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(cpu: policy->cpu, MSR_AMD64_FREQ_SENSITIVITY_ACTUAL, |
55 | l: &actual.l, h: &actual.h); |
56 | rdmsr_on_cpu(cpu: policy->cpu, MSR_AMD64_FREQ_SENSITIVITY_REFERENCE, |
57 | l: &reference.l, h: &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 | target_freq: policy->cur - 1, |
95 | efficiencies: 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 | |
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(vendor: 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(dev: pcidev); |
130 | } |
131 | |
132 | if (rdmsrl_safe(MSR_AMD64_FREQ_SENSITIVITY_ACTUAL, p: &val)) |
133 | return -ENODEV; |
134 | |
135 | if (!(val >> CLASS_CODE_SHIFT)) |
136 | return -ENODEV; |
137 | |
138 | od_register_powersave_bias_handler(f: amd_powersave_bias_target, |
139 | POWERSAVE_BIAS_DEF); |
140 | return 0; |
141 | } |
142 | late_initcall(amd_freq_sensitivity_init); |
143 | |
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 | |