I would like to configure the AD7298 linux driver with the device tree? Is this possible or does it need modifications to the module? If so can you show me an example of such a patch?
If you are using the internal reference you can use the driver with device tree.
spi-bus.txt\spi\bindings\devicetree\Documentation - kernel/git/torvalds/linux.git - Linux kernel source tree
Only if you use external reference the driver needs some minor tweak to get the reference voltage from the regulator framework.