diff --git a/src/mainboard/asus/p8x7x-series/variants/p8z77-m/early_init.c b/src/mainboard/asus/p8x7x-series/variants/p8z77-m/early_init.c
new file mode 100644
index 0000000..dfcdd23
--- /dev/null
+++ b/src/mainboard/asus/p8x7x-series/variants/p8z77-m/early_init.c
@@ -0,0 +1,107 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#include <bootblock_common.h>
+#include <northbridge/intel/sandybridge/raminit_native.h>
+#include <northbridge/intel/sandybridge/raminit.h>
+#include <northbridge/intel/sandybridge/pei_data.h>
+#include <southbridge/intel/bd82x6x/pch.h>
+
+#include <superio/nuvoton/common/nuvoton.h>
+#include <superio/nuvoton/nct6779d/nct6779d.h>
+
+#include <option.h>
+
+#define SERIAL_DEV PNP_DEV(0x2e, NCT6779D_SP1)
+
+const struct southbridge_usb_port mainboard_usb_ports[] = {
+	/* {enable, current, oc_pin} */
+	{1, 2, 0}, /* Port 0: USB3 front internal header, top */
+	{1, 2, 0}, /* Port 1: USB3 front internal header, bottom */
+	{1, 2, 1}, /* Port 2: USB3 rear, top */
+	{1, 2, 1}, /* Port 3: USB3 rear, bottom */
+	{1, 2, 2}, /* Port 4: USB2 rear, PS2 top */
+	{1, 2, 2}, /* Port 5: USB2 rear, PS2 bottom */
+	{1, 2, 3}, /* Port 6: USB2 rear, ETH, top */
+	{1, 2, 3}, /* Port 7: USB2 rear, ETH, bottom */
+	{1, 2, 4}, /* Port 8: USB2 internal header USB910, top */
+	{1, 2, 4}, /* Port 9: USB2 internal header USB910, bottom */
+	{1, 2, 6}, /* Port 10: USB2 internal header USB1112, top */
+	{1, 2, 5}, /* Port 11: USB2 internal header USB1112, bottom */
+	{1, 2, 5}, /* Port 12: USB2 internal header USB1314, top */
+	{1, 2, 6}  /* Port 13: USB2 internal header USB1314, bottom */
+};
+
+void bootblock_mainboard_early_init(void)
+{
+	nuvoton_enable_serial(SERIAL_DEV, CONFIG_TTYS0_BASE);
+
+	/*
+	 * TODO: Put PCIe root port 7 (00:1c.6) into subtractive decode and have it accept I/O
+	 * cycles. This should allow a POST card in the PCI slot, connected via an ASM1083
+	 * bridge to this port, to receive POST codes.
+	 */
+}
+
+void mainboard_get_spd(spd_raw_data *spd, bool id_only)
+{
+	read_spd(&spd[0], 0x50, id_only);
+	read_spd(&spd[1], 0x51, id_only);
+	read_spd(&spd[2], 0x52, id_only);
+	read_spd(&spd[3], 0x53, id_only);
+}
+
+int mainboard_should_reset_usb(int s3resume)
+{
+	return !s3resume;
+}
+
+void mainboard_fill_pei_data(struct pei_data *pei)
+{
+	uint8_t spdaddr[] = {0xa0, 0xa2, 0xa4, 0xa6}; /* SMBus mul 2 */
+	uint16_t usbcfg[16][3] = {
+		/* {enabled, oc_pin, cable len 0x0080=<8inches/20cm} */
+		{1, 0, 0x0080}, {1, 0, 0x0080}, {1, 1, 0x0080}, {1, 1, 0x0080}, {1, 2, 0x0080},
+		{1, 2, 0x0080}, {1, 3, 0x0080}, {1, 3, 0x0080}, {1, 4, 0x0080}, {1, 4, 0x0080},
+		{1, 6, 0x0080}, {1, 5, 0x0080}, {1, 5, 0x0080}, {1, 6, 0x0080}
+	};
+
+	memcpy(pei->spd_addresses, &spdaddr, sizeof(spdaddr));
+
+	pei->gbe_enable = 0;	   /* Board uses no Intel GbE but a RTL8111F */
+	pei->max_ddr3_freq = 1600; /* 1333=Sandy; 1600=Ivy */
+
+	memcpy(pei->usb_port_config, &usbcfg, sizeof(usbcfg));
+
+	/* ASUS P8Z77-M manual lists some supported DIMMs down to 1.25v */
+	pei->ddr3lv_support = 1;
+	/*
+	 * PCIe 3.0 support. As we use Ivy Bridge, let's enable it,
+	 * but might cause some system instability!
+	 */
+	pei->pcie_init = 1;
+	/*
+	 * 4 bit switch mask. 0=not switchable, 1=switchable
+	 * Means once it's loaded the OS, it can swap ports
+	 * from/to EHCI/xHCI. Z77 has four USB3 ports, so 0xf
+	 */
+	pei->usb3.hs_port_switch_mask = 0xf;
+	/*
+	 * USB 3 mode settings.
+	 * These are obtained from option table then bit masked to keep within range.
+	 */
+	/*
+	 * 0 = Disable: work always as USB 2.0(ehci)
+	 * 1 = Enable: work always as USB 3.0(xhci)
+	 * 2 = Auto: work as USB2.0(ehci) until OS loads USB3 xhci driver
+	 * 3 = Smart Auto : same than Auto, but if OS loads USB3 driver
+	 *     and reboots, it will keep the USB3.0 speed
+	 */
+	pei->usb3.mode = get_uint_option("usb3_mode", 1) & 0x3;
+	/* 1=Load xHCI pre-OS drv */
+	pei->usb3.preboot_support = get_uint_option("usb3_drv", 1) & 0x1;
+	/*
+	 * 0=Don't use xHCI streams for better compatibility
+	 * 1=use xHCI streams for better speed
+	 */
+	pei->usb3.xhci_streams = get_uint_option("usb3_streams", 1) & 0x1;
+}