[CPUFREQ][3/6] cpufreq: get_cpu_idle_time() changes in ondemand for idle-microaccounting
[linux-2.6.git] / drivers / cpufreq / cpufreq_userspace.c
1
2 /*
3  *  linux/drivers/cpufreq/cpufreq_userspace.c
4  *
5  *  Copyright (C)  2001 Russell King
6  *            (C)  2002 - 2004 Dominik Brodowski <linux@brodo.de>
7  *
8  * This program is free software; you can redistribute it and/or modify
9  * it under the terms of the GNU General Public License version 2 as
10  * published by the Free Software Foundation.
11  *
12  */
13
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/cpu.h>
22 #include <linux/types.h>
23 #include <linux/fs.h>
24 #include <linux/sysfs.h>
25 #include <linux/mutex.h>
26
27 #include <asm/uaccess.h>
28
29
30 /**
31  * A few values needed by the userspace governor
32  */
33 static DEFINE_PER_CPU(unsigned int, cpu_max_freq);
34 static DEFINE_PER_CPU(unsigned int, cpu_min_freq);
35 static DEFINE_PER_CPU(unsigned int, cpu_cur_freq); /* current CPU freq */
36 static DEFINE_PER_CPU(unsigned int, cpu_set_freq); /* CPU freq desired by
37                                                         userspace */
38 static DEFINE_PER_CPU(unsigned int, cpu_is_managed);
39
40 static DEFINE_MUTEX     (userspace_mutex);
41 static int cpus_using_userspace_governor;
42
43 #define dprintk(msg...) \
44         cpufreq_debug_printk(CPUFREQ_DEBUG_GOVERNOR, "userspace", msg)
45
46 /* keep track of frequency transitions */
47 static int
48 userspace_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
49                        void *data)
50 {
51         struct cpufreq_freqs *freq = data;
52
53         if (!per_cpu(cpu_is_managed, freq->cpu))
54                 return 0;
55
56         dprintk("saving cpu_cur_freq of cpu %u to be %u kHz\n",
57                         freq->cpu, freq->new);
58         per_cpu(cpu_cur_freq, freq->cpu) = freq->new;
59
60         return 0;
61 }
62
63 static struct notifier_block userspace_cpufreq_notifier_block = {
64         .notifier_call  = userspace_cpufreq_notifier
65 };
66
67
68 /**
69  * cpufreq_set - set the CPU frequency
70  * @policy: pointer to policy struct where freq is being set
71  * @freq: target frequency in kHz
72  *
73  * Sets the CPU frequency to freq.
74  */
75 static int cpufreq_set(struct cpufreq_policy *policy, unsigned int freq)
76 {
77         int ret = -EINVAL;
78
79         dprintk("cpufreq_set for cpu %u, freq %u kHz\n", policy->cpu, freq);
80
81         mutex_lock(&userspace_mutex);
82         if (!per_cpu(cpu_is_managed, policy->cpu))
83                 goto err;
84
85         per_cpu(cpu_set_freq, policy->cpu) = freq;
86
87         if (freq < per_cpu(cpu_min_freq, policy->cpu))
88                 freq = per_cpu(cpu_min_freq, policy->cpu);
89         if (freq > per_cpu(cpu_max_freq, policy->cpu))
90                 freq = per_cpu(cpu_max_freq, policy->cpu);
91
92         /*
93          * We're safe from concurrent calls to ->target() here
94          * as we hold the userspace_mutex lock. If we were calling
95          * cpufreq_driver_target, a deadlock situation might occur:
96          * A: cpufreq_set (lock userspace_mutex) -> cpufreq_driver_target(lock policy->lock)
97          * B: cpufreq_set_policy(lock policy->lock) -> __cpufreq_governor -> cpufreq_governor_userspace (lock userspace_mutex)
98          */
99         ret = __cpufreq_driver_target(policy, freq, CPUFREQ_RELATION_L);
100
101  err:
102         mutex_unlock(&userspace_mutex);
103         return ret;
104 }
105
106
107 static ssize_t show_speed(struct cpufreq_policy *policy, char *buf)
108 {
109         return sprintf(buf, "%u\n", per_cpu(cpu_cur_freq, policy->cpu));
110 }
111
112 static int cpufreq_governor_userspace(struct cpufreq_policy *policy,
113                                    unsigned int event)
114 {
115         unsigned int cpu = policy->cpu;
116         int rc = 0;
117
118         switch (event) {
119         case CPUFREQ_GOV_START:
120                 if (!cpu_online(cpu))
121                         return -EINVAL;
122                 BUG_ON(!policy->cur);
123                 mutex_lock(&userspace_mutex);
124
125                 if (cpus_using_userspace_governor == 0) {
126                         cpufreq_register_notifier(
