cpufreq_userspace.c revision 9e76988e9390a4ff4d171f690586d0c58186b47e 
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#include <asm/uaccess.h>
28
29
30/**
31 * A few values needed by the userspace governor
32 */
33static unsigned int	cpu_max_freq[NR_CPUS];
34static unsigned int	cpu_min_freq[NR_CPUS];
35static unsigned int	cpu_cur_freq[NR_CPUS]; /* current CPU freq */
36static unsigned int	cpu_set_freq[NR_CPUS]; /* CPU freq desired by userspace */
37static unsigned int	cpu_is_managed[NR_CPUS];
38
39static DEFINE_MUTEX	(userspace_mutex);
40static int cpus_using_userspace_governor;
41
42#define dprintk(msg...) cpufreq_debug_printk(CPUFREQ_DEBUG_GOVERNOR, "userspace", msg)
43
44/* keep track of frequency transitions */
45static int
46userspace_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
47                       void *data)
48{
49        struct cpufreq_freqs *freq = data;
50
51	if (!cpu_is_managed[freq->cpu])
52		return 0;
53
54	dprintk("saving cpu_cur_freq of cpu %u to be %u kHz\n",
55			freq->cpu, freq->new);
56	cpu_cur_freq[freq->cpu] = freq->new;
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	dprintk("cpufreq_set for cpu %u, freq %u kHz\n", policy->cpu, freq);
78
79	mutex_lock(&userspace_mutex);
80	if (!cpu_is_managed[policy->cpu])
81		goto err;
82
83	cpu_set_freq[policy->cpu] = freq;
84
85	if (freq < cpu_min_freq[policy->cpu])
86		freq = cpu_min_freq[policy->cpu];
87	if (freq > cpu_max_freq[policy->cpu])
88		freq = 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) -> cpufreq_driver_target(lock policy->lock)
95	 * B: cpufreq_set_policy(lock policy->lock) -> __cpufreq_governor -> cpufreq_governor_userspace (lock userspace_mutex)
96	 */
97	ret = __cpufreq_driver_target(policy, freq, CPUFREQ_RELATION_L);
98
99 err:
100	mutex_unlock(&userspace_mutex);
101	return ret;
102}
103
104
105static ssize_t show_speed(struct cpufreq_policy *policy, char *buf)
106{
107	return sprintf(buf, "%u\n", cpu_cur_freq[policy->cpu]);
108}
109
110static int cpufreq_governor_userspace(struct cpufreq_policy *policy,
111				   unsigned int event)
112{
113	unsigned int cpu = policy->cpu;
114	int rc = 0;
115
116	switch (event) {
117	case CPUFREQ_GOV_START:
118		if (!cpu_online(cpu))
119			return -EINVAL;
120		BUG_ON(!policy->cur);
121		mutex_lock(&userspace_mutex);
122
123		if (cpus_using_userspace_governor == 0) {
124			cpufreq_register_notifier(
125					&userspace_cpufreq_notifier_block,
126					CPUFREQ_TRANSITION_NOTIFIER);
127		}
128		cpus_using_userspace_governor++;
129
130		cpu_is_managed[cpu] = 1;
131		cpu_min_freq[cpu] = policy->min;
132		cpu_max_freq[cpu] = policy->max;
133		cpu_cur_freq[cpu] = policy->cur;
134		cpu_set_freq[cpu] = policy->cur;
135		dprintk("managing cpu %u started (%u - %u kHz, currently %u kHz)\n", cpu, cpu_min_freq[cpu], cpu_max_freq[cpu], cpu_cur_freq[cpu]);
136
137		mutex_unlock(&userspace_mutex);
138		break;
139	case CPUFREQ_GOV_STOP:
140		mutex_lock(&userspace_mutex);
141		cpus_using_userspace_governor--;
142		if (cpus_using_userspace_governor == 0) {
143			cpufreq_unregister_notifier(
144					&userspace_cpufreq_notifier_block,
145					CPUFREQ_TRANSITION_NOTIFIER);
146		}
147
148		cpu_is_managed[cpu] = 0;
149		cpu_min_freq[cpu] = 0;
150		cpu_max_freq[cpu] = 0;
151		cpu_set_freq[cpu] = 0;
152		dprintk("managing cpu %u stopped\n", cpu);
153		mutex_unlock(&userspace_mutex);
154		break;
155	case CPUFREQ_GOV_LIMITS:
156		mutex_lock(&userspace_mutex);
157		dprintk("limit event for cpu %u: %u - %u kHz,"
158			"currently %u kHz, last set to %u kHz\n",
159			cpu, policy->min, policy->max,
160			cpu_cur_freq[cpu], cpu_set_freq[cpu]);
161		if (policy->max < cpu_set_freq[cpu]) {
162			__cpufreq_driver_target(policy, policy->max,
163						CPUFREQ_RELATION_H);
164		}
165		else if (policy->min > cpu_set_freq[cpu]) {
166			__cpufreq_driver_target(policy, policy->min,
167						CPUFREQ_RELATION_L);
168		}
169		else {
170			__cpufreq_driver_target(policy, cpu_set_freq[cpu],
171						CPUFREQ_RELATION_L);
172		}
173		cpu_min_freq[cpu] = policy->min;
174		cpu_max_freq[cpu] = policy->max;
175		cpu_cur_freq[cpu] = policy->cur;
176		mutex_unlock(&userspace_mutex);
177		break;
178	}
179	return rc;
180}
181
182
183struct cpufreq_governor cpufreq_gov_userspace = {
184	.name		= "userspace",
185	.governor	= cpufreq_governor_userspace,
186	.store_setspeed	= cpufreq_set,
187	.show_setspeed	= show_speed,
188	.owner		= THIS_MODULE,
189};
190EXPORT_SYMBOL(cpufreq_gov_userspace);
191
192static int __init cpufreq_gov_userspace_init(void)
193{
194	return cpufreq_register_governor(&cpufreq_gov_userspace);
195}
196
197
198static void __exit cpufreq_gov_userspace_exit(void)
199{
200	cpufreq_unregister_governor(&cpufreq_gov_userspace);
201}
202
203
204MODULE_AUTHOR ("Dominik Brodowski <linux@brodo.de>, Russell King <rmk@arm.linux.org.uk>");
205MODULE_DESCRIPTION ("CPUfreq policy governor 'userspace'");
206MODULE_LICENSE ("GPL");
207
208#ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_USERSPACE
209fs_initcall(cpufreq_gov_userspace_init);
210#else
211module_init(cpufreq_gov_userspace_init);
212#endif
213module_exit(cpufreq_gov_userspace_exit);
214