SAFE public projects git trees. - safe/jmp/linux-2.6/blob - drivers/cpufreq/cpufreq_userspace.c

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