GNU Linux-libre 5.19-rc6-gnu
[releases.git] / drivers / cpufreq / cpufreq_userspace.c
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 MODULE_AUTHOR("Dominik Brodowski <linux@brodo.de>, "
130                 "Russell King <rmk@arm.linux.org.uk>");
131 MODULE_DESCRIPTION("CPUfreq policy governor 'userspace'");
132 MODULE_LICENSE("GPL");
133
134 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_USERSPACE
135 struct cpufreq_governor *cpufreq_default_governor(void)
136 {
137         return &cpufreq_gov_userspace;
138 }
139 #endif
140
141 cpufreq_governor_init(cpufreq_gov_userspace);
142 cpufreq_governor_exit(cpufreq_gov_userspace);