Summary:
This driver supports the following methods to trigger gathering random bits from the hardware:
1. interrupt when the FIFO is full (default) fed into the harvest queue
2. callout (when BCM2835_RNG_USE_CALLOUT is defined) every second if hz is less than 100, otherwise hz / 100, feeding the random bits into the harvest queue
If the kernel is booted with verbose enabled, the contents of the registers will be dumped after the RBG is started during the attach routine.
Author: hackagadget_gmail.com (Stephen J. Kiernan)
Test Plan: Built RPI2 kernel and booted on board. Tested the different methods to feed the harvest queue (callout, interrupt) and the interrupt driven approach seems best. However, keeping the other method for people to be able to experiment with.
Reviewed By: adrian, delphij, markm
Differential Revision: https://reviews.freebsd.org/D6888
