LXR linux/drivers/cpufreq/cpufreq

   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
  21static DEFINE_PER_CPU(unsigned int, cpu_is_managed);
  22static 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 */
  31static 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
  47static ssize_t show_speed(struct cpufreq_policy *policy, char *buf)
  48{
  49        return sprintf(buf, "%u\n", policy->cur);
  50}
  51
  52static 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
  93static
  94#endif
  95struct 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
 103static int __init cpufreq_gov_userspace_init(void)
 104{
 105        return cpufreq_register_governor(&cpufreq_gov_userspace);
 106}
 107
 108static void __exit cpufreq_gov_userspace_exit(void)
 109{
 110        cpufreq_unregister_governor(&cpufreq_gov_userspace);
 111}
 112
 113MODULE_AUTHOR("Dominik Brodowski <linux@brodo.de>, "
 114                "Russell King <rmk@arm.linux.org.uk>");
 115MODULE_DESCRIPTION("CPUfreq policy governor 'userspace'");
 116MODULE_LICENSE("GPL");
 117
 118#ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_USERSPACE
 119fs_initcall(cpufreq_gov_userspace_init);
 120#else
 121module_init(cpufreq_gov_userspace_init);
 122#endif
 123module_exit(cpufreq_gov_userspace_exit);
 124