drivers/cpufreq/cpufreq_governor_attr_set.c

   1 /*
   2  * Abstract code for CPUFreq governor tunable sysfs attributes.
   3  *
   4  * Copyright (C) 2016, Intel Corporation
   5  * Author: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  */
  11
  12 #include "cpufreq_governor.h"
  13
  14 static inline struct gov_attr_set *to_gov_attr_set(struct kobject *kobj)
  15 {
  16         return container_of(kobj, struct gov_attr_set, kobj);
  17 }
  18
  19 static inline struct governor_attr *to_gov_attr(struct attribute *attr)
  20 {
  21         return container_of(attr, struct governor_attr, attr);
  22 }
  23
  24 static ssize_t governor_show(struct kobject *kobj, struct attribute *attr,
  25                              char *buf)
  26 {
  27         struct governor_attr *gattr = to_gov_attr(attr);
  28
  29         return gattr->show(to_gov_attr_set(kobj), buf);
  30 }
  31
  32 static ssize_t governor_store(struct kobject *kobj, struct attribute *attr,
  33                               const char *buf, size_t count)
  34 {
  35         struct gov_attr_set *attr_set = to_gov_attr_set(kobj);
  36         struct governor_attr *gattr = to_gov_attr(attr);
  37         int ret;
  38
  39         mutex_lock(&attr_set->update_lock);
  40         ret = attr_set->usage_count ? gattr->store(attr_set, buf, count) : -EBUSY;
  41         mutex_unlock(&attr_set->update_lock);
  42         return ret;
  43 }
  44
  45 const struct sysfs_ops governor_sysfs_ops = {
  46         .show   = governor_show,
  47         .store  = governor_store,
  48 };
  49 EXPORT_SYMBOL_GPL(governor_sysfs_ops);
  50
  51 void gov_attr_set_init(struct gov_attr_set *attr_set, struct list_head *list_node)
  52 {
  53         INIT_LIST_HEAD(&attr_set->policy_list);
  54         mutex_init(&attr_set->update_lock);
  55         attr_set->usage_count = 1;
  56         list_add(list_node, &attr_set->policy_list);
  57 }
  58 EXPORT_SYMBOL_GPL(gov_attr_set_init);
  59
  60 void gov_attr_set_get(struct gov_attr_set *attr_set, struct list_head *list_node)
  61 {
  62         mutex_lock(&attr_set->update_lock);
  63         attr_set->usage_count++;
  64         list_add(list_node, &attr_set->policy_list);
  65         mutex_unlock(&attr_set->update_lock);
  66 }
  67 EXPORT_SYMBOL_GPL(gov_attr_set_get);
  68
  69 unsigned int gov_attr_set_put(struct gov_attr_set *attr_set, struct list_head *list_node)
  70 {
  71         unsigned int count;
  72
  73         mutex_lock(&attr_set->update_lock);
  74         list_del(list_node);
  75         count = --attr_set->usage_count;
  76         mutex_unlock(&attr_set->update_lock);
  77         if (count)
  78                 return count;
  79
  80         kobject_put(&attr_set->kobj);
  81         mutex_destroy(&attr_set->update_lock);
  82         return 0;
  83 }
  84 EXPORT_SYMBOL_GPL(gov_attr_set_put);