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1
2/*
3 * linux/drivers/cpufreq/cpufreq_userspace.c
4 *
5 * Copyright (C) 2001 Russell King
6 * (C) 2002 - 2004 Dominik Brodowski <linux@brodo.de>
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License version 2 as
10 * published by the Free Software Foundation.
11 *
12 */
13
14#include <linux/kernel.h>
15#include <linux/module.h>
16#include <linux/smp.h>
17#include <linux/init.h>
18#include <linux/spinlock.h>
19#include <linux/interrupt.h>
20#include <linux/cpufreq.h>
21#include <linux/cpu.h>
22#include <linux/types.h>
23#include <linux/fs.h>
24#include <linux/sysfs.h>
25#include <linux/mutex.h>
26
27/**
28 * A few values needed by the userspace governor
29 */
30static DEFINE_PER_CPU(unsigned int, cpu_max_freq);
31static DEFINE_PER_CPU(unsigned int, cpu_min_freq);
32static DEFINE_PER_CPU(unsigned int, cpu_cur_freq); /* current CPU freq */
33static DEFINE_PER_CPU(unsigned int, cpu_set_freq); /* CPU freq desired by
34 userspace */
35static DEFINE_PER_CPU(unsigned int, cpu_is_managed);
36
37static DEFINE_MUTEX(userspace_mutex);
38static int cpus_using_userspace_governor;
39
40/* keep track of frequency transitions */
41static int
42userspace_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
43 void *data)
44{
45 struct cpufreq_freqs *freq = data;
46
47 if (!per_cpu(cpu_is_managed, freq->cpu))
48 return 0;
49
50 pr_debug("saving cpu_cur_freq of cpu %u to be %u kHz\n",
51 freq->cpu, freq->new);
52 per_cpu(cpu_cur_freq, freq->cpu) = freq->new;
53
54 return 0;
55}
56
57static struct notifier_block userspace_cpufreq_notifier_block = {
58 .notifier_call = userspace_cpufreq_notifier
59};
60
61
62/**
63 * cpufreq_set - set the CPU frequency
64 * @policy: pointer to policy struct where freq is being set
65 * @freq: target frequency in kHz
66 *
67 * Sets the CPU frequency to freq.
68 */
69static int cpufreq_set(struct cpufreq_policy *policy, unsigned int freq)
70{
71 int ret = -EINVAL;
72
73 pr_debug("cpufreq_set for cpu %u, freq %u kHz\n", policy->cpu, freq);
74
75 mutex_lock(&userspace_mutex);
76 if (!per_cpu(cpu_is_managed, policy->cpu))
77 goto err;
78
79 per_cpu(cpu_set_freq, policy->cpu) = freq;
80
81 if (freq < per_cpu(cpu_min_freq, policy->cpu))
82 freq = per_cpu(cpu_min_freq, policy->cpu);
83 if (freq > per_cpu(cpu_max_freq, policy->cpu))
84 freq = per_cpu(cpu_max_freq, policy->cpu);
85
86 /*
87 * We're safe from concurrent calls to ->target() here
88 * as we hold the userspace_mutex lock. If we were calling
89 * cpufreq_driver_target, a deadlock situation might occur:
90 * A: cpufreq_set (lock userspace_mutex) ->
91 * cpufreq_driver_target(lock policy->lock)
92 * B: cpufreq_set_policy(lock policy->lock) ->
93 * __cpufreq_governor ->
94 * cpufreq_governor_userspace (lock userspace_mutex)
95 */
96 ret = __cpufreq_driver_target(policy, freq, CPUFREQ_RELATION_L);
97
98 err:
99 mutex_unlock(&userspace_mutex);
100 return ret;
101}
102
103
104static ssize_t show_speed(struct cpufreq_policy *policy, char *buf)
105{
106 return sprintf(buf, "%u\n", per_cpu(cpu_cur_freq, policy->cpu));
107}
108
109static int cpufreq_governor_userspace(struct cpufreq_policy *policy,
110 unsigned int event)
111{
112 unsigned int cpu = policy->cpu;
113 int rc = 0;
114
115 switch (event) {
116 case CPUFREQ_GOV_START:
117 if (!cpu_online(cpu))
118 return -EINVAL;
119 BUG_ON(!policy->cur);
120 mutex_lock(&userspace_mutex);
121
122 if (cpus_using_userspace_governor == 0) {
123 cpufreq_register_notifier(
124 &userspace_cpufreq_notifier_block,
125 CPUFREQ_TRANSITION_NOTIFIER);
