drivers/cpufreq/amd_freq_sensitivity.c

   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 #include <asm/cpu_device_id.h>
  22
  23 #include "cpufreq_ondemand.h"
  24
  25 #define MSR_AMD64_FREQ_SENSITIVITY_ACTUAL       0xc0010080
  26 #define MSR_AMD64_FREQ_SENSITIVITY_REFERENCE    0xc0010081
  27 #define CLASS_CODE_SHIFT                        56
  28 #define POWERSAVE_BIAS_MAX                      1000
  29 #define POWERSAVE_BIAS_DEF                      400
  30
  31 struct cpu_data_t {
  32         u64 actual;
  33         u64 reference;
  34         unsigned int freq_prev;
  35 };
  36
  37 static DEFINE_PER_CPU(struct cpu_data_t, cpu_data);
  38
  39 static unsigned int amd_powersave_bias_target(struct cpufreq_policy *policy,
  40                                               unsigned int freq_next,
  41                                               unsigned int relation)
  42 {
  43         int sensitivity;
  44         long d_actual, d_reference;
  45         struct msr actual, reference;
  46         struct cpu_data_t *data = &per_cpu(cpu_data, policy->cpu);
  47         struct policy_dbs_info *policy_dbs = policy->governor_data;
  48         struct dbs_data *od_data = policy_dbs->dbs_data;
  49         struct od_dbs_tuners *od_tuners = od_data->tuners;
  50
  51         if (!policy->freq_table)
  52                 return freq_next;
  53
  54         rdmsr_on_cpu(policy->cpu, MSR_AMD64_FREQ_SENSITIVITY_ACTUAL,
  55                 &actual.l, &actual.h);
  56         rdmsr_on_cpu(policy->cpu, MSR_AMD64_FREQ_SENSITIVITY_REFERENCE,
  57                 &reference.l, &reference.h);
  58         actual.h &= 0x00ffffff;
  59         reference.h &= 0x00ffffff;
  60
  61         /* counter wrapped around, so stay on current frequency */
  62         if (actual.q < data->actual || reference.q < data->reference) {
  63                 freq_next = policy->cur;
  64                 goto out;
  65         }
  66
  67         d_actual = actual.q - data->actual;
  68         d_reference = reference.q - data->reference;
  69
  70         /* divide by 0, so stay on current frequency as well */
  71         if (d_reference == 0) {
  72                 freq_next = policy->cur;
  73                 goto out;
  74         }
  75
  76         sensitivity = POWERSAVE_BIAS_MAX -
  77                 (POWERSAVE_BIAS_MAX * (d_reference - d_actual) / d_reference);
  78
  79         clamp(sensitivity, 0, POWERSAVE_BIAS_MAX);
  80
  81         /* this workload is not CPU bound, so choose a lower freq */
  82         if (sensitivity < od_tuners->powersave_bias) {
  83                 if (data->freq_prev == policy->cur)
  84                         freq_next = policy->cur;
  85
  86                 if (freq_next > policy->cur)
  87                         freq_next = policy->cur;
  88                 else if (freq_next < policy->cur)
  89                         freq_next = policy->min;
  90                 else {
  91                         unsigned int index;
  92
  93                         index = cpufreq_table_find_index_h(policy,
  94                                                            policy->cur - 1);
  95                         freq_next = policy->freq_table[index].frequency;
  96                 }
  97
  98                 data->freq_prev = freq_next;
  99         } else
 100                 data->freq_prev = 0;
 101
 102 out:
 103         data->actual = actual.q;
 104         data->reference = reference.q;
 105         return freq_next;
 106 }
 107
 108 static int __init amd_freq_sensitivity_init(void)
 109 {
 110         u64 val;
 111         struct pci_dev *pcidev;
 112         unsigned int pci_vendor;
 113
 114         if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD)
 115                 pci_vendor = PCI_VENDOR_ID_AMD;
 116         else if (boot_cpu_data.x86_vendor == X86_VENDOR_HYGON)
 117                 pci_vendor = PCI_VENDOR_ID_HYGON;
 118         else
 119                 return -ENODEV;
 120
 121         pcidev = pci_get_device(pci_vendor,
 122                         PCI_DEVICE_ID_AMD_KERNCZ_SMBUS, NULL);
 123
 124         if (!pcidev) {
 125                 if (!boot_cpu_has(X86_FEATURE_PROC_FEEDBACK))
 126                         return -ENODEV;
 127         }
 128
 129         if (rdmsrl_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");