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
18static DEFINE_PER_CPU(unsigned int, cpu_is_managed);
19static 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 */
28static 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);
43err:
44    mutex_unlock(&userspace_mutex);
45    return ret;
46}
47
48static ssize_t show_speed(struct cpufreq_policy *policy, char *buf)
49{
50    return sprintf(buf, "%u\n", policy->cur);
51}
52
53static 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
66static 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
74static 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
90static 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
99static 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
119static 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
131MODULE_AUTHOR("Dominik Brodowski <linux@brodo.de>, "
132              "Russell King <rmk@arm.linux.org.uk>");
133MODULE_DESCRIPTION("CPUfreq policy governor 'userspace'");
134MODULE_LICENSE("GPL");
135
136#ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_USERSPACE
137struct cpufreq_governor *cpufreq_default_governor(void)
138{
139    return &cpufreq_gov_userspace;
140}
141#endif
142
143cpufreq_governor_init(cpufreq_gov_userspace);
144cpufreq_governor_exit(cpufreq_gov_userspace);
145