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
18 struct userspace_data {
19 unsigned long user_frequency;
20 bool valid;
21 };
22
devfreq_userspace_func(struct devfreq * df,unsigned long * freq)23 static 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
set_freq_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)35 static 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(buf, 0, &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(&devfreq->lock);
56 return err;
57 }
58
set_freq_show(struct device * dev,struct device_attribute * attr,char * buf)59 static 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, "%lu\n", data->user_frequency);
71 else
72 err = sprintf(buf, "undefined\n");
73 mutex_unlock(&devfreq->lock);
74 return err;
75 }
76
77 static DEVICE_ATTR_RW(set_freq);
78 static struct attribute *dev_entries[] = {
79 &dev_attr_set_freq.attr,
80 NULL,
81 };
82 static const struct attribute_group dev_attr_group = {
83 .name = DEVFREQ_GOV_USERSPACE,
84 .attrs = dev_entries,
85 };
86
userspace_init(struct devfreq * devfreq)87 static int userspace_init(struct devfreq *devfreq)
88 {
89 int err = 0;
90 struct userspace_data *data = kzalloc_obj(struct userspace_data);
91
92 if (!data) {
93 err = -ENOMEM;
94 goto out;
95 }
96 data->valid = false;
97 devfreq->governor_data = data;
98
99 err = sysfs_create_group(&devfreq->dev.kobj, &dev_attr_group);
100 out:
101 return err;
102 }
103
userspace_exit(struct devfreq * devfreq)104 static void userspace_exit(struct devfreq *devfreq)
105 {
106 /*
107 * Remove the sysfs entry, unless this is being called after
108 * device_del(), which should have done this already via kobject_del().
109 */
110 if (devfreq->dev.kobj.sd)
111 sysfs_remove_group(&devfreq->dev.kobj, &dev_attr_group);
112
113 kfree(devfreq->governor_data);
114 devfreq->governor_data = NULL;
115 }
116
devfreq_userspace_handler(struct devfreq * devfreq,unsigned int event,void * data)117 static int devfreq_userspace_handler(struct devfreq *devfreq,
118 unsigned int event, void *data)
119 {
120 int ret = 0;
121
122 switch (event) {
123 case DEVFREQ_GOV_START:
124 ret = userspace_init(devfreq);
125 break;
126 case DEVFREQ_GOV_STOP:
127 userspace_exit(devfreq);
128 break;
129 default:
130 break;
131 }
132
133 return ret;
134 }
135
136 static struct devfreq_governor devfreq_userspace = {
137 .name = DEVFREQ_GOV_USERSPACE,
138 .get_target_freq = devfreq_userspace_func,
139 .event_handler = devfreq_userspace_handler,
140 };
141
devfreq_userspace_init(void)142 static int __init devfreq_userspace_init(void)
143 {
144 return devfreq_add_governor(&devfreq_userspace);
145 }
146 subsys_initcall(devfreq_userspace_init);
147
devfreq_userspace_exit(void)148 static void __exit devfreq_userspace_exit(void)
149 {
150 int ret;
151
152 ret = devfreq_remove_governor(&devfreq_userspace);
153 if (ret)
154 pr_err("%s: failed remove governor %d\n", __func__, ret);
155
156 return;
157 }
158 module_exit(devfreq_userspace_exit);
159 MODULE_DESCRIPTION("DEVFREQ Userspace governor");
160 MODULE_LICENSE("GPL");
161