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/cpufreq.h>
17#include <linux/init.h>
18#include <linux/module.h>
19#include <linux/mutex.h>
20
21static DEFINE_PER_CPU(unsigned int, cpu_is_managed);
22static DEFINE_MUTEX(userspace_mutex);
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
35	pr_debug("cpufreq_set for cpu %u, freq %u kHz\n", policy->cpu, freq);
36
37	mutex_lock(&userspace_mutex);
38	if (!per_cpu(cpu_is_managed, policy->cpu))
39		goto err;
40
41	ret = __cpufreq_driver_target(policy, freq, CPUFREQ_RELATION_L);
42 err:
43	mutex_unlock(&userspace_mutex);
44	return ret;
45}
46
47static ssize_t show_speed(struct cpufreq_policy *policy, char *buf)
48{
49	return sprintf(buf, "%u\n", policy->cur);
50}
51
52static int cpufreq_governor_userspace(struct cpufreq_policy *policy,
53				   unsigned int event)
54{
55	unsigned int cpu = policy->cpu;
56	int rc = 0;
57
58	switch (event) {
59	case CPUFREQ_GOV_START:
60		BUG_ON(!policy->cur);
61		pr_debug("started managing cpu %u\n", cpu);
62
63		mutex_lock(&userspace_mutex);
64		per_cpu(cpu_is_managed, cpu) = 1;
65		mutex_unlock(&userspace_mutex);
66		break;
67	case CPUFREQ_GOV_STOP:
68		pr_debug("managing cpu %u stopped\n", cpu);
69
70		mutex_lock(&userspace_mutex);
71		per_cpu(cpu_is_managed, cpu) = 0;
72		mutex_unlock(&userspace_mutex);
73		break;
74	case CPUFREQ_GOV_LIMITS:
75		mutex_lock(&userspace_mutex);
76		pr_debug("limit event for cpu %u: %u - %u kHz, currently %u kHz\n",
77			cpu, policy->min, policy->max,
78			policy->cur);
79
80		if (policy->max < policy->cur)
81			__cpufreq_driver_target(policy, policy->max,
82						CPUFREQ_RELATION_H);
83		else if (policy->min > policy->cur)
84			__cpufreq_driver_target(policy, policy->min,
85						CPUFREQ_RELATION_L);
86		mutex_unlock(&userspace_mutex);
87		break;
88	}
89	return rc;
90}
91
92#ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_USERSPACE
93static
94#endif
95struct cpufreq_governor cpufreq_gov_userspace = {
96	.name		= "userspace",
97	.governor	= cpufreq_governor_userspace,
98	.store_setspeed	= cpufreq_set,
99	.show_setspeed	= show_speed,
100	.owner		= THIS_MODULE,
101};
102
103static int __init cpufreq_gov_userspace_init(void)
104{
105	return cpufreq_register_governor(&cpufreq_gov_userspace);
106}
107
108static void __exit cpufreq_gov_userspace_exit(void)
109{
110	cpufreq_unregister_governor(&cpufreq_gov_userspace);
111}
112
113MODULE_AUTHOR("Dominik Brodowski <linux@brodo.de>, "
114		"Russell King <rmk@arm.linux.org.uk>");
115MODULE_DESCRIPTION("CPUfreq policy governor 'userspace'");
116MODULE_LICENSE("GPL");
117
118#ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_USERSPACE
119fs_initcall(cpufreq_gov_userspace_init);
120#else
121module_init(cpufreq_gov_userspace_init);
122#endif
123module_exit(cpufreq_gov_userspace_exit);
124