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");