falco: Add ACPI code to describe the I2C touchpad device

If the SerialIO devices are put into