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(lock: &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, fmt: "%lu\n", data->user_frequency);
67 else
68 err = sprintf(buf, fmt: "undefined\n");
69 mutex_unlock(lock: &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(size: 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(kobj: &devfreq->dev.kobj, grp: &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(kobj: &devfreq->dev.kobj, grp: &dev_attr_group);
109
110 kfree(objp: 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(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(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

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