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kernel/linux-imx6_3.14.28/drivers/cpufreq/cpufreq_userspace.c 3.06 KB
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  /*
   *  linux/drivers/cpufreq/cpufreq_userspace.c
   *
   *  Copyright (C)  2001 Russell King
   *            (C)  2002 - 2004 Dominik Brodowski <linux@brodo.de>
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 as
   * published by the Free Software Foundation.
   *
   */
  
  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  
  #include <linux/cpufreq.h>
  #include <linux/init.h>
  #include <linux/module.h>
  #include <linux/mutex.h>
  
  static DEFINE_PER_CPU(unsigned int, cpu_is_managed);
  static DEFINE_MUTEX(userspace_mutex);
  
  /**
   * cpufreq_set - set the CPU frequency
   * @policy: pointer to policy struct where freq is being set
   * @freq: target frequency in kHz
   *
   * Sets the CPU frequency to freq.
   */
  static int cpufreq_set(struct cpufreq_policy *policy, unsigned int freq)
  {
  	int ret = -EINVAL;
  
  	pr_debug("cpufreq_set for cpu %u, freq %u kHz
  ", policy->cpu, freq);
  
  	mutex_lock(&userspace_mutex);
  	if (!per_cpu(cpu_is_managed, policy->cpu))
  		goto err;
  
  	ret = __cpufreq_driver_target(policy, freq, CPUFREQ_RELATION_L);
   err:
  	mutex_unlock(&userspace_mutex);
  	return ret;
  }
  
  static ssize_t show_speed(struct cpufreq_policy *policy, char *buf)
  {
  	return sprintf(buf, "%u
  ", policy->cur);
  }
  
  static int cpufreq_governor_userspace(struct cpufreq_policy *policy,
  				   unsigned int event)
  {
  	unsigned int cpu = policy->cpu;
  	int rc = 0;
  
  	switch (event) {
  	case CPUFREQ_GOV_START:
  		BUG_ON(!policy->cur);
  		pr_debug("started managing cpu %u
  ", cpu);
  
  		mutex_lock(&userspace_mutex);
  		per_cpu(cpu_is_managed, cpu) = 1;
  		mutex_unlock(&userspace_mutex);
  		break;
  	case CPUFREQ_GOV_STOP:
  		pr_debug("managing cpu %u stopped
  ", cpu);
  
  		mutex_lock(&userspace_mutex);
  		per_cpu(cpu_is_managed, cpu) = 0;
  		mutex_unlock(&userspace_mutex);
  		break;
  	case CPUFREQ_GOV_LIMITS:
  		mutex_lock(&userspace_mutex);
  		pr_debug("limit event for cpu %u: %u - %u kHz, currently %u kHz
  ",
  			cpu, policy->min, policy->max,
  			policy->cur);
  
  		if (policy->max < policy->cur)
  			__cpufreq_driver_target(policy, policy->max,
  						CPUFREQ_RELATION_H);
  		else if (policy->min > policy->cur)
  			__cpufreq_driver_target(policy, policy->min,
  						CPUFREQ_RELATION_L);
  		mutex_unlock(&userspace_mutex);
  		break;
  	}
  	return rc;
  }
  
  #ifndef CONFIG_CPU_FREQ_DEFAULT_GOV_USERSPACE
  static
  #endif
  struct cpufreq_governor cpufreq_gov_userspace = {
  	.name		= "userspace",
  	.governor	= cpufreq_governor_userspace,
  	.store_setspeed	= cpufreq_set,
  	.show_setspeed	= show_speed,
  	.owner		= THIS_MODULE,
  };
  
  static int __init cpufreq_gov_userspace_init(void)
  {
  	return cpufreq_register_governor(&cpufreq_gov_userspace);
  }
  
  static void __exit cpufreq_gov_userspace_exit(void)
  {
  	cpufreq_unregister_governor(&cpufreq_gov_userspace);
  }
  
  MODULE_AUTHOR("Dominik Brodowski <linux@brodo.de>, "
  		"Russell King <rmk@arm.linux.org.uk>");
  MODULE_DESCRIPTION("CPUfreq policy governor 'userspace'");
  MODULE_LICENSE("GPL");
  
  #ifdef CONFIG_CPU_FREQ_DEFAULT_GOV_USERSPACE
  fs_initcall(cpufreq_gov_userspace_init);
  #else
  module_init(cpufreq_gov_userspace_init);
  #endif
  module_exit(cpufreq_gov_userspace_exit);