ugen and newbus

Hi,


On the new usb stack the ugen driver attaches to all usb devices and
generates a devd attach event but doesnt actually have a device entry.

It either needs to be a device or use a different devd notification. It
would be easier if it was a device as that takes care of the housekeeping. 

I am not sure that the best way to attach it into the device tree, a
ugen device represents a physical unit and may have multiple usb drivers
attach (like a 3g device with a built in sd reader).

ehci0
 usbus0
  uhub0
   umass0
   umass1
   uhub1
    u3g0
    umass2
    uplcom0
    uplcom1

This would become 

ehci0
 usbus0
  ugen0
   uhub0
    ugen1
     umass0
    ugen2
     umass1
   ugen3
    uhub1
     ugen4
      u3g0
      umass2
     ugen5
      uplcom0
     ugen6
      uplcom1

Is that the right way to do it?


Andrew