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 /**
  28  * A few values needed by the userspace governor
  29  */
  30 static DEFINE_PER_CPU(unsigned int, cpu_max_freq);
  31 static DEFINE_PER_CPU(unsigned int, cpu_min_freq);
  32 static DEFINE_PER_CPU(unsigned int, cpu_cur_freq); /* current CPU freq */
  33 static DEFINE_PER_CPU(unsigned int, cpu_set_freq); /* CPU freq desired by
  34                                                         userspace */
  35 static DEFINE_PER_CPU(unsigned int, cpu_is_managed);
  36
  37 static DEFINE_MUTEX(userspace_mutex);
  38 static int cpus_using_userspace_governor;
  39
  40 #define dprintk(msg...) \
  41         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         if (!per_cpu(cpu_is_managed, freq->cpu))
  51                 return 0;
  52
  53         dprintk("saving cpu_cur_freq of cpu %u to be %u kHz\n",
  54                         freq->cpu, freq->new);
  55         per_cpu(cpu_cur_freq, freq->cpu) = freq->new;
  56
  57         return 0;
  58 }
  59
  60 static struct notifier_block userspace_cpufreq_notifier_block = {
  61         .notifier_call  = userspace_cpufreq_notifier
  62 };
  63
  64
  65 /**
  66  * cpufreq_set - set the CPU frequency
  67  * @policy: pointer to policy struct where freq is being set
  68  * @freq: target frequency in kHz
  69  *
  70  * Sets the CPU frequency to freq.
  71  */
  72 static int cpufreq_set(struct cpufreq_policy *policy, unsigned int freq)
  73 {
  74         int ret = -EINVAL;
  75
  76         dprintk("cpufreq_set for cpu %u, freq %u kHz\n", policy->cpu, freq);
  77
  78         mutex_lock(&userspace_mutex);
  79         if (!per_cpu(cpu_is_managed, policy->cpu))
  80                 goto err;
  81
  82         per_cpu(cpu_set_freq, policy->cpu) = freq;
  83
  84         if (freq < per_cpu(cpu_min_freq, policy->cpu))
  85                 freq = per_cpu(cpu_min_freq, policy->cpu);
  86         if (freq > per_cpu(cpu_max_freq, policy->cpu))
  87                 freq = per_cpu(cpu_max_freq, policy->cpu);
  88
  89         /*
  90          * We're safe from concurrent calls to ->target() here
  91          * as we hold the userspace_mutex lock. If we were calling
  92          * cpufreq_driver_target, a deadlock situation might occur:
  93          * A: cpufreq_set (lock userspace_mutex) ->
  94          *      cpufreq_driver_target(lock policy->lock)
  95          * B: cpufreq_set_policy(lock policy->lock) ->
  96          *      __cpufreq_governor ->
  97          *         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 #ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_USERSPACE
 191 static
 192 #endif
 193 struct cpufreq_governor cpufreq_gov_userspace = {
 194         .name           = "userspace",
 195         .governor       = cpufreq_governor_userspace,
 196         .store_setspeed = cpufreq_set,
 197         .show_setspeed  = show_speed,
 198         .owner          = THIS_MODULE,
 199 };
 200
 201 static int __init cpufreq_gov_userspace_init(void)
 202 {
 203         return cpufreq_register_governor(&cpufreq_gov_userspace);
 204 }
 205
 206
 207 static void __exit cpufreq_gov_userspace_exit(void)
 208 {
 209         cpufreq_unregister_governor(&cpufreq_gov_userspace);
 210 }
 211
 212
 213 MODULE_AUTHOR("Dominik Brodowski <linux@brodo.de>, "
 214                 "Russell King <rmk@arm.linux.org.uk>");
 215 MODULE_DESCRIPTION("CPUfreq policy governor 'userspace'");
 216 MODULE_LICENSE("GPL");
 217
 218 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_USERSPACE
 219 fs_initcall(cpufreq_gov_userspace_init);
 220 #else
 221 module_init(cpufreq_gov_userspace_init);
 222 #endif
 223 module_exit(cpufreq_gov_userspace_exit);