google/kahlee: Add ChromeOS SMBIOS Board ID

Kahlee uses 3 GPIO(144, 140, 135) pins to identify the
board revision.

Change-Id: Ia9693db6d6506af7ff40db0b3ce4cc6c1469f6ef
Signed-off-by: Marc Jones <marcj303@gmail.com>
Reviewed-on: https://review.coreboot.org/19837
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

src/mainboard/google/kahlee/Kconfig

@@ -27,6 +27,7 @@ config BOARD_SPECIFIC_OPTIONS # dummy
 	select HAVE_MP_TABLE
 	select HAVE_ACPI_TABLES
 	select GFXUMA
+	select GOOGLE_SMBIOS_MAINBOARD_VERSION
 	select MAINBOARD_HAS_CHROMEOS
 	select MAINBOARD_HAS_LPC_TPM
 	select SERIRQ_CONTINUOUS_MODE

src/mainboard/google/kahlee/Makefile.inc

@@ -20,11 +20,13 @@ bootblock-y += ec.c
 bootblock-y += gpio.c
 
 romstage-y += BiosCallOuts.c
+romstage-y += boardid.c
 romstage-y += chromeos.c
 romstage-y += gpio.c
 romstage-y += OemCustomize.c
 
 ramstage-y += BiosCallOuts.c
+ramstage-y += boardid.c
 ramstage-y += chromeos.c
 ramstage-y += ec.c
 ramstage-y += gpio.c

src/mainboard/google/kahlee/boardid.c

@@ -0,0 +1,36 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright (C) 2017 Advanced Micro Devices, 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.
+ */
+
+#include <boardid.h>
+#include <console/console.h>
+#include <gpio.h>
+
+uint8_t board_id(void)
+{
+	MAYBE_STATIC int id = -1;
+
+	gpio_t gpios[] = {
+		GPIO_135,
+		GPIO_140,
+		GPIO_144,
+	};
+
+	if (id < 0) {
+		id = gpio_base2_value(gpios, ARRAY_SIZE(gpios));
+		printk(BIOS_SPEW, "Board ID: %#x.\n", id);
+	}
+
+	return id;
+}