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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  15
  16 #include <linux/kernel.h>
  17 #include <linux/module.h>
  18 #include <linux/smp.h>
  19 #include <linux/init.h>
  20 #include <linux/spinlock.h>
  21 #include <linux/interrupt.h>
  22 #include <linux/cpufreq.h>
  23 #include <linux/cpu.h>
  24 #include <linux/types.h>
  25 #include <linux/fs.h>
  26 #include <linux/sysfs.h>
  27 #include <linux/mutex.h>
  28
  29 /**
  30  * A few values needed by the userspace governor
  31  */
  32 static DEFINE_PER_CPU(unsigned int, cpu_max_freq);
  33 static DEFINE_PER_CPU(unsigned int, cpu_min_freq);
  34 static DEFINE_PER_CPU(unsigned int, cpu_cur_freq); /* current CPU freq */
  35 static DEFINE_PER_CPU(unsigned int, cpu_set_freq); /* CPU freq desired by
  36                                                         userspace */
  37 static DEFINE_PER_CPU(unsigned int, cpu_is_managed);
  38
  39 static DEFINE_MUTEX(userspace_mutex);
  40 static int cpus_using_userspace_governor;
  41
  42 /* keep track of frequency transitions */
  43 static int
  44 userspace_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
  45         void *data)
  46 {
  47         struct cpufreq_freqs *freq = data;
  48
  49         if (!per_cpu(cpu_is_managed, freq->cpu))
  50                 return 0;
  51
  52         if (val == CPUFREQ_POSTCHANGE) {
  53                 pr_debug("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
  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         pr_debug("cpufreq_set for cpu %u, freq %u kHz\n", policy->cpu, freq);
  78
  79         mutex_lock(&userspace_mutex);
  80         if (!per_cpu(cpu_is_managed, policy->cpu))
  81                 goto err;
  82
  83         per_cpu(cpu_set_freq, policy->cpu) = freq;
  84
  85         if (freq < per_cpu(cpu_min_freq, policy->cpu))
  86                 freq = per_cpu(cpu_min_freq, policy->cpu);
  87         if (freq > per_cpu(cpu_max_freq, policy->cpu))
  88                 freq = per_cpu(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) ->
  95          *      cpufreq_driver_target(lock policy->lock)
  96          * B: cpufreq_set_policy(lock policy->lock) ->
  97          *      __cpufreq_governor ->
  98          *         cpufreq_governor_userspace (lock userspace_mutex)
  99          */
 100         ret = __cpufreq_driver_target(policy, freq, CPUFREQ_RELATION_L);
 101
 102  err:
 103         mutex_unlock(&userspace_mutex);
 104         return ret;
 105 }
 106
 107
 108 static ssize_t show_speed(struct cpufreq_policy *policy, char *buf)
 109 {
 110         return sprintf(buf, "%u\n", per_cpu(cpu_cur_freq, policy->cpu));
 111 }
 112
 113 static int cpufreq_governor_userspace(struct cpufreq_policy *policy,
 114                                    unsigned int event)
 115 {
 116         unsigned int cpu = policy->cpu;
 117         int rc = 0;
 118
 119         switch (event) {
 120         case CPUFREQ_GOV_START:
 121                 if (!cpu_online(cpu))
 122                         return -EINVAL;
 123                 BUG_ON(!policy->cur);
 124                 mutex_lock(&userspace_mutex);
 125
 126                 if (cpus_using_userspace_governor == 0) {
 127                         cpufreq_register_notifier(
 128                                         &userspace_cpufreq_notifier_block,
 129                                         CPUFREQ_TRANSITION_NOTIFIER);
 130                 }
 131                 cpus_using_userspace_governor++;
 132
 133                 per_cpu(cpu_is_managed, cpu) = 1;
 134                 per_cpu(cpu_min_freq, cpu) = policy->min;
 135                 per_cpu(cpu_max_freq, cpu) = policy->max;
 136                 per_cpu(cpu_cur_freq, cpu) = policy->cur;
 137                 per_cpu(cpu_set_freq, cpu) = policy->cur;
