NetBSD maps every uhidev device to one or more uhid
devices. Each uhid device only supports one report ID.
The parent device uhidev creates one uhid device per
report ID found in the hardware's report descriptor.
In the event there are no report ID(s) found within the
report descriptor, only one uhid device with a report ID
of 0 is created.
In order to remain compatible with existing hidapi APIs,
all the uhid devices created by the parent uhidev device
must be opened under the same hid_device instance to ensure
that we can route reports to their appropriate uhid device.
Internally the uhid driver will insert the report ID as
needed so we must also omit the report ID in any situation
where the hidapi API expects it to be included in the
report data stream.
Given the design of uhid, it must be augmented with extra
platform specific APIs to ensure that the exact relationship
between uhidev devices and uhid devices can be determined.
The NetBSD implementation does this via the drvctl kernel
driver. At present there is no known way to do this on OpenBSD
for a uhid implementation to be at the same level as the
NetBSD one.