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
15 MODULE_AUTHOR("Dmitry Torokhov <dtor@mail.ru>");
16 MODULE_DESCRIPTION("Generic implementation of a polled input device");
17 MODULE_LICENSE("GPL v2");
18 MODULE_VERSION("0.1");
19
20 static DEFINE_MUTEX(polldev_mutex);
21 static int polldev_users;
22 static struct workqueue_struct *polldev_wq;
23
24 static 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
49 static 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
59 static 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 unsigned long delay;
64
65 dev->poll(dev);
66
67 delay = msecs_to_jiffies(dev->poll_interval);
68 if (delay >= HZ)
69 delay = round_jiffies_relative(delay);
70
71 queue_delayed_work(polldev_wq, &dev->work, delay);
72 }
73
74 static int input_open_polled_device(struct input_dev *input)
75 {
76 struct input_polled_dev *dev = input->private;
77 int error;
78
79 error = input_polldev_start_workqueue();
80 if (error)
81 return error;
82
83 if (dev->flush)
84 dev->flush(dev);
85
86 queue_delayed_work(polldev_wq, &dev->work,
87 msecs_to_jiffies(dev->poll_interval));
88
89 return 0;
90 }
91
92 static void input_close_polled_device(struct input_dev *input)
93 {
94 struct input_polled_dev *dev = input->private;
95
96 cancel_delayed_work_sync(&dev->work);
97 input_polldev_stop_workqueue();
98 }
99
100 /**
101 * input_allocate_polled_device - allocated memory polled device
102 *
103 * The function allocates memory for a polled device and also
104 * for an input device associated with this polled device.
105 */
106 struct input_polled_dev *input_allocate_polled_device(void)
107 {
108 struct input_polled_dev *dev;
109
110 dev = kzalloc(sizeof(struct input_polled_dev), GFP_KERNEL);
111 if (!dev)
112 return NULL;
113
114 dev->input = input_allocate_device();
115 if (!dev->input) {
116 kfree(dev);
117 return NULL;
118 }
119
120 return dev;
121 }
122 EXPORT_SYMBOL(input_allocate_polled_device);
123
124 /**
125 * input_free_polled_device - free memory allocated for polled device
126 * @dev: device to free
127 *
128 * The function frees memory allocated for polling device and drops
129 * reference to the associated input device (if present).
130 */
131 void input_free_polled_device(struct input_polled_dev *dev)
132 {
133 if (dev) {
134 input_free_device(dev->input);
135 kfree(dev);
136 }
137 }
138 EXPORT_SYMBOL(input_free_polled_device);
139
140 /**
141 * input_register_polled_device - register polled device
142 * @dev: device to register
143 *
144 * The function registers previously initialized polled input device
145 * with input layer. The device should be allocated with call to
146 * input_allocate_polled_device(). Callers should also set up poll()
147 * method and set up capabilities (id, name, phys, bits) of the
148 * corresponing input_dev structure.
149 */
150 int input_register_polled_device(struct input_polled_dev *dev)
151 {
152 struct input_dev *input = dev->input;
153
154 INIT_DELAYED_WORK(&dev->work, input_polled_device_work);
155 if (!dev->poll_interval)
156 dev->poll_interval = 500;
157 input->private = dev;
158 input->open = input_open_polled_device;
159 input->close = input_close_polled_device;
160
161 return input_register_device(input);
162 }
163 EXPORT_SYMBOL(input_register_polled_device);
164
165 /**
166 * input_unregister_polled_device - unregister polled device
167 * @dev: device to unregister
168 *
169 * The function unregisters previously registered polled input
170 * device from input layer. Polling is stopped and device is
171 * ready to be freed with call to input_free_polled_device().
172 * Callers should not attempt to access dev->input pointer
173 * after calling this function.
174 */
175 void input_unregister_polled_device(struct input_polled_dev *dev)
176 {
177 input_unregister_device(dev->input);
178 dev->input = NULL;
179 }
180 EXPORT_SYMBOL(input_unregister_polled_device);
181
182
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