Root/drivers/input/input-polldev.c

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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
12
13#include <linux/jiffies.h>
14#include <linux/slab.h>
15#include <linux/mutex.h>
16#include <linux/workqueue.h>
17#include <linux/module.h>
18#include <linux/input-polldev.h>
19
20MODULE_AUTHOR("Dmitry Torokhov <dtor@mail.ru>");
21MODULE_DESCRIPTION("Generic implementation of a polled input device");
22MODULE_LICENSE("GPL v2");
23MODULE_VERSION("0.1");
24
25static void input_polldev_queue_work(struct input_polled_dev *dev)
26{
27    unsigned long delay;
28
29    delay = msecs_to_jiffies(dev->poll_interval);
30    if (delay >= HZ)
31        delay = round_jiffies_relative(delay);
32
33    queue_delayed_work(system_freezable_wq, &dev->work, delay);
34}
35
36static void input_polled_device_work(struct work_struct *work)
37{
38    struct input_polled_dev *dev =
39        container_of(work, struct input_polled_dev, work.work);
40
41    dev->poll(dev);
42    input_polldev_queue_work(dev);
43}
44
45static int input_open_polled_device(struct input_dev *input)
46{
47    struct input_polled_dev *dev = input_get_drvdata(input);
48
49    if (dev->open)
50        dev->open(dev);
51
52    /* Only start polling if polling is enabled */
53    if (dev->poll_interval > 0) {
54        dev->poll(dev);
55        input_polldev_queue_work(dev);
56    }
57
58    return 0;
59}
60
61static void input_close_polled_device(struct input_dev *input)
62{
63    struct input_polled_dev *dev = input_get_drvdata(input);
64
65    cancel_delayed_work_sync(&dev->work);
66
67    if (dev->close)
68        dev->close(dev);
69}
70
71/* SYSFS interface */
72
73static ssize_t input_polldev_get_poll(struct device *dev,
74                      struct device_attribute *attr, char *buf)
75{
76    struct input_polled_dev *polldev = dev_get_drvdata(dev);
77
78    return sprintf(buf, "%d\n", polldev->poll_interval);
79}
80
81static ssize_t input_polldev_set_poll(struct device *dev,
82                struct device_attribute *attr, const char *buf,
83                size_t count)
84{
85    struct input_polled_dev *polldev = dev_get_drvdata(dev);
86    struct input_dev *input = polldev->input;
87    unsigned int interval;
88    int err;
89
90    err = kstrtouint(buf, 0, &interval);
91    if (err)
92        return err;
93
94    if (interval < polldev->poll_interval_min)
95        return -EINVAL;
96
97    if (interval > polldev->poll_interval_max)
98        return -EINVAL;
99
100    mutex_lock(&input->mutex);
101
102    polldev->poll_interval = interval;
103
104    if (input->users) {
105        cancel_delayed_work_sync(&polldev->work);
106        if (polldev->poll_interval > 0)
107            input_polldev_queue_work(polldev);
108    }
109
110    mutex_unlock(&input->mutex);
111
112    return count;
113}
114
115static DEVICE_ATTR(poll, S_IRUGO | S_IWUSR, input_polldev_get_poll,
116                        input_polldev_set_poll);
117
118
119static ssize_t input_polldev_get_max(struct device *dev,
120                     struct device_attribute *attr, char *buf)
121{
122    struct input_polled_dev *polldev = dev_get_drvdata(dev);
123
124    return sprintf(buf, "%d\n", polldev->poll_interval_max);
125}
126
127static DEVICE_ATTR(max, S_IRUGO, input_polldev_get_max, NULL);
128
129static ssize_t input_polldev_get_min(struct device *dev,
130                     struct device_attribute *attr, char *buf)
131{
132    struct input_polled_dev *polldev = dev_get_drvdata(dev);
133
134    return sprintf(buf, "%d\n", polldev->poll_interval_min);
135}
136
137static DEVICE_ATTR(min, S_IRUGO, input_polldev_get_min, NULL);
138
139static struct attribute *sysfs_attrs[] = {
140    &dev_attr_poll.attr,
141    &dev_attr_max.attr,
142    &dev_attr_min.attr,
143    NULL
144};
145
146static struct attribute_group input_polldev_attribute_group = {
147    .attrs = sysfs_attrs
148};
149
150/**
151 * input_allocate_polled_device - allocate memory for polled device
152 *
153 * The function allocates memory for a polled device and also
154 * for an input device associated with this polled device.
155 */
156struct input_polled_dev *input_allocate_polled_device(void)
157{
158    struct input_polled_dev *dev;
159
160    dev = kzalloc(sizeof(struct input_polled_dev), GFP_KERNEL);
161    if (!dev)
162        return NULL;
163
164    dev->input = input_allocate_device();
165    if (!dev->input) {
166        kfree(dev);
167        return NULL;
168    }
169
170    return dev;
171}
172EXPORT_SYMBOL(input_allocate_polled_device);
173
174/**
175 * input_free_polled_device - free memory allocated for polled device
176 * @dev: device to free
177 *
178 * The function frees memory allocated for polling device and drops
179 * reference to the associated input device.
180 */
181void input_free_polled_device(struct input_polled_dev *dev)
182{
183    if (dev) {
184        input_free_device(dev->input);
185        kfree(dev);
186    }
187}
188EXPORT_SYMBOL(input_free_polled_device);
189
190/**
191 * input_register_polled_device - register polled device
192 * @dev: device to register
193 *
194 * The function registers previously initialized polled input device
195 * with input layer. The device should be allocated with call to
196 * input_allocate_polled_device(). Callers should also set up poll()
197 * method and set up capabilities (id, name, phys, bits) of the
198 * corresponding input_dev structure.
199 */
200int input_register_polled_device(struct input_polled_dev *dev)
201{
202    struct input_dev *input = dev->input;
203    int error;
204
205    input_set_drvdata(input, dev);
206    INIT_DELAYED_WORK(&dev->work, input_polled_device_work);
207    if (!dev->poll_interval)
208        dev->poll_interval = 500;
209    if (!dev->poll_interval_max)
210        dev->poll_interval_max = dev->poll_interval;
211    input->open = input_open_polled_device;
212    input->close = input_close_polled_device;
213
214    error = input_register_device(input);
215    if (error)
216        return error;
217
218    error = sysfs_create_group(&input->dev.kobj,
219                   &input_polldev_attribute_group);
220    if (error) {
221        input_unregister_device(input);
222        return error;
223    }
224
225    /*
226     * Take extra reference to the underlying input device so
227     * that it survives call to input_unregister_polled_device()
228     * and is deleted only after input_free_polled_device()
229     * has been invoked. This is needed to ease task of freeing
230     * sparse keymaps.
231     */
232    input_get_device(input);
233
234    return 0;
235}
236EXPORT_SYMBOL(input_register_polled_device);
237
238/**
239 * input_unregister_polled_device - unregister polled device
240 * @dev: device to unregister
241 *
242 * The function unregisters previously registered polled input
243 * device from input layer. Polling is stopped and device is
244 * ready to be freed with call to input_free_polled_device().
245 */
246void input_unregister_polled_device(struct input_polled_dev *dev)
247{
248    sysfs_remove_group(&dev->input->dev.kobj,
249               &input_polldev_attribute_group);
250
251    input_unregister_device(dev->input);
252}
253EXPORT_SYMBOL(input_unregister_polled_device);
254

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