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 
21 static DEFINE_PER_CPU(unsigned int, cpu_is_managed);
22 static 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  */
31 static 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 
47 static ssize_t show_speed(struct cpufreq_policy *policy, char *buf)
48 {
49 	return sprintf(buf, "%u\n", policy->cur);
50 }
51 
52 static 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
93 static
94 #endif
95 struct 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 
103 static int __init cpufreq_gov_userspace_init(void)
104 {
105 	return cpufreq_register_governor(&cpufreq_gov_userspace);
106 }
107 
108 static void __exit cpufreq_gov_userspace_exit(void)
109 {
110 	cpufreq_unregister_governor(&cpufreq_gov_userspace);
111 }
112 
113 MODULE_AUTHOR("Dominik Brodowski <linux@brodo.de>, "
114 		"Russell King <rmk@arm.linux.org.uk>");
115 MODULE_DESCRIPTION("CPUfreq policy governor 'userspace'");
116 MODULE_LICENSE("GPL");
117 
118 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_USERSPACE
119 fs_initcall(cpufreq_gov_userspace_init);
120 #else
121 module_init(cpufreq_gov_userspace_init);
122 #endif
123 module_exit(cpufreq_gov_userspace_exit);
124