Serial port driver?

FUNCTIONS:

PVOID
MmMapIoSpace(
IN PHYSICAL_ADDRESS PhysicalAddress,
IN ULONG NumberOfBytes,
IN BOOLEAN CacheEnable
);

BOOLEAN
HalTranslateBusAddress(
IN INTERFACE_TYPE InterfaceType,
IN ULONG BusNumber,
IN PHYSICAL_ADDRESS BusAddress,
IN OUT PULONG AddressSpace,
OUT PPHYSICAL_ADDRESS TranslatedAddress
);
VOID
WRITE_PORT_ULONG(
IN PULONG Port,
IN ULONG Value
);

WRITE_PORT_ULONG writes a ULONG value to the specified port address.

I need this function for DMA access to the serial port!!
How can I determine the port address???
Can someone fill in this functions specifically for serial port I didn’t
find any resource that would show this thing?!(They are connected together).

How can I get the address of serial port and write/read to/from this address
on the most easiest way?

Regards
Neno