127                                         &userspace_cpufreq_notifier_block,
128                                         CPUFREQ_TRANSITION_NOTIFIER);
129                 }
130                 cpus_using_userspace_governor++;
131
132                 per_cpu(cpu_is_managed, cpu) = 1;
133                 per_cpu(cpu_min_freq, cpu) = policy->min;
134                 per_cpu(cpu_max_freq, cpu) = policy->max;
135                 per_cpu(cpu_cur_freq, cpu) = policy->cur;
136                 per_cpu(cpu_set_freq, cpu) = policy->cur;
137                 dprintk("managing cpu %u started "
138                         "(%u - %u kHz, currently %u kHz)\n",
139                                 cpu,
140                                 per_cpu(cpu_min_freq, cpu),
141                                 per_cpu(cpu_max_freq, cpu),
142                                 per_cpu(cpu_cur_freq, cpu));
143
144                 mutex_unlock(&userspace_mutex);
145                 break;
146         case CPUFREQ_GOV_STOP:
147                 mutex_lock(&userspace_mutex);
148                 cpus_using_userspace_governor--;
149                 if (cpus_using_userspace_governor == 0) {
150                         cpufreq_unregister_notifier(
151                                         &userspace_cpufreq_notifier_block,
152                                         CPUFREQ_TRANSITION_NOTIFIER);
153                 }
154
155                 per_cpu(cpu_is_managed, cpu) = 0;
156                 per_cpu(cpu_min_freq, cpu) = 0;
157                 per_cpu(cpu_max_freq, cpu) = 0;
158                 per_cpu(cpu_set_freq, cpu) = 0;
159                 dprintk("managing cpu %u stopped\n", cpu);
160                 mutex_unlock(&userspace_mutex);
161                 break;
162         case CPUFREQ_GOV_LIMITS:
163                 mutex_lock(&userspace_mutex);
164                 dprintk("limit event for cpu %u: %u - %u kHz, "
165                         "currently %u kHz, last set to %u kHz\n",
166                         cpu, policy->min, policy->max,
167                         per_cpu(cpu_cur_freq, cpu),
168                         per_cpu(cpu_set_freq, cpu));
169                 if (policy->max < per_cpu(cpu_set_freq, cpu)) {
170                         __cpufreq_driver_target(policy, policy->max,
171                                                 CPUFREQ_RELATION_H);
172                 } else if (policy->min > per_cpu(cpu_set_freq, cpu)) {
173                         __cpufreq_driver_target(policy, policy->min,
174                                                 CPUFREQ_RELATION_L);
175                 } else {
176                         __cpufreq_driver_target(policy,
177                                                 per_cpu(cpu_set_freq, cpu),
178                                                 CPUFREQ_RELATION_L);
179                 }
180                 per_cpu(cpu_min_freq, cpu) = policy->min;
181                 per_cpu(cpu_max_freq, cpu) = policy->max;
182                 per_cpu(cpu_cur_freq, cpu) = policy->cur;
183                 mutex_unlock(&userspace_mutex);
184                 break;
185         }
186         return rc;
187 }
188
189
190 struct cpufreq_governor cpufreq_gov_userspace = {
191         .name           = "userspace",
192         .governor       = cpufreq_governor_userspace,
193         .store_setspeed = cpufreq_set,
194         .show_setspeed  = show_speed,
195         .owner          = THIS_MODULE,
196 };
197 EXPORT_SYMBOL(cpufreq_gov_userspace);
198
199 static int __init cpufreq_gov_userspace_init(void)
200 {
201         return cpufreq_register_governor(&cpufreq_gov_userspace);
202 }
203
204
205 static void __exit cpufreq_gov_userspace_exit(void)
206 {
207         cpufreq_unregister_governor(&cpufreq_gov_userspace);
208 }
209
210
211 MODULE_AUTHOR ("Dominik Brodowski <linux@brodo.de>, Russell King <rmk@arm.linux.org.uk>");
212 MODULE_DESCRIPTION ("CPUfreq policy governor 'userspace'");
213 MODULE_LICENSE ("GPL");
214
215 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_USERSPACE
216 fs_initcall(cpufreq_gov_userspace_init);
217 #else
218 module_init(cpufreq_gov_userspace_init);
219 #endif
220 module_exit(cpufreq_gov_userspace_exit);