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Linux kernel mirror (for testing)
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linux
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
33struct cpu_data_t {
34 u64 actual;
35 u64 reference;
36 unsigned int freq_prev;
37};
38
39static DEFINE_PER_CPU(struct cpu_data_t, cpu_data);
40
41static 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
104out:
105 data->actual = actual.q;
106 data->reference = reference.q;
107 return freq_next;
108}
109
110static int __init amd_freq_sensitivity_init(void)
111{
112 u64 val;
113 struct pci_dev *pcidev;
114 unsigned int pci_vendor;
115
116 if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD)
117 pci_vendor = PCI_VENDOR_ID_AMD;
118 else if (boot_cpu_data.x86_vendor == X86_VENDOR_HYGON)
119 pci_vendor = PCI_VENDOR_ID_HYGON;
120 else
121 return -ENODEV;
122
123 pcidev = pci_get_device(pci_vendor,
124 PCI_DEVICE_ID_AMD_KERNCZ_SMBUS, NULL);
125
126 if (!pcidev) {
127 if (!static_cpu_has(X86_FEATURE_PROC_FEEDBACK))
128 return -ENODEV;
129 }
130
131 if (rdmsrl_safe(MSR_AMD64_FREQ_SENSITIVITY_ACTUAL, &val))
132 return -ENODEV;
133
134 if (!(val >> CLASS_CODE_SHIFT))
135 return -ENODEV;
136
137 od_register_powersave_bias_handler(amd_powersave_bias_target,
138 POWERSAVE_BIAS_DEF);
139 return 0;
140}
141late_initcall(amd_freq_sensitivity_init);
142
143static void __exit amd_freq_sensitivity_exit(void)
144{
145 od_unregister_powersave_bias_handler();
146}
147module_exit(amd_freq_sensitivity_exit);
148
149static const struct x86_cpu_id amd_freq_sensitivity_ids[] = {
150 X86_FEATURE_MATCH(X86_FEATURE_PROC_FEEDBACK),
151 {}
152};
153MODULE_DEVICE_TABLE(x86cpu, amd_freq_sensitivity_ids);
154
155MODULE_AUTHOR("Jacob Shin <jacob.shin@amd.com>");
156MODULE_DESCRIPTION("AMD frequency sensitivity feedback powersave bias for "
157 "the ondemand governor.");
158MODULE_LICENSE("GPL");