1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
|
/*
* linux/drivers/cpufreq/cpufreq_userspace.c
*
* Copyright (C) 2001 Russell King
* (C) 2002 - 2004 Dominik Brodowski <linux@brodo.de>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/smp.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/interrupt.h>
#include <linux/cpufreq.h>
#include <linux/types.h>
#include <linux/fs.h>
#include <linux/sysfs.h>
#include <linux/mutex.h>
#include <asm/uaccess.h>
/**
* A few values needed by the userspace governor
*/
static unsigned int cpu_max_freq[NR_CPUS];
static unsigned int cpu_min_freq[NR_CPUS];
static unsigned int cpu_cur_freq[NR_CPUS]; /* current CPU freq */
static unsigned int cpu_set_freq[NR_CPUS]; /* CPU freq desired by userspace */
static unsigned int cpu_is_managed[NR_CPUS];
static DEFINE_MUTEX (userspace_mutex);
#define dprintk(msg...) cpufreq_debug_printk(CPUFREQ_DEBUG_GOVERNOR, "userspace", msg)
/* keep track of frequency transitions */
static int
userspace_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
void *data)
{
struct cpufreq_freqs *freq = data;
dprintk("saving cpu_cur_freq of cpu %u to be %u kHz\n", freq->cpu, freq->new);
cpu_cur_freq[freq->cpu] = freq->new;
return 0;
}
static struct notifier_block userspace_cpufreq_notifier_block = {
.notifier_call = userspace_cpufreq_notifier
};
/**
* cpufreq_set - set the CPU frequency
* @freq: target frequency in kHz
* @cpu: CPU for which the frequency is to be set
*
* Sets the CPU frequency to freq.
*/
static int cpufreq_set(unsigned int freq, struct cpufreq_policy *policy)
{
int ret = -EINVAL;
dprintk("cpufreq_set for cpu %u, freq %u kHz\n", policy->cpu, freq);
mutex_lock(&userspace_mutex);
if (!cpu_is_managed[policy->cpu])
goto err;
cpu_set_freq[policy->cpu] = freq;
if (freq < cpu_min_freq[policy->cpu])
freq = cpu_min_freq[policy->cpu];
if (freq > cpu_max_freq[policy->cpu])
freq = cpu_max_freq[policy->cpu];
/*
* We're safe from concurrent calls to ->target() here
* as we hold the userspace_mutex lock. If we were calling
* cpufreq_driver_target, a deadlock situation might occur:
* A: cpufreq_set (lock userspace_mutex) -> cpufreq_driver_target(lock policy->lock)
* B: cpufreq_set_policy(lock policy->lock) -> __cpufreq_governor -> cpufreq_governor_userspace (lock userspace_mutex)
*/
ret = __cpufreq_driver_target(policy, freq, CPUFREQ_RELATION_L);
err:
mutex_unlock(&userspace_mutex);
return ret;
}
/************************** sysfs interface ************************/
static ssize_t show_speed (struct cpufreq_policy *policy, char *buf)
{
return sprintf (buf, "%u\n", cpu_cur_freq[policy->cpu]);
}
static ssize_t
store_speed (struct cpufreq_policy *policy, const char *buf, size_t count)
{
unsigned int freq = 0;
unsigned int ret;
ret = sscanf (buf, "%u", &freq);
if (ret != 1)
return -EINVAL;
cpufreq_set(freq, policy);
return count;
}
static struct freq_attr freq_attr_scaling_setspeed =
{
.attr = { .name = "scaling_setspeed", .mode = 0644, .owner = THIS_MODULE },
.show = show_speed,
.store = store_speed,
};
static int cpufreq_governor_userspace(struct cpufreq_policy *policy,
unsigned int event)
{
unsigned int cpu = policy->cpu;
switch (event) {
case CPUFREQ_GOV_START:
if (!cpu_online(cpu))
return -EINVAL;
BUG_ON(!policy->cur);
mutex_lock(&userspace_mutex);
cpu_is_managed[cpu] = 1;
cpu_min_freq[cpu] = policy->min;
cpu_max_freq[cpu] = policy->max;
cpu_cur_freq[cpu] = policy->cur;
cpu_set_freq[cpu] = policy->cur;
sysfs_create_file (&policy->kobj, &freq_attr_scaling_setspeed.attr);
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]);
mutex_unlock(&userspace_mutex);
break;
case CPUFREQ_GOV_STOP:
mutex_lock(&userspace_mutex);
cpu_is_managed[cpu] = 0;
cpu_min_freq[cpu] = 0;
cpu_max_freq[cpu] = 0;
cpu_set_freq[cpu] = 0;
sysfs_remove_file (&policy->kobj, &freq_attr_scaling_setspeed.attr);
dprintk("managing cpu %u stopped\n", cpu);
mutex_unlock(&userspace_mutex);
break;
case CPUFREQ_GOV_LIMITS:
mutex_lock(&userspace_mutex);
dprintk("limit event for cpu %u: %u - %u kHz,"
"currently %u kHz, last set to %u kHz\n",
cpu, policy->min, policy->max,
cpu_cur_freq[cpu], cpu_set_freq[cpu]);
if (policy->max < cpu_set_freq[cpu]) {
__cpufreq_driver_target(policy, policy->max,
CPUFREQ_RELATION_H);
}
else if (policy->min > cpu_set_freq[cpu]) {
__cpufreq_driver_target(policy, policy->min,
CPUFREQ_RELATION_L);
}
else {
__cpufreq_driver_target(policy, cpu_set_freq[cpu],
CPUFREQ_RELATION_L);
}
cpu_min_freq[cpu] = policy->min;
cpu_max_freq[cpu] = policy->max;
cpu_cur_freq[cpu] = policy->cur;
mutex_unlock(&userspace_mutex);
break;
}
return 0;
}
struct cpufreq_governor cpufreq_gov_userspace = {
.name = "userspace",
.governor = cpufreq_governor_userspace,
.owner = THIS_MODULE,
};
EXPORT_SYMBOL(cpufreq_gov_userspace);
static int __init cpufreq_gov_userspace_init(void)
{
cpufreq_register_notifier(&userspace_cpufreq_notifier_block, CPUFREQ_TRANSITION_NOTIFIER);
return cpufreq_register_governor(&cpufreq_gov_userspace);
}
static void __exit cpufreq_gov_userspace_exit(void)
{
cpufreq_unregister_governor(&cpufreq_gov_userspace);
cpufreq_unregister_notifier(&userspace_cpufreq_notifier_block, CPUFREQ_TRANSITION_NOTIFIER);
}
MODULE_AUTHOR ("Dominik Brodowski <linux@brodo.de>, Russell King <rmk@arm.linux.org.uk>");
MODULE_DESCRIPTION ("CPUfreq policy governor 'userspace'");
MODULE_LICENSE ("GPL");
fs_initcall(cpufreq_gov_userspace_init);
module_exit(cpufreq_gov_userspace_exit);
|
