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 
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 
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 
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