There are many other peripherals and/or protocols (such as I2S, USB, one wire). The implementation and the main concepts should be pretty similar to the peripherals covered so far. At this stage I do not plan to do it in this book. At least not in the near future.
Various micro-controllers may also support DMA access to some peripherals. In this case the
Character Driver that was covered in UART chapter must be replaced with some kind of
Block Driver, that will allow issuing of multiple read/write requests at the same time and will receive only "operation complete" notifications from the Device. I leave implementation of it as an excercise for the reader. At least for now.