// SPDX-License-Identifier: GPL-2.0-or-later
/*
* amd-pstate.c - AMD Processor P-state Frequency Driver
*
* Copyright (C) 2021 Advanced Micro Devices, Inc. All Rights Reserved.
*
* Author: Huang Rui <ray.huang@amd.com>
*
* AMD P-State introduces a new CPU performance scaling design for AMD
* processors using the ACPI Collaborative Performance and Power Control (CPPC)
* feature which works with the AMD SMU firmware providing a finer grained
* frequency control range. It is to replace the legacy ACPI P-States control,
* allows a flexible, low-latency interface for the Linux kernel to directly
* communicate the performance hints to hardware.
*
* AMD P-State is supported on recent AMD Zen base CPU series include some of
* Zen2 and Zen3 processors. _CPC needs to be present in the ACPI tables of AMD
* P-State supported system. And there are two types of hardware implementations
* for AMD P-State: 1) Full MSR Solution and 2) Shared Memory Solution.
* X86_FEATURE_CPPC CPU feature flag is used to distinguish the different types.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/smp.h>
#include <linux/sched.h>
#include <linux/cpufreq.h>
#include <linux/compiler.h>
#include <linux/dmi.h>
#include <linux/slab.h>
#include <linux/acpi.h>
#include <linux/io.h>
#include <linux/delay.h>
#include <linux/uaccess.h>
#include <linux/static_call.h>
#include <linux/amd-pstate.h>
#include <acpi/processor.h>
#include <acpi/cppc_acpi.h>
#include <asm/msr.h>
#include <asm/processor.h>
#include <asm/cpufeature.h>
#include <asm/cpu_device_id.h>
#include "amd-pstate-trace.h"
#define AMD_PSTATE_TRANSITION_LATENCY 20000
#define AMD_PSTATE_TRANSITION_DELAY 1000
/*
* TODO: We need more time to fine tune processors with shared memory solution
* with community together.
*
* There are some performance drops on the CPU benchmarks which reports from
* Suse. We are co-working with them to fine tune the shared memory solution. So
* we disable it by default to go acpi-cpufreq on these processors and add a
* module parameter to be able to enable it manually for debugging.
*/
static struct cpufreq_driver *current_pstate_driver;
static struct cpufreq_driver amd_pstate_driver;
static struct cpufreq_driver amd_pstate_epp_driver;
static int cppc_state = AMD_PSTATE_DISABLE;
/*
* AMD Energy Preference Performance (EPP)
* The EPP is used in the CCLK DPM controller to drive
* the frequency that a core is going to operate during
* short periods of activity. EPP values will be utilized for
* different OS profiles (balanced, performance, power savings)
* display strings corresponding to EPP index in the
* energy_perf_strings[]
* index String
*-------------------------------------
* 0 default
* 1 performance
* 2 balance_performance
* 3 balance_power
* 4 power
*/
enum energy_perf_value_index {
EPP_INDEX_DEFAULT = 0,
EPP_INDEX_PERFORMANCE,
EPP_INDEX_BALANCE_PERFORMANCE,
EPP_INDEX_BALANCE_POWERSAVE,
EPP_INDEX_POWERSAVE,
};
static 