I would like to suggest an Idea for 2017, and ask the community to reflect on it. If the community thinks its useful, I will add the idea to the gsoc-idea-page
So the project aims to develop a set of C-library and examples for the PRUs to be able to access other peripherals on the SoC (ADC, McSPI etc). This will be helpful in cases where PRUs are to be used as a processing unit (and not as a fast I/O unit) and pre-process the raw data maybe using some filtering algorithms.
The project in all will involve developing C-libraries for the PRUs, DT-overlays for specific peripheral which we want to be initialized by the Kernel and a simple driver that would keep the SoC peripheral with itself on behalf of PRUs so as to prevent interference by any other driver.
This project will also be useful along with the project that aims at loading Arduino sketches onto PRUs.
PS : I was also thinking for some kind of DMA support for PRUs.