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
amd_powersave_bias_target(struct cpufreq_policy * policy,unsigned int freq_next,unsigned int relation)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 relation & CPUFREQ_RELATION_E);
96 freq_next = policy->freq_table[index].frequency;
97 }
98
99 data->freq_prev = freq_next;
100 } else
101 data->freq_prev = 0;
102
103 out:
104 data->actual = actual.q;
105 data->reference = reference.q;
106 return freq_next;
107 }
108
amd_freq_sensitivity_init(void)109 static int __init amd_freq_sensitivity_init(void)
110 {
111 u64 val;
112 struct pci_dev *pcidev;
113 unsigned int pci_vendor;
114
115 if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD)
116 pci_vendor = PCI_VENDOR_ID_AMD;
117 else if (boot_cpu_data.x86_vendor == X86_VENDOR_HYGON)
118 pci_vendor = PCI_VENDOR_ID_HYGON;
119 else
120 return -ENODEV;
121
122 pcidev = pci_get_device(pci_vendor,
123 PCI_DEVICE_ID_AMD_KERNCZ_SMBUS, NULL);
124
125 if (!pcidev) {
126 if (!boot_cpu_has(X86_FEATURE_PROC_FEEDBACK))
127 return -ENODEV;
128 } else {
129 pci_dev_put(pcidev);
130 }
131
132 if (rdmsrl_safe(MSR_AMD64_FREQ_SENSITIVITY_ACTUAL, &val))
133 return -ENODEV;
134
135 if (!(val >> CLASS_CODE_SHIFT))
136 return -ENODEV;
137
138 od_register_powersave_bias_handler(amd_powersave_bias_target,
139 POWERSAVE_BIAS_DEF);
140 return 0;
141 }
142 late_initcall(amd_freq_sensitivity_init);
143
amd_freq_sensitivity_exit(void)144 static void __exit amd_freq_sensitivity_exit(void)
145 {
146 od_unregister_powersave_bias_handler();
147 }
148 module_exit(amd_freq_sensitivity_exit);
149
150 static const struct x86_cpu_id __maybe_unused amd_freq_sensitivity_ids[] = {
151 X86_MATCH_FEATURE(X86_FEATURE_PROC_FEEDBACK, NULL),
152 {}
153 };
154 MODULE_DEVICE_TABLE(x86cpu, amd_freq_sensitivity_ids);
155
156 MODULE_AUTHOR("Jacob Shin <jacob.shin@amd.com>");
157 MODULE_DESCRIPTION("AMD frequency sensitivity feedback powersave bias for "
158 "the ondemand governor.");
159 MODULE_LICENSE("GPL");
160