purism/librem13: Add support for Purism Librem 13 mainboard

This adds support for booting the Purism Librem 13 mainboard
with coreboot, using binaries extracted from the original BIOS
and from a Broadwell Chromebook.

The following features have been tested on Ubuntu 15.10:
- Input: Keyboard and Trackpad
- SATA: Internal HDD and M.2 NGFF
- Network: WiFi and Ethernet
- USB: Bluetooth, Camera, SD Card, Ports (1xUSB2 and 1xUSB3)
- Video: Internal panel and HDMI port
- Internal speakers and microphone (headphones do not work)
- EC handling for battery, AC, lid, special keys

These binaries are extracted from the original BIOS:
- VGA BIOS
- Management Engine
- Intel Firmware Descriptor

These binaries are extracted from a Broadwell Chromebook BIOS:
- MemoryInit reference code binary
- SiliconInit reference code binary

This was developed and tested on an Librem 13 device.  For those
who may want to do more development you can use EHCI debug and the
right USB port to get coreboot output.

Change-Id: Ia72e2d7ddc8ba5eef63819e5677122a5a5c705d8
Signed-off-by: Duncan Laurie <dlaurie@google.com>
Reviewed-on: https://review.coreboot.org/13026
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Tested-by: build bot (Jenkins)
diff --git a/src/mainboard/purism/Kconfig b/src/mainboard/purism/Kconfig
new file mode 100644
index 0000000..ff6eb41
--- /dev/null
+++ b/src/mainboard/purism/Kconfig
@@ -0,0 +1,31 @@
+##
+## This file is part of the coreboot project.
+##
+## Copyright (C) 2015 Google Inc.
+##
+## This program is free software; you can redistribute it and/or modify
+## it under the terms of the GNU General Public License as published by
+## the Free Software Foundation; version 2 of the License.
+##
+## This program is distributed in the hope that it will be useful,
+## but WITHOUT ANY WARRANTY; without even the implied warranty of
+## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+## GNU General Public License for more details.
+##
+
+if VENDOR_PURISM
+
+choice
+	prompt "Mainboard model"
+
+source "src/mainboard/purism/*/Kconfig.name"
+
+endchoice
+
+source "src/mainboard/purism/*/Kconfig"
+
+config MAINBOARD_VENDOR
+	string "Mainboard Vendor"
+	default "Purism"
+
+endif # VENDOR_PURISM