1 /* 2 * amd_freq_sensitivity.c: AMD frequency sensitivity feedback powersave bias 3 * for the ondemand governor. 4 * 5 * Copyright (C) 2013 Advanced Micro Devices, Inc. 6 * 7 * Author: Jacob Shin <jacob.shin@amd.com> 8 * 9 * This program is free software; you can redistribute it and/or modify 10 * it under the terms of the GNU General Public License version 2 as 11 * published by the Free Software Foundation. 12 */ 13 14 #include <linux/kernel.h> 15 #include <linux/module.h> 16 #include <linux/types.h> 17 #include <linux/percpu-defs.h> 18 #include <linux/init.h> 19 #include <linux/mod_devicetable.h> 20 21 #include <asm/msr.h> 22 #include <asm/cpufeature.h> 23 24 #include "cpufreq_governor.h" 25 26 #define MSR_AMD64_FREQ_SENSITIVITY_ACTUAL 0xc0010080 27 #define MSR_AMD64_FREQ_SENSITIVITY_REFERENCE 0xc0010081 28 #define CLASS_CODE_SHIFT 56 29 #define POWERSAVE_BIAS_MAX 1000 30 #define POWERSAVE_BIAS_DEF 400 31 32 struct cpu_data_t { 33 u64 actual; 34 u64 reference; 35 unsigned int freq_prev; 36 }; 37 38 static DEFINE_PER_CPU(struct cpu_data_t, cpu_data); 39 40 static unsigned int amd_powersave_bias_target(struct cpufreq_policy *policy, 41 unsigned int freq_next, 42 unsigned int relation) 43 { 44 int sensitivity; 45 long d_actual, d_reference; 46 struct msr actual, reference; 47 struct cpu_data_t *data = &per_cpu(cpu_data, policy->cpu); 48 struct dbs_data *od_data = policy->governor_data; 49 struct od_dbs_tuners *od_tuners = od_data->tuners; 50 struct od_cpu_dbs_info_s *od_info = 51 od_data->cdata->get_cpu_dbs_info_s(policy->cpu); 52 53 if (!od_info->freq_table) 54 return freq_next; 55 56 rdmsr_on_cpu(policy->cpu, MSR_AMD64_FREQ_SENSITIVITY_ACTUAL, 57 &actual.l, &actual.h); 58 rdmsr_on_cpu(policy->cpu, MSR_AMD64_FREQ_SENSITIVITY_REFERENCE, 59 &reference.l, &reference.h); 60 actual.h &= 0x00ffffff; 61 reference.h &= 0x00ffffff; 62 63 /* counter wrapped around, so stay on current frequency */ 64 if (actual.q < data->actual || reference.q < data->reference) { 65 freq_next = policy->cur; 66 goto out; 67 } 68 69 d_actual = actual.q - data->actual; 70 d_reference = reference.q - data->reference; 71 72 /* divide by 0, so stay on current frequency as well */ 73 if (d_reference == 0) { 74 freq_next = policy->cur; 75 goto out; 76 } 77 78 sensitivity = POWERSAVE_BIAS_MAX - 79 (POWERSAVE_BIAS_MAX * (d_reference - d_actual) / d_reference); 80 81 clamp(sensitivity, 0, POWERSAVE_BIAS_MAX); 82 83 /* this workload is not CPU bound, so choose a lower freq */ 84 if (sensitivity < od_tuners->powersave_bias) { 85 if (data->freq_prev == policy->cur) 86 freq_next = policy->cur; 87 88 if (freq_next > policy->cur) 89 freq_next = policy->cur; 90 else if (freq_next < policy->cur) 91 freq_next = policy->min; 92 else { 93 unsigned int index; 94 95 cpufreq_frequency_table_target(policy, 96 od_info->freq_table, policy->cur - 1, 97 CPUFREQ_RELATION_H, &index); 98 freq_next = od_info->freq_table[index].frequency; 99 } 100 101 data->freq_prev = freq_next; 102 } else 103 data->freq_prev = 0; 104 105 out: 106 data->actual = actual.q; 107 data->reference = reference.q; 108 return freq_next; 109 } 110 111 static int __init amd_freq_sensitivity_init(void) 112 { 113 u64 val; 114 115 if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD) 116 return -ENODEV; 117 118 if (!static_cpu_has(X86_FEATURE_PROC_FEEDBACK)) 119 return -ENODEV; 120 121 if (rdmsrl_safe(MSR_AMD64_FREQ_SENSITIVITY_ACTUAL, &val)) 122 return -ENODEV; 123 124 if (!(val >> CLASS_CODE_SHIFT)) 125 return -ENODEV; 126 127 od_register_powersave_bias_handler(amd_powersave_bias_target, 128 POWERSAVE_BIAS_DEF); 129 return 0; 130 } 131 late_initcall(amd_freq_sensitivity_init); 132 133 static void __exit amd_freq_sensitivity_exit(void) 134 { 135 od_unregister_powersave_bias_handler(); 136 } 137 module_exit(amd_freq_sensitivity_exit); 138 139 static const struct x86_cpu_id amd_freq_sensitivity_ids[] = { 140 X86_FEATURE_MATCH(X86_FEATURE_PROC_FEEDBACK), 141 {} 142 }; 143 MODULE_DEVICE_TABLE(x86cpu, amd_freq_sensitivity_ids); 144 145 MODULE_AUTHOR("Jacob Shin <jacob.shin@amd.com>"); 146 MODULE_DESCRIPTION("AMD frequency sensitivity feedback powersave bias for " 147 "the ondemand governor."); 148 MODULE_LICENSE("GPL"); 149