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
 30struct cpu_data_t {
 31	u64 actual;
 32	u64 reference;
 33	unsigned int freq_prev;
 34};
 35
 36static DEFINE_PER_CPU(struct cpu_data_t, cpu_data);
 37
 38static 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
101out:
102	data->actual = actual.q;
103	data->reference = reference.q;
104	return freq_next;
105}
106
107static 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}
138late_initcall(amd_freq_sensitivity_init);
139
140static void __exit amd_freq_sensitivity_exit(void)
141{
142	od_unregister_powersave_bias_handler();
143}
144module_exit(amd_freq_sensitivity_exit);
145
146static const struct x86_cpu_id amd_freq_sensitivity_ids[] = {
147	X86_FEATURE_MATCH(X86_FEATURE_PROC_FEEDBACK),
148	{}
149};
150MODULE_DEVICE_TABLE(x86cpu, amd_freq_sensitivity_ids);
151
152MODULE_AUTHOR("Jacob Shin <jacob.shin@amd.com>");
153MODULE_DESCRIPTION("AMD frequency sensitivity feedback powersave bias for "
154		"the ondemand governor.");
155MODULE_LICENSE("GPL");