System clock for PRU, BeagleBone Black

I’ve been searching for information regarding SPI on the PRU. I’m starting to understand assembly programming and the memory mappings,
but i’m unable to find information on system clocks.

I’ve been through the AM335x-Manual where i found a lot of information on the mcSPI-module and its registers, and I’ve been looking at the PRCM-list.
Does anyone have a simple example of how i could enable and check the state of one of the internal clocks in the PRU program?

(The purpose of the program is to demonstrate usage of PRU rather than to ship the whole process to the mcSPI-module)