1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 *  linux/drivers/devfreq/governor_userspace.c
  4 *
  5 *  Copyright (C) 2011 Samsung Electronics
  6 *	MyungJoo Ham <myungjoo.ham@samsung.com>
  7 */
  8
  9#include <linux/slab.h>
 10#include <linux/device.h>
 11#include <linux/devfreq.h>
 12#include <linux/pm.h>
 13#include <linux/mutex.h>
 14#include <linux/module.h>
 15#include "governor.h"
 16
 17struct userspace_data {
 18	unsigned long user_frequency;
 19	bool valid;
 20};
 21
 22static int devfreq_userspace_func(struct devfreq *df, unsigned long *freq)
 23{
 24	struct userspace_data *data = df->governor_data;
 25
 26	if (data->valid)
 27		*freq = data->user_frequency;
 28	else
 29		*freq = df->previous_freq; /* No user freq specified yet */
 30
 31	return 0;
 32}
 33
 34static ssize_t set_freq_store(struct device *dev, struct device_attribute *attr,
 35			      const char *buf, size_t count)
 36{
 37	struct devfreq *devfreq = to_devfreq(dev);
 38	struct userspace_data *data;
 39	unsigned long wanted;
 40	int err = 0;
 41
 42	mutex_lock(&devfreq->lock);
 43	data = devfreq->governor_data;
 44
 45	sscanf(buf, "%lu", &wanted);
 46	data->user_frequency = wanted;
 47	data->valid = true;
 48	err = update_devfreq(devfreq);
 49	if (err == 0)
 50		err = count;
 51	mutex_unlock(&devfreq->lock);
 52	return err;
 53}
 54
 55static ssize_t set_freq_show(struct device *dev,
 56			     struct device_attribute *attr, char *buf)
 57{
 58	struct devfreq *devfreq = to_devfreq(dev);
 59	struct userspace_data *data;
 60	int err = 0;
 61
 62	mutex_lock(&devfreq->lock);
 63	data = devfreq->governor_data;
 64
 65	if (data->valid)
 66		err = sprintf(buf, "%lu\n", data->user_frequency);
 67	else
 68		err = sprintf(buf, "undefined\n");
 69	mutex_unlock(&devfreq->lock);
 70	return err;
 71}
 72
 73static DEVICE_ATTR_RW(set_freq);
 74static struct attribute *dev_entries[] = {
 75	&dev_attr_set_freq.attr,
 76	NULL,
 77};
 78static const struct attribute_group dev_attr_group = {
 79	.name	= DEVFREQ_GOV_USERSPACE,
 80	.attrs	= dev_entries,
 81};
 82
 83static int userspace_init(struct devfreq *devfreq)
 84{
 85	int err = 0;
 86	struct userspace_data *data = kzalloc(sizeof(struct userspace_data),
 87					      GFP_KERNEL);
 88
 89	if (!data) {
 90		err = -ENOMEM;
 91		goto out;
 92	}
 93	data->valid = false;
 94	devfreq->governor_data = data;
 95
 96	err = sysfs_create_group(&devfreq->dev.kobj, &dev_attr_group);
 97out:
 98	return err;
 99}
100
101static void userspace_exit(struct devfreq *devfreq)
102{
103	/*
104	 * Remove the sysfs entry, unless this is being called after
105	 * device_del(), which should have done this already via kobject_del().
106	 */
107	if (devfreq->dev.kobj.sd)
108		sysfs_remove_group(&devfreq->dev.kobj, &dev_attr_group);
109
110	kfree(devfreq->governor_data);
111	devfreq->governor_data = NULL;
112}
113
114static int devfreq_userspace_handler(struct devfreq *devfreq,
115			unsigned int event, void *data)
116{
117	int ret = 0;
118
119	switch (event) {
120	case DEVFREQ_GOV_START:
121		ret = userspace_init(devfreq);
122		break;
123	case DEVFREQ_GOV_STOP:
124		userspace_exit(devfreq);
125		break;
126	default:
127		break;
128	}
129
130	return ret;
131}
132
133static struct devfreq_governor devfreq_userspace = {
134	.name = DEVFREQ_GOV_USERSPACE,
135	.get_target_freq = devfreq_userspace_func,
136	.event_handler = devfreq_userspace_handler,
137};
138
139static int __init devfreq_userspace_init(void)
140{
141	return devfreq_add_governor(&devfreq_userspace);
142}
143subsys_initcall(devfreq_userspace_init);
144
145static void __exit devfreq_userspace_exit(void)
146{
147	int ret;
148
149	ret = devfreq_remove_governor(&devfreq_userspace);
150	if (ret)
151		pr_err("%s: failed remove governor %d\n", __func__, ret);
152
153	return;
154}
155module_exit(devfreq_userspace_exit);
156MODULE_LICENSE("GPL");