diff --git a/src/mainboard/siemens/mc_apl1/variants/mc_apl3/mainboard.c b/src/mainboard/siemens/mc_apl1/variants/mc_apl3/mainboard.c
new file mode 100644
index 0000000..ccf3ab8
--- /dev/null
+++ b/src/mainboard/siemens/mc_apl1/variants/mc_apl3/mainboard.c
@@ -0,0 +1,98 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright (C) 2018 Siemens AG
+ *
+ * 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 <bootstate.h>
+#include <console/console.h>
+#include <device/pci_ids.h>
+#include <device/pci_ops.h>
+#include <gpio.h>
+#include <hwilib.h>
+#include <intelblocks/lpc_lib.h>
+#include <intelblocks/pcr.h>
+#include <soc/pcr_ids.h>
+#include <timer.h>
+#include <timestamp.h>
+#include <baseboard/variants.h>
+
+#define TX_DWORD3	0xa8c
+
+void variant_mainboard_final(void)
+{
+	struct device *dev = NULL;
+
+	/*
+	 * PIR6 register mapping for PCIe root ports
+	 * INTA#->PIRQB#, INTB#->PIRQC#, INTC#->PIRQD#, INTD#-> PIRQA#
+	 */
+	pcr_write16(PID_ITSS, 0x314c, 0x0321);
+
+	/* Disable clock outputs 1-5 (CLKOUT) for XIO2001 PCIe to PCI Bridge. */
+	dev = dev_find_device(PCI_VENDOR_ID_TI, PCI_DEVICE_ID_TI_XIO2001, 0);
+	if (dev)
+		pci_write_config8(dev, 0xd8, 0x3e);
+
+	/* Enable CLKRUN_EN for power gating LPC */
+	lpc_enable_pci_clk_cntl();
+
+	/*
+	 * Enable LPC PCE (Power Control Enable) by setting IOSF-SB port 0xD2
+	 * offset 0x341D bit3 and bit0.
+	 * Enable LPC CCE (Clock Control Enable) by setting IOSF-SB port 0xD2
+	 * offset 0x341C bit [3:0].
+	 */
+	pcr_or32(PID_LPC, PCR_LPC_PRC, (PCR_LPC_CCE_EN | PCR_LPC_PCE_EN));
+
+	/*
+	 * Correct the SATA transmit signal via the High Speed I/O Transmit
+	 * Control Register 3.
+	 * Bit [23:16] set the output voltage swing for TX line.
+	 * The value 0x4a sets the swing level to 0.58 V.
+	 */
+	pcr_rmw32(PID_MODPHY, TX_DWORD3, (0x00 << 16), (0x4a << 16));
+}
+
+static void wait_for_legacy_dev(void *unused)
+{
+	uint32_t legacy_delay, us_since_boot;
+	struct stopwatch sw;
+
+	/* Open main hwinfo block. */
+	if (hwilib_find_blocks("hwinfo.hex") != CB_SUCCESS)
+		return;
+
+	/* Get legacy delay parameter from hwinfo. */
+	if (hwilib_get_field(LegacyDelay, (uint8_t *) &legacy_delay,
+			      sizeof(legacy_delay)) != sizeof(legacy_delay))
+		return;
+
+	us_since_boot = get_us_since_boot();
+	/* No need to wait if the time since boot is already long enough.*/
+	if (us_since_boot > legacy_delay)
+		return;
+	stopwatch_init_msecs_expire(&sw, (legacy_delay - us_since_boot) / 1000);
+	printk(BIOS_NOTICE, "Wait remaining %d of %d us for legacy devices...",
+			legacy_delay - us_since_boot, legacy_delay);
+	stopwatch_wait_until_expired(&sw);
+	printk(BIOS_NOTICE, "done!\n");
+}
+
+static void finalize_boot(void *unused)
+{
+	/* Set coreboot ready LED. */
+	gpio_output(CNV_RGI_DT, 1);
+}
+
+BOOT_STATE_INIT_ENTRY(BS_DEV_ENUMERATE, BS_ON_ENTRY, wait_for_legacy_dev, NULL);
+BOOT_STATE_INIT_ENTRY(BS_PAYLOAD_BOOT, BS_ON_ENTRY, finalize_boot, NULL);