126 }
127 cpus_using_userspace_governor++;
128
129 per_cpu(cpu_is_managed, cpu) = 1;
130 per_cpu(cpu_min_freq, cpu) = policy->min;
131 per_cpu(cpu_max_freq, cpu) = policy->max;
132 per_cpu(cpu_cur_freq, cpu) = policy->cur;
133 per_cpu(cpu_set_freq, cpu) = policy->cur;
134 pr_debug("managing cpu %u started "
135 "(%u - %u kHz, currently %u kHz)\n",
136 cpu,
137 per_cpu(cpu_min_freq, cpu),
138 per_cpu(cpu_max_freq, cpu),
139 per_cpu(cpu_cur_freq, cpu));
140
141 mutex_unlock(&userspace_mutex);
142 break;
143 case CPUFREQ_GOV_STOP:
144 mutex_lock(&userspace_mutex);
145 cpus_using_userspace_governor--;
146 if (cpus_using_userspace_governor == 0) {
147 cpufreq_unregister_notifier(
148 &userspace_cpufreq_notifier_block,
149 CPUFREQ_TRANSITION_NOTIFIER);
150 }
151
152 per_cpu(cpu_is_managed, cpu) = 0;
153 per_cpu(cpu_min_freq, cpu) = 0;
154 per_cpu(cpu_max_freq, cpu) = 0;
155 per_cpu(cpu_set_freq, cpu) = 0;
156 pr_debug("managing cpu %u stopped\n", cpu);
157 mutex_unlock(&userspace_mutex);
158 break;
159 case CPUFREQ_GOV_LIMITS:
160 mutex_lock(&userspace_mutex);
161 pr_debug("limit event for cpu %u: %u - %u kHz, "
162 "currently %u kHz, last set to %u kHz\n",
163 cpu, policy->min, policy->max,
164 per_cpu(cpu_cur_freq, cpu),
165 per_cpu(cpu_set_freq, cpu));
166 if (policy->max < per_cpu(cpu_set_freq, cpu)) {
167 __cpufreq_driver_target(policy, policy->max,
168 CPUFREQ_RELATION_H);
169 } else if (policy->min > per_cpu(cpu_set_freq, cpu)) {
170 __cpufreq_driver_target(policy, policy->min,
171 CPUFREQ_RELATION_L);
172 } else {
173 __cpufreq_driver_target(policy,
174 per_cpu(cpu_set_freq, cpu),
175 CPUFREQ_RELATION_L);
176 }
177 per_cpu(cpu_min_freq, cpu) = policy->min;
178 per_cpu(cpu_max_freq, cpu) = policy->max;
179 per_cpu(cpu_cur_freq, cpu) = policy->cur;
180 mutex_unlock(&userspace_mutex);
181 break;
182 }
183 return rc;
184}
185
186
187#ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_USERSPACE
188static
189#endif
190struct cpufreq_governor cpufreq_gov_userspace = {
191 .name = "userspace",
192 .governor = cpufreq_governor_userspace,
193 .store_setspeed = cpufreq_set,
194 .show_setspeed = show_speed,
195 .owner = THIS_MODULE,
196};
197
198static int __init cpufreq_gov_userspace_init(void)
199{
200 return cpufreq_register_governor(&cpufreq_gov_userspace);
201}
202
203
204static void __exit cpufreq_gov_userspace_exit(void)
205{
206 cpufreq_unregister_governor(&cpufreq_gov_userspace);
207}
208
209
210MODULE_AUTHOR("Dominik Brodowski <linux@brodo.de>, "
211 "Russell King <rmk@arm.linux.org.uk>");
212MODULE_DESCRIPTION("CPUfreq policy governor 'userspace'");
213MODULE_LICENSE("GPL");
214
215#ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_USERSPACE
216fs_initcall(cpufreq_gov_userspace_init);
217#else
218module_init(cpufreq_gov_userspace_init);
219#endif
220module_exit(cpufreq_gov_userspace_exit);
1// SPDX-License-Identifier: GPL-2.0-only
2
3/*
4 * linux/drivers/cpufreq/cpufreq_userspace.c
5 *
6 * Copyright (C) 2001 Russell King
7 * (C) 2002 - 2004 Dominik Brodowski <linux@brodo.de>
8 */
9
10#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
11
12#include <linux/cpufreq.h>
13#include <linux/init.h>
14#include <linux/module.h>
15#include <linux/mutex.h>
16#include <linux/slab.h>
17
18struct userspace_policy {
19 unsigned int is_managed;
20 unsigned int setspeed;
21 struct mutex mutex;
22};
23
24/**
25 * cpufreq_set - set the CPU frequency
26 * @policy: pointer to policy struct where freq is being set
27 * @freq: target frequency in kHz
28 *
29 * Sets the CPU frequency to freq.
