This is an example devicetree based board driver implementation which can be used as a reference.
The board driver initializes the devicetree manager library with the incoming namespace in order to provide connection to |fuchsia_boot::Items| protocol. Once the manager is reads the devicetree using the |fuchsia_boot::Items| protocol, it is used to walk the devicetree and collect node properties. During the devicetree walk, several visitors can be provided to parse and collect node properties. In this example we are using the default visitor set which parses all the standard bindings supported in Fuchsia. See visitors folder for more details. Once the walk is completed, the manager is invoked to publish all the devices/nodes.
Typically the devicetree blob (DTB) is passed down by the bootloader to the kernel as a | ZBI_TYPE_DEVICETREE| item and made available to the board driver via |fuchsia_boot::Items| protocol. In boards where the bootloader is not yet capable of passing the DTB (typically during board bringup), the kernel ZBI can be appended with the devicetree blob at build time using |zbi_input| and |kernel_zbi_extra_deps|. See BUILD.gn for more details.
The integration test creates a test realm with driver framework, platform bus and the board driver components running in it. The DTB is passed as a test data resource and is provided to the board driver through the fake |fuchsia_boot::Items| protocol implemented in the board-test-helper library. The test creates a platform bus device with specified VID, PID to which the board driver will bind to. The board driver would then parse the devicetree and create other child nodes. A typical test would be to enumerate the nodes created.