1 // SPDX-License-Identifier: GPL-2.0-only
2 
3 /*
4  *  linux/drivers/cpufreq/cpufreq_userspace.c
5  *
6  *  Copyright (C)  2001 Russell King
7  *            (C)  2002 - 2004 Dominik Brodowski <linux@brodo.de>
8  */
9 
10 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
11 
12 #include <linux/cpufreq.h>
13 #include <linux/init.h>
14 #include <linux/module.h>
15 #include <linux/mutex.h>
16 #include <linux/slab.h>
17 
18 static DEFINE_PER_CPU(unsigned int, cpu_is_managed);
19 static DEFINE_MUTEX(userspace_mutex);
20 
21 /**
22  * cpufreq_set - set the CPU frequency
23  * @policy: pointer to policy struct where freq is being set
24  * @freq: target frequency in kHz
25  *
26  * Sets the CPU frequency to freq.
27  */
28 static int cpufreq_set(struct cpufreq_policy *policy, unsigned int freq)
29 {
30 	int ret = -EINVAL;
31 	unsigned int *setspeed = policy->governor_data;
32 
33 	pr_debug("cpufreq_set for cpu %u, freq %u kHz\n", policy->cpu, freq);
34 
35 	mutex_lock(&userspace_mutex);
36 	if (!per_cpu(cpu_is_managed, policy->cpu))
37 		goto err;
38 
39 	*setspeed = freq;
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_userspace_policy_init(struct cpufreq_policy *policy)
53 {
54 	unsigned int *setspeed;
55 
56 	setspeed = kzalloc(sizeof(*setspeed), GFP_KERNEL);
57 	if (!setspeed)
58 		return -ENOMEM;
59 
60 	policy->governor_data = setspeed;
61 	return 0;
62 }
63 
64 static void cpufreq_userspace_policy_exit(struct cpufreq_policy *policy)
65 {
66 	mutex_lock(&userspace_mutex);
67 	kfree(policy->governor_data);
68 	policy->governor_data = NULL;
69 	mutex_unlock(&userspace_mutex);
70 }
71 
72 static int cpufreq_userspace_policy_start(struct cpufreq_policy *policy)
73 {
74 	unsigned int *setspeed = policy->governor_data;
75 
76 	BUG_ON(!policy->cur);
77 	pr_debug("started managing cpu %u\n", policy->cpu);
78 
79 	mutex_lock(&userspace_mutex);
80 	per_cpu(cpu_is_managed, policy->cpu) = 1;
81 	*setspeed = policy->cur;
82 	mutex_unlock(&userspace_mutex);
83 	return 0;
84 }
85 
86 static void cpufreq_userspace_policy_stop(struct cpufreq_policy *policy)
87 {
88 	unsigned int *setspeed = policy->governor_data;
89 
90 	pr_debug("managing cpu %u stopped\n", policy->cpu);
91 
92 	mutex_lock(&userspace_mutex);
93 	per_cpu(cpu_is_managed, policy->cpu) = 0;
94 	*setspeed = 0;
95 	mutex_unlock(&userspace_mutex);
96 }
97 
98 static void cpufreq_userspace_policy_limits(struct cpufreq_policy *policy)
99 {
100 	unsigned int *setspeed = policy->governor_data;
101 
102 	mutex_lock(&userspace_mutex);
103 
104 	pr_debug("limit event for cpu %u: %u - %u kHz, currently %u kHz, last set to %u kHz\n",
105 		 policy->cpu, policy->min, policy->max, policy->cur, *setspeed);
106 
107 	if (policy->max < *setspeed)
108 		__cpufreq_driver_target(policy, policy->max, CPUFREQ_RELATION_H);
109 	else if (policy->min > *setspeed)
110 		__cpufreq_driver_target(policy, policy->min, CPUFREQ_RELATION_L);
111 	else
112 		__cpufreq_driver_target(policy, *setspeed, CPUFREQ_RELATION_L);
113 
114 	mutex_unlock(&userspace_mutex);
115 }
116 
117 static struct cpufreq_governor cpufreq_gov_userspace = {
118 	.name		= "userspace",
119 	.init		= cpufreq_userspace_policy_init,
120 	.exit		= cpufreq_userspace_policy_exit,
121 	.start		= cpufreq_userspace_policy_start,
122 	.stop		= cpufreq_userspace_policy_stop,
123 	.limits		= cpufreq_userspace_policy_limits,
124 	.store_setspeed	= cpufreq_set,
125 	.show_setspeed	= show_speed,
126 	.owner		= THIS_MODULE,
127 };
128 
129 static int __init cpufreq_gov_userspace_init(void)
130 {
131 	return cpufreq_register_governor(&cpufreq_gov_userspace);
132 }
133 
134 static void __exit cpufreq_gov_userspace_exit(void)
135 {
136 	cpufreq_unregister_governor(&cpufreq_gov_userspace);
137 }
138 
139 MODULE_AUTHOR("Dominik Brodowski <linux@brodo.de>, "
140 		"Russell King <rmk@arm.linux.org.uk>");
141 MODULE_DESCRIPTION("CPUfreq policy governor 'userspace'");
142 MODULE_LICENSE("GPL");
143 
144 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_USERSPACE
145 struct cpufreq_governor *cpufreq_default_governor(void)
146 {
147 	return &cpufreq_gov_userspace;
148 }
149 
150 core_initcall(cpufreq_gov_userspace_init);
151 #else
152 module_init(cpufreq_gov_userspace_init);
153 #endif
154 module_exit(cpufreq_gov_userspace_exit);
155