google/kahlee: Add ASL for Elan touchpad

Add ASL for the Elan touchpad driver connection in ChromeOS.
This is based on the Auron and Rambi ASL. The AMD ACPI code
doesn't have the auto table generation the newer Intel
Chrome SOC use.

Device visible to OS: /sys/bus/acpi/devices/ELAN0000

Change-Id: Id3fc8c8855b0296f43a502e81143498d663468ec
Signed-off-by: Ivy Jian <ivy_jian@compal.com>
Signed-off-by: Marc Jones <marcj303@gmail.com>
Reviewed-on: https://review.coreboot.org/19844
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

src/mainboard/google/kahlee/acpi/mainboard.asl

@@ -34,3 +34,27 @@ Name (SSFG, 0x0D)
 Name (OSVR, 3)		/* WinXp = 1, Vista = 2, Linux = 3, WinCE = 4 */
 Name (OSV, Ones)	/* Assume nothing */
 Name (PMOD, One)	/* Assume APIC */
+
+Device (ETPA)
+{
+	Name (_HID, "ELAN0000")
+	Name (_DDN, "Elan Touchpad")
+	Name (_UID, 1)
+	Name (ISTP, 1)	/* Touchpad */
+
+	Name (_CRS, ResourceTemplate()
+	{
+		I2cSerialBus (
+			0x15,			/* SlaveAddress */
+			ControllerInitiated,	/* SlaveMode */
+			400000,			/* ConnectionSpeed */
+			AddressingMode7Bit,	/* AddressingMode */
+			"\\_SB.I2CD",		/* ResourceSource */
+		)
+		GpioInt (Level, ActiveLow, ExclusiveAndWake, PullNone,,
+			"\\_SB.GPIO") { 0x5 }
+	})
+
+	/* Allow device to power off in S0 */
+	Name (_S0W, 3)
+}