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