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 
17 struct userspace_data {
18 	unsigned long user_frequency;
19 	bool valid;
20 };
21 
22 static int devfreq_userspace_func(struct devfreq *df, unsigned long *freq)
23 {
24 	struct userspace_data *data = df->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 
34 static ssize_t store_freq(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->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 
55 static ssize_t show_freq(struct device *dev, struct device_attribute *attr,
56 			 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->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 
73 static DEVICE_ATTR(set_freq, 0644, show_freq, store_freq);
74 static struct attribute *dev_entries[] = {
75 	&dev_attr_set_freq.attr,
76 	NULL,
77 };
78 static const struct attribute_group dev_attr_group = {
79 	.name	= DEVFREQ_GOV_USERSPACE,
80 	.attrs	= dev_entries,
81 };
82 
83 static 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->data = data;
95 
96 	err = sysfs_create_group(&devfreq->dev.kobj, &dev_attr_group);
97 out:
98 	return err;
99 }
100 
101 static 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->data);
111 	devfreq->data = NULL;
112 }
113 
114 static 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 
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,
137 };
138 
139 static int __init devfreq_userspace_init(void)
140 {
141 	return devfreq_add_governor(&devfreq_userspace);
142 }
143 subsys_initcall(devfreq_userspace_init);
144 
145 static 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 }
155 module_exit(devfreq_userspace_exit);
156 MODULE_LICENSE("GPL");
157