glados: Add touchscreen device in ACPI

Add the ELAN touchscreen device in ACPI to bind it to the I2C
device at bus I2C0, address 0x10, interrupt 31 (GPP_E7).

BUG=chrome-os-partner:43514
BRANCH=none
TEST=boot on glados P2 and see touchscreen initialized by kernel

Original-Change-Id: I23b071b2767547baed239c94216cda6162d045dd
Original-Signed-off-by: Duncan Laurie <dlaurie@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/293512
Original-Reviewed-by: Aaron Durbin <adurbin@chromium.org>

Change-Id: I8a9492e6fa1f650cef0871329ae8944caffdaf5a
Signed-off-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-on: http://review.coreboot.org/11278
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

src/mainboard/google/glados/acpi/mainboard.asl

@@ -22,6 +22,9 @@
 #define BOARD_TOUCHPAD_I2C_ADDR			0x15
 #define BOARD_TOUCHPAD_IRQ			GPP_B3_IRQ
 
+#define BOARD_TOUCHSCREEN_I2C_ADDR		0x10
+#define BOARD_TOUCHSCREEN_IRQ			GPP_E7_IRQ
+
 #define BOARD_HP_MIC_CODEC_I2C_ADDR		0x1a
 #define BOARD_LEFT_SPEAKER_AMP_I2C_ADDR		0x34
 #define BOARD_RIGHT_SPEAKER_AMP_I2C_ADDR	0x35
@@ -72,6 +75,38 @@ Scope (\_SB.PCI0.LPCB)
 	#include <drivers/pc80/tpm/acpi/tpm.asl>
 }
 
+Scope (\_SB.PCI0.I2C0)
+{
+	/* Touchscreen */
+	Device (ELTS)
+	{
+		Name (_HID, "ELAN0001")
+		Name (_DDN, "Elan Touchscreen")
+		Name (_UID, 1)
+		Name (_S0W, 4)
+
+		Name (_CRS, ResourceTemplate()
+		{
+			I2cSerialBus (
+				BOARD_TOUCHSCREEN_I2C_ADDR,
+				ControllerInitiated,
+				400000,
+				AddressingMode7Bit,
+				"\\_SB.PCI0.I2C0",
+			)
+			Interrupt (ResourceConsumer, Edge, ActiveLow)
+			{
+				BOARD_TOUCHSCREEN_IRQ
+			}
+		})
+
+		Method (_STA)
+		{
+			Return (0xF)
+		}
+	}
+}
+
 Scope (\_SB.PCI0.I2C1)
 {
 	/* Touchpad */