media: v4l: async: Obtain async connection based on sub-device

Add v4l2_async_connection_unique() function for obtaining a struct
v4l2_async_connection, typically allocated by drivers together with their
own information on an external sub-device.

The relation between connections and sub-devices still remains 1:1 but
this code becomes more complex when the relation soon changes.

Signed-off-by: Sakari Ailus <[email protected]>
Tested-by: Philipp Zabel <[email protected]> # imx6qp
Tested-by: Niklas Söderlund <[email protected]> # rcar + adv746x
Tested-by: Aishwarya Kothari <[email protected]> # Apalis i.MX6Q with TC358743
Tested-by: Lad Prabhakar <[email protected]> # Renesas RZ/G2L SMARC
Signed-off-by: Mauro Carvalho Chehab <[email protected]>

1 files changed, 7 insertions, 0 deletions

diff --git a/drivers/media/v4l2-core/v4l2-async.c b/drivers/media/v4l2-core/v4l2-async.c
index 95fecf39ba65..cb962b0fc2bc 100644
--- a/drivers/media/v4l2-core/v4l2-async.c
+++ b/drivers/media/v4l2-core/v4l2-async.c
@@ -751,6 +751,13 @@ __v4l2_async_nf_add_i2c(struct v4l2_async_notifier *notifier, int adapter_id,
 }
 EXPORT_SYMBOL_GPL(__v4l2_async_nf_add_i2c);
 
+struct v4l2_async_connection *
+v4l2_async_connection_unique(struct v4l2_subdev *sd)
+{
+	return sd->asd;
+}
+EXPORT_SYMBOL_GPL(v4l2_async_connection_unique);
+
 int v4l2_async_register_subdev(struct v4l2_subdev *sd)
 {
 	struct v4l2_async_notifier *subdev_notifier;