text: // SPDX-License-Identifier: GPL-2.0-only
  /*
   * Abstract code for CPUFreq governor tunable sysfs attributes.
   *
   * Copyright (C) 2016, Intel Corporation
   * Author: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
   */
  
  #include "cpufreq_governor.h"
  
  static inline struct gov_attr_set *to_gov_attr_set(struct kobject *kobj)
  {
  	return container_of(kobj, struct gov_attr_set, kobj);
  }
  
  static inline struct governor_attr *to_gov_attr(struct attribute *attr)
  {
  	return container_of(attr, struct governor_attr, attr);
  }
  
  static ssize_t governor_show(struct kobject *kobj, struct attribute *attr,
  			     char *buf)
  {
  	struct governor_attr *gattr = to_gov_attr(attr);
  
  	return gattr->show(to_gov_attr_set(kobj), buf);
  }
  
  static ssize_t governor_store(struct kobject *kobj, struct attribute *attr,
  			      const char *buf, size_t count)
  {
  	struct gov_attr_set *attr_set = to_gov_attr_set(kobj);
  	struct governor_attr *gattr = to_gov_attr(attr);
  	int ret;
  
  	mutex_lock(&attr_set->update_lock);
  	ret = attr_set->usage_count ? gattr->store(attr_set, buf, count) : -EBUSY;
  	mutex_unlock(&attr_set->update_lock);
  	return ret;
  }
  
  const struct sysfs_ops governor_sysfs_ops = {
  	.show	= governor_show,
  	.store	= governor_store,
  };
  EXPORT_SYMBOL_GPL(governor_sysfs_ops);
  
  void gov_attr_set_init(struct gov_attr_set *attr_set, struct list_head *list_node)
  {
  	INIT_LIST_HEAD(&attr_set->policy_list);
  	mutex_init(&attr_set->update_lock);
  	attr_set->usage_count = 1;
  	list_add(list_node, &attr_set->policy_list);
  }
  EXPORT_SYMBOL_GPL(gov_attr_set_init);
  
  void gov_attr_set_get(struct gov_attr_set *attr_set, struct list_head *list_node)
  {
  	mutex_lock(&attr_set->update_lock);
  	attr_set->usage_count++;
  	list_add(list_node, &attr_set->policy_list);
  	mutex_unlock(&attr_set->update_lock);
  }
  EXPORT_SYMBOL_GPL(gov_attr_set_get);
  
  unsigned int gov_attr_set_put(struct gov_attr_set *attr_set, struct list_head *list_node)
  {
  	unsigned int count;
  
  	mutex_lock(&attr_set->update_lock);
  	list_del(list_node);
  	count = --attr_set->usage_count;
  	mutex_unlock(&attr_set->update_lock);
  	if (count)
  		return count;
  
  	kobject_put(&attr_set->kobj);
  	mutex_destroy(&attr_set->update_lock);
  	return 0;
  }
  EXPORT_SYMBOL_GPL(gov_attr_set_put);
  