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);