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);
85