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 <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 
54 	mutex_lock(&devfreq->lock);
55 	data = devfreq->data;
56 
57 	sscanf(buf, "%lu", &wanted);
58 	data->user_frequency = wanted;
59 	data->valid = true;
60 	err = update_devfreq(devfreq);
61 	if (err == 0)
62 		err = count;
63 	mutex_unlock(&devfreq->lock);
64 	return err;
65 }
66 
67 static ssize_t show_freq(struct device *dev, struct device_attribute *attr,
68 			 char *buf)
69 {
70 	struct devfreq *devfreq = to_devfreq(dev);
71 	struct userspace_data *data;
72 	int err = 0;
73 
74 	mutex_lock(&devfreq->lock);
75 	data = devfreq->data;
76 
77 	if (data->valid)
78 		err = sprintf(buf, "%lu\n", data->user_frequency);
79 	else
80 		err = sprintf(buf, "undefined\n");
81 	mutex_unlock(&devfreq->lock);
82 	return err;
83 }
84 
85 static DEVICE_ATTR(set_freq, 0644, show_freq, store_freq);
86 static struct attribute *dev_entries[] = {
87 	&dev_attr_set_freq.attr,
88 	NULL,
89 };
90 static struct attribute_group dev_attr_group = {
91 	.name	= "userspace",
92 	.attrs	= dev_entries,
93 };
94 
95 static int userspace_init(struct devfreq *devfreq)
96 {
97 	int err = 0;
98 	struct userspace_data *data = kzalloc(sizeof(struct userspace_data),
99 					      GFP_KERNEL);
100 
101 	if (!data) {
102 		err = -ENOMEM;
103 		goto out;
104 	}
105 	data->valid = false;
106 	devfreq->data = data;
107 
108 	err = sysfs_create_group(&devfreq->dev.kobj, &dev_attr_group);
109 out:
110 	return err;
111 }
112 
113 static void userspace_exit(struct devfreq *devfreq)
114 {
115 	sysfs_remove_group(&devfreq->dev.kobj, &dev_attr_group);
116 	kfree(devfreq->data);
117 	devfreq->data = NULL;
118 }
119 
120 static int devfreq_userspace_handler(struct devfreq *devfreq,
121 			unsigned int event, void *data)
122 {
123 	int ret = 0;
124 
125 	switch (event) {
126 	case DEVFREQ_GOV_START:
127 		ret = userspace_init(devfreq);
128 		break;
129 	case DEVFREQ_GOV_STOP:
130 		userspace_exit(devfreq);
131 		break;
132 	default:
133 		break;
134 	}
135 
136 	return ret;
137 }
138 
139 static struct devfreq_governor devfreq_userspace = {
140 	.name = "userspace",
141 	.get_target_freq = devfreq_userspace_func,
142 	.event_handler = devfreq_userspace_handler,
143 };
144 
145 static int __init devfreq_userspace_init(void)
146 {
147 	return devfreq_add_governor(&devfreq_userspace);
148 }
149 subsys_initcall(devfreq_userspace_init);
150 
151 static void __exit devfreq_userspace_exit(void)
152 {
153 	int ret;
154 
155 	ret = devfreq_remove_governor(&devfreq_userspace);
156 	if (ret)
157 		pr_err("%s: failed remove governor %d\n", __func__, ret);
158 
159 	return;
160 }
161 module_exit(devfreq_userspace_exit);
162 MODULE_LICENSE("GPL");
163