If you look at the Renesas 3.14 BSP, you'll notice that we didn't use the "EDT-FT5X06" driver (drivers/input/touchscreen/edt-ft5x06.c) that was already in the kernel. Instead, we made one.
The reason is that the"EDT" is a special version of the chip as it mentions at the top of the edt-ft5x06.c file. And, this chip doesn't act the same so the driver is somewhat useless.
/*
* This is a driver for the EDT "Polytouch" family of touch controllers
* based on the FocalTech FT5x06 line of chips.
*
* Development of this driver has been sponsored by Glyn:
*/
So what you can do is just steal the one out of the Renesas 3.14 BSP.
Or, you do a Google search for "ft5x06_ts.c" and you can see there are a couple other versions out there you can choose from (they are all GPL, so it's not problem using them either).
> Can someone guide me through the correct process to make the touchscreen work please?
I'm not sure I can 'guide' you, but you can at least look at the commits from the file we added so you can see how we added it.
Then, just look in the board-rskrza1.c file and copy everything that has to do with ft5x06 and I2C in order to see how we registered it.
github.com/.../board-rskrza1.c
Note that this driver does not support Device Tree, so you will have to register the platform driver in your board-xxx.c driver.