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");
157