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