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 void cpufreq_userspace_policy_exit(struct cpufreq_policy *policy)
69 {
70 	mutex_lock(&userspace_mutex);
71 	kfree(policy->governor_data);
72 	policy->governor_data = NULL;
73 	mutex_unlock(&userspace_mutex);
74 }
75 
76 static int cpufreq_userspace_policy_start(struct cpufreq_policy *policy)
77 {
78 	unsigned int *setspeed = policy->governor_data;
79 
80 	BUG_ON(!policy->cur);
81 	pr_debug("started managing cpu %u\n", policy->cpu);
82 
83 	mutex_lock(&userspace_mutex);
84 	per_cpu(cpu_is_managed, policy->cpu) = 1;
85 	*setspeed = policy->cur;
86 	mutex_unlock(&userspace_mutex);
87 	return 0;
88 }
89 
90 static void cpufreq_userspace_policy_stop(struct cpufreq_policy *policy)
91 {
92 	unsigned int *setspeed = policy->governor_data;
93 
94 	pr_debug("managing cpu %u stopped\n", policy->cpu);
95 
96 	mutex_lock(&userspace_mutex);
97 	per_cpu(cpu_is_managed, policy->cpu) = 0;
98 	*setspeed = 0;
99 	mutex_unlock(&userspace_mutex);
100 }
101 
102 static void cpufreq_userspace_policy_limits(struct cpufreq_policy *policy)
103 {
104 	unsigned int *setspeed = policy->governor_data;
105 
106 	mutex_lock(&userspace_mutex);
107 
108 	pr_debug("limit event for cpu %u: %u - %u kHz, currently %u kHz, last set to %u kHz\n",
109 		 policy->cpu, policy->min, policy->max, policy->cur, *setspeed);
110 
111 	if (policy->max < *setspeed)
112 		__cpufreq_driver_target(policy, policy->max, CPUFREQ_RELATION_H);
113 	else if (policy->min > *setspeed)
114 		__cpufreq_driver_target(policy, policy->min, CPUFREQ_RELATION_L);
115 	else
116 		__cpufreq_driver_target(policy, *setspeed, CPUFREQ_RELATION_L);
117 
118 	mutex_unlock(&userspace_mutex);
119 }
120 
121 static struct cpufreq_governor cpufreq_gov_userspace = {
122 	.name		= "userspace",
123 	.init		= cpufreq_userspace_policy_init,
124 	.exit		= cpufreq_userspace_policy_exit,
125 	.start		= cpufreq_userspace_policy_start,
126 	.stop		= cpufreq_userspace_policy_stop,
127 	.limits		= cpufreq_userspace_policy_limits,
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