30 */
31static int cpufreq_set(struct cpufreq_policy *policy, unsigned int freq)
32{
33 int ret = -EINVAL;
34 struct userspace_policy *userspace = policy->governor_data;
35
36 pr_debug("cpufreq_set for cpu %u, freq %u kHz\n", policy->cpu, freq);
37
38 mutex_lock(&userspace->mutex);
39 if (!userspace->is_managed)
40 goto err;
41
42 userspace->setspeed = freq;
43
44 ret = __cpufreq_driver_target(policy, freq, CPUFREQ_RELATION_L);
45 err:
46 mutex_unlock(&userspace->mutex);
47 return ret;
48}
49
50static ssize_t show_speed(struct cpufreq_policy *policy, char *buf)
51{
52 return sprintf(buf, "%u\n", policy->cur);
53}
54
55static int cpufreq_userspace_policy_init(struct cpufreq_policy *policy)
56{
57 struct userspace_policy *userspace;
58
59 userspace = kzalloc(sizeof(*userspace), GFP_KERNEL);
60 if (!userspace)
61 return -ENOMEM;
62
63 mutex_init(&userspace->mutex);
64
65 policy->governor_data = userspace;
66 return 0;
67}
68
69/*
70 * Any routine that writes to the policy struct will hold the "rwsem" of
71 * policy struct that means it is free to free "governor_data" here.
72 */
73static void cpufreq_userspace_policy_exit(struct cpufreq_policy *policy)
74{
75 kfree(policy->governor_data);
76 policy->governor_data = NULL;
77}
78
79static int cpufreq_userspace_policy_start(struct cpufreq_policy *policy)
80{
81 struct userspace_policy *userspace = policy->governor_data;
82
83 BUG_ON(!policy->cur);
84 pr_debug("started managing cpu %u\n", policy->cpu);
85
86 mutex_lock(&userspace->mutex);
87 userspace->is_managed = 1;
88 userspace->setspeed = policy->cur;
89 mutex_unlock(&userspace->mutex);
90 return 0;
91}
92
93static void cpufreq_userspace_policy_stop(struct cpufreq_policy *policy)
94{
95 struct userspace_policy *userspace = policy->governor_data;
96
97 pr_debug("managing cpu %u stopped\n", policy->cpu);
98
99 mutex_lock(&userspace->mutex);
100 userspace->is_managed = 0;
101 userspace->setspeed = 0;
102 mutex_unlock(&userspace->mutex);
103}
104
105static void cpufreq_userspace_policy_limits(struct cpufreq_policy *policy)
106{
107 struct userspace_policy *userspace = policy->governor_data;
108
109 mutex_lock(&userspace->mutex);
110
111 pr_debug("limit event for cpu %u: %u - %u kHz, currently %u kHz, last set to %u kHz\n",
112 policy->cpu, policy->min, policy->max, policy->cur, userspace->setspeed);
113
114 if (policy->max < userspace->setspeed)
115 __cpufreq_driver_target(policy, policy->max,
116 CPUFREQ_RELATION_H);
117 else if (policy->min > userspace->setspeed)
118 __cpufreq_driver_target(policy, policy->min,
119 CPUFREQ_RELATION_L);
120 else
121 __cpufreq_driver_target(policy, userspace->setspeed,
122 CPUFREQ_RELATION_L);
123
124 mutex_unlock(&userspace->mutex);
125}
126
127static struct cpufreq_governor cpufreq_gov_userspace = {
128 .name = "userspace",
129 .init = cpufreq_userspace_policy_init,
130 .exit = cpufreq_userspace_policy_exit,
131 .start = cpufreq_userspace_policy_start,
132 .stop = cpufreq_userspace_policy_stop,
133 .limits = cpufreq_userspace_policy_limits,
134 .store_setspeed = cpufreq_set,
135 .show_setspeed = show_speed,
136 .owner = THIS_MODULE,
137};
138
139MODULE_AUTHOR("Dominik Brodowski <linux@brodo.de>, "
140 "Russell King <rmk@arm.linux.org.uk>");
141MODULE_DESCRIPTION("CPUfreq policy governor 'userspace'");
142MODULE_LICENSE("GPL");
143
144#ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_USERSPACE
145struct cpufreq_governor *cpufreq_default_governor(void)
146{
147 return &cpufreq_gov_userspace;
148}
149#endif
150
151cpufreq_governor_init(cpufreq_gov_userspace);
152cpufreq_governor_exit(cpufreq_gov_userspace);