Support for Fintek F81866

[Vincenzo Ferraro <enzo@stepautomation.it>]

Good evening to everyone,

I'm using Debian 9 stable release with kernel-image-686-pae.
I have a board with the Fintek F81866 super io chipset.
I see that serial ports /dev/ttyS0 and /dev/ttyS1 are working properly 
but /dev/ttyS2 and /dev/ttyS3 are not.
Looking at the source code i found that probably the current kernel 
lacks of specific support
for Fintek F81866 (file: 8250_fintek.c).
Try with Debian testing and serial ports work all properly. Looking at 
the current mainline kernel source
(file: 8250_fintek.c) i see that there is a specific support for F81866.
Is it possible to support it on next stable kernel patch ?

Thank you for your attention.

Regards
    Vincenzo Ferraro