LXR linux/drivers/cpufreq/amd_freq

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * amd_freq_sensitivity.c: AMD frequency sensitivity feedback powersave bias
   4 *                         for the ondemand governor.
   5 *
   6 * Copyright (C) 2013 Advanced Micro Devices, Inc.
   7 *
   8 * Author: Jacob Shin <jacob.shin@amd.com>
   9 */
  10
  11#include <linux/kernel.h>
  12#include <linux/module.h>
  13#include <linux/types.h>
  14#include <linux/pci.h>
  15#include <linux/percpu-defs.h>
  16#include <linux/init.h>
  17#include <linux/mod_devicetable.h>
  18
  19#include <asm/msr.h>
  20#include <asm/cpufeature.h>
  21#include <asm/cpu_device_id.h>
  22
  23#include "cpufreq_ondemand.h"
  24
  25#define MSR_AMD64_FREQ_SENSITIVITY_ACTUAL       0xc0010080
  26#define MSR_AMD64_FREQ_SENSITIVITY_REFERENCE    0xc0010081
  27#define CLASS_CODE_SHIFT                        56
  28#define POWERSAVE_BIAS_MAX                      1000
  29#define POWERSAVE_BIAS_DEF                      400
  30
  31struct cpu_data_t {
  32        u64 actual;
  33        u64 reference;
  34        unsigned int freq_prev;
  35};
  36
  37static DEFINE_PER_CPU(struct cpu_data_t, cpu_data);
  38
  39static unsigned int amd_powersave_bias_target(struct cpufreq_policy *policy,
  40                                              unsigned int freq_next,
  41                                              unsigned int relation)
  42{
  43        int sensitivity;
  44        long d_actual, d_reference;
  45        struct msr actual, reference;
  46        struct cpu_data_t *data = &per_cpu(cpu_data, policy->cpu);
  47        struct policy_dbs_info *policy_dbs = policy->governor_data;
  48        struct dbs_data *od_data = policy_dbs->dbs_data;
  49        struct od_dbs_tuners *od_tuners = od_data->tuners;
  50
  51        if (!policy->freq_table)
  52                return freq_next;
  53
  54        rdmsr_on_cpu(policy->cpu, MSR_AMD64_FREQ_SENSITIVITY_ACTUAL,
  55                &actual.l, &actual.h);
  56        rdmsr_on_cpu(policy->cpu, MSR_AMD64_FREQ_SENSITIVITY_REFERENCE,
  57                &reference.l, &reference.h);
  58        actual.h &= 0x00ffffff;
  59        reference.h &= 0x00ffffff;
  60
  61        /* counter wrapped around, so stay on current frequency */
  62        if (actual.q < data->actual || reference.q < data->reference) {
  63                freq_next = policy->cur;
  64                goto out;
  65        }
  66
  67        d_actual = actual.q - data->actual;
  68        d_reference = reference.q - data->reference;
  69
  70        /* divide by 0, so stay on current frequency as well */
  71        if (d_reference == 0) {
  72                freq_next = policy->cur;
  73                goto out;
  74        }
  75
  76        sensitivity = POWERSAVE_BIAS_MAX -
  77                (POWERSAVE_BIAS_MAX * (d_reference - d_actual) / d_reference);
  78
  79        clamp(sensitivity, 0, POWERSAVE_BIAS_MAX);
  80
  81        /* this workload is not CPU bound, so choose a lower freq */
  82        if (sensitivity < od_tuners->powersave_bias) {
  83                if (data->freq_prev == policy->cur)
  84                        freq_next = policy->cur;
  85
  86                if (freq_next > policy->cur)
  87                        freq_next = policy->cur;
  88                else if (freq_next < policy->cur)
  89                        freq_next = policy->min;
  90                else {
  91                        unsigned int index;
  92
  93                        index = cpufreq_table_find_index_h(policy,
  94                                                           policy->cur - 1);
  95                        freq_next = policy->freq_table[index].frequency;
  96                }
  97
  98                data->freq_prev = freq_next;
  99        } else
 100                data->freq_prev = 0;
 101
 102out:
 103        data->actual = actual.q;
 104        data->reference = reference.q;
 105        return freq_next;
 106}
 107
 108static int __init amd_freq_sensitivity_init(void)
 109{
 110        u64 val;
 111        struct pci_dev *pcidev;
 112        unsigned int pci_vendor;
 113
 114        if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD)
 115                pci_vendor = PCI_VENDOR_ID_AMD;
 116        else if (boot_cpu_data.x86_vendor == X86_VENDOR_HYGON)
 117                pci_vendor = PCI_VENDOR_ID_HYGON;
 118        else
 119                return -ENODEV;
 120
 121        pcidev = pci_get_device(pci_vendor,
 122                        PCI_DEVICE_ID_AMD_KERNCZ_SMBUS, NULL);
 123
 124        if (!pcidev) {
 125                if (!boot_cpu_has(X86_FEATURE_PROC_FEEDBACK))
 126                        return -ENODEV;
 127        }
 128
 129        if (rdmsrl_safe(MSR_AMD64_FREQ_SENSITIVITY_ACTUAL, &val))
 130                return -ENODEV;
 131
 132        if (!(val >> CLASS_CODE_SHIFT))
 133                return -ENODEV;
 134
 135        od_register_powersave_bias_handler(amd_powersave_bias_target,
 136                        POWERSAVE_BIAS_DEF);
 137        return 0;
 138}
 139late_initcall(amd_freq_sensitivity_init);
 140
 141static void __exit amd_freq_sensitivity_exit(void)
 142{
 143        od_unregister_powersave_bias_handler();
 144}
 145module_exit(amd_freq_sensitivity_exit);
 146
 147static const struct x86_cpu_id __maybe_unused amd_freq_sensitivity_ids[] = {
 148        X86_MATCH_FEATURE(X86_FEATURE_PROC_FEEDBACK, NULL),
 149        {}
 150};
 151MODULE_DEVICE_TABLE(x86cpu, amd_freq_sensitivity_ids);
 152
 153MODULE_AUTHOR("Jacob Shin <jacob.shin@amd.com>");
 154MODULE_DESCRIPTION("AMD frequency sensitivity feedback powersave bias for "
 155                "the ondemand governor.");
 156MODULE_LICENSE("GPL");
 157