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
20struct userspace_data {
21	unsigned long user_frequency;
22	bool valid;
23};
24
25static 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
45static 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
67static 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
85static DEVICE_ATTR(set_freq, 0644, show_freq, store_freq);
86static struct attribute *dev_entries[] = {
87	&dev_attr_set_freq.attr,
88	NULL,
89};
90static struct attribute_group dev_attr_group = {
91	.name	= "userspace",
92	.attrs	= dev_entries,
93};
94
95static 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);
109out:
110	return err;
111}
112
113static 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
120static 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
139static struct devfreq_governor devfreq_userspace = {
140	.name = "userspace",
141	.get_target_freq = devfreq_userspace_func,
142	.event_handler = devfreq_userspace_handler,
143};
144
145static int __init devfreq_userspace_init(void)
146{
147	return devfreq_add_governor(&devfreq_userspace);
148}
149subsys_initcall(devfreq_userspace_init);
150
151static 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}
161module_exit(devfreq_userspace_exit);
162MODULE_LICENSE("GPL");
163