 138                 pr_debug("managing cpu %u started "
 139                         "(%u - %u kHz, currently %u kHz)\n",
 140                                 cpu,
 141                                 per_cpu(cpu_min_freq, cpu),
 142                                 per_cpu(cpu_max_freq, cpu),
 143                                 per_cpu(cpu_cur_freq, cpu));
 144
 145                 mutex_unlock(&userspace_mutex);
 146                 break;
 147         case CPUFREQ_GOV_STOP:
 148                 mutex_lock(&userspace_mutex);
 149                 cpus_using_userspace_governor--;
 150                 if (cpus_using_userspace_governor == 0) {
 151                         cpufreq_unregister_notifier(
 152                                         &userspace_cpufreq_notifier_block,
 153                                         CPUFREQ_TRANSITION_NOTIFIER);
 154                 }
 155
 156                 per_cpu(cpu_is_managed, cpu) = 0;
 157                 per_cpu(cpu_min_freq, cpu) = 0;
 158                 per_cpu(cpu_max_freq, cpu) = 0;
 159                 per_cpu(cpu_set_freq, cpu) = 0;
 160                 pr_debug("managing cpu %u stopped\n", cpu);
 161                 mutex_unlock(&userspace_mutex);
 162                 break;
 163         case CPUFREQ_GOV_LIMITS:
 164                 mutex_lock(&userspace_mutex);
 165                 pr_debug("limit event for cpu %u: %u - %u kHz, "
 166                         "currently %u kHz, last set to %u kHz\n",
 167                         cpu, policy->min, policy->max,
 168                         per_cpu(cpu_cur_freq, cpu),
 169                         per_cpu(cpu_set_freq, cpu));
 170                 if (policy->max < per_cpu(cpu_set_freq, cpu)) {
 171                         __cpufreq_driver_target(policy, policy->max,
 172                                                 CPUFREQ_RELATION_H);
 173                 } else if (policy->min > per_cpu(cpu_set_freq, cpu)) {
 174                         __cpufreq_driver_target(policy, policy->min,
 175                                                 CPUFREQ_RELATION_L);
 176                 } else {
 177                         __cpufreq_driver_target(policy,
 178                                                 per_cpu(cpu_set_freq, cpu),
 179                                                 CPUFREQ_RELATION_L);
 180                 }
 181                 per_cpu(cpu_min_freq, cpu) = policy->min;
 182                 per_cpu(cpu_max_freq, cpu) = policy->max;
 183                 per_cpu(cpu_cur_freq, cpu) = policy->cur;
 184                 mutex_unlock(&userspace_mutex);
 185                 break;
 186         }
 187         return rc;
 188 }
 189
 190
 191 #ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_USERSPACE
 192 static
 193 #endif
 194 struct cpufreq_governor cpufreq_gov_userspace = {
 195         .name           = "userspace",
 196         .governor       = cpufreq_governor_userspace,
 197         .store_setspeed = cpufreq_set,
 198         .show_setspeed  = show_speed,
 199         .owner          = THIS_MODULE,
 200 };
 201
 202 static int __init cpufreq_gov_userspace_init(void)
 203 {
 204         return cpufreq_register_governor(&cpufreq_gov_userspace);
 205 }
 206
 207
 208 static void __exit cpufreq_gov_userspace_exit(void)
 209 {
 210         cpufreq_unregister_governor(&cpufreq_gov_userspace);
 211 }
 212
 213
 214 MODULE_AUTHOR("Dominik Brodowski <linux@brodo.de>, "
 215                 "Russell King <rmk@arm.linux.org.uk>");
 216 MODULE_DESCRIPTION("CPUfreq policy governor 'userspace'");
 217 MODULE_LICENSE("GPL");
 218
 219 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_USERSPACE
 220 fs_initcall(cpufreq_gov_userspace_init);
 221 #else
 222 module_init(cpufreq_gov_userspace_init);
 223 #endif
 224 module_exit(cpufreq_gov_userspace_exit);