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