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 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 rdmsr_on_cpu(policy->cpu, MSR_AMD64_FREQ_SENSITIVITY_ACTUAL, 54 &actual.l, &actual.h); 55 rdmsr_on_cpu(policy->cpu, MSR_AMD64_FREQ_SENSITIVITY_REFERENCE, 56 &reference.l, &reference.h); 57 actual.h &= 0x00ffffff; 58 reference.h &= 0x00ffffff; 59 60 /* counter wrapped around, so stay on current frequency */ 61 if (actual.q < data->actual || reference.q < data->reference) { 62 freq_next = policy->cur; 63 goto out; 64 } 65 66 d_actual = actual.q - data->actual; 67 d_reference = reference.q - data->reference; 68 69 /* divide by 0, so stay on current frequency as well */ 70 if (d_reference == 0) { 71 freq_next = policy->cur; 72 goto out; 73 } 74 75 sensitivity = POWERSAVE_BIAS_MAX - 76 (POWERSAVE_BIAS_MAX * (d_reference - d_actual) / d_reference); 77 78 clamp(sensitivity, 0, POWERSAVE_BIAS_MAX); 79 80 /* this workload is not CPU bound, so choose a lower freq */ 81 if (sensitivity < od_tuners->powersave_bias) { 82 if (data->freq_prev == policy->cur) 83 freq_next = policy->cur; 84 85 if (freq_next > policy->cur) 86 freq_next = policy->cur; 87 else if (freq_next < policy->cur) 88 freq_next = policy->min; 89 else { 90 unsigned int index; 91 92 index = cpufreq_table_find_index_h(policy, 93 policy->cur - 1); 94 freq_next = policy->freq_table[index].frequency; 95 } 96 97 data->freq_prev = freq_next; 98 } else 99 data->freq_prev = 0; 100 101 out: 102 data->actual = actual.q; 103 data->reference = reference.q; 104 return freq_next; 105 } 106 107 static int __init amd_freq_sensitivity_init(void) 108 { 109 u64 val; 110 struct pci_dev *pcidev; 111 unsigned int pci_vendor; 112 113 if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD) 114 pci_vendor = PCI_VENDOR_ID_AMD; 115 else if (boot_cpu_data.x86_vendor == X86_VENDOR_HYGON) 116 pci_vendor = PCI_VENDOR_ID_HYGON; 117 else 118 return -ENODEV; 119 120 pcidev = pci_get_device(pci_vendor, 121 PCI_DEVICE_ID_AMD_KERNCZ_SMBUS, NULL); 122 123 if (!pcidev) { 124 if (!boot_cpu_has(X86_FEATURE_PROC_FEEDBACK)) 125 return -ENODEV; 126 } 127 128 if (rdmsrl_safe(MSR_AMD64_FREQ_SENSITIVITY_ACTUAL, &val)) 129 return -ENODEV; 130 131 if (!(val >> CLASS_CODE_SHIFT)) 132 return -ENODEV; 133 134 od_register_powersave_bias_handler(amd_powersave_bias_target, 135 POWERSAVE_BIAS_DEF); 136 return 0; 137 } 138 late_initcall(amd_freq_sensitivity_init); 139 140 static void __exit amd_freq_sensitivity_exit(void) 141 { 142 od_unregister_powersave_bias_handler(); 143 } 144 module_exit(amd_freq_sensitivity_exit); 145 146 static const struct x86_cpu_id amd_freq_sensitivity_ids[] = { 147 X86_FEATURE_MATCH(X86_FEATURE_PROC_FEEDBACK), 148 {} 149 }; 150 MODULE_DEVICE_TABLE(x86cpu, amd_freq_sensitivity_ids); 151 152 MODULE_AUTHOR("Jacob Shin <jacob.shin@amd.com>"); 153 MODULE_DESCRIPTION("AMD frequency sensitivity feedback powersave bias for " 154 "the ondemand governor."); 155 MODULE_LICENSE("GPL"); 156