1 /* drivers/misc/timed_output.c
2 *
3 * Copyright (C) 2009 Google, Inc.
4 * Author: Mike Lockwood <lockwood@android.com>
5 *
6 * This software is licensed under the terms of the GNU General Public
7 * License version 2, as published by the Free Software Foundation, and
8 * may be copied, distributed, and modified under those terms.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
15 */
16
17 #include <linux/module.h>
18 #include <linux/types.h>
19 #include <linux/device.h>
20 #include <linux/fs.h>
21 #include <linux/err.h>
22
23 #include "timed_output.h"
24
25 static struct class *timed_output_class;
26 static atomic_t device_count;
27
enable_show(struct device * dev,struct device_attribute * attr,char * buf)28 static ssize_t enable_show(struct device *dev, struct device_attribute *attr,
29 char *buf)
30 {
31 struct timed_output_dev *tdev = dev_get_drvdata(dev);
32 int remaining = tdev->get_time(tdev);
33
34 return sprintf(buf, "%d\n", remaining);
35 }
36
enable_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t size)37 static ssize_t enable_store(
38 struct device *dev, struct device_attribute *attr,
39 const char *buf, size_t size)
40 {
41 struct timed_output_dev *tdev = dev_get_drvdata(dev);
42 int value;
43
44 if (sscanf(buf, "%d", &value) != 1)
45 return -EINVAL;
46
47 tdev->enable(tdev, value);
48
49 return size;
50 }
51
52 static DEVICE_ATTR(enable, S_IRUGO | S_IWUSR, enable_show, enable_store);
53
create_timed_output_class(void)54 static int create_timed_output_class(void)
55 {
56 if (!timed_output_class) {
57 timed_output_class = class_create(THIS_MODULE, "timed_output");
58 if (IS_ERR(timed_output_class))
59 return PTR_ERR(timed_output_class);
60 atomic_set(&device_count, 0);
61 }
62
63 return 0;
64 }
65
timed_output_dev_register(struct timed_output_dev * tdev)66 int timed_output_dev_register(struct timed_output_dev *tdev)
67 {
68 int ret;
69
70 if (!tdev || !tdev->name || !tdev->enable || !tdev->get_time)
71 return -EINVAL;
72
73 ret = create_timed_output_class();
74 if (ret < 0)
75 return ret;
76
77 tdev->index = atomic_inc_return(&device_count);
78 tdev->dev = device_create(timed_output_class, NULL,
79 MKDEV(0, tdev->index), NULL, tdev->name);
80 if (IS_ERR(tdev->dev))
81 return PTR_ERR(tdev->dev);
82
83 ret = device_create_file(tdev->dev, &dev_attr_enable);
84 if (ret < 0)
85 goto err_create_file;
86
87 dev_set_drvdata(tdev->dev, tdev);
88 tdev->state = 0;
89 return 0;
90
91 err_create_file:
92 device_destroy(timed_output_class, MKDEV(0, tdev->index));
93 printk(KERN_ERR "timed_output: Failed to register driver %s\n",
94 tdev->name);
95
96 return ret;
97 }
98 EXPORT_SYMBOL_GPL(timed_output_dev_register);
99
timed_output_dev_unregister(struct timed_output_dev * tdev)100 void timed_output_dev_unregister(struct timed_output_dev *tdev)
101 {
102 device_remove_file(tdev->dev, &dev_attr_enable);
103 device_destroy(timed_output_class, MKDEV(0, tdev->index));
104 dev_set_drvdata(tdev->dev, NULL);
105 }
106 EXPORT_SYMBOL_GPL(timed_output_dev_unregister);
107
timed_output_init(void)108 static int __init timed_output_init(void)
109 {
110 return create_timed_output_class();
111 }
112
timed_output_exit(void)113 static void __exit timed_output_exit(void)
114 {
115 class_destroy(timed_output_class);
116 }
117
118 module_init(timed_output_init);
119 module_exit(timed_output_exit);
120
121 MODULE_AUTHOR("Mike Lockwood <lockwood@android.com>");
122 MODULE_DESCRIPTION("timed output class driver");
123 MODULE_LICENSE("GPL");
124