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