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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 <[email protected]>
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(&userspace->mutex);
39 if (!userspace->is_managed)
40 goto err;
41
42 userspace->setspeed = freq;
43
44 ret = __cpufreq_driver_target(policy, freq, CPUFREQ_RELATION_L);
45 err:
46 mutex_unlock(&userspace->mutex);
47 return ret;
48}
49
50static ssize_t show_speed(struct cpufreq_policy *policy, char *buf)
51{
52 struct userspace_policy *userspace = policy->governor_data;
53
54 return sprintf(buf, "%u\n", userspace->setspeed);
55}
56
57static int cpufreq_userspace_policy_init(struct cpufreq_policy *policy)
58{
59 struct userspace_policy *userspace;
60
61 userspace = kzalloc_obj(*userspace);
62 if (!userspace)
63 return -ENOMEM;
64
65 mutex_init(&userspace->mutex);
66
67 policy->governor_data = userspace;
68 return 0;
69}
70
71/*
72 * Any routine that writes to the policy struct will hold the "rwsem" of
73 * policy struct that means it is free to free "governor_data" here.
74 */
75static void cpufreq_userspace_policy_exit(struct cpufreq_policy *policy)
76{
77 kfree(policy->governor_data);
78 policy->governor_data = NULL;
79}
80
81static int cpufreq_userspace_policy_start(struct cpufreq_policy *policy)
82{
83 struct userspace_policy *userspace = policy->governor_data;
84
85 BUG_ON(!policy->cur);
86 pr_debug("started managing cpu %u\n", policy->cpu);
87
88 mutex_lock(&userspace->mutex);
89 userspace->is_managed = 1;
90 userspace->setspeed = policy->cur;
91 mutex_unlock(&userspace->mutex);
92 return 0;
93}
94
95static void cpufreq_userspace_policy_stop(struct cpufreq_policy *policy)
96{
97 struct userspace_policy *userspace = policy->governor_data;
98
99 pr_debug("managing cpu %u stopped\n", policy->cpu);
100
101 mutex_lock(&userspace->mutex);
102 userspace->is_managed = 0;
103 userspace->setspeed = 0;
104 mutex_unlock(&userspace->mutex);
105}
106
107static void cpufreq_userspace_policy_limits(struct cpufreq_policy *policy)
108{
109 struct userspace_policy *userspace = policy->governor_data;
110
111 mutex_lock(&userspace->mutex);
112
113 pr_debug("limit event for cpu %u: %u - %u kHz, currently %u kHz, last set to %u kHz\n",
114 policy->cpu, policy->min, policy->max, policy->cur, userspace->setspeed);
115
116 if (policy->max < userspace->setspeed)
117 __cpufreq_driver_target(policy, policy->max,
118 CPUFREQ_RELATION_H);
119 else if (policy->min > userspace->setspeed)
120 __cpufreq_driver_target(policy, policy->min,
121 CPUFREQ_RELATION_L);
122 else
123 __cpufreq_driver_target(policy, userspace->setspeed,
124 CPUFREQ_RELATION_L);
125
126 mutex_unlock(&userspace->mutex);
127}
128
129static struct cpufreq_governor cpufreq_gov_userspace = {
130 .name = "userspace",
131 .init = cpufreq_userspace_policy_init,
132 .exit = cpufreq_userspace_policy_exit,
133 .start = cpufreq_userspace_policy_start,
134 .stop = cpufreq_userspace_policy_stop,
135 .limits = cpufreq_userspace_policy_limits,
136 .store_setspeed = cpufreq_set,
137 .show_setspeed = show_speed,
138 .owner = THIS_MODULE,
139 .flags = CPUFREQ_GOV_STRICT_TARGET,
140};
141
142MODULE_AUTHOR("Dominik Brodowski <[email protected]>, "
143 "Russell King <[email protected]>");
144MODULE_DESCRIPTION("CPUfreq policy governor 'userspace'");
145MODULE_LICENSE("GPL");
146
147#ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_USERSPACE
148struct cpufreq_governor *cpufreq_default_governor(void)
149{
150 return &cpufreq_gov_userspace;
151}
152#endif
153
154cpufreq_governor_init(cpufreq_gov_userspace);
155cpufreq_governor_exit(cpufreq_gov_userspace);