timed_output.c revision b28e7d5807051184270c40d4bc48db947189f107 
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#define pr_fmt(fmt) "timed_output: " fmt
18
19#include <linux/module.h>
20#include <linux/types.h>
21#include <linux/device.h>
22#include <linux/fs.h>
23#include <linux/err.h>
24
25#include "timed_output.h"
26
27static struct class *timed_output_class;
28static atomic_t device_count;
29
30static ssize_t enable_show(struct device *dev, struct device_attribute *attr,
31			   char *buf)
32{
33	struct timed_output_dev *tdev = dev_get_drvdata(dev);
34	int remaining = tdev->get_time(tdev);
35
36	return sprintf(buf, "%d\n", remaining);
37}
38
39static ssize_t enable_store(struct device *dev, struct device_attribute *attr,
40			    const char *buf, size_t size)
41{
42	struct timed_output_dev *tdev = dev_get_drvdata(dev);
43	int value;
44
45	if (sscanf(buf, "%d", &value) != 1)
46		return -EINVAL;
47
48	tdev->enable(tdev, value);
49
50	return size;
51}
52static DEVICE_ATTR_RW(enable);
53
54static struct attribute *timed_output_attrs[] = {
55	&dev_attr_enable.attr,
56	NULL,
57};
58ATTRIBUTE_GROUPS(timed_output);
59
60static int create_timed_output_class(void)
61{
62	if (!timed_output_class) {
63		timed_output_class = class_create(THIS_MODULE, "timed_output");
64		if (IS_ERR(timed_output_class))
65			return PTR_ERR(timed_output_class);
66		atomic_set(&device_count, 0);
67		timed_output_class->dev_groups = timed_output_groups;
68	}
69
70	return 0;
71}
72
73int timed_output_dev_register(struct timed_output_dev *tdev)
74{
75	int ret;
76
77	if (!tdev || !tdev->name || !tdev->enable || !tdev->get_time)
78		return -EINVAL;
79
80	ret = create_timed_output_class();
81	if (ret < 0)
82		return ret;
83
84	tdev->index = atomic_inc_return(&device_count);
85	tdev->dev = device_create(timed_output_class, NULL,
86		MKDEV(0, tdev->index), NULL, "%s", tdev->name);
87	if (IS_ERR(tdev->dev))
88		return PTR_ERR(tdev->dev);
89
90	dev_set_drvdata(tdev->dev, tdev);
91	tdev->state = 0;
92	return 0;
93}
94EXPORT_SYMBOL_GPL(timed_output_dev_register);
95
96void timed_output_dev_unregister(struct timed_output_dev *tdev)
97{
98	tdev->enable(tdev, 0);
99	device_destroy(timed_output_class, MKDEV(0, tdev->index));
100}
101EXPORT_SYMBOL_GPL(timed_output_dev_unregister);
102
103static int __init timed_output_init(void)
104{
105	return create_timed_output_class();
106}
107
108static void __exit timed_output_exit(void)
109{
110	class_destroy(timed_output_class);
111}
112
113module_init(timed_output_init);
114module_exit(timed_output_exit);
115
116MODULE_AUTHOR("Mike Lockwood <lockwood@android.com>");
117MODULE_DESCRIPTION("timed output class driver");
118MODULE_LICENSE("GPL");
119