soc/apollolake: Add early serial driver for BOOTBLOCK_CONSOLE

Early UART driver is for bootblock and romstage. It is supposed to be used
when BOOTBLOCK_CONSOLE is enabled. This also adds few configuration bits
in bootblock requiered for serial to be set up.

Change-Id: I15520d566f107797e68d618885d4379e73d0fa45
Signed-off-by: Andrey Petrov <andrey.petrov@intel.com>
Reviewed-on: https://review.coreboot.org/13677
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

src/mainboard/intel/apollolake_rvp/bootblock.c

@@ -0,0 +1,30 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright (C) 2016 Intel Corp.
+ * (Written by Andrey Petrov <andrey.petrov@intel.com> for Intel Corp.)
+ *
+ * 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; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#include <bootblock_common.h>
+#include <console/console.h>
+#include <soc/gpio.h>
+#include <soc/gpio_defs.h>
+#include <soc/uart.h>
+
+static struct pad_config aplk_rvp_gpios[] = {
+	PAD_CFG_NF(GPIO_46, NATIVE, DEEP, NF1),		/* UART2 RX*/
+	PAD_CFG_NF(GPIO_47, NATIVE, DEEP, NF1)		/* UART2 TX*/
+};
+
+void bootblock_mainboard_early_init(void)
+{
+	if (IS_ENABLED(CONFIG_BOOTBLOCK_CONSOLE)) {
+		gpio_configure_pads(aplk_rvp_gpios, ARRAY_SIZE(aplk_rvp_gpios));
+		lpss_console_uart_init();
+	}
+}