Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
15
16#include <linux/kernel.h>
17#include <linux/module.h>
18#include <linux/smp.h>
19#include <linux/init.h>
20#include <linux/spinlock.h>
21#include <linux/interrupt.h>
22#include <linux/cpufreq.h>
23#include <linux/cpu.h>
24#include <linux/types.h>
25#include <linux/fs.h>
26#include <linux/sysfs.h>
27#include <linux/mutex.h>
28
29/**
30 * A few values needed by the userspace governor
31 */
32static DEFINE_PER_CPU(unsigned int, cpu_max_freq);
33static DEFINE_PER_CPU(unsigned int, cpu_min_freq);
34static DEFINE_PER_CPU(unsigned int, cpu_cur_freq); /* current CPU freq */
35static DEFINE_PER_CPU(unsigned int, cpu_set_freq); /* CPU freq desired by
36 userspace */
37static DEFINE_PER_CPU(unsigned int, cpu_is_managed);
38
39static DEFINE_MUTEX(userspace_mutex);
40static int cpus_using_userspace_governor;
41
42/* keep track of frequency transitions */
43static int
44userspace_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
45 void *data)
46{
47 struct cpufreq_freqs *freq = data;
48
49 if (!per_cpu(cpu_is_managed, freq->cpu))
50 return 0;
51
52 if (val == CPUFREQ_POSTCHANGE) {
53 pr_debug("saving cpu_cur_freq of cpu %u to be %u kHz\n",
54 freq->cpu, freq->new);
55 per_cpu(cpu_cur_freq, freq->cpu) = freq->new;
56 }
57
58 return 0;
59}
60
61static struct notifier_block userspace_cpufreq_notifier_block = {
62 .notifier_call = userspace_cpufreq_notifier
63};
64
65
66/**
67 * cpufreq_set - set the CPU frequency
68 * @policy: pointer to policy struct where freq is being set
69 * @freq: target frequency in kHz
70 *
71 * Sets the CPU frequency to freq.
72 */
73static int cpufreq_set(struct cpufreq_policy *policy, unsigned int freq)
74{
75 int ret = -EINVAL;
76
77 pr_debug("cpufreq_set for cpu %u, freq %u kHz\n", policy->cpu, freq);
78
79 mutex_lock(&userspace_mutex);
80 if (!per_cpu(cpu_is_managed, policy->cpu))
81 goto err;
82
83 per_cpu(cpu_set_freq, policy->cpu) = freq;
84
85 if (freq < per_cpu(cpu_min_freq, policy->cpu))
86 freq = per_cpu(cpu_min_freq, policy->cpu);
87 if (freq > per_cpu(cpu_max_freq, policy->cpu))
88 freq = per_cpu(cpu_max_freq, policy->cpu);
89
90 /*
91 * We're safe from concurrent calls to ->target() here
92 * as we hold the userspace_mutex lock. If we were calling
93 * cpufreq_driver_target, a deadlock situation might occur:
94 * A: cpufreq_set (lock userspace_mutex) ->
95 * cpufreq_driver_target(lock policy->lock)
96 * B: cpufreq_set_policy(lock policy->lock) ->
97 * __cpufreq_governor ->
98 * cpufreq_governor_userspace (lock userspace_mutex)
99 */
100 ret = __cpufreq_driver_target(policy, freq, CPUFREQ_RELATION_L);
101
102 err:
103 mutex_unlock(&userspace_mutex);
104 return ret;
105}
106
107
108static ssize_t show_speed(struct cpufreq_policy *policy, char *buf)
109{
110 return sprintf(buf, "%u\n", per_cpu(cpu_cur_freq, policy->cpu));
111}
112
113static int cpufreq_governor_userspace(struct cpufreq_policy *policy,
114 unsigned int event)
115{
116 unsigned int cpu = policy->cpu;
117 int rc = 0;
118
119 switch (event) {
120 case CPUFREQ_GOV_START:
121 if (!cpu_online(cpu))
