drivers/cpufreq/amd_freq_sensitivity.c

   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/pci.h>
  18 #include <linux/percpu-defs.h>
  19 #include <linux/init.h>
  20 #include <linux/mod_devicetable.h>
  21
  22 #include <asm/msr.h>
  23 #include <asm/cpufeature.h>
  24
  25 #include "cpufreq_ondemand.h"
  26
  27 #define MSR_AMD64_FREQ_SENSITIVITY_ACTUAL       0xc0010080
  28 #define MSR_AMD64_FREQ_SENSITIVITY_REFERENCE    0xc0010081
  29 #define CLASS_CODE_SHIFT                        56
  30 #define POWERSAVE_BIAS_MAX                      1000
  31 #define POWERSAVE_BIAS_DEF                      400
  32
  33 struct cpu_data_t {
  34         u64 actual;
  35         u64 reference;
  36         unsigned int freq_prev;
  37 };
  38
  39 static DEFINE_PER_CPU(struct cpu_data_t, cpu_data);
  40
  41 static unsigned int amd_powersave_bias_target(struct cpufreq_policy *policy,
  42                                               unsigned int freq_next,
  43                                               unsigned int relation)
  44 {
  45         int sensitivity;
  46         long d_actual, d_reference;
  47         struct msr actual, reference;
  48         struct cpu_data_t *data = &per_cpu(cpu_data, policy->cpu);
  49         struct policy_dbs_info *policy_dbs = policy->governor_data;
  50         struct dbs_data *od_data = policy_dbs->dbs_data;
  51         struct od_dbs_tuners *od_tuners = od_data->tuners;
  52
  53         if (!policy->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                         index = cpufreq_table_find_index_h(policy,
  96                                                            policy->cur - 1);
  97                         freq_next = policy->freq_table[index].frequency;
  98                 }
  99
 100                 data->freq_prev = freq_next;
 101         } else
 102                 data->freq_prev = 0;
 103
 104 out:
 105         data->actual = actual.q;
 106         data->reference = reference.q;
 107         return freq_next;
 108 }
 109
 110 static int __init amd_freq_sensitivity_init(void)
 111 {
 112         u64 val;
 113         struct pci_dev *pcidev;
 114
 115         if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD)
 116                 return -ENODEV;
 117
 118         pcidev = pci_get_device(PCI_VENDOR_ID_AMD,
 119                         PCI_DEVICE_ID_AMD_KERNCZ_SMBUS, NULL);
 120
 121         if (!pcidev) {
 122                 if (!static_cpu_has(X86_FEATURE_PROC_FEEDBACK))
 123                         return -ENODEV;
 124         }
 125
 126         if (rdmsrl_safe(MSR_AMD64_FREQ_SENSITIVITY_ACTUAL, &val))
 127                 return -ENODEV;
 128
 129         if (!(val >> CLASS_CODE_SHIFT))
 130                 return -ENODEV;
 131
 132         od_register_powersave_bias_handler(amd_powersave_bias_target,
 133                         POWERSAVE_BIAS_DEF);
 134         return 0;
 135 }
 136 late_initcall(amd_freq_sensitivity_init);
 137
 138 static void __exit amd_freq_sensitivity_exit(void)
 139 {
 140         od_unregister_powersave_bias_handler();
 141 }
 142 module_exit(amd_freq_sensitivity_exit);
 143
 144 static const struct x86_cpu_id amd_freq_sensitivity_ids[] = {
 145         X86_FEATURE_MATCH(X86_FEATURE_PROC_FEEDBACK),
 146         {}
 147 };
 148 MODULE_DEVICE_TABLE(x86cpu, amd_freq_sensitivity_ids);
 149
 150 MODULE_AUTHOR("Jacob Shin <jacob.shin@amd.com>");
 151 MODULE_DESCRIPTION("AMD frequency sensitivity feedback powersave bias for "
 152                 "the ondemand governor.");
 153 MODULE_LICENSE("GPL");