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
devfreq_userspace_func(struct devfreq * df,unsigned long * freq)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
store_freq(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)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
show_freq(struct device * dev,struct device_attribute * attr,char * buf)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
userspace_init(struct devfreq * devfreq)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
userspace_exit(struct devfreq * devfreq)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
devfreq_userspace_handler(struct devfreq * devfreq,unsigned int event,void * data)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
devfreq_userspace_init(void)139 static int __init devfreq_userspace_init(void)
140 {
141 return devfreq_add_governor(&devfreq_userspace);
142 }
143 subsys_initcall(devfreq_userspace_init);
144
devfreq_userspace_exit(void)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