[media] v4l: subdev: Add device node support

Create a device node named subdevX for every registered subdev.

As the device node is registered before the subdev core::s_config
function is called, return -EGAIN on open until initialization
completes.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Vimarsh Zutshi <vimarsh.zutshi@gmail.com>
Acked-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 37 insertions, 0 deletions

diff --git a/drivers/media/video/v4l2-device.c b/drivers/media/video/v4l2-device.c
index ce64fe16bc6..8c0ad8b372d 100644
--- a/drivers/media/video/v4l2-device.c
+++ b/drivers/media/video/v4l2-device.c
@@ -124,16 +124,20 @@ int v4l2_device_register_subdev(struct v4l2_device *v4l2_dev,
 	/* Check for valid input */
 	if (v4l2_dev == NULL || sd == NULL || !sd->name[0])
 		return -EINVAL;
+
 	/* Warn if we apparently re-register a subdev */
 	WARN_ON(sd->v4l2_dev != NULL);
+
 	if (!try_module_get(sd->owner))
 		return -ENODEV;
+
 	sd->v4l2_dev = v4l2_dev;
 	if (sd->internal_ops && sd->internal_ops->registered) {
 		err = sd->internal_ops->registered(sd);
 		if (err)
 			return err;
 	}
+
 	/* This just returns 0 if either of the two args is NULL */
 	err = v4l2_ctrl_add_handler(v4l2_dev->ctrl_handler, sd->ctrl_handler);
 	if (err) {
@@ -141,24 +145,57 @@ int v4l2_device_register_subdev(struct v4l2_device *v4l2_dev,
 			sd->internal_ops->unregistered(sd);
 		return err;
 	}
+
 	spin_lock(&v4l2_dev->lock);
 	list_add_tail(&sd->list, &v4l2_dev->subdevs);
 	spin_unlock(&v4l2_dev->lock);
+
 	return 0;
 }
 EXPORT_SYMBOL_GPL(v4l2_device_register_subdev);
 
+int v4l2_device_register_subdev_nodes(struct v4l2_device *v4l2_dev)
+{
+	struct video_device *vdev;
+	struct v4l2_subdev *sd;
+	int err;
+
+	/* Register a device node for every subdev marked with the
+	 * V4L2_SUBDEV_FL_HAS_DEVNODE flag.
+	 */
+	list_for_each_entry(sd, &v4l2_dev->subdevs, list) {
+		if (!(sd->flags & V4L2_SUBDEV_FL_HAS_DEVNODE))
+			continue;
+
+		vdev = &sd->devnode;
+		strlcpy(vdev->name, sd->name, sizeof(vdev->name));
+		vdev->v4l2_dev = v4l2_dev;
+		vdev->fops = &v4l2_subdev_fops;
+		vdev->release = video_device_release_empty;
+		err = __video_register_device(vdev, VFL_TYPE_SUBDEV, -1, 1,
+					      sd->owner);
+		if (err < 0)
+			return err;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(v4l2_device_register_subdev_nodes);
+
 void v4l2_device_unregister_subdev(struct v4l2_subdev *sd)
 {
 	/* return if it isn't registered */
 	if (sd == NULL || sd->v4l2_dev == NULL)
 		return;
+
 	spin_lock(&sd->v4l2_dev->lock);
 	list_del(&sd->list);
 	spin_unlock(&sd->v4l2_dev->lock);
 	if (sd->internal_ops && sd->internal_ops->unregistered)
 		sd->internal_ops->unregistered(sd);
 	sd->v4l2_dev = NULL;
+
+	video_unregister_device(&sd->devnode);
 	module_put(sd->owner);
 }
 EXPORT_SYMBOL_GPL(v4l2_device_unregister_subdev);