Bare Metal I/O documentation help

Where do I find an architecture document on Cortex-A bare metal I/O?  The ARMv8 architecture document doesn't seem to address this, unless I've missed it. I'd like to be able to communicate with the usual devices (USB keyboard and mouse, monitor via HDMI, and mass storage devices such as SD card, USB flash drive, and USB spinning hard drive). It would be nice to know about how to program the graphics chip, but that is for later.  Txt mode is good enough for now.  Any other suggestions are appreciated.

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