governor_userspace.c

  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/devfreq-governor.h>
 13#include <linux/kstrtox.h>
 14#include <linux/pm.h>
 15#include <linux/mutex.h>
 16#include <linux/module.h>
 17
 18struct userspace_data {
 19	unsigned long user_frequency;
 20	bool valid;
 21};
 22
 23static int devfreq_userspace_func(struct devfreq *df, unsigned long *freq)
 24{
 25	struct userspace_data *data = df->governor_data;
 26
 27	if (data->valid)
 28		*freq = data->user_frequency;
 29	else
 30		*freq = df->previous_freq; /* No user freq specified yet */
 31
 32	return 0;
 33}
 34
 35static ssize_t set_freq_store(struct device *dev, struct device_attribute *attr,
 36			      const char *buf, size_t count)
 37{
 38	struct devfreq *devfreq = to_devfreq(dev);
 39	struct userspace_data *data;
 40	unsigned long wanted;
 41	int err = 0;
 42
 43	err = kstrtoul(buf, 0, &wanted);
 44	if (err)
 45		return err;
 46
 47	mutex_lock(&devfreq->lock);
 48	data = devfreq->governor_data;
 49
 50	data->user_frequency = wanted;
 51	data->valid = true;
 52	err = update_devfreq(devfreq);
 53	if (err == 0)
 54		err = count;
 55	mutex_unlock(&devfreq->lock);
 56	return err;
 57}
 58
 59static ssize_t set_freq_show(struct device *dev,
 60			     struct device_attribute *attr, char *buf)
 61{
 62	struct devfreq *devfreq = to_devfreq(dev);
 63	struct userspace_data *data;
 64	int err = 0;
 65
 66	mutex_lock(&devfreq->lock);
 67	data = devfreq->governor_data;
 68
 69	if (data->valid)
 70		err = sprintf(buf, "%lu\n", data->user_frequency);
 71	else
 72		err = sprintf(buf, "undefined\n");
 73	mutex_unlock(&devfreq->lock);
 74	return err;
 75}
 76
 77static DEVICE_ATTR_RW(set_freq);
 78static struct attribute *dev_entries[] = {
 79	&dev_attr_set_freq.attr,
 80	NULL,
 81};
 82static const struct attribute_group dev_attr_group = {
 83	.name	= DEVFREQ_GOV_USERSPACE,
 84	.attrs	= dev_entries,
 85};
 86
 87static int userspace_init(struct devfreq *devfreq)
 88{
 89	int err = 0;
 90	struct userspace_data *data = kzalloc(sizeof(struct userspace_data),
 91					      GFP_KERNEL);
 92
 93	if (!data) {
 94		err = -ENOMEM;
 95		goto out;
 96	}
 97	data->valid = false;
 98	devfreq->governor_data = data;
 99
100	err = sysfs_create_group(&devfreq->dev.kobj, &dev_attr_group);
101out:
102	return err;
103}
104
105static void userspace_exit(struct devfreq *devfreq)
106{
107	/*
108	 * Remove the sysfs entry, unless this is being called after
109	 * device_del(), which should have done this already via kobject_del().
110	 */
111	if (devfreq->dev.kobj.sd)
112		sysfs_remove_group(&devfreq->dev.kobj, &dev_attr_group);
113
114	kfree(devfreq->governor_data);
115	devfreq->governor_data = NULL;
116}
117
118static int devfreq_userspace_handler(struct devfreq *devfreq,
119			unsigned int event, void *data)
120{
121	int ret = 0;
122
123	switch (event) {
124	case DEVFREQ_GOV_START:
125		ret = userspace_init(devfreq);
126		break;
127	case DEVFREQ_GOV_STOP:
128		userspace_exit(devfreq);
129		break;
130	default:
131		break;
132	}
133
134	return ret;
135}
136
137static struct devfreq_governor devfreq_userspace = {
138	.name = DEVFREQ_GOV_USERSPACE,
139	.get_target_freq = devfreq_userspace_func,
140	.event_handler = devfreq_userspace_handler,
141};
142
143static int __init devfreq_userspace_init(void)
144{
145	return devfreq_add_governor(&devfreq_userspace);
146}
147subsys_initcall(devfreq_userspace_init);
148
149static void __exit devfreq_userspace_exit(void)
150{
151	int ret;
152
153	ret = devfreq_remove_governor(&devfreq_userspace);
154	if (ret)
155		pr_err("%s: failed remove governor %d\n", __func__, ret);
156
157	return;
158}
159module_exit(devfreq_userspace_exit);
160MODULE_DESCRIPTION("DEVFREQ Userspace governor");
161MODULE_LICENSE("GPL");