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 };
117