122 return -EINVAL;
123 BUG_ON(!policy->cur);
124 mutex_lock(&userspace_mutex);
125
126 if (cpus_using_userspace_governor == 0) {
127 cpufreq_register_notifier(
128 &userspace_cpufreq_notifier_block,
129 CPUFREQ_TRANSITION_NOTIFIER);
130 }
131 cpus_using_userspace_governor++;
132
133 per_cpu(cpu_is_managed, cpu) = 1;
134 per_cpu(cpu_min_freq, cpu) = policy->min;
135 per_cpu(cpu_max_freq, cpu) = policy->max;
136 per_cpu(cpu_cur_freq, cpu) = policy->cur;
137 per_cpu(cpu_set_freq, cpu) = policy->cur;
138 pr_debug("managing cpu %u started "
139 "(%u - %u kHz, currently %u kHz)\n",
140 cpu,
141 per_cpu(cpu_min_freq, cpu),
142 per_cpu(cpu_max_freq, cpu),
143 per_cpu(cpu_cur_freq, cpu));
144
145 mutex_unlock(&userspace_mutex);
146 break;
147 case CPUFREQ_GOV_STOP:
148 mutex_lock(&userspace_mutex);
149 cpus_using_userspace_governor--;
150 if (cpus_using_userspace_governor == 0) {
151 cpufreq_unregister_notifier(
152 &userspace_cpufreq_notifier_block,
153 CPUFREQ_TRANSITION_NOTIFIER);
154 }
155
156 per_cpu(cpu_is_managed, cpu) = 0;
157 per_cpu(cpu_min_freq, cpu) = 0;
158 per_cpu(cpu_max_freq, cpu) = 0;
159 per_cpu(cpu_set_freq, cpu) = 0;
160 pr_debug("managing cpu %u stopped\n", cpu);
161 mutex_unlock(&userspace_mutex);
162 break;
163 case CPUFREQ_GOV_LIMITS:
164 mutex_lock(&userspace_mutex);
165 pr_debug("limit event for cpu %u: %u - %u kHz, "
166 "currently %u kHz, last set to %u kHz\n",
167 cpu, policy->min, policy->max,
168 per_cpu(cpu_cur_freq, cpu),
169 per_cpu(cpu_set_freq, cpu));
170 if (policy->max < per_cpu(cpu_set_freq, cpu)) {
171 __cpufreq_driver_target(policy, policy->max,
172 CPUFREQ_RELATION_H);
173 } else if (policy->min > per_cpu(cpu_set_freq, cpu)) {
174 __cpufreq_driver_target(policy, policy->min,
175 CPUFREQ_RELATION_L);
176 } else {
177 __cpufreq_driver_target(policy,
178 per_cpu(cpu_set_freq, cpu),
179 CPUFREQ_RELATION_L);
180 }
181 per_cpu(cpu_min_freq, cpu) = policy->min;
182 per_cpu(cpu_max_freq, cpu) = policy->max;
183 per_cpu(cpu_cur_freq, cpu) = policy->cur;
184 mutex_unlock(&userspace_mutex);
185 break;
186 }
187 return rc;
188}
189
190
191#ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_USERSPACE
192static
193#endif
194struct cpufreq_governor cpufreq_gov_userspace = {
195 .name = "userspace",
196 .governor = cpufreq_governor_userspace,
197 .store_setspeed = cpufreq_set,
198 .show_setspeed = show_speed,
199 .owner = THIS_MODULE,
200};
201
202static int __init cpufreq_gov_userspace_init(void)
203{
204 return cpufreq_register_governor(&cpufreq_gov_userspace);
205}
206
207
208static void __exit cpufreq_gov_userspace_exit(void)
209{
210 cpufreq_unregister_governor(&cpufreq_gov_userspace);
211}
212
213
214MODULE_AUTHOR("Dominik Brodowski <linux@brodo.de>, "
215 "Russell King <rmk@arm.linux.org.uk>");
216MODULE_DESCRIPTION("CPUfreq policy governor 'userspace'");
217MODULE_LICENSE("GPL");
218
219#ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_USERSPACE
220fs_initcall(cpufreq_gov_userspace_init);
221#else
222module_init(cpufreq_gov_userspace_init);
223#endif
224module_exit(cpufreq_gov_userspace_exit);