mb/google/poppy/variants/rammus: add sku info into smbios table

This patch adds the mainboard.c in order to support the sku id in smbios
table where the sku id is queried from the eeprom via EC.

BUG=b:113714761
BRANCH=master
TEST=check the result of 'dmidecode'

Change-Id: I3413784cca1ac10a2468d84f2d06c0e1d701fdcb
Signed-off-by: Zhuohao Lee <zhuohao@chromium.org>
Reviewed-on: https://review.coreboot.org/28426
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Furquan Shaikh <furquan@google.com>

src/mainboard/google/poppy/variants/rammus/Makefile.inc

@@ -6,3 +6,4 @@ romstage-y += memory.c
 
 ramstage-y += gpio.c
 ramstage-y += nhlt.c
+ramstage-y += mainboard.c

src/mainboard/google/poppy/variants/rammus/mainboard.c

@@ -0,0 +1,44 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright 2018 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.
+ */
+
+#include <baseboard/variants.h>
+#include <ec/google/chromeec/ec.h>
+#include <smbios.h>
+#include <string.h>
+
+#define SKU_UNKNOWN     0xFFFFFFFF
+
+uint32_t variant_board_sku(void)
+{
+	static uint32_t sku_id = SKU_UNKNOWN;
+	uint32_t id;
+
+	if (sku_id != SKU_UNKNOWN)
+		return sku_id;
+	if (google_chromeec_cbi_get_sku_id(&id))
+		return SKU_UNKNOWN;
+	sku_id = id;
+
+	return sku_id;
+}
+
+const char *smbios_mainboard_sku(void)
+{
+	static char sku_str[14]; /* sku{0..4294967295} */
+
+	snprintf(sku_str, sizeof(sku_str), "sku%u", variant_board_sku());
+
+	return sku_str;
+}