mips: Allow memory to be identity mapped in the TLB

Introduce identity_map() function. It takes a memory range and
identity maps it entirely in the TLB table, if possible. As a result
the virtual and physical address ranges are the same.

The function attempts to use as large of a page size as possible for
each region in order to conserve TLB entries.

BUG=chrome-os-partner:36258
BRANCH=none
TEST=Build and boot on Pistachio with the rest of the patches applied.

Change-Id: I4d781b04699e069a71c49a0c6ca15c7a6b42a468
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Original-Commit-Id: 234d32edfd201019b7a723316a79c932c62ce87e
Original-Change-Id: If3e2392b19555cb6dbae8b5559c1b1e53a313637
Original-Signed-off-by: Andrew Bresticker <abrestic@chromium.org>
Original-Signed-off-by: Vadim Bendebury <vbendeb@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/246693
Reviewed-on: http://review.coreboot.org/9815
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
4 files changed