summaryrefslogtreecommitdiffstats
path: root/drivers/devfreq/governor_userspace.c
blob: ab9db7adb3adec069134f5abe8d20a04325f48e7 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
// SPDX-License-Identifier: GPL-2.0-only
/*
 *  linux/drivers/devfreq/governor_userspace.c
 *
 *  Copyright (C) 2011 Samsung Electronics
 *	MyungJoo Ham <myungjoo.ham@samsung.com>
 */

#include <linux/slab.h>
#include <linux/device.h>
#include <linux/devfreq.h>
#include <linux/pm.h>
#include <linux/mutex.h>
#include <linux/module.h>
#include "governor.h"

struct userspace_data {
	unsigned long user_frequency;
	bool valid;
};

static int devfreq_userspace_func(struct devfreq *df, unsigned long *freq)
{
	struct userspace_data *data = df->data;

	if (data->valid)
		*freq = data->user_frequency;
	else
		*freq = df->previous_freq; /* No user freq specified yet */

	return 0;
}

static ssize_t set_freq_store(struct device *dev, struct device_attribute *attr,
			      const char *buf, size_t count)
{
	struct devfreq *devfreq = to_devfreq(dev);
	struct userspace_data *data;
	unsigned long wanted;
	int err = 0;

	mutex_lock(&devfreq->lock);
	data = devfreq->data;

	sscanf(buf, "%lu", &wanted);
	data->user_frequency = wanted;
	data->valid = true;
	err = update_devfreq(devfreq);
	if (err == 0)
		err = count;
	mutex_unlock(&devfreq->lock);
	return err;
}

static ssize_t set_freq_show(struct device *dev,
			     struct device_attribute *attr, char *buf)
{
	struct devfreq *devfreq = to_devfreq(dev);
	struct userspace_data *data;
	int err = 0;

	mutex_lock(&devfreq->lock);
	data = devfreq->data;

	if (data->valid)
		err = sprintf(buf, "%lu\n", data->user_frequency);
	else
		err = sprintf(buf, "undefined\n");
	mutex_unlock(&devfreq->lock);
	return err;
}

static DEVICE_ATTR_RW(set_freq);
static struct attribute *dev_entries[] = {
	&dev_attr_set_freq.attr,
	NULL,
};
static const struct attribute_group dev_attr_group = {
	.name	= DEVFREQ_GOV_USERSPACE,
	.attrs	= dev_entries,
};

static int userspace_init(struct devfreq *devfreq)
{
	int err = 0;
	struct userspace_data *data = kzalloc(sizeof(struct userspace_data),
					      GFP_KERNEL);

	if (!data) {
		err = -ENOMEM;
		goto out;
	}
	data->valid = false;
	devfreq->data = data;

	err = sysfs_create_group(&devfreq->dev.kobj, &dev_attr_group);
out:
	return err;
}

static void userspace_exit(struct devfreq *devfreq)
{
	/*
	 * Remove the sysfs entry, unless this is being called after
	 * device_del(), which should have done this already via kobject_del().
	 */
	if (devfreq->dev.kobj.sd)
		sysfs_remove_group(&devfreq->dev.kobj, &dev_attr_group);

	kfree(devfreq->data);
	devfreq->data = NULL;
}

static int devfreq_userspace_handler(struct devfreq *devfreq,
			unsigned int event, void *data)
{
	int ret = 0;

	switch (event) {
	case DEVFREQ_GOV_START:
		ret = userspace_init(devfreq);
		break;
	case DEVFREQ_GOV_STOP:
		userspace_exit(devfreq);
		break;
	default:
		break;
	}

	return ret;
}

static struct devfreq_governor devfreq_userspace = {
	.name = DEVFREQ_GOV_USERSPACE,
	.get_target_freq = devfreq_userspace_func,
	.event_handler = devfreq_userspace_handler,
};

static int __init devfreq_userspace_init(void)
{
	return devfreq_add_governor(&devfreq_userspace);
}
subsys_initcall(devfreq_userspace_init);

static void __exit devfreq_userspace_exit(void)
{
	int ret;

	ret = devfreq_remove_governor(&devfreq_userspace);
	if (ret)
		pr_err("%s: failed remove governor %d\n", __func__, ret);

	return;
}
module_exit(devfreq_userspace_exit);
MODULE_LICENSE("GPL");