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 		unsigned long adjusted_freq = data->user_frequency;
31 
32 		if (df->max_freq && adjusted_freq > df->max_freq)
33 			adjusted_freq = df->max_freq;
34 
35 		if (df->min_freq && adjusted_freq < df->min_freq)
36 			adjusted_freq = df->min_freq;
37 
38 		*freq = adjusted_freq;
39 	} else {
40 		*freq = df->previous_freq; /* No user freq specified yet */
41 	}
42 	return 0;
43 }
44 
45 static ssize_t store_freq(struct device *dev, struct device_attribute *attr,
46 			  const char *buf, size_t count)
47 {
48 	struct devfreq *devfreq = to_devfreq(dev);
49 	struct userspace_data *data;
50 	unsigned long wanted;
51 	int err = 0;
52 
53 	mutex_lock(&devfreq->lock);
54 	data = devfreq->data;
55 
56 	sscanf(buf, "%lu", &wanted);
57 	data->user_frequency = wanted;
58 	data->valid = true;
59 	err = update_devfreq(devfreq);
60 	if (err == 0)
61 		err = count;
62 	mutex_unlock(&devfreq->lock);
63 	return err;
64 }
65 
66 static ssize_t show_freq(struct device *dev, struct device_attribute *attr,
67 			 char *buf)
68 {
69 	struct devfreq *devfreq = to_devfreq(dev);
70 	struct userspace_data *data;
71 	int err = 0;
72 
73 	mutex_lock(&devfreq->lock);
74 	data = devfreq->data;
75 
76 	if (data->valid)
77 		err = sprintf(buf, "%lu\n", data->user_frequency);
78 	else
79 		err = sprintf(buf, "undefined\n");
80 	mutex_unlock(&devfreq->lock);
81 	return err;
82 }
83 
84 static DEVICE_ATTR(set_freq, 0644, show_freq, store_freq);
85 static struct attribute *dev_entries[] = {
86 	&dev_attr_set_freq.attr,
87 	NULL,
88 };
89 static const struct attribute_group dev_attr_group = {
90 	.name	= DEVFREQ_GOV_USERSPACE,
91 	.attrs	= dev_entries,
92 };
93 
94 static int userspace_init(struct devfreq *devfreq)
95 {
96 	int err = 0;
97 	struct userspace_data *data = kzalloc(sizeof(struct userspace_data),
98 					      GFP_KERNEL);
99 
100 	if (!data) {
101 		err = -ENOMEM;
102 		goto out;
103 	}
104 	data->valid = false;
105 	devfreq->data = data;
106 
107 	err = sysfs_create_group(&devfreq->dev.kobj, &dev_attr_group);
108 out:
109 	return err;
110 }
111 
112 static void userspace_exit(struct devfreq *devfreq)
113 {
114 	/*
115 	 * Remove the sysfs entry, unless this is being called after
116 	 * device_del(), which should have done this already via kobject_del().
117 	 */
118 	if (devfreq->dev.kobj.sd)
119 		sysfs_remove_group(&devfreq->dev.kobj, &dev_attr_group);
120 
121 	kfree(devfreq->data);
122 	devfreq->data = NULL;
123 }
124 
125 static int devfreq_userspace_handler(struct devfreq *devfreq,
126 			unsigned int event, void *data)
127 {
128 	int ret = 0;
129 
130 	switch (event) {
131 	case DEVFREQ_GOV_START:
132 		ret = userspace_init(devfreq);
133 		break;
134 	case DEVFREQ_GOV_STOP:
135 		userspace_exit(devfreq);
136 		break;
137 	default:
138 		break;
139 	}
140 
141 	return ret;
142 }
143 
144 static struct devfreq_governor devfreq_userspace = {
145 	.name = "userspace",
146 	.get_target_freq = devfreq_userspace_func,
147 	.event_handler = devfreq_userspace_handler,
148 };
149 
150 static int __init devfreq_userspace_init(void)
151 {
152 	return devfreq_add_governor(&devfreq_userspace);
153 }
154 subsys_initcall(devfreq_userspace_init);
155 
156 static void __exit devfreq_userspace_exit(void)
157 {
158 	int ret;
159 
160 	ret = devfreq_remove_governor(&devfreq_userspace);
161 	if (ret)
162 		pr_err("%s: failed remove governor %d\n", __func__, ret);
163 
164 	return;
165 }
166 module_exit(devfreq_userspace_exit);
167 MODULE_LICENSE("GPL");
168