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 #include <linux/slab.h>
21 
22 static DEFINE_PER_CPU(unsigned int, cpu_is_managed);
23 static DEFINE_MUTEX(userspace_mutex);
24 
25 /**
26  * cpufreq_set - set the CPU frequency
27  * @policy: pointer to policy struct where freq is being set
28  * @freq: target frequency in kHz
29  *
30  * Sets the CPU frequency to freq.
31  */
32 static int cpufreq_set(struct cpufreq_policy *policy, unsigned int freq)
33 {
34 	int ret = -EINVAL;
35 	unsigned int *setspeed = policy->governor_data;
36 
37 	pr_debug("cpufreq_set for cpu %u, freq %u kHz\n", policy->cpu, freq);
38 
39 	mutex_lock(&userspace_mutex);
40 	if (!per_cpu(cpu_is_managed, policy->cpu))
41 		goto err;
42 
43 	*setspeed = freq;
44 
45 	ret = __cpufreq_driver_target(policy, freq, CPUFREQ_RELATION_L);
46  err:
47 	mutex_unlock(&userspace_mutex);
48 	return ret;
49 }
50 
51 static ssize_t show_speed(struct cpufreq_policy *policy, char *buf)
52 {
53 	return sprintf(buf, "%u\n", policy->cur);
54 }
55 
56 static int cpufreq_userspace_policy_init(struct cpufreq_policy *policy)
57 {
58 	unsigned int *setspeed;
59 
60 	setspeed = kzalloc(sizeof(*setspeed), GFP_KERNEL);
61 	if (!setspeed)
62 		return -ENOMEM;
63 
64 	policy->governor_data = setspeed;
65 	return 0;
66 }
67 
68 static int cpufreq_governor_userspace(struct cpufreq_policy *policy,
69 				   unsigned int event)
70 {
71 	unsigned int *setspeed = policy->governor_data;
72 	unsigned int cpu = policy->cpu;
73 	int rc = 0;
74 
75 	if (event == CPUFREQ_GOV_POLICY_INIT)
76 		return cpufreq_userspace_policy_init(policy);
77 
78 	if (!setspeed)
79 		return -EINVAL;
80 
81 	switch (event) {
82 	case CPUFREQ_GOV_POLICY_EXIT:
83 		mutex_lock(&userspace_mutex);
84 		policy->governor_data = NULL;
85 		kfree(setspeed);
86 		mutex_unlock(&userspace_mutex);
87 		break;
88 	case CPUFREQ_GOV_START:
89 		BUG_ON(!policy->cur);
90 		pr_debug("started managing cpu %u\n", cpu);
91 
92 		mutex_lock(&userspace_mutex);
93 		per_cpu(cpu_is_managed, cpu) = 1;
94 		*setspeed = policy->cur;
95 		mutex_unlock(&userspace_mutex);
96 		break;
97 	case CPUFREQ_GOV_STOP:
98 		pr_debug("managing cpu %u stopped\n", cpu);
99 
100 		mutex_lock(&userspace_mutex);
101 		per_cpu(cpu_is_managed, cpu) = 0;
102 		*setspeed = 0;
103 		mutex_unlock(&userspace_mutex);
104 		break;
105 	case CPUFREQ_GOV_LIMITS:
106 		mutex_lock(&userspace_mutex);
107 		pr_debug("limit event for cpu %u: %u - %u kHz, currently %u kHz, last set to %u kHz\n",
108 			cpu, policy->min, policy->max, policy->cur, *setspeed);
109 
110 		if (policy->max < *setspeed)
111 			__cpufreq_driver_target(policy, policy->max,
112 						CPUFREQ_RELATION_H);
113 		else if (policy->min > *setspeed)
114 			__cpufreq_driver_target(policy, policy->min,
115 						CPUFREQ_RELATION_L);
116 		else
117 			__cpufreq_driver_target(policy, *setspeed,
118 						CPUFREQ_RELATION_L);
119 		mutex_unlock(&userspace_mutex);
120 		break;
121 	}
122 	return rc;
123 }
124 
125 static struct cpufreq_governor cpufreq_gov_userspace = {
126 	.name		= "userspace",
127 	.governor	= cpufreq_governor_userspace,
128 	.store_setspeed	= cpufreq_set,
129 	.show_setspeed	= show_speed,
130 	.owner		= THIS_MODULE,
131 };
132 
133 static int __init cpufreq_gov_userspace_init(void)
134 {
135 	return cpufreq_register_governor(&cpufreq_gov_userspace);
136 }
137 
138 static void __exit cpufreq_gov_userspace_exit(void)
139 {
140 	cpufreq_unregister_governor(&cpufreq_gov_userspace);
141 }
142 
143 MODULE_AUTHOR("Dominik Brodowski <linux@brodo.de>, "
144 		"Russell King <rmk@arm.linux.org.uk>");
145 MODULE_DESCRIPTION("CPUfreq policy governor 'userspace'");
146 MODULE_LICENSE("GPL");
147 
148 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_USERSPACE
149 struct cpufreq_governor *cpufreq_default_governor(void)
150 {
151 	return &cpufreq_gov_userspace;
152 }
153 
154 fs_initcall(cpufreq_gov_userspace_init);
155 #else
156 module_init(cpufreq_gov_userspace_init);
157 #endif
158 module_exit(cpufreq_gov_userspace_exit);
159