drivers/cpufreq/cpufreq_governor_attr_set.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * Abstract code for CPUFreq governor tunable sysfs attributes.
0004  *
0005  * Copyright (C) 2016, Intel Corporation
0006  * Author: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
0007  */
0008
0009 #include "cpufreq_governor.h"
0010
0011 static inline struct governor_attr *to_gov_attr(struct attribute *attr)
0012 {
0013     return container_of(attr, struct governor_attr, attr);
0014 }
0015
0016 static ssize_t governor_show(struct kobject *kobj, struct attribute *attr,
0017                  char *buf)
0018 {
0019     struct governor_attr *gattr = to_gov_attr(attr);
0020
0021     return gattr->show(to_gov_attr_set(kobj), buf);
0022 }
0023
0024 static ssize_t governor_store(struct kobject *kobj, struct attribute *attr,
0025                   const char *buf, size_t count)
0026 {
0027     struct gov_attr_set *attr_set = to_gov_attr_set(kobj);
0028     struct governor_attr *gattr = to_gov_attr(attr);
0029     int ret;
0030
0031     mutex_lock(&attr_set->update_lock);
0032     ret = attr_set->usage_count ? gattr->store(attr_set, buf, count) : -EBUSY;
0033     mutex_unlock(&attr_set->update_lock);
0034     return ret;
0035 }
0036
0037 const struct sysfs_ops governor_sysfs_ops = {
0038     .show   = governor_show,
0039     .store  = governor_store,
0040 };
0041 EXPORT_SYMBOL_GPL(governor_sysfs_ops);
0042
0043 void gov_attr_set_init(struct gov_attr_set *attr_set, struct list_head *list_node)
0044 {
0045     INIT_LIST_HEAD(&attr_set->policy_list);
0046     mutex_init(&attr_set->update_lock);
0047     attr_set->usage_count = 1;
0048     list_add(list_node, &attr_set->policy_list);
0049 }
0050 EXPORT_SYMBOL_GPL(gov_attr_set_init);
0051
0052 void gov_attr_set_get(struct gov_attr_set *attr_set, struct list_head *list_node)
0053 {
0054     mutex_lock(&attr_set->update_lock);
0055     attr_set->usage_count++;
0056     list_add(list_node, &attr_set->policy_list);
0057     mutex_unlock(&attr_set->update_lock);
0058 }
0059 EXPORT_SYMBOL_GPL(gov_attr_set_get);
0060
0061 unsigned int gov_attr_set_put(struct gov_attr_set *attr_set, struct list_head *list_node)
0062 {
0063     unsigned int count;
0064
0065     mutex_lock(&attr_set->update_lock);
0066     list_del(list_node);
0067     count = --attr_set->usage_count;
0068     mutex_unlock(&attr_set->update_lock);
0069     if (count)
0070         return count;
0071
0072     mutex_destroy(&attr_set->update_lock);
0073     kobject_put(&attr_set->kobj);
0074     return 0;
0075 }
0076 EXPORT_SYMBOL_GPL(gov_attr_set_put);