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>

2 files changed, 140 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
  *
diff --git a/include/media/v4l2-fwnode.h b/include/media/v4l2-fwnode.h
index 7adec9851d9e..ac605af9b877 100644
--- a/include/media/v4l2-fwnode.h
+++ b/include/media/v4l2-fwnode.h
@@ -25,6 +25,8 @@
 #include <media/v4l2-mediabus.h>
 
 struct fwnode_handle;
+struct v4l2_async_notifier;
+struct v4l2_async_subdev;
 
 #define V4L2_FWNODE_CSI2_MAX_DATA_LANES	4
 
@@ -122,4 +124,120 @@ int v4l2_fwnode_parse_link(struct fwnode_handle *fwnode,
 			   struct v4l2_fwnode_link *link);
 void v4l2_fwnode_put_link(struct v4l2_fwnode_link *link);
 
+/**
+ * v4l2_async_notifier_parse_fwnode_endpoints - Parse V4L2 fwnode endpoints in a
+ *						device node
+ * @dev: the device the endpoints of which are to be parsed
+ * @notifier: notifier for @dev
+ * @asd_struct_size: size of the driver's async sub-device struct, including
+ *		     sizeof(struct v4l2_async_subdev). The &struct
+ *		     v4l2_async_subdev shall be the first member of
+ *		     the driver's async sub-device struct, i.e. both
+ *		     begin at the same memory address.
+ * @parse_endpoint: Driver's callback function called on each V4L2 fwnode
+ *		    endpoint. Optional.
+ *		    Return: %0 on success
+ *			    %-ENOTCONN if the endpoint is to be skipped but this
+ *				       should not be considered as an error
+ *			    %-EINVAL if the endpoint configuration is invalid
+ *
+ * Parse the fwnode endpoints of the @dev device and populate the async sub-
+ * devices array of the notifier. The @parse_endpoint callback function is
+ * called for each endpoint with the corresponding async sub-device pointer to
+ * let the caller initialize the driver-specific part of the async sub-device
+ * structure.
+ *
+ * The notifier memory shall be zeroed before this function is called on the
+ * notifier.
+ *
+ * This function may not be called on a registered notifier and may be called on
+ * a notifier only once.
+ *
+ * Do not change the notifier's subdevs array, take references to the subdevs
+ * array itself or change the notifier's num_subdevs field. This is because this
+ * function allocates and reallocates the subdevs array based on parsing
+ * endpoints.
+ *
+ * The &struct v4l2_fwnode_endpoint passed to the callback function
+ * @parse_endpoint is released once the function is finished. If there is a need
+ * to retain that configuration, the user needs to allocate memory for it.
+ *
+ * Any notifier populated using this function must be released with a call to
+ * v4l2_async_notifier_cleanup() after it has been unregistered and the async
+ * sub-devices are no longer in use, even if the function returned an error.
+ *
+ * Return: %0 on success, including when no async sub-devices are found
+ *	   %-ENOMEM if memory allocation failed
+ *	   %-EINVAL if graph or endpoint parsing failed
+ *	   Other error codes as returned by @parse_endpoint
+ */
+int v4l2_async_notifier_parse_fwnode_endpoints(
+	struct device *dev, struct v4l2_async_notifier *notifier,
+	size_t asd_struct_size,
+	int (*parse_endpoint)(struct device *dev,
+			      struct v4l2_fwnode_endpoint *vep,
+			      struct v4l2_async_subdev *asd));
+
+/**
+ * v4l2_async_notifier_parse_fwnode_endpoints_by_port - Parse V4L2 fwnode
+ *							endpoints of a port in a
+ *							device node
+ * @dev: the device the endpoints of which are to be parsed
+ * @notifier: notifier for @dev
+ * @asd_struct_size: size of the driver's async sub-device struct, including
+ *		     sizeof(struct v4l2_async_subdev). The &struct
+ *		     v4l2_async_subdev shall be the first member of
+ *		     the driver's async sub-device struct, i.e. both
+ *		     begin at the same memory address.
+ * @port: port number where endpoints are to be parsed
+ * @parse_endpoint: Driver's callback function called on each V4L2 fwnode
+ *		    endpoint. Optional.
+ *		    Return: %0 on success
+ *			    %-ENOTCONN if the endpoint is to be skipped but this
+ *				       should not be considered as an error
+ *			    %-EINVAL if the endpoint configuration is invalid
+ *
+ * This function is just like v4l2_async_notifier_parse_fwnode_endpoints() with
+ * the exception that it only parses endpoints in a given port. This is useful
+ * on devices that have both sinks and sources: the async sub-devices connected
+ * to sources have already been configured by another driver (on capture
+ * devices). In this case the driver must know which ports to parse.
+ *
+ * Parse the fwnode endpoints of the @dev device on a given @port and populate
+ * the async sub-devices array of the notifier. The @parse_endpoint callback
+ * function is called for each endpoint with the corresponding async sub-device
+ * pointer to let the caller initialize the driver-specific part of the async
+ * sub-device structure.
+ *
+ * The notifier memory shall be zeroed before this function is called on the
+ * notifier the first time.
+ *
+ * This function may not be called on a registered notifier and may be called on
+ * a notifier only once per port.
+ *
+ * Do not change the notifier's subdevs array, take references to the subdevs
+ * array itself or change the notifier's num_subdevs field. This is because this
+ * function allocates and reallocates the subdevs array based on parsing
+ * endpoints.
+ *
+ * The &struct v4l2_fwnode_endpoint passed to the callback function
+ * @parse_endpoint is released once the function is finished. If there is a need
+ * to retain that configuration, the user needs to allocate memory for it.
+ *
+ * Any notifier populated using this function must be released with a call to
+ * v4l2_async_notifier_cleanup() after it has been unregistered and the async
+ * sub-devices are no longer in use, even if the function returned an error.
+ *
+ * Return: %0 on success, including when no async sub-devices are found
+ *	   %-ENOMEM if memory allocation failed
+ *	   %-EINVAL if graph or endpoint parsing failed
+ *	   Other error codes as returned by @parse_endpoint
+ */
+int v4l2_async_notifier_parse_fwnode_endpoints_by_port(
+	struct device *dev, struct v4l2_async_notifier *notifier,
+	size_t asd_struct_size, unsigned int port,
+	int (*parse_endpoint)(struct device *dev,
+			      struct v4l2_fwnode_endpoint *vep,
+			      struct v4l2_async_subdev *asd));
+
 #endif /* _V4L2_FWNODE_H */