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linux
1/*
2 * Generic implementation of a polled input device
3
4 * Copyright (c) 2007 Dmitry Torokhov
5 *
6 * This program is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License version 2 as published by
8 * the Free Software Foundation.
9 */
10
11#include <linux/jiffies.h>
12#include <linux/mutex.h>
13#include <linux/input-polldev.h>
14
15MODULE_AUTHOR("Dmitry Torokhov <dtor@mail.ru>");
16MODULE_DESCRIPTION("Generic implementation of a polled input device");
17MODULE_LICENSE("GPL v2");
18MODULE_VERSION("0.1");
19
20static DEFINE_MUTEX(polldev_mutex);
21static int polldev_users;
22static struct workqueue_struct *polldev_wq;
23
24static int input_polldev_start_workqueue(void)
25{
26 int retval;
27
28 retval = mutex_lock_interruptible(&polldev_mutex);
29 if (retval)
30 return retval;
31
32 if (!polldev_users) {
33 polldev_wq = create_singlethread_workqueue("ipolldevd");
34 if (!polldev_wq) {
35 printk(KERN_ERR "input-polldev: failed to create "
36 "ipolldevd workqueue\n");
37 retval = -ENOMEM;
38 goto out;
39 }
40 }
41
42 polldev_users++;
43
44 out:
45 mutex_unlock(&polldev_mutex);
46 return retval;
47}
48
49static void input_polldev_stop_workqueue(void)
50{
51 mutex_lock(&polldev_mutex);
52
53 if (!--polldev_users)
54 destroy_workqueue(polldev_wq);
55
56 mutex_unlock(&polldev_mutex);
57}
58
59static void input_polled_device_work(struct work_struct *work)
60{
61 struct input_polled_dev *dev =
62 container_of(work, struct input_polled_dev, work.work);
63
64 dev->poll(dev);
65 queue_delayed_work(polldev_wq, &dev->work,
66 msecs_to_jiffies(dev->poll_interval));
67}
68
69static int input_open_polled_device(struct input_dev *input)
70{
71 struct input_polled_dev *dev = input->private;
72 int error;
73
74 error = input_polldev_start_workqueue();
75 if (error)
76 return error;
77
78 if (dev->flush)
79 dev->flush(dev);
80
81 queue_delayed_work(polldev_wq, &dev->work,
82 msecs_to_jiffies(dev->poll_interval));
83
84 return 0;
85}
86
87static void input_close_polled_device(struct input_dev *input)
88{
89 struct input_polled_dev *dev = input->private;
90
91 cancel_rearming_delayed_workqueue(polldev_wq, &dev->work);
92 input_polldev_stop_workqueue();
93}
94
95/**
96 * input_allocate_polled_device - allocated memory polled device
97 *
98 * The function allocates memory for a polled device and also
99 * for an input device associated with this polled device.
100 */
101struct input_polled_dev *input_allocate_polled_device(void)
102{
103 struct input_polled_dev *dev;
104
105 dev = kzalloc(sizeof(struct input_polled_dev), GFP_KERNEL);
106 if (!dev)
107 return NULL;
108
109 dev->input = input_allocate_device();
110 if (!dev->input) {
111 kfree(dev);
112 return NULL;
113 }
114
115 return dev;
116}
117EXPORT_SYMBOL(input_allocate_polled_device);
118
119/**
120 * input_free_polled_device - free memory allocated for polled device
121 * @dev: device to free
122 *
123 * The function frees memory allocated for polling device and drops
124 * reference to the associated input device (if present).
125 */
126void input_free_polled_device(struct input_polled_dev *dev)
127{
128 if (dev) {
129 input_free_device(dev->input);
130 kfree(dev);
131 }
132}
133EXPORT_SYMBOL(input_free_polled_device);
134
135/**
136 * input_register_polled_device - register polled device
137 * @dev: device to register
138 *
139 * The function registers previously initialized polled input device
140 * with input layer. The device should be allocated with call to
141 * input_allocate_polled_device(). Callers should also set up poll()
142 * method and set up capabilities (id, name, phys, bits) of the
143 * corresponing input_dev structure.
144 */
145int input_register_polled_device(struct input_polled_dev *dev)
146{
147 struct input_dev *input = dev->input;
148
149 INIT_DELAYED_WORK(&dev->work, input_polled_device_work);
150 if (!dev->poll_interval)
151 dev->poll_interval = 500;
152 input->private = dev;
153 input->open = input_open_polled_device;
154 input->close = input_close_polled_device;
155
156 return input_register_device(input);
157}
158EXPORT_SYMBOL(input_register_polled_device);
159
160/**
161 * input_unregister_polled_device - unregister polled device
162 * @dev: device to unregister
163 *
164 * The function unregisters previously registered polled input
165 * device from input layer. Polling is stopped and device is
166 * ready to be freed with call to input_free_polled_device().
167 * Callers should not attempt to access dev->input pointer
168 * after calling this function.
169 */
170void input_unregister_polled_device(struct input_polled_dev *dev)
171{
172 input_unregister_device(dev->input);
173 dev->input = NULL;
174}
175EXPORT_SYMBOL(input_unregister_polled_device);
176