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
18struct userspace_policy {
19 unsigned int is_managed;
20 unsigned int setspeed;
21 struct mutex mutex;
22};
23
24/**
25 * cpufreq_set - set the CPU frequency
26 * @policy: pointer to policy struct where freq is being set
27 * @freq: target frequency in kHz
28 *
29 * Sets the CPU frequency to freq.
30 */
31static int cpufreq_set(struct cpufreq_policy *policy, unsigned int freq)
32{
33 int ret = -EINVAL;
34 struct userspace_policy *userspace = policy->governor_data;
35
36 pr_debug("cpufreq_set for cpu %u, freq %u kHz\n", policy->cpu, freq);
37
38 mutex_lock(lock: &userspace->mutex);
39 if (!userspace->is_managed)
40 goto err;
41
42 userspace->setspeed = freq;
43
44 ret = __cpufreq_driver_target(policy, target_freq: freq, CPUFREQ_RELATION_L);
45 err:
46 mutex_unlock(lock: &userspace->mutex);
47 return ret;
48}
49
50static ssize_t show_speed(struct cpufreq_policy *policy, char *buf)
51{
52 return sprintf(buf, fmt: "%u\n", policy->cur);
53}
54
55static int cpufreq_userspace_policy_init(struct cpufreq_policy *policy)
56{
57 struct userspace_policy *userspace;
58
59 userspace = kzalloc(sizeof(*userspace), GFP_KERNEL);
60 if (!userspace)
61 return -ENOMEM;
62
63 mutex_init(&userspace->mutex);
64
65 policy->governor_data = userspace;
66 return 0;
67}
68
69/*
70 * Any routine that writes to the policy struct will hold the "rwsem" of
71 * policy struct that means it is free to free "governor_data" here.
72 */
73static void cpufreq_userspace_policy_exit(struct cpufreq_policy *policy)
74{
75 kfree(objp: policy->governor_data);
76 policy->governor_data = NULL;
77}
78
79static int cpufreq_userspace_policy_start(struct cpufreq_policy *policy)
80{
81 struct userspace_policy *userspace = policy->governor_data;
82
83 BUG_ON(!policy->cur);
84 pr_debug("started managing cpu %u\n", policy->cpu);
85
86 mutex_lock(lock: &userspace->mutex);
87 userspace->is_managed = 1;
88 userspace->setspeed = policy->cur;
89 mutex_unlock(lock: &userspace->mutex);
90 return 0;
91}
92
93static void cpufreq_userspace_policy_stop(struct cpufreq_policy *policy)
94{
95 struct userspace_policy *userspace = policy->governor_data;
96
97 pr_debug("managing cpu %u stopped\n", policy->cpu);
98
99 mutex_lock(lock: &userspace->mutex);
100 userspace->is_managed = 0;
101 userspace->setspeed = 0;
102 mutex_unlock(lock: &userspace->mutex);
103}
104
105static void cpufreq_userspace_policy_limits(struct cpufreq_policy *policy)
106{
107 struct userspace_policy *userspace = policy->governor_data;
108
109 mutex_lock(lock: &userspace->mutex);
110
111 pr_debug("limit event for cpu %u: %u - %u kHz, currently %u kHz, last set to %u kHz\n",
112 policy->cpu, policy->min, policy->max, policy->cur, userspace->setspeed);
113
114 if (policy->max < userspace->setspeed)
115 __cpufreq_driver_target(policy, target_freq: policy->max,
116 CPUFREQ_RELATION_H);
117 else if (policy->min > userspace->setspeed)
118 __cpufreq_driver_target(policy, target_freq: policy->min,
119 CPUFREQ_RELATION_L);
120 else
121 __cpufreq_driver_target(policy, target_freq: userspace->setspeed,
122 CPUFREQ_RELATION_L);
123
124 mutex_unlock(lock: &userspace->mutex);
125}
126
127static struct cpufreq_governor cpufreq_gov_userspace = {
128 .name = "userspace",
129 .init = cpufreq_userspace_policy_init,
130 .exit = cpufreq_userspace_policy_exit,
131 .start = cpufreq_userspace_policy_start,
132 .stop = cpufreq_userspace_policy_stop,
133 .limits = cpufreq_userspace_policy_limits,
134 .store_setspeed = cpufreq_set,
135 .show_setspeed = show_speed,
136 .owner = THIS_MODULE,
137 .flags = CPUFREQ_GOV_STRICT_TARGET,
138};
139
140MODULE_AUTHOR("Dominik Brodowski <linux@brodo.de>, "
141 "Russell King <rmk@arm.linux.org.uk>");
142MODULE_DESCRIPTION("CPUfreq policy governor 'userspace'");
143MODULE_LICENSE("GPL");
144
145#ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_USERSPACE
146struct cpufreq_governor *cpufreq_default_governor(void)
147{
148 return &cpufreq_gov_userspace;
149}
150#endif
151
152cpufreq_governor_init(cpufreq_gov_userspace);
153cpufreq_governor_exit(cpufreq_gov_userspace);
154