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 *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
show_speed(struct cpufreq_policy * policy,char * buf)47 static ssize_t show_speed(struct cpufreq_policy *policy, char *buf)
48 {
49 return sprintf(buf, "%u\n", policy->cur);
50 }
51
cpufreq_userspace_policy_init(struct cpufreq_policy * policy)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
cpufreq_userspace_policy_exit(struct cpufreq_policy * policy)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
cpufreq_userspace_policy_start(struct cpufreq_policy * policy)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
cpufreq_userspace_policy_stop(struct cpufreq_policy * policy)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
cpufreq_userspace_policy_limits(struct cpufreq_policy * policy)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
cpufreq_default_governor(void)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);
143
