input-polldev.c 7.16 KB
Newer Older
1 2 3 4 5 6 7 8 9 10
/*
 * Generic implementation of a polled input device

 * Copyright (c) 2007 Dmitry Torokhov
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published by
 * the Free Software Foundation.
 */

11 12
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

13
#include <linux/jiffies.h>
14
#include <linux/slab.h>
15 16 17
#include <linux/mutex.h>
#include <linux/input-polldev.h>

18 19 20 21 22
MODULE_AUTHOR("Dmitry Torokhov <dtor@mail.ru>");
MODULE_DESCRIPTION("Generic implementation of a polled input device");
MODULE_LICENSE("GPL v2");
MODULE_VERSION("0.1");

23 24 25 26 27 28 29 30 31 32 33 34 35 36 37
static DEFINE_MUTEX(polldev_mutex);
static int polldev_users;
static struct workqueue_struct *polldev_wq;

static int input_polldev_start_workqueue(void)
{
	int retval;

	retval = mutex_lock_interruptible(&polldev_mutex);
	if (retval)
		return retval;

	if (!polldev_users) {
		polldev_wq = create_singlethread_workqueue("ipolldevd");
		if (!polldev_wq) {
38
			pr_err("failed to create ipolldevd workqueue\n");
39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
			retval = -ENOMEM;
			goto out;
		}
	}

	polldev_users++;

 out:
	mutex_unlock(&polldev_mutex);
	return retval;
}

static void input_polldev_stop_workqueue(void)
{
	mutex_lock(&polldev_mutex);

	if (!--polldev_users)
		destroy_workqueue(polldev_wq);

	mutex_unlock(&polldev_mutex);
}

61
static void input_polldev_queue_work(struct input_polled_dev *dev)
62
{
63
	unsigned long delay;
64

65 66 67 68 69
	delay = msecs_to_jiffies(dev->poll_interval);
	if (delay >= HZ)
		delay = round_jiffies_relative(delay);

	queue_delayed_work(polldev_wq, &dev->work, delay);
70 71
}

72 73 74 75 76 77 78 79 80
static void input_polled_device_work(struct work_struct *work)
{
	struct input_polled_dev *dev =
		container_of(work, struct input_polled_dev, work.work);

	dev->poll(dev);
	input_polldev_queue_work(dev);
}

81 82
static int input_open_polled_device(struct input_dev *input)
{
83
	struct input_polled_dev *dev = input_get_drvdata(input);
84 85 86 87 88 89
	int error;

	error = input_polldev_start_workqueue();
	if (error)
		return error;

90 91
	if (dev->open)
		dev->open(dev);
92

93 94 95
	/* Only start polling if polling is enabled */
	if (dev->poll_interval > 0)
		queue_delayed_work(polldev_wq, &dev->work, 0);
96 97 98 99 100 101

	return 0;
}

static void input_close_polled_device(struct input_dev *input)
{
102
	struct input_polled_dev *dev = input_get_drvdata(input);
103

104
	cancel_delayed_work_sync(&dev->work);
105 106 107 108 109 110
	/*
	 * Clean up work struct to remove references to the workqueue.
	 * It may be destroyed by the next call. This causes problems
	 * at next device open-close in case of poll_interval == 0.
	 */
	INIT_DELAYED_WORK(&dev->work, dev->work.work.func);
111
	input_polldev_stop_workqueue();
112 113 114

	if (dev->close)
		dev->close(dev);
115 116
}

117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193
/* SYSFS interface */

static ssize_t input_polldev_get_poll(struct device *dev,
				      struct device_attribute *attr, char *buf)
{
	struct input_polled_dev *polldev = dev_get_drvdata(dev);

	return sprintf(buf, "%d\n", polldev->poll_interval);
}

static ssize_t input_polldev_set_poll(struct device *dev,
				struct device_attribute *attr, const char *buf,
				size_t count)
{
	struct input_polled_dev *polldev = dev_get_drvdata(dev);
	struct input_dev *input = polldev->input;
	unsigned long interval;

	if (strict_strtoul(buf, 0, &interval))
		return -EINVAL;

	if (interval < polldev->poll_interval_min)
		return -EINVAL;

	if (interval > polldev->poll_interval_max)
		return -EINVAL;

	mutex_lock(&input->mutex);

	polldev->poll_interval = interval;

	if (input->users) {
		cancel_delayed_work_sync(&polldev->work);
		if (polldev->poll_interval > 0)
			input_polldev_queue_work(polldev);
	}

	mutex_unlock(&input->mutex);

	return count;
}

static DEVICE_ATTR(poll, S_IRUGO | S_IWUSR, input_polldev_get_poll,
					    input_polldev_set_poll);


static ssize_t input_polldev_get_max(struct device *dev,
				     struct device_attribute *attr, char *buf)
{
	struct input_polled_dev *polldev = dev_get_drvdata(dev);

	return sprintf(buf, "%d\n", polldev->poll_interval_max);
}

static DEVICE_ATTR(max, S_IRUGO, input_polldev_get_max, NULL);

static ssize_t input_polldev_get_min(struct device *dev,
				     struct device_attribute *attr, char *buf)
{
	struct input_polled_dev *polldev = dev_get_drvdata(dev);

	return sprintf(buf, "%d\n", polldev->poll_interval_min);
}

static DEVICE_ATTR(min, S_IRUGO, input_polldev_get_min, NULL);

static struct attribute *sysfs_attrs[] = {
	&dev_attr_poll.attr,
	&dev_attr_max.attr,
	&dev_attr_min.attr,
	NULL
};

static struct attribute_group input_polldev_attribute_group = {
	.attrs = sysfs_attrs
};

194
/**
195
 * input_allocate_polled_device - allocate memory for polled device
196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222
 *
 * The function allocates memory for a polled device and also
 * for an input device associated with this polled device.
 */
struct input_polled_dev *input_allocate_polled_device(void)
{
	struct input_polled_dev *dev;

	dev = kzalloc(sizeof(struct input_polled_dev), GFP_KERNEL);
	if (!dev)
		return NULL;

	dev->input = input_allocate_device();
	if (!dev->input) {
		kfree(dev);
		return NULL;
	}

	return dev;
}
EXPORT_SYMBOL(input_allocate_polled_device);

/**
 * input_free_polled_device - free memory allocated for polled device
 * @dev: device to free
 *
 * The function frees memory allocated for polling device and drops
223
 * reference to the associated input device.
224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241
 */
void input_free_polled_device(struct input_polled_dev *dev)
{
	if (dev) {
		input_free_device(dev->input);
		kfree(dev);
	}
}
EXPORT_SYMBOL(input_free_polled_device);

/**
 * input_register_polled_device - register polled device
 * @dev: device to register
 *
 * The function registers previously initialized polled input device
 * with input layer. The device should be allocated with call to
 * input_allocate_polled_device(). Callers should also set up poll()
 * method and set up capabilities (id, name, phys, bits) of the
242
 * corresponding input_dev structure.
243 244 245 246
 */
int input_register_polled_device(struct input_polled_dev *dev)
{
	struct input_dev *input = dev->input;
247
	int error;
248

249
	input_set_drvdata(input, dev);
250 251 252
	INIT_DELAYED_WORK(&dev->work, input_polled_device_work);
	if (!dev->poll_interval)
		dev->poll_interval = 500;
253 254
	if (!dev->poll_interval_max)
		dev->poll_interval_max = dev->poll_interval;
255 256 257
	input->open = input_open_polled_device;
	input->close = input_close_polled_device;

258 259 260 261 262 263 264 265 266 267 268
	error = input_register_device(input);
	if (error)
		return error;

	error = sysfs_create_group(&input->dev.kobj,
				   &input_polldev_attribute_group);
	if (error) {
		input_unregister_device(input);
		return error;
	}

269 270 271 272 273 274 275 276 277
	/*
	 * Take extra reference to the underlying input device so
	 * that it survives call to input_unregister_polled_device()
	 * and is deleted only after input_free_polled_device()
	 * has been invoked. This is needed to ease task of freeing
	 * sparse keymaps.
	 */
	input_get_device(input);

278
	return 0;
279 280 281 282 283 284 285 286 287 288 289 290 291
}
EXPORT_SYMBOL(input_register_polled_device);

/**
 * input_unregister_polled_device - unregister polled device
 * @dev: device to unregister
 *
 * The function unregisters previously registered polled input
 * device from input layer. Polling is stopped and device is
 * ready to be freed with call to input_free_polled_device().
 */
void input_unregister_polled_device(struct input_polled_dev *dev)
{
292 293 294
	sysfs_remove_group(&dev->input->dev.kobj,
			   &input_polldev_attribute_group);

295 296 297 298
	input_unregister_device(dev->input);
}
EXPORT_SYMBOL(input_unregister_polled_device);