arm: libpayload: Add cache coherent DMA memory definition and management

This patch adds a mechanism to set aside a region of cache-coherent
(i.e. usually uncached) virtual memory, which can be used to communicate
with DMA devices without automatic cache snooping (common on ARM)
without the need of explicit flush/invalidation instructions in the
driver code.

This works by setting aside said region in the (board-specific) page
table setup, as exemplary done in this patch for the Snow and Pit
boards. It uses a new mechanism for adding board-specific Coreboot table
entries to describe this region in an entry with the LB_DMA tag.

Libpayload's memory allocator is enhanced to be able to operate on
distinct types/regions of memory. It provides dma_malloc() and
dma_memalign() functions for use in drivers, which by default just
operate on the same heap as their traditional counterparts. However, if
the Coreboot table parsing code finds a CB_DMA section, further requests
through the dma_xxx() functions will return memory from the region
described therein instead.

Change-Id: Ia9c249249e936bbc3eb76e7b4822af2230ffb186
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/167155
(cherry picked from commit d142ccdcd902a9d6ab4d495fbe6cbe85c61a5f01)
Signed-off-by: Isaac Christensen <isaac.christensen@se-eng.com>
Reviewed-on: http://review.coreboot.org/6622
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
chromeos: On ARM platforms VBNV lives in the EC

This patch renames the x86 way of doing things to
explicitly mention CMOS (which is not available on
our ARM platforms) and adds an implementation to
get VBNV through the Chrome EC. We might want to
refine this further in the future to allow VBNV
in the EC even on x86 platforms. Will be fixed when
that appears. Also, not all ARM platforms running
ChromeOS might use the Google EC in the future, in
which case this code will need additional work.

Signed-off-by: Stefan Reinauer <reinauer@google.com>

Change-Id: Ice09d0e277dbb131f9ad763e762e8877007db901
Reviewed-on: https://chromium-review.googlesource.com/167540
Reviewed-by: David Hendrix <dhendrix@chromium.org>
Tested-by: Stefan Reinauer <reinauer@google.com>
Commit-Queue: Stefan Reinauer <reinauer@google.com>
(cherry picked from commit 8df6cdbcacb082af88c069ef8b542b44ff21d97a)
Signed-off-by: Isaac Christensen <isaac.christensen@se-eng.com>
Reviewed-on: http://review.coreboot.org/6616
Tested-by: build bot (Jenkins)
Reviewed-by: David Hendricks <dhendrix@chromium.org>