Understanding's snippet of athn(9) code

[Farhan Khan <farhan@farhan.codes>]

Hi all,
I am trying to understand a snippet of athn(9) code for the purpose of
porting to FreeBSD. I am reading the function athn_usb_htc_setup()
located in /usr/src/sys/dev/usb/if_athn_usb.c. After tracing it
through, it seems to terminate at a usbd_setup_xfer(9) call.

Is this the equivalent of setting up which USB function will handle
which channel? This function seems similar to FreeBSD's
usbd_transfer_setup(9), which I believe does that. If so, how is that
different from athn_usb_open_pipes()?

If not, what does athn_usb_htc_setup() do? It is not clear to me and
therefore I am having trouble making the translation.

(Sorry for the double-post on current-users%netbsd.org@localhost, I was directed
to post here after consulting with a user on IRC)

Thank you!
Farhan