1 /*
2 * linux/drivers/devfreq/governor_simpleondemand.c
3 *
4 * Copyright (C) 2011 Samsung Electronics
5 * MyungJoo Ham <myungjoo.ham@samsung.com>
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
10 */
11
12 #include <linux/slab.h>
13 #include <linux/device.h>
14 #include <linux/devfreq.h>
15 #include <linux/pm.h>
16 #include <linux/mutex.h>
17 #include <linux/module.h>
18 #include "governor.h"
19
20 struct userspace_data {
21 unsigned long user_frequency;
22 bool valid;
23 };
24
devfreq_userspace_func(struct devfreq * df,unsigned long * freq)25 static int devfreq_userspace_func(struct devfreq *df, unsigned long *freq)
26 {
27 struct userspace_data *data = df->data;
28
29 if (data->valid) {
30 unsigned long adjusted_freq = data->user_frequency;
31
32 if (df->max_freq && adjusted_freq > df->max_freq)
33 adjusted_freq = df->max_freq;
34
35 if (df->min_freq && adjusted_freq < df->min_freq)
36 adjusted_freq = df->min_freq;
37
38 *freq = adjusted_freq;
39 } else {
40 *freq = df->previous_freq; /* No user freq specified yet */
41 }
42 return 0;
43 }
44
store_freq(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)45 static ssize_t store_freq(struct device *dev, struct device_attribute *attr,
46 const char *buf, size_t count)
47 {
48 struct devfreq *devfreq = to_devfreq(dev);
49 struct userspace_data *data;
50 unsigned long wanted;
51 int err = 0;
52
53
54 mutex_lock(&devfreq->lock);
55 data = devfreq->data;
56
57 sscanf(buf, "%lu", &wanted);
58 data->user_frequency = wanted;
59 data->valid = true;
60 err = update_devfreq(devfreq);
61 if (err == 0)
62 err = count;
63 mutex_unlock(&devfreq->lock);
64 return err;
65 }
66
show_freq(struct device * dev,struct device_attribute * attr,char * buf)67 static ssize_t show_freq(struct device *dev, struct device_attribute *attr,
68 char *buf)
69 {
70 struct devfreq *devfreq = to_devfreq(dev);
71 struct userspace_data *data;
72 int err = 0;
73
74 mutex_lock(&devfreq->lock);
75 data = devfreq->data;
76
77 if (data->valid)
78 err = sprintf(buf, "%lu\n", data->user_frequency);
79 else
80 err = sprintf(buf, "undefined\n");
81 mutex_unlock(&devfreq->lock);
82 return err;
83 }
84
85 static DEVICE_ATTR(set_freq, 0644, show_freq, store_freq);
86 static struct attribute *dev_entries[] = {
87 &dev_attr_set_freq.attr,
88 NULL,
89 };
90 static struct attribute_group dev_attr_group = {
91 .name = "userspace",
92 .attrs = dev_entries,
93 };
94
userspace_init(struct devfreq * devfreq)95 static int userspace_init(struct devfreq *devfreq)
96 {
97 int err = 0;
98 struct userspace_data *data = kzalloc(sizeof(struct userspace_data),
99 GFP_KERNEL);
100
101 if (!data) {
102 err = -ENOMEM;
103 goto out;
104 }
105 data->valid = false;
106 devfreq->data = data;
107
108 err = sysfs_create_group(&devfreq->dev.kobj, &dev_attr_group);
109 out:
110 return err;
111 }
112
userspace_exit(struct devfreq * devfreq)113 static void userspace_exit(struct devfreq *devfreq)
114 {
115 sysfs_remove_group(&devfreq->dev.kobj, &dev_attr_group);
116 kfree(devfreq->data);
117 devfreq->data = NULL;
118 }
119
devfreq_userspace_handler(struct devfreq * devfreq,unsigned int event,void * data)120 static int devfreq_userspace_handler(struct devfreq *devfreq,
121 unsigned int event, void *data)
122 {
123 int ret = 0;
124
125 switch (event) {
126 case DEVFREQ_GOV_START:
127 ret = userspace_init(devfreq);
128 break;
129 case DEVFREQ_GOV_STOP:
130 userspace_exit(devfreq);
131 break;
132 default:
133 break;
134 }
135
136 return ret;
137 }
138
139 static struct devfreq_governor devfreq_userspace = {
140 .name = "userspace",
141 .get_target_freq = devfreq_userspace_func,
142 .event_handler = devfreq_userspace_handler,
143 };
144
devfreq_userspace_init(void)145 static int __init devfreq_userspace_init(void)
146 {
147 return devfreq_add_governor(&devfreq_userspace);
148 }
149 subsys_initcall(devfreq_userspace_init);
150
devfreq_userspace_exit(void)151 static void __exit devfreq_userspace_exit(void)
152 {
153 int ret;
154
155 ret = devfreq_remove_governor(&devfreq_userspace);
156 if (ret)
157 pr_err("%s: failed remove governor %d\n", __func__, ret);
158
159 return;
160 }
161 module_exit(devfreq_userspace_exit);
162 MODULE_LICENSE("GPL");
163