Tutorial for memory-mapped I/O?

Is there a tutorial, or guide someone could point to which might explain how to setup very basic hardware (maybe just a register, or a counter) and show how to read and write from this in Linux? (using mmap, I imagine).
I'm using Vivado 2015.2.
I've seen this one, but it's explained using Xilinx Platform Studio and it seems tricky to apply this to Vivado: http://fpga.org/2013/05/28/how-to-design-and-access-a-memory-mapped-devi...