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kernel/linux-imx6_3.14.28/drivers/cpuidle/governor.c 2.21 KB
6b13f685e   김민수   BSP 최초 추가
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  /*
   * governor.c - governor support
   *
   * (C) 2006-2007 Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
   *               Shaohua Li <shaohua.li@intel.com>
   *               Adam Belay <abelay@novell.com>
   *
   * This code is licenced under the GPL.
   */
  
  #include <linux/mutex.h>
  #include <linux/module.h>
  #include <linux/cpuidle.h>
  
  #include "cpuidle.h"
  
  LIST_HEAD(cpuidle_governors);
  struct cpuidle_governor *cpuidle_curr_governor;
  
  /**
   * __cpuidle_find_governor - finds a governor of the specified name
   * @str: the name
   *
   * Must be called with cpuidle_lock acquired.
   */
  static struct cpuidle_governor * __cpuidle_find_governor(const char *str)
  {
  	struct cpuidle_governor *gov;
  
  	list_for_each_entry(gov, &cpuidle_governors, governor_list)
  		if (!strnicmp(str, gov->name, CPUIDLE_NAME_LEN))
  			return gov;
  
  	return NULL;
  }
  
  /**
   * cpuidle_switch_governor - changes the governor
   * @gov: the new target governor
   *
   * NOTE: "gov" can be NULL to specify disabled
   * Must be called with cpuidle_lock acquired.
   */
  int cpuidle_switch_governor(struct cpuidle_governor *gov)
  {
  	struct cpuidle_device *dev;
  
  	if (gov == cpuidle_curr_governor)
  		return 0;
  
  	cpuidle_uninstall_idle_handler();
  
  	if (cpuidle_curr_governor) {
  		list_for_each_entry(dev, &cpuidle_detected_devices, device_list)
  			cpuidle_disable_device(dev);
  		module_put(cpuidle_curr_governor->owner);
  	}
  
  	cpuidle_curr_governor = gov;
  
  	if (gov) {
  		if (!try_module_get(cpuidle_curr_governor->owner))
  			return -EINVAL;
  		list_for_each_entry(dev, &cpuidle_detected_devices, device_list)
  			cpuidle_enable_device(dev);
  		cpuidle_install_idle_handler();
  		printk(KERN_INFO "cpuidle: using governor %s
  ", gov->name);
  	}
  
  	return 0;
  }
  
  /**
   * cpuidle_register_governor - registers a governor
   * @gov: the governor
   */
  int cpuidle_register_governor(struct cpuidle_governor *gov)
  {
  	int ret = -EEXIST;
  
  	if (!gov || !gov->select)
  		return -EINVAL;
  
  	if (cpuidle_disabled())
  		return -ENODEV;
  
  	mutex_lock(&cpuidle_lock);
  	if (__cpuidle_find_governor(gov->name) == NULL) {
  		ret = 0;
  		list_add_tail(&gov->governor_list, &cpuidle_governors);
  		if (!cpuidle_curr_governor ||
  		    cpuidle_curr_governor->rating < gov->rating)
  			cpuidle_switch_governor(gov);
  	}
  	mutex_unlock(&cpuidle_lock);
  
  	return ret;
  }