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 31 struct cpu_data_t { 32 u64 actual; 33 u64 reference; 34 unsigned int freq_prev; 35 }; 36 37 static DEFINE_PER_CPU(struct cpu_data_t, cpu_data); 38 39 static 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 } else 101 data->freq_prev = 0; 102 103 out: 104 data->actual = actual.q; 105 data->reference = reference.q; 106 return freq_next; 107 } 108 109 static 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 else 120 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 } 142 late_initcall(amd_freq_sensitivity_init); 143 144 static void __exit amd_freq_sensitivity_exit(void) 145 { 146 od_unregister_powersave_bias_handler(); 147 } 148 module_exit(amd_freq_sensitivity_exit); 149 150 static const struct x86_cpu_id __maybe_unused amd_freq_sensitivity_ids[] = { 151 X86_MATCH_FEATURE(X86_FEATURE_PROC_FEEDBACK, NULL), 152 {} 153 }; 154 MODULE_DEVICE_TABLE(x86cpu, amd_freq_sensitivity_ids); 155 156 MODULE_AUTHOR("Jacob Shin <jacob.shin@amd.com>"); 157 MODULE_DESCRIPTION("AMD frequency sensitivity feedback powersave bias for " 158 "the ondemand governor."); 159 MODULE_LICENSE("GPL"); 160