tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
2 * linux/drivers/cpufreq/cpufreq_userspace.c
3 *
4 * Copyright (C) 2001 Russell King
5 * (C) 2002 - 2004 Dominik Brodowski <linux@brodo.de>
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
10 *
11 */
12
13#include <linux/config.h>
14#include <linux/kernel.h>
15#include <linux/module.h>
16#include <linux/smp.h>
17#include <linux/init.h>
18#include <linux/spinlock.h>
19#include <linux/interrupt.h>
20#include <linux/cpufreq.h>
21#include <linux/types.h>
22#include <linux/fs.h>
23#include <linux/sysfs.h>
24
25#include <asm/uaccess.h>
26
27
28/**
29 * A few values needed by the userspace governor
30 */
31static unsigned int cpu_max_freq[NR_CPUS];
32static unsigned int cpu_min_freq[NR_CPUS];
33static unsigned int cpu_cur_freq[NR_CPUS]; /* current CPU freq */
34static unsigned int cpu_set_freq[NR_CPUS]; /* CPU freq desired by userspace */
35static unsigned int cpu_is_managed[NR_CPUS];
36static struct cpufreq_policy current_policy[NR_CPUS];
37
38static DECLARE_MUTEX (userspace_sem);
39
40#define dprintk(msg...) cpufreq_debug_printk(CPUFREQ_DEBUG_GOVERNOR, "userspace", msg)
41
42/* keep track of frequency transitions */
43static int
44userspace_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
45 void *data)
46{
47 struct cpufreq_freqs *freq = data;
48
49 dprintk("saving cpu_cur_freq of cpu %u to be %u kHz\n", freq->cpu, freq->new);
50 cpu_cur_freq[freq->cpu] = freq->new;
51
52 return 0;
53}
54
55static struct notifier_block userspace_cpufreq_notifier_block = {
56 .notifier_call = userspace_cpufreq_notifier
57};
58
59
60/**
61 * cpufreq_set - set the CPU frequency
62 * @freq: target frequency in kHz
63 * @cpu: CPU for which the frequency is to be set
64 *
65 * Sets the CPU frequency to freq.
66 */
67static int cpufreq_set(unsigned int freq, unsigned int cpu)
68{
69 int ret = -EINVAL;
70
71 dprintk("cpufreq_set for cpu %u, freq %u kHz\n", cpu, freq);
72
73 down(&userspace_sem);
74 if (!cpu_is_managed[cpu])
75 goto err;
76
77 cpu_set_freq[cpu] = freq;
78
79 if (freq < cpu_min_freq[cpu])
80 freq = cpu_min_freq[cpu];
81 if (freq > cpu_max_freq[cpu])
82 freq = cpu_max_freq[cpu];
83
84 /*
85 * We're safe from concurrent calls to ->target() here
86 * as we hold the userspace_sem lock. If we were calling
87 * cpufreq_driver_target, a deadlock situation might occur:
88 * A: cpufreq_set (lock userspace_sem) -> cpufreq_driver_target(lock policy->lock)
89 * B: cpufreq_set_policy(lock policy->lock) -> __cpufreq_governor -> cpufreq_governor_userspace (lock userspace_sem)
90 */
91 ret = __cpufreq_driver_target(¤t_policy[cpu], freq,
92 CPUFREQ_RELATION_L);
93
94 err:
95 up(&userspace_sem);
96 return ret;
97}
98
99
100/************************** sysfs interface ************************/
101static ssize_t show_speed (struct cpufreq_policy *policy, char *buf)
102{
103 return sprintf (buf, "%u\n", cpu_cur_freq[policy->cpu]);
104}
105
106static ssize_t
107store_speed (struct cpufreq_policy *policy, const char *buf, size_t count)
108{
109 unsigned int freq = 0;
110 unsigned int ret;
111
112 ret = sscanf (buf, "%u", &freq);
113 if (ret != 1)
