/dev/ttyS3 shows different I/O ports on lspci & setserial -g

["Dr. Sachin Kale" <sauravsk@agd2.dot.net.in>]

Hello,

I have got an internal modem on /dev/ttyS3 ( COM 4 ) Its details are
as follows -

01:09.0 Communication controller: ESS Technology: Unknown device 2838
(rev 01)
 Subsystem: ESS Technology: Unknown device 2838
 Control: I/O+ Mem- BusMaster- SpecCycle- MemWINV- VGASnoop- ParErr-
Stepping- SERR- FastB2B-
 Status: Cap+ 66Mhz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort-
<TAbort- <MAbort- >SERR- <PERR-
 Interrupt: pin A routed to IRQ 11
 Region 0: I/O ports at c000
 Capabilities: [c0] Power Management version 2
  Flags: PMEClk- AuxPwr- DSI- D1- D2+ PME+
  Status: D0 PME-Enable- DSel=0 DScale=0 PME-

Note I/O ports are c000; Interrupt is 11.

output of setserial -g /dev/ttyS* is -

/dev/ttyS15: No such device
/dev/ttyS0, UART: 16550A, Port: 0x03f8, IRQ: 4
/dev/ttyS1, UART: 16550A, Port: 0x02f8, IRQ: 3
/dev/ttyS2, UART: unknown, Port: 0x03e8, IRQ: 4
/dev/ttyS3, UART: 16450, Port: 0x02e8, IRQ: 3

NOte that /dev/ttyS3 shows port as 0x02e8 ( which matches with com4
details in win98 ) IRQ is 3 ( win98 it is 11 )

Can you tell meI why this difference in port is there; when using
lspci & setserial commands.

And is that the reason why I get this message  -

esscom.o: init_module: Device or resource busy
Hint: this error can be caused by incorrect module parameters,
including invalid IO or IRQ parameters

on insmod -f esscom.o ( a module driver for ESS modem )

I have checked lsof /dev/ttyS* ; /devttyS3 is free.

Thanks

sachin
( I am using the same kernel ( 2.2.12-20) against which this module
was compiled. )
( this is deb 2.2 + win 98 )