Input driver on 1.15.1 vs. 1.19.6

[Software Orchestration]

Hi, I have a client that has a working serial input driver on Ubuntu 14.04, which is running the Xorg 1.15.1 server.
I'm tasked with getting this to work on Ubuntu 18.04 which is running Xorg 1.19.6
In looking at the X.Org Server wiki page:
https://en.wikipedia.org/wiki/X.Org_Server
I see that 1.15.1 is not supported anymore, but 1.19.6 still is.
My question is if anything would have changed for the input device driver specs between these versions that would effect a serial input device? This is a touch screen, but it interfaces through serial.
The code uses xf86ReadSerial() and xf86WriteSerial().

Are there any examples using the latest Xorg server available? The code does compile so I'm guessing those functions are in the current interfaces, or are different ones available now?

The sources go back pretty far on 14.04 and I see ifdefs for XFREE86_V3 and XFREE86_V4.
As such I was looking for some example code that shows how to interface with the 1.19.6 server, which is current for Ubuntu 18.04.
Any advice?

Alan

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