lenovo/t420s: Add new port.

This is based on x220 and t520. Tested on i7 model with usb3.
There is no support for nvidia gpu and optimus.

Change-Id: I6ca9436ccec3024095d02078e5e450147841e463
Signed-off-by: Nicolas Reinecke <nr@das-labor.org>
Reviewed-on: http://review.coreboot.org/7974
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
Tested-by: build bot (Jenkins)
Reviewed-by: Philipp Deppenwiese <zaolin@das-labor.org>
Reviewed-by: Peter Stuge <peter@stuge.se>
diff --git a/src/mainboard/lenovo/t420s/Kconfig b/src/mainboard/lenovo/t420s/Kconfig
new file mode 100644
index 0000000..72605d1
--- /dev/null
+++ b/src/mainboard/lenovo/t420s/Kconfig
@@ -0,0 +1,74 @@
+if BOARD_LENOVO_T420S
+
+config BOARD_SPECIFIC_OPTIONS # dummy
+	def_bool y
+	select SYSTEM_TYPE_LAPTOP
+	select CPU_INTEL_SOCKET_RPGA988B
+	select NORTHBRIDGE_INTEL_SANDYBRIDGE_NATIVE
+	select SOUTHBRIDGE_INTEL_BD82X6X
+	select EC_LENOVO_PMH7
+	select EC_LENOVO_H8
+	select BOARD_ROMSIZE_KB_8192
+	select HAVE_ACPI_TABLES
+	select HAVE_OPTION_TABLE
+	select HAVE_CMOS_DEFAULT
+	select HAVE_ACPI_RESUME
+	select INTEL_INT15
+	select VGA
+	select INTEL_EDID
+	select MAINBOARD_HAS_NATIVE_VGA_INIT
+	select MAINBOARD_HAS_NATIVE_VGA_INIT_TEXTMODECFG
+	select SANDYBRIDGE_LVDS
+
+	# Workaround for EC/KBC IRQ1.
+	select SERIRQ_CONTINUOUS_MODE
+
+config HAVE_IFD_BIN
+	bool
+	default n
+
+config HAVE_ME_BIN
+	bool
+	default n
+
+config MAINBOARD_DIR
+	string
+	default lenovo/t420s
+
+config MAINBOARD_PART_NUMBER
+	string
+	default "ThinkPad T420s"
+
+config MMCONF_BASE_ADDRESS
+	hex
+	default 0xf0000000
+
+config MAX_CPUS
+	int
+	default 8
+
+config USBDEBUG_HCD_INDEX
+	int
+	default 2
+
+config DRAM_RESET_GATE_GPIO
+	int
+	default 10
+
+config VGA_BIOS_FILE
+	string
+	default "pci8086,0126.rom"
+
+config VGA_BIOS_ID
+	string
+	default "8086,0126"
+
+config MAINBOARD_PCI_SUBSYSTEM_VENDOR_ID
+	hex
+	default 0x17aa
+
+config MAINBOARD_PCI_SUBSYSTEM_DEVICE_ID
+	hex
+	default 0x21d2
+
+endif # BOARD_LENOVO_T420S