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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * amd_freq_sensitivity.c: AMD frequency sensitivity feedback powersave bias4 * 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 0xc001008026#define MSR_AMD64_FREQ_SENSITIVITY_REFERENCE 0xc001008127#define CLASS_CODE_SHIFT 5628#define POWERSAVE_BIAS_MAX 100029#define POWERSAVE_BIAS_DEF 40030 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 relation & CPUFREQ_RELATION_E);96 freq_next = policy->freq_table[index].frequency;97 }98 99 data->freq_prev = freq_next;100 } else101 data->freq_prev = 0;102 103out:104 data->actual = actual.q;105 data->reference = reference.q;106 return freq_next;107}108 109static int __init amd_freq_sensitivity_init(void)110{111 u64 val;112 struct pci_dev *pcidev;113 unsigned int pci_vendor;114 115 if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD)116 pci_vendor = PCI_VENDOR_ID_AMD;117 else if (boot_cpu_data.x86_vendor == X86_VENDOR_HYGON)118 pci_vendor = PCI_VENDOR_ID_HYGON;119 else120 return -ENODEV;121 122 pcidev = pci_get_device(pci_vendor,123 PCI_DEVICE_ID_AMD_KERNCZ_SMBUS, NULL);124 125 if (!pcidev) {126 if (!boot_cpu_has(X86_FEATURE_PROC_FEEDBACK))127 return -ENODEV;128 } else {129 pci_dev_put(pcidev);130 }131 132 if (rdmsrl_safe(MSR_AMD64_FREQ_SENSITIVITY_ACTUAL, &val))133 return -ENODEV;134 135 if (!(val >> CLASS_CODE_SHIFT))136 return -ENODEV;137 138 od_register_powersave_bias_handler(amd_powersave_bias_target,139 POWERSAVE_BIAS_DEF);140 return 0;141}142late_initcall(amd_freq_sensitivity_init);143 144static void __exit amd_freq_sensitivity_exit(void)145{146 od_unregister_powersave_bias_handler();147}148module_exit(amd_freq_sensitivity_exit);149 150static const struct x86_cpu_id __maybe_unused amd_freq_sensitivity_ids[] = {151 X86_MATCH_FEATURE(X86_FEATURE_PROC_FEEDBACK, NULL),152 {}153};154MODULE_DEVICE_TABLE(x86cpu, amd_freq_sensitivity_ids);155 156MODULE_AUTHOR("Jacob Shin <jacob.shin@amd.com>");157MODULE_DESCRIPTION("AMD frequency sensitivity feedback powersave bias for "158 "the ondemand governor.");159MODULE_LICENSE("GPL");160