linux - drivers/devfreq/governor

160 lines · 3.4 KiB

1	// SPDX-License-Identifier: GPL-2.0-only
2	/*
3	* linux/drivers/devfreq/governor_userspace.c
4	*
5	* Copyright (C) 2011 Samsung Electronics
6	* MyungJoo Ham <[email protected]>
7	*/
8
9	#include <linux/slab.h>
10	#include <linux/device.h>
11	#include <linux/devfreq.h>
12	#include <linux/devfreq-governor.h>
13	#include <linux/kstrtox.h>
14	#include <linux/pm.h>
15	#include <linux/mutex.h>
16	#include <linux/module.h>
17
18	struct userspace_data {
19	unsigned long user_frequency;
20	bool valid;
21	};
22
23	static int devfreq_userspace_func(struct devfreq df, unsigned long freq)
24	{
25	struct userspace_data *data = df->governor_data;
26
27	if (data->valid)
28	*freq = data->user_frequency;
29	else
30	freq = df->previous_freq; / No user freq specified yet */
31
32	return 0;
33	}
34
35	static ssize_t set_freq_store(struct device dev, struct device_attribute attr,
36	const char *buf, size_t count)
37	{
38	struct devfreq *devfreq = to_devfreq(dev);
39	struct userspace_data *data;
40	unsigned long wanted;
41	int err = 0;
42
43	err = kstrtoul(buf, 0, &wanted);
44	if (err)
45	return err;
46
47	mutex_lock(&devfreq->lock);
48	data = devfreq->governor_data;
49
50	data->user_frequency = wanted;
51	data->valid = true;
52	err = update_devfreq(devfreq);
53	if (err == 0)
54	err = count;
55	mutex_unlock(&devfreq->lock);
56	return err;
57	}
58
59	static ssize_t set_freq_show(struct device *dev,
60	struct device_attribute attr, char buf)
61	{
62	struct devfreq *devfreq = to_devfreq(dev);
63	struct userspace_data *data;
64	int err = 0;
65
66	mutex_lock(&devfreq->lock);
67	data = devfreq->governor_data;
68
69	if (data->valid)
70	err = sprintf(buf, "%lu\n", data->user_frequency);
71	else
72	err = sprintf(buf, "undefined\n");
73	mutex_unlock(&devfreq->lock);
74	return err;
75	}
76
77	static DEVICE_ATTR_RW(set_freq);
78	static struct attribute *dev_entries[] = {
79	&dev_attr_set_freq.attr,
80	NULL,
81	};
82	static const struct attribute_group dev_attr_group = {
83	.name = DEVFREQ_GOV_USERSPACE,
84	.attrs = dev_entries,
85	};
86
87	static int userspace_init(struct devfreq *devfreq)
88	{
89	int err = 0;
90	struct userspace_data *data = kzalloc_obj(struct userspace_data);
91
92	if (!data) {
93	err = -ENOMEM;
94	goto out;
95	}
96	data->valid = false;
97	devfreq->governor_data = data;
98
99	err = sysfs_create_group(&devfreq->dev.kobj, &dev_attr_group);
100	out:
101	return err;
102	}
103
104	static void userspace_exit(struct devfreq *devfreq)
105	{
106	/*
107	* Remove the sysfs entry, unless this is being called after
108	* device_del(), which should have done this already via kobject_del().
109	*/
110	if (devfreq->dev.kobj.sd)
111	sysfs_remove_group(&devfreq->dev.kobj, &dev_attr_group);
112
113	kfree(devfreq->governor_data);
114	devfreq->governor_data = NULL;
115	}
116
117	static int devfreq_userspace_handler(struct devfreq *devfreq,
118	unsigned int event, void *data)
119	{
120	int ret = 0;
121
122	switch (event) {
123	case DEVFREQ_GOV_START:
124	ret = userspace_init(devfreq);
125	break;
126	case DEVFREQ_GOV_STOP:
127	userspace_exit(devfreq);
128	break;
129	default:
130	break;
131	}
132
133	return ret;
134	}
135
136	static struct devfreq_governor devfreq_userspace = {
137	.name = DEVFREQ_GOV_USERSPACE,
138	.get_target_freq = devfreq_userspace_func,
139	.event_handler = devfreq_userspace_handler,
140	};
141
142	static int __init devfreq_userspace_init(void)
143	{
144	return devfreq_add_governor(&devfreq_userspace);
145	}
146	subsys_initcall(devfreq_userspace_init);
147
148	static void __exit devfreq_userspace_exit(void)
149	{
150	int ret;
151
152	ret = devfreq_remove_governor(&devfreq_userspace);
153	if (ret)
154	pr_err("%s: failed remove governor %d\n", __func__, ret);
155
156	return;
157	}
158	module_exit(devfreq_userspace_exit);
159	MODULE_DESCRIPTION("DEVFREQ Userspace governor");
160	MODULE_LICENSE("GPL");