Technically touchscreen chip is FT5406 but all hardware
communication is performed by VideCore and only final results
are presented to ARM part through memory region shared between
VC and ARM.
evdev is used as userland interface. FT5406 supports up to
10 touchpoints, but for now driver emulates single touch device
because I do not have GUI bits to test this functionality.
Driver is not enabled in default config for RPI and RPI2
Tested with: evdev-dump, tslib
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
