1/*
2 * linux/drivers/devfreq/governor_userspace.c
3 *
4 * Copyright (C) 2011 Samsung Electronics
5 * MyungJoo Ham <myungjoo.ham@samsung.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 <linux/slab.h>
13#include <linux/device.h>
14#include <linux/devfreq.h>
15#include <linux/pm.h>
16#include <linux/mutex.h>
17#include <linux/module.h>
18#include "governor.h"
19
20struct userspace_data {
21 unsigned long user_frequency;
22 bool valid;
23};
24
25static int devfreq_userspace_func(struct devfreq *df, unsigned long *freq)
26{
27 struct userspace_data *data = df->data;
28
29 if (data->valid)
30 *freq = data->user_frequency;
31 else
32 *freq = df->previous_freq; /* No user freq specified yet */
33
34 return 0;
35}
36
37static ssize_t store_freq(struct device *dev, struct device_attribute *attr,
38 const char *buf, size_t count)
39{
40 struct devfreq *devfreq = to_devfreq(dev);
41 struct userspace_data *data;
42 unsigned long wanted;
43 int err = 0;
44
45 mutex_lock(&devfreq->lock);
46 data = devfreq->data;
47
48 sscanf(buf, "%lu", &wanted);
49 data->user_frequency = wanted;
50 data->valid = true;
51 err = update_devfreq(devfreq);
52 if (err == 0)
53 err = count;
54 mutex_unlock(&devfreq->lock);
55 return err;
56}
57
58static ssize_t show_freq(struct device *dev, struct device_attribute *attr,
59 char *buf)
60{
61 struct devfreq *devfreq = to_devfreq(dev);
62 struct userspace_data *data;
63 int err = 0;
64
65 mutex_lock(&devfreq->lock);
66 data = devfreq->data;
67
68 if (data->valid)
69 err = sprintf(buf, "%lu\n", data->user_frequency);
70 else
71 err = sprintf(buf, "undefined\n");
72 mutex_unlock(&devfreq->lock);
73 return err;
74}
75
76static DEVICE_ATTR(set_freq, 0644, show_freq, store_freq);
77static struct attribute *dev_entries[] = {
78 &dev_attr_set_freq.attr,
79 NULL,
80};
81static const struct attribute_group dev_attr_group = {
82 .name = DEVFREQ_GOV_USERSPACE,
83 .attrs = dev_entries,
84};
85
86static int userspace_init(struct devfreq *devfreq)
87{
88 int err = 0;
89 struct userspace_data *data = kzalloc(sizeof(struct userspace_data),
90 GFP_KERNEL);
91
92 if (!data) {
93 err = -ENOMEM;
94 goto out;
95 }
96 data->valid = false;
97 devfreq->data = data;
98
99 err = sysfs_create_group(&devfreq->dev.kobj, &dev_attr_group);
100out:
101 return err;
102}
103
104static 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->data);
114 devfreq->data = NULL;
115}
116
117static 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
136static struct devfreq_governor devfreq_userspace = {
137 .name = "userspace",
138 .get_target_freq = devfreq_userspace_func,
139 .event_handler = devfreq_userspace_handler,
140};
141
142static int __init devfreq_userspace_init(void)
143{
144 return devfreq_add_governor(&devfreq_userspace);
145}
146subsys_initcall(devfreq_userspace_init);
147
148static 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}
158module_exit(devfreq_userspace_exit);
159MODULE_LICENSE("GPL");
160