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(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 
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 
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