drivers/cpufreq/cpufreq_governor_attr_set.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Abstract code for CPUFreq governor tunable sysfs attributes.
   4  *
   5  * Copyright (C) 2016, Intel Corporation
   6  * Author: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
   7  */
   8
   9 #include "cpufreq_governor.h"
  10
  11 static inline struct gov_attr_set *to_gov_attr_set(struct kobject *kobj)
  12 {
  13         return container_of(kobj, struct gov_attr_set, kobj);
  14 }
  15
  16 static inline struct governor_attr *to_gov_attr(struct attribute *attr)
  17 {
  18         return container_of(attr, struct governor_attr, attr);
  19 }
  20
  21 static ssize_t governor_show(struct kobject *kobj, struct attribute *attr,
  22                              char *buf)
  23 {
  24         struct governor_attr *gattr = to_gov_attr(attr);
  25
  26         return gattr->show(to_gov_attr_set(kobj), buf);
  27 }
  28
  29 static ssize_t governor_store(struct kobject *kobj, struct attribute *attr,
  30                               const char *buf, size_t count)
  31 {
  32         struct gov_attr_set *attr_set = to_gov_attr_set(kobj);
  33         struct governor_attr *gattr = to_gov_attr(attr);
  34         int ret;
  35
  36         mutex_lock(&attr_set->update_lock);
  37         ret = attr_set->usage_count ? gattr->store(attr_set, buf, count) : -EBUSY;
  38         mutex_unlock(&attr_set->update_lock);
  39         return ret;
  40 }
  41
  42 const struct sysfs_ops governor_sysfs_ops = {
  43         .show   = governor_show,
  44         .store  = governor_store,
  45 };
  46 EXPORT_SYMBOL_GPL(governor_sysfs_ops);
  47
  48 void gov_attr_set_init(struct gov_attr_set *attr_set, struct list_head *list_node)
  49 {
  50         INIT_LIST_HEAD(&attr_set->policy_list);
  51         mutex_init(&attr_set->update_lock);
  52         attr_set->usage_count = 1;
  53         list_add(list_node, &attr_set->policy_list);
  54 }
  55 EXPORT_SYMBOL_GPL(gov_attr_set_init);
  56
  57 void gov_attr_set_get(struct gov_attr_set *attr_set, struct list_head *list_node)
  58 {
  59         mutex_lock(&attr_set->update_lock);
  60         attr_set->usage_count++;
  61         list_add(list_node, &attr_set->policy_list);
  62         mutex_unlock(&attr_set->update_lock);
  63 }
  64 EXPORT_SYMBOL_GPL(gov_attr_set_get);
  65
  66 unsigned int gov_attr_set_put(struct gov_attr_set *attr_set, struct list_head *list_node)
  67 {
  68         unsigned int count;
  69
  70         mutex_lock(&attr_set->update_lock);
  71         list_del(list_node);
  72         count = --attr_set->usage_count;
  73         mutex_unlock(&attr_set->update_lock);
  74         if (count)
  75                 return count;
  76
  77         kobject_put(&attr_set->kobj);
  78         mutex_destroy(&attr_set->update_lock);
  79         return 0;
  80 }
  81 EXPORT_SYMBOL_GPL(gov_attr_set_put);