root/drivers/cpufreq/amd_freq_sensitivity.c

DEFINITIONS

1. amd_powersave_bias_target
2. amd_freq_sensitivity_init
3. amd_freq_sensitivity_exit

   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");