114 return -EINVAL;
115
116 cpufreq_set(freq, policy->cpu);
117
118 return count;
119}
120
121static struct freq_attr freq_attr_scaling_setspeed =
122{
123 .attr = { .name = "scaling_setspeed", .mode = 0644, .owner = THIS_MODULE },
124 .show = show_speed,
125 .store = store_speed,
126};
127
128static int cpufreq_governor_userspace(struct cpufreq_policy *policy,
129 unsigned int event)
130{
131 unsigned int cpu = policy->cpu;
132 switch (event) {
133 case CPUFREQ_GOV_START:
134 if (!cpu_online(cpu))
135 return -EINVAL;
136 BUG_ON(!policy->cur);
137 down(&userspace_sem);
138 cpu_is_managed[cpu] = 1;
139 cpu_min_freq[cpu] = policy->min;
140 cpu_max_freq[cpu] = policy->max;
141 cpu_cur_freq[cpu] = policy->cur;
142 cpu_set_freq[cpu] = policy->cur;
143 sysfs_create_file (&policy->kobj, &freq_attr_scaling_setspeed.attr);
144 memcpy (¤t_policy[cpu], policy, sizeof(struct cpufreq_policy));
145 dprintk("managing cpu %u started (%u - %u kHz, currently %u kHz)\n", cpu, cpu_min_freq[cpu], cpu_max_freq[cpu], cpu_cur_freq[cpu]);
146 up(&userspace_sem);
147 break;
148 case CPUFREQ_GOV_STOP:
149 down(&userspace_sem);
150 cpu_is_managed[cpu] = 0;
151 cpu_min_freq[cpu] = 0;
152 cpu_max_freq[cpu] = 0;
153 cpu_set_freq[cpu] = 0;
154 sysfs_remove_file (&policy->kobj, &freq_attr_scaling_setspeed.attr);
155 dprintk("managing cpu %u stopped\n", cpu);
156 up(&userspace_sem);
157 break;
158 case CPUFREQ_GOV_LIMITS:
159 down(&userspace_sem);
160 cpu_min_freq[cpu] = policy->min;
161 cpu_max_freq[cpu] = policy->max;
162 dprintk("limit event for cpu %u: %u - %u kHz, currently %u kHz, last set to %u kHz\n", cpu, cpu_min_freq[cpu], cpu_max_freq[cpu], cpu_cur_freq[cpu], cpu_set_freq[cpu]);
163 if (policy->max < cpu_set_freq[cpu]) {
164 __cpufreq_driver_target(¤t_policy[cpu], policy->max,
165 CPUFREQ_RELATION_H);
166 } else if (policy->min > cpu_set_freq[cpu]) {
167 __cpufreq_driver_target(¤t_policy[cpu], policy->min,
168 CPUFREQ_RELATION_L);
169 } else {
170 __cpufreq_driver_target(¤t_policy[cpu], cpu_set_freq[cpu],
171 CPUFREQ_RELATION_L);
172 }
173 memcpy (¤t_policy[cpu], policy, sizeof(struct cpufreq_policy));
174 up(&userspace_sem);
175 break;
176 }
177 return 0;
178}
179
180
181struct cpufreq_governor cpufreq_gov_userspace = {
182 .name = "userspace",
183 .governor = cpufreq_governor_userspace,
184 .owner = THIS_MODULE,
185};
186EXPORT_SYMBOL(cpufreq_gov_userspace);
187
188static int __init cpufreq_gov_userspace_init(void)
189{
190 cpufreq_register_notifier(&userspace_cpufreq_notifier_block, CPUFREQ_TRANSITION_NOTIFIER);
191 return cpufreq_register_governor(&cpufreq_gov_userspace);
192}
193
194
195static void __exit cpufreq_gov_userspace_exit(void)
196{
197 cpufreq_unregister_governor(&cpufreq_gov_userspace);
198 cpufreq_unregister_notifier(&userspace_cpufreq_notifier_block, CPUFREQ_TRANSITION_NOTIFIER);
199}
200
201
202MODULE_AUTHOR ("Dominik Brodowski <linux@brodo.de>, Russell King <rmk@arm.linux.org.uk>");
203MODULE_DESCRIPTION ("CPUfreq policy governor 'userspace'");
204MODULE_LICENSE ("GPL");
205
206fs_initcall(cpufreq_gov_userspace_init);
207module_exit(cpufreq_gov_userspace_exit);