libpayload: ipq808x: introduce uart driver

This adds a UART driver for the ipq8064 controller. It still does not
quite work in the receive direction - the receive FIFO returns read
data in 32 bit chunks, which means that 4 keys need to be pressed
before a character pops out of the driver (and it reports it as a
single character).

This issue is being addressed separately, the driver is being checked
in to facilitate concurrent development.

BUG=chrome-os-partner:27784, chrome-os-partner:29313

TEST=with deptcharge modifications in place, the AP148 board comes up
     to the depthcharge prompt:

Starting depthcharge on storm...

Original-Change-Id: Ief2cfcca73494be5c4147881144470078adcefb8
Original-Signed-off-by: Vadim Bendebury <vbendeb@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/202045
Original-Reviewed-by: Deepa Dinamani <deepad@codeaurora.org>
Original-Reviewed-by: Stefan Reinauer <reinauer@chromium.org>
(cherry picked from commit 4499318fb9a4e663c504d7c41380ccf2aa89da29)
Signed-off-by: Marc Jones <marc.jones@se-eng.com>

Change-Id: I3e07d7568c20c0e570222971ff219de3a6d9b7cc
Reviewed-on: http://review.coreboot.org/8061
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

0 files changed, 0 insertions, 0 deletions