drivers/input/evdev.c

Source file repositories/reference/linux-study-clean/drivers/input/evdev.c

File Facts

System
Linux kernel
Corpus path
drivers/input/evdev.c
Extension
.c
Size
33168 bytes
Lines
1447
Domain
Driver Families
Bucket
drivers/input
Inferred role
Driver Families: operation-table or driver-model contract
Status
pattern implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

static const struct file_operations evdev_fops = {
	.owner		= THIS_MODULE,
	.read		= evdev_read,
	.write		= evdev_write,
	.poll		= evdev_poll,
	.open		= evdev_open,
	.release	= evdev_release,
	.unlocked_ioctl	= evdev_ioctl,
#ifdef CONFIG_COMPAT
	.compat_ioctl	= evdev_ioctl_compat,
#endif
	.fasync		= evdev_fasync,
};

/*
 * Mark device non-existent. This disables writes, ioctls and
 * prevents new users from opening the device. Already posted
 * blocking reads will stay, however new ones will fail.
 */
static void evdev_mark_dead(struct evdev *evdev)
{
	mutex_lock(&evdev->mutex);
	evdev->exist = false;
	mutex_unlock(&evdev->mutex);
}

static void evdev_cleanup(struct evdev *evdev)
{
	struct input_handle *handle = &evdev->handle;

	evdev_mark_dead(evdev);
	evdev_hangup(evdev);

	/* evdev is marked dead so no one else accesses evdev->open */
	if (evdev->open) {
		input_flush_device(handle, NULL);
		input_close_device(handle);
	}
}

/*
 * Create new evdev device. Note that input core serializes calls
 * to connect and disconnect.
 */
static int evdev_connect(struct input_handler *handler, struct input_dev *dev,
			 const struct input_device_id *id)
{
	struct evdev *evdev;
	int minor;
	int dev_no;
	int error;

	minor = input_get_new_minor(EVDEV_MINOR_BASE, EVDEV_MINORS, true);
	if (minor < 0) {
		error = minor;
		pr_err("failed to reserve new minor: %d\n", error);
		return error;
	}

	evdev = kzalloc_obj(struct evdev);
	if (!evdev) {
		error = -ENOMEM;
		goto err_free_minor;
	}

	INIT_LIST_HEAD(&evdev->client_list);
	spin_lock_init(&evdev->client_lock);
	mutex_init(&evdev->mutex);
	evdev->exist = true;

	dev_no = minor;
	/* Normalize device number if it falls into legacy range */
	if (dev_no < EVDEV_MINOR_BASE + EVDEV_MINORS)
		dev_no -= EVDEV_MINOR_BASE;
	dev_set_name(&evdev->dev, "event%d", dev_no);

	evdev->handle.dev = input_get_device(dev);
	evdev->handle.name = dev_name(&evdev->dev);
	evdev->handle.handler = handler;
	evdev->handle.private = evdev;

	evdev->dev.devt = MKDEV(INPUT_MAJOR, minor);
	evdev->dev.class = &input_class;
	evdev->dev.parent = &dev->dev;
	evdev->dev.release = evdev_free;
	device_initialize(&evdev->dev);

	error = input_register_handle(&evdev->handle);
	if (error)
		goto err_free_evdev;

Annotation

Implementation Notes