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 */
cpufreq_set(struct cpufreq_policy * policy,unsigned int freq)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
40 *setspeed = freq;
41
42 ret = __cpufreq_driver_target(policy, freq, CPUFREQ_RELATION_L);
43 err:
44 mutex_unlock(&userspace_mutex);
45 return ret;
46 }
47
show_speed(struct cpufreq_policy * policy,char * buf)48 static ssize_t show_speed(struct cpufreq_policy *policy, char *buf)
49 {
50 return sprintf(buf, "%u\n", policy->cur);
51 }
52
cpufreq_userspace_policy_init(struct cpufreq_policy * policy)53 static int cpufreq_userspace_policy_init(struct cpufreq_policy *policy)
54 {
55 unsigned int *setspeed;
56
57 setspeed = kzalloc(sizeof(*setspeed), GFP_KERNEL);
58 if (!setspeed) {
59 return -ENOMEM;
60 }
61
62 policy->governor_data = setspeed;
63 return 0;
64 }
65
cpufreq_userspace_policy_exit(struct cpufreq_policy * policy)66 static void cpufreq_userspace_policy_exit(struct cpufreq_policy *policy)
67 {
68 mutex_lock(&userspace_mutex);
69 kfree(policy->governor_data);
70 policy->governor_data = NULL;
71 mutex_unlock(&userspace_mutex);
72 }
73
cpufreq_userspace_policy_start(struct cpufreq_policy * policy)74 static int cpufreq_userspace_policy_start(struct cpufreq_policy *policy)
75 {
76 unsigned int *setspeed = policy->governor_data;
77
78 BUG_ON(!policy->cur);
79 pr_debug("started managing cpu %u\n", policy->cpu);
80
81 mutex_lock(&userspace_mutex);
82 per_cpu(cpu_is_managed, policy->cpu) = 1;
83 if (!*setspeed) {
84 *setspeed = policy->cur;
85 }
86 mutex_unlock(&userspace_mutex);
87 return 0;
88 }
89
cpufreq_userspace_policy_stop(struct cpufreq_policy * policy)90 static void cpufreq_userspace_policy_stop(struct cpufreq_policy *policy)
91 {
92 pr_debug("managing cpu %u stopped\n", policy->cpu);
93
94 mutex_lock(&userspace_mutex);
95 per_cpu(cpu_is_managed, policy->cpu) = 0;
96 mutex_unlock(&userspace_mutex);
97 }
98
cpufreq_userspace_policy_limits(struct cpufreq_policy * policy)99 static void cpufreq_userspace_policy_limits(struct cpufreq_policy *policy)
100 {
101 unsigned int *setspeed = policy->governor_data;
102
103 mutex_lock(&userspace_mutex);
104
105 pr_debug("limit event for cpu %u: %u - %u kHz, currently %u kHz, last set to %u kHz\n", policy->cpu, policy->min,
106 policy->max, policy->cur, *setspeed);
107
108 if (policy->max < *setspeed) {
109 __cpufreq_driver_target(policy, policy->max, CPUFREQ_RELATION_H);
110 } else if (policy->min > *setspeed) {
111 __cpufreq_driver_target(policy, policy->min, CPUFREQ_RELATION_L);
112 } else {
113 __cpufreq_driver_target(policy, *setspeed, CPUFREQ_RELATION_L);
114 }
115
116 mutex_unlock(&userspace_mutex);
117 }
118
119 static struct cpufreq_governor cpufreq_gov_userspace = {
120 .name = "userspace",
121 .init = cpufreq_userspace_policy_init,
122 .exit = cpufreq_userspace_policy_exit,
123 .start = cpufreq_userspace_policy_start,
124 .stop = cpufreq_userspace_policy_stop,
125 .limits = cpufreq_userspace_policy_limits,
126 .store_setspeed = cpufreq_set,
127 .show_setspeed = show_speed,
128 .owner = THIS_MODULE,
129 };
130
131 MODULE_AUTHOR("Dominik Brodowski <linux@brodo.de>, "
132 "Russell King <rmk@arm.linux.org.uk>");
133 MODULE_DESCRIPTION("CPUfreq policy governor 'userspace'");
134 MODULE_LICENSE("GPL");
135
136 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_USERSPACE
cpufreq_default_governor(void)137 struct cpufreq_governor *cpufreq_default_governor(void)
138 {
139 return &cpufreq_gov_userspace;
140 }
141 #endif
142
143 cpufreq_governor_init(cpufreq_gov_userspace);
144 cpufreq_governor_exit(cpufreq_gov_userspace);
145