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
 31struct cpu_data_t {
 32	u64 actual;
 33	u64 reference;
 34	unsigned int freq_prev;
 35};
 36
 37static DEFINE_PER_CPU(struct cpu_data_t, cpu_data);
 38
 39static 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
103out:
104	data->actual = actual.q;
105	data->reference = reference.q;
106	return freq_next;
107}
108
109static 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}
142late_initcall(amd_freq_sensitivity_init);
143
144static void __exit amd_freq_sensitivity_exit(void)
145{
146	od_unregister_powersave_bias_handler();
147}
148module_exit(amd_freq_sensitivity_exit);
149
150static const struct x86_cpu_id __maybe_unused amd_freq_sensitivity_ids[] = {
151	X86_MATCH_FEATURE(X86_FEATURE_PROC_FEEDBACK, NULL),
152	{}
153};
154MODULE_DEVICE_TABLE(x86cpu, amd_freq_sensitivity_ids);
155
156MODULE_AUTHOR("Jacob Shin <jacob.shin@amd.com>");
157MODULE_DESCRIPTION("AMD frequency sensitivity feedback powersave bias for "
158		"the ondemand governor.");
159MODULE_LICENSE("GPL");