PM / devfreq: Add basic governors
[linux-2.6.git] / drivers / devfreq / governor_userspace.c
1 /*
2  *  linux/drivers/devfreq/governor_simpleondemand.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 "governor.h"
18
19 struct userspace_data {
20         unsigned long user_frequency;
21         bool valid;
22 };
23
24 static int devfreq_userspace_func(struct devfreq *df, unsigned long *freq)
25 {
26         struct userspace_data *data = df->data;
27
28         if (!data->valid)
29                 *freq = df->previous_freq; /* No user freq specified yet */
30         else
31                 *freq = data->user_frequency;
32         return 0;
33 }
34
35 static ssize_t store_freq(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
44         mutex_lock(&devfreq->lock);
45         data = devfreq->data;
46
47         sscanf(buf, "%lu", &wanted);
48         data->user_frequency = wanted;
49         data->valid = true;
50         err = update_devfreq(devfreq);
51         if (err == 0)
52                 err = count;
53         mutex_unlock(&devfreq->lock);
54         return err;
55 }
56
57 static ssize_t show_freq(struct device *dev, struct device_attribute *attr,
58                          char *buf)
59 {
60         struct devfreq *devfreq = to_devfreq(dev);
61         struct userspace_data *data;
62         int err = 0;
63
64         mutex_lock(&devfreq->lock);
65         data = devfreq->data;
66
67         if (data->valid)
68                 err = sprintf(buf, "%lu\n", data->user_frequency);
69         else
70                 err = sprintf(buf, "undefined\n");
71         mutex_unlock(&devfreq->lock);
72         return err;
73 }
74
75 static DEVICE_ATTR(set_freq, 0644, show_freq, store_freq);
76 static struct attribute *dev_entries[] = {
77         &dev_attr_set_freq.attr,
78         NULL,
79 };
80 static struct attribute_group dev_attr_group = {
81         .name   = "userspace",
82         .attrs  = dev_entries,
83 };
84
85 static int userspace_init(struct devfreq *devfreq)
86 {
87         int err = 0;
88         struct userspace_data *data = kzalloc(sizeof(struct userspace_data),
89                                               GFP_KERNEL);
90
91         if (!data) {
92                 err = -ENOMEM;
93                 goto out;
94         }
95         data->valid = false;
96         devfreq->data = data;
97
98         err = sysfs_create_group(&devfreq->dev.kobj, &dev_attr_group);
99 out:
100         return err;
101 }
102
103 static void userspace_exit(struct devfreq *devfreq)
104 {
105         sysfs_remove_group(&devfreq->dev.kobj, &dev_attr_group);
106         kfree(devfreq->data);
107         devfreq->data = NULL;
108 }
109
110 const struct devfreq_governor devfreq_userspace = {
111         .name = "userspace",
112         .get_target_freq = devfreq_userspace_func,
113         .init = userspace_init,
114         .exit = userspace_exit,
115         .no_central_polling = true,
116 };