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
 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	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
 66static 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
 84static DEVICE_ATTR(set_freq, 0644, show_freq, store_freq);
 85static struct attribute *dev_entries[] = {
 86	&dev_attr_set_freq.attr,
 87	NULL,
 88};
 89static const struct attribute_group dev_attr_group = {
 90	.name	= DEVFREQ_GOV_USERSPACE,
 91	.attrs	= dev_entries,
 92};
 93
 94static 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);
108out:
109	return err;
110}
111
112static 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
125static 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
144static struct devfreq_governor devfreq_userspace = {
145	.name = "userspace",
146	.get_target_freq = devfreq_userspace_func,
147	.event_handler = devfreq_userspace_handler,
148};
149
150static int __init devfreq_userspace_init(void)
151{
152	return devfreq_add_governor(&devfreq_userspace);
153}
154subsys_initcall(devfreq_userspace_init);
155
156static 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}
166module_exit(devfreq_userspace_exit);
167MODULE_LICENSE("GPL");