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(s: buf, base: 0, res: &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(lock: &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, fmt: "%lu\n", data->user_frequency);
71 else
72 err = sprintf(buf, fmt: "undefined\n");
73 mutex_unlock(lock: &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(kobj: &devfreq->dev.kobj, grp: &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(kobj: &devfreq->dev.kobj, grp: &dev_attr_group);
113
114 kfree(objp: 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(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(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");
162

source code of linux/drivers/devfreq/governor_userspace.c