uxrcom —
Exar XR21V141x USB serial adapter
uxrcom* at uhub?
ucom* at uxrcom?
The uxrcom driver supports serial adapters based on the
  XR21V1410, XR21V1412 and XR21V1414 chipsets. Devices range from single port to
  eight port (implemented as a USB hub and two uxrcom
  four port instances behind it). Examples of hardware known to work with this
  driver are:
  - Gearmo GM-U28RS232 8 Port USB to Serial DB9 RS232 Adapter
-  
 
The uxrcom driver attaches the Exar XR21V141x multiport
  chipset with individual port drivers via
  ucom(4), which makes it behave
  like a tty(4).
The uxrcom device driver first appeared in
  OpenBSD 6.5 and in NetBSD 9.1.
The uxrcom driver for the single port XR21V1410 was
  written by Mark Kettenis
  <kettenis@openbsd.org>.
  The multi-port NetBSD driver is based on the
  OpenBSD driver but uses the common
  umodem(4) framework. The
  NetBSD driver was written by by Simon
  Burge ⟨simonb@netbsd.org⟩.