media: v4l: fwnode: Support generic parsing of graph endpoints in a device

Add two functions for parsing devices graph endpoints:
v4l2_async_notifier_parse_fwnode_endpoints and
v4l2_async_notifier_parse_fwnode_endpoints_by_port. The former iterates
over all endpoints whereas the latter only iterates over the endpoints in
a given port.

The former is mostly useful for existing drivers that currently implement
the iteration over all the endpoints themselves whereas the latter is
especially intended for devices with both sinks and sources: async
sub-devices for external devices connected to the device's sources will
have already been set up, or the external sub-devices are part of the
master device.

Depends-on: ("device property: preserve usecount for node passed to of_fwnode_graph_get_port_parent()")

Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

1 files changed, 22 insertions, 2 deletions

diff --git a/include/media/v4l2-async.h b/include/media/v4l2-async.h
index c69d8c8a66d0..329aeebd1a80 100644
--- a/include/media/v4l2-async.h
+++ b/include/media/v4l2-async.h
@@ -18,7 +18,6 @@ struct device;
 struct device_node;
 struct v4l2_device;
 struct v4l2_subdev;
-struct v4l2_async_notifier;
 
 /* A random max subdevice number, used to allocate an array on stack */
 #define V4L2_MAX_SUBDEVS 128U
@@ -50,6 +49,10 @@ enum v4l2_async_match_type {
  * @match:	union of per-bus type matching data sets
  * @list:	used to link struct v4l2_async_subdev objects, waiting to be
  *		probed, to a notifier->waiting list
+ *
+ * When this struct is used as a member in a driver specific struct,
+ * the driver specific struct shall contain the &struct
+ * v4l2_async_subdev as its first member.
  */
 struct v4l2_async_subdev {
 	enum v4l2_async_match_type match_type;
@@ -78,7 +81,8 @@ struct v4l2_async_subdev {
 /**
  * struct v4l2_async_notifier - v4l2_device notifier data
  *
- * @num_subdevs: number of subdevices
+ * @num_subdevs: number of subdevices used in the subdevs array
+ * @max_subdevs: number of subdevices allocated in the subdevs array
  * @subdevs:	array of pointers to subdevice descriptors
  * @v4l2_dev:	pointer to struct v4l2_device
  * @waiting:	list of struct v4l2_async_subdev, waiting for their drivers
@@ -90,6 +94,7 @@ struct v4l2_async_subdev {
  */
 struct v4l2_async_notifier {
 	unsigned int num_subdevs;
+	unsigned int max_subdevs;
 	struct v4l2_async_subdev **subdevs;
 	struct v4l2_device *v4l2_dev;
 	struct list_head waiting;
@@ -121,6 +126,21 @@ int v4l2_async_notifier_register(struct v4l2_device *v4l2_dev,
 void v4l2_async_notifier_unregister(struct v4l2_async_notifier *notifier);
 
 /**
+ * v4l2_async_notifier_cleanup - clean up notifier resources
+ * @notifier: the notifier the resources of which are to be cleaned up
+ *
+ * Release memory resources related to a notifier, including the async
+ * sub-devices allocated for the purposes of the notifier but not the notifier
+ * itself. The user is responsible for calling this function to clean up the
+ * notifier after calling @v4l2_async_notifier_parse_fwnode_endpoints.
+ *
+ * There is no harm from calling v4l2_async_notifier_cleanup in other
+ * cases as long as its memory has been zeroed after it has been
+ * allocated.
+ */
+void v4l2_async_notifier_cleanup(struct v4l2_async_notifier *notifier);
+
+/**
  * v4l2_async_register_subdev - registers a sub-device to the asynchronous
  * 	subdevice framework
  *