libcamera: media_object: Expose entity type

Add a new field to the MediaEntity class to identify the type of
interface it exposes to userspace. The MediaEntity constructor is
changed to take a media_v2_interface pointer instead of just the device
node major and minor to have access to the interface type.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Tested-by: Martin Kepplinger <martin.kepplinger@puri.sm>

include/libcamera/internal/media_object.h

@@ -88,9 +88,17 @@ private:
 class MediaEntity : public MediaObject
 {
 public:
+	enum class Type {
+		Invalid,
+		MediaEntity,
+		V4L2Subdevice,
+		V4L2VideoDevice,
+	};
+
 	const std::string &name() const { return name_; }
 	unsigned int function() const { return function_; }
 	unsigned int flags() const { return flags_; }
+	Type type() const { return type_; }
 	const std::string &deviceNode() const { return deviceNode_; }
 	unsigned int deviceMajor() const { return major_; }
 	unsigned int deviceMinor() const { return minor_; }
@@ -108,13 +116,14 @@ private:
 	friend class MediaDevice;
 
 	MediaEntity(MediaDevice *dev, const struct media_v2_entity *entity,
-		    unsigned int major = 0, unsigned int minor = 0);
+		    const struct media_v2_interface *iface);
 
 	void addPad(MediaPad *pad);
 
 	std::string name_;
 	unsigned int function_;
 	unsigned int flags_;
+	Type type_;
 	std::string deviceNode_;
 	unsigned int major_;
 	unsigned int minor_;

src/libcamera/media_device.cpp

@@ -652,14 +652,7 @@ bool MediaDevice::populateEntities(const struct media_v2_topology &topology)
 		 */
 		struct media_v2_interface *iface =
 			findInterface(topology, ent->id);
-
-		MediaEntity *entity;
-		if (iface)
-			entity = new MediaEntity(this, ent,
-						 iface->devnode.major,
-						 iface->devnode.minor);
-		else
-			entity = new MediaEntity(this, ent);
+		MediaEntity *entity = new MediaEntity(this, ent, iface);
 
 		if (!addObject(entity)) {
 			delete entity;

src/libcamera/media_object.cpp

@@ -247,6 +247,23 @@ void MediaPad::addLink(MediaLink *link)
  * may expose a deviceNode().
  */
 
+/**
+ * \enum MediaEntity::Type
+ * \brief The type of the interface exposed by the entity to userspace
+ *
+ * \var MediaEntity::Type::Invalid
+ * \brief Invalid or unsupported entity type
+ *
+ * \var MediaEntity::Type::MediaEntity
+ * \brief Plain media entity with no userspace interface
+ *
+ * \var MediaEntity::Type::V4L2VideoDevice
+ * \brief V4L2 video device with a V4L2 video device node
+ *
+ * \var MediaEntity::Type::V4L2Subdevice
+ * \brief V4L2 subdevice with a V4L2 subdev device node
+ */
+
 /**
  * \fn MediaEntity::name()
  * \brief Retrieve the entity name
@@ -273,6 +290,15 @@ void MediaPad::addLink(MediaLink *link)
  * \return The entity's flags
  */
 
+/**
+ * \fn MediaEntity::type()
+ * \brief Retrieve the entity's type
+ *
+ * The entity type identifies the type of interface exposed to userspace.
+ *
+ * \return The entity's type
+ */
+
 /**
  * \fn MediaEntity::deviceNode()
  * \brief Retrieve the entity's device node path, if any
@@ -356,16 +382,32 @@ int MediaEntity::setDeviceNode(const std::string &deviceNode)
  * \brief Construct a MediaEntity
  * \param[in] dev The media device this entity belongs to
  * \param[in] entity The media entity kernel data
- * \param[in] major The major number of the entity associated interface
- * \param[in] minor The minor number of the entity associated interface
+ * \param[in] iface The entity interface data (may be null)
  */
 MediaEntity::MediaEntity(MediaDevice *dev,
 			 const struct media_v2_entity *entity,
-			 unsigned int major, unsigned int minor)
+			 const struct media_v2_interface *iface)
 	: MediaObject(dev, entity->id), name_(entity->name),
 	  function_(entity->function), flags_(entity->flags),
-	  major_(major), minor_(minor)
+	  type_(Type::MediaEntity), major_(0), minor_(0)
 {
+	if (!iface)
+		return;
+
+	switch (iface->intf_type) {
+	case MEDIA_INTF_T_V4L_VIDEO:
+		type_ = Type::V4L2VideoDevice;
+		break;
+	case MEDIA_INTF_T_V4L_SUBDEV:
+		type_ = Type::V4L2Subdevice;
+		break;
+	default:
+		type_ = Type::Invalid;
+		return;
+	}
+
+	major_ = iface->devnode.major;
+	minor_ = iface->devnode.minor;
 }
 
 /**