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 governor_attr *to_gov_attr(struct attribute *attr)
  12 {
  13         return container_of(attr, struct governor_attr, attr);
  14 }
  15
  16 static ssize_t governor_show(struct kobject *kobj, struct attribute *attr,
  17                              char *buf)
  18 {
  19         struct governor_attr *gattr = to_gov_attr(attr);
  20
  21         return gattr->show(to_gov_attr_set(kobj), buf);
  22 }
  23
  24 static ssize_t governor_store(struct kobject *kobj, struct attribute *attr,
  25                               const char *buf, size_t count)
  26 {
  27         struct gov_attr_set *attr_set = to_gov_attr_set(kobj);
  28         struct governor_attr *gattr = to_gov_attr(attr);
  29         int ret;
  30
  31         mutex_lock(&attr_set->update_lock);
  32         ret = attr_set->usage_count ? gattr->store(attr_set, buf, count) : -EBUSY;
  33         mutex_unlock(&attr_set->update_lock);
  34         return ret;
  35 }
  36
  37 const struct sysfs_ops governor_sysfs_ops = {
  38         .show   = governor_show,
  39         .store  = governor_store,
  40 };
  41 EXPORT_SYMBOL_GPL(governor_sysfs_ops);
  42
  43 void gov_attr_set_init(struct gov_attr_set *attr_set, struct list_head *list_node)
  44 {
  45         INIT_LIST_HEAD(&attr_set->policy_list);
  46         mutex_init(&attr_set->update_lock);
  47         attr_set->usage_count = 1;
  48         list_add(list_node, &attr_set->policy_list);
  49 }
  50 EXPORT_SYMBOL_GPL(gov_attr_set_init);
  51
  52 void gov_attr_set_get(struct gov_attr_set *attr_set, struct list_head *list_node)
  53 {
  54         mutex_lock(&attr_set->update_lock);
  55         attr_set->usage_count++;
  56         list_add(list_node, &attr_set->policy_list);
  57         mutex_unlock(&attr_set->update_lock);
  58 }
  59 EXPORT_SYMBOL_GPL(gov_attr_set_get);
  60
  61 unsigned int gov_attr_set_put(struct gov_attr_set *attr_set, struct list_head *list_node)
  62 {
  63         unsigned int count;
  64
  65         mutex_lock(&attr_set->update_lock);
  66         list_del(list_node);
  67         count = --attr_set->usage_count;
  68         mutex_unlock(&attr_set->update_lock);
  69         if (count)
  70                 return count;
  71
  72         mutex_destroy(&attr_set->update_lock);
  73         kobject_put(&attr_set->kobj);
  74         return 0;
  75 }
  76 EXPORT_SYMBOL_GPL(gov_attr_set_put);