char device driver and bus ?

 hi all, as we known, linux kernel device driver have three layers:
bus, device and dirver.
  but when a char device register, i will added to:
chrdevs[MAX_PROBE_HASH] and it seems dont blong to any bus.
  does it means that the kernel only use the array
chrdevs[MAX_PROBE_HASH] to manager the driver and device?
  for example, a usb driver and usb device will mach by ID, but when a
serial driver and serial device will mach by what ?

 if a char deveice doesnt blong to any bus, how to traversal the
char devices?
the array of chrdevs[MAX_PROBE_HASH] doest EXPORT_SYMBOL