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);
77