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
18 #include <asm/msr.h>
19 #include <asm/cpufeature.h>
20 #include <asm/cpu_device_id.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
amd_powersave_bias_target(struct cpufreq_policy * policy,unsigned int freq_next,unsigned int relation)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 rdmsrq_on_cpu(policy->cpu, MSR_AMD64_FREQ_SENSITIVITY_ACTUAL, &actual.q);
54 rdmsrq_on_cpu(policy->cpu, MSR_AMD64_FREQ_SENSITIVITY_REFERENCE, &reference.q);
55 actual.h &= 0x00ffffff;
56 reference.h &= 0x00ffffff;
57
58 /* counter wrapped around, so stay on current frequency */
59 if (actual.q < data->actual || reference.q < data->reference) {
60 freq_next = policy->cur;
61 goto out;
62 }
63
64 d_actual = actual.q - data->actual;
65 d_reference = reference.q - data->reference;
66
67 /* divide by 0, so stay on current frequency as well */
68 if (d_reference == 0) {
69 freq_next = policy->cur;
70 goto out;
71 }
72
73 sensitivity = POWERSAVE_BIAS_MAX -
74 (POWERSAVE_BIAS_MAX * (d_reference - d_actual) / d_reference);
75
76 clamp(sensitivity, 0, POWERSAVE_BIAS_MAX);
77
78 /* this workload is not CPU bound, so choose a lower freq */
79 if (sensitivity < od_tuners->powersave_bias) {
80 if (data->freq_prev == policy->cur)
81 freq_next = policy->cur;
82
83 if (freq_next > policy->cur)
84 freq_next = policy->cur;
85 else if (freq_next < policy->cur)
86 freq_next = policy->min;
87 else {
88 unsigned int index;
89
90 index = cpufreq_table_find_index_h(policy,
91 policy->cur - 1,
92 relation & CPUFREQ_RELATION_E);
93 freq_next = policy->freq_table[index].frequency;
94 }
95
96 data->freq_prev = freq_next;
97 } else
98 data->freq_prev = 0;
99
100 out:
101 data->actual = actual.q;
102 data->reference = reference.q;
103 return freq_next;
104 }
105
amd_freq_sensitivity_init(void)106 static int __init amd_freq_sensitivity_init(void)
107 {
108 u64 val;
109 struct pci_dev *pcidev;
110 unsigned int pci_vendor;
111
112 if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD)
113 pci_vendor = PCI_VENDOR_ID_AMD;
114 else if (boot_cpu_data.x86_vendor == X86_VENDOR_HYGON)
115 pci_vendor = PCI_VENDOR_ID_HYGON;
116 else
117 return -ENODEV;
118
119 pcidev = pci_get_device(pci_vendor,
120 PCI_DEVICE_ID_AMD_KERNCZ_SMBUS, NULL);
121
122 if (!pcidev) {
123 if (!boot_cpu_has(X86_FEATURE_PROC_FEEDBACK))
124 return -ENODEV;
125 } else {
126 pci_dev_put(pcidev);
127 }
128
129 if (rdmsrq_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
amd_freq_sensitivity_exit(void)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");
157