USB serial device naming

[Trevor Blackwell]

I can't seem to find a way to match USB serial ports & tty names. I  
have two serial USB devices, which I can distinguish easily from  
"usbconfig show_ifdrv"

	ugen2.2: <URG-Series USB Driver Hokuyo Data Flex for USB> at usbus2,  
cfg=0 md=HOST spd=FULL (12Mbps) pwr=ON
	ugen2.2.0: umodem0: <Hokuyo Data Flex for USB URG-Series USB Driver,  
class 2/0, rev 2.00/1.00, addr 2>
	ugen2.3: <USB-Serial Controller Prolific Technology Inc.> at usbus2,  
cfg=0 md=HOST spd=FULL (12Mbps) pwr=ON
	ugen2.3.0: uplcom0: <Prolific Technology Inc. USB-Serial Controller,  
class 0/0, rev 1.10/3.00, addr 3>

and they result in two ttys:
	/dev/cuaU0
	/dev/cuaU1

but I can't figure out how to map the USB devices to tty names. It  
depends on what order they come up in. They're assigned sequentially  
by a bitmap system in usb_serial.c

How can my code figure this out? I think what I want is some sort of  
ioctl on the raw USB device or usbconfig option to tell me what tty it  
appears as.

--
Trevor Blackwell		650 776 7870	tlb at tlb.org