <asm/processor.h>
#include <asm/topology.h>

#define CPPC_HIGHEST_PERF_PERFORMANCE …
#define CPPC_HIGHEST_PERF_PREFCORE …

enum amd_pref_core { … };
static enum amd_pref_core amd_pref_core_detected;
static u64 boost_numerator;

/* Refer to drivers/acpi/cppc_acpi.c for the description of functions */

bool cpc_supported_by_cpu(void)
{ … }

bool cpc_ffh_supported(void)
{ … }

int cpc_read_ffh(int cpunum, struct cpc_reg *reg, u64 *val)
{ … }

int cpc_write_ffh(int cpunum, struct cpc_reg *reg, u64 val)
{ … }

static void amd_set_max_freq_ratio(void)
{ … }

static DEFINE_MUTEX(freq_invariance_lock);

void init_freq_invariance_cppc(void)
{ … }

/*
 * Get the highest performance register value.
 * @cpu: CPU from which to get highest performance.
 * @highest_perf: Return address for highest performance value.
 *
 * Return: 0 for success, negative error code otherwise.
 */
int amd_get_highest_perf(unsigned int cpu, u32 *highest_perf)
{ … }
EXPORT_SYMBOL_GPL(…);

/**
 * amd_detect_prefcore: Detect if CPUs in the system support preferred cores
 * @detected: Output variable for the result of the detection.
 *
 * Determine whether CPUs in the system support preferred cores. On systems
 * that support preferred cores, different highest perf values will be found
 * on different cores. On other systems, the highest perf value will be the
 * same on all cores.
 *
 * The result of the detection will be stored in the 'detected' parameter.
 *
 * Return: 0 for success, negative error code otherwise
 */
int amd_detect_prefcore(bool *detected)
{ … }
EXPORT_SYMBOL_GPL(…);

/**
 * amd_get_boost_ratio_numerator: Get the numerator to use for boost ratio calculation
 * @cpu: CPU to get numerator for.
 * @numerator: Output variable for numerator.
 *
 * Determine the numerator to use for calculating the boost ratio on
 * a CPU. On systems that support preferred cores, this will be a hardcoded
 * value. On other systems this will the highest performance register value.
 *
 * If booting the system with amd-pstate enabled but preferred cores disabled then
 * the correct boost numerator will be returned to match hardware capabilities
 * even if the preferred cores scheduling hints are not enabled.
 *
 * Return: 0 for success, negative error code otherwise.
 */
int amd_get_boost_ratio_numerator(unsigned int cpu, u64 *numerator)
{ … }
EXPORT_SYMBOL_GPL(…);