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/cpufreq.h>
  17 #include <linux/init.h>
  18 #include <linux/module.h>
  19 #include <linux/mutex.h>
  20
  21 static DEFINE_PER_CPU(unsigned int, cpu_is_managed);
  22 static DEFINE_MUTEX(userspace_mutex);
  23
  24 /**
  25  * cpufreq_set - set the CPU frequency
  26  * @policy: pointer to policy struct where freq is being set
  27  * @freq: target frequency in kHz
  28  *
  29  * Sets the CPU frequency to freq.
  30  */
  31 static int cpufreq_set(struct cpufreq_policy *policy, unsigned int freq)
  32 {
  33         int ret = -EINVAL;
  34
  35         pr_debug("cpufreq_set for cpu %u, freq %u kHz\n", policy->cpu, freq);
  36
  37         mutex_lock(&userspace_mutex);
  38         if (!per_cpu(cpu_is_managed, policy->cpu))
  39                 goto err;
  40
  41         ret = __cpufreq_driver_target(policy, freq, CPUFREQ_RELATION_L);
  42  err:
  43         mutex_unlock(&userspace_mutex);
  44         return ret;
  45 }
  46
  47 static ssize_t show_speed(struct cpufreq_policy *policy, char *buf)
  48 {
  49         return sprintf(buf, "%u\n", policy->cur);
  50 }
  51
  52 static int cpufreq_governor_userspace(struct cpufreq_policy *policy,
  53                                    unsigned int event)
  54 {
  55         unsigned int cpu = policy->cpu;
  56         int rc = 0;
  57
  58         switch (event) {
  59         case CPUFREQ_GOV_START:
  60                 BUG_ON(!policy->cur);
  61                 pr_debug("started managing cpu %u\n", cpu);
  62
  63                 mutex_lock(&userspace_mutex);
  64                 per_cpu(cpu_is_managed, cpu) = 1;
  65                 mutex_unlock(&userspace_mutex);
  66                 break;
  67         case CPUFREQ_GOV_STOP:
  68                 pr_debug("managing cpu %u stopped\n", cpu);
  69
  70                 mutex_lock(&userspace_mutex);
  71                 per_cpu(cpu_is_managed, cpu) = 0;
  72                 mutex_unlock(&userspace_mutex);
  73                 break;
  74         case CPUFREQ_GOV_LIMITS:
  75                 mutex_lock(&userspace_mutex);
  76                 pr_debug("limit event for cpu %u: %u - %u kHz, currently %u kHz\n",
  77                         cpu, policy->min, policy->max,
  78                         policy->cur);
  79
  80                 if (policy->max < policy->cur)
  81                         __cpufreq_driver_target(policy, policy->max,
  82                                                 CPUFREQ_RELATION_H);
  83                 else if (policy->min > policy->cur)
  84                         __cpufreq_driver_target(policy, policy->min,
  85                                                 CPUFREQ_RELATION_L);
  86                 mutex_unlock(&userspace_mutex);
  87                 break;
  88         }
  89         return rc;
  90 }
  91
  92 #ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_USERSPACE
  93 static
  94 #endif
  95 struct cpufreq_governor cpufreq_gov_userspace = {
  96         .name           = "userspace",
  97         .governor       = cpufreq_governor_userspace,
  98         .store_setspeed = cpufreq_set,
  99         .show_setspeed  = show_speed,
 100         .owner          = THIS_MODULE,
 101 };
 102
 103 static int __init cpufreq_gov_userspace_init(void)
 104 {
 105         return cpufreq_register_governor(&cpufreq_gov_userspace);
 106 }
 107
 108 static void __exit cpufreq_gov_userspace_exit(void)
 109 {
 110         cpufreq_unregister_governor(&cpufreq_gov_userspace);
 111 }
 112
 113 MODULE_AUTHOR("Dominik Brodowski <linux@brodo.de>, "
 114                 "Russell King <rmk@arm.linux.org.uk>");
 115 MODULE_DESCRIPTION("CPUfreq policy governor 'userspace'");
 116 MODULE_LICENSE("GPL");
 117
 118 #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_USERSPACE
 119 fs_initcall(cpufreq_gov_userspace_init);
 120 #else
 121 module_init(cpufreq_gov_userspace_init);
 122 #endif
 123 module_exit(cpufreq_gov_userspace_exit);