1 // SPDX-License-Identifier: GPL-2.0-only
3 * linux/drivers/devfreq/governor_userspace.c
5 * Copyright (C) 2011 Samsung Electronics
6 * MyungJoo Ham <myungjoo.ham@samsung.com>
9 #include <linux/slab.h>
10 #include <linux/device.h>
11 #include <linux/devfreq.h>
13 #include <linux/mutex.h>
14 #include <linux/module.h>
17 struct userspace_data
{
18 unsigned long user_frequency
;
22 static int devfreq_userspace_func(struct devfreq
*df
, unsigned long *freq
)
24 struct userspace_data
*data
= df
->data
;
27 *freq
= data
->user_frequency
;
29 *freq
= df
->previous_freq
; /* No user freq specified yet */
34 static ssize_t
store_freq(struct device
*dev
, struct device_attribute
*attr
,
35 const char *buf
, size_t count
)
37 struct devfreq
*devfreq
= to_devfreq(dev
);
38 struct userspace_data
*data
;
42 mutex_lock(&devfreq
->lock
);
45 sscanf(buf
, "%lu", &wanted
);
46 data
->user_frequency
= wanted
;
48 err
= update_devfreq(devfreq
);
51 mutex_unlock(&devfreq
->lock
);
55 static ssize_t
show_freq(struct device
*dev
, struct device_attribute
*attr
,
58 struct devfreq
*devfreq
= to_devfreq(dev
);
59 struct userspace_data
*data
;
62 mutex_lock(&devfreq
->lock
);
66 err
= sprintf(buf
, "%lu\n", data
->user_frequency
);
68 err
= sprintf(buf
, "undefined\n");
69 mutex_unlock(&devfreq
->lock
);
73 static DEVICE_ATTR(set_freq
, 0644, show_freq
, store_freq
);
74 static struct attribute
*dev_entries
[] = {
75 &dev_attr_set_freq
.attr
,
78 static const struct attribute_group dev_attr_group
= {
79 .name
= DEVFREQ_GOV_USERSPACE
,
83 static int userspace_init(struct devfreq
*devfreq
)
86 struct userspace_data
*data
= kzalloc(sizeof(struct userspace_data
),
96 err
= sysfs_create_group(&devfreq
->dev
.kobj
, &dev_attr_group
);
101 static void userspace_exit(struct devfreq
*devfreq
)
104 * Remove the sysfs entry, unless this is being called after
105 * device_del(), which should have done this already via kobject_del().
107 if (devfreq
->dev
.kobj
.sd
)
108 sysfs_remove_group(&devfreq
->dev
.kobj
, &dev_attr_group
);
110 kfree(devfreq
->data
);
111 devfreq
->data
= NULL
;
114 static int devfreq_userspace_handler(struct devfreq
*devfreq
,
115 unsigned int event
, void *data
)
120 case DEVFREQ_GOV_START
:
121 ret
= userspace_init(devfreq
);
123 case DEVFREQ_GOV_STOP
:
124 userspace_exit(devfreq
);
133 static struct devfreq_governor devfreq_userspace
= {
134 .name
= DEVFREQ_GOV_USERSPACE
,
135 .get_target_freq
= devfreq_userspace_func
,
136 .event_handler
= devfreq_userspace_handler
,
139 static int __init
devfreq_userspace_init(void)
141 return devfreq_add_governor(&devfreq_userspace
);
143 subsys_initcall(devfreq_userspace_init
);
145 static void __exit
devfreq_userspace_exit(void)
149 ret
= devfreq_remove_governor(&devfreq_userspace
);
151 pr_err("%s: failed remove governor %d\n", __func__
, ret
);
155 module_exit(devfreq_userspace_exit
);
156 MODULE_LICENSE("GPL");