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 
20 struct userspace_data {
21 	unsigned long user_frequency;
22 	bool valid;
23 };
24 
25 static 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 
37 static 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 
58 static 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 
76 static DEVICE_ATTR(set_freq, 0644, show_freq, store_freq);
77 static struct attribute *dev_entries[] = {
78 	&dev_attr_set_freq.attr,
79 	NULL,
80 };
81 static const struct attribute_group dev_attr_group = {
82 	.name	= DEVFREQ_GOV_USERSPACE,
83 	.attrs	= dev_entries,
84 };
85 
86 static 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);
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->data);
114 	devfreq->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 = "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_LICENSE("GPL");
160