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
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 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
amd_freq_sensitivity_init(void)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
amd_freq_sensitivity_exit(void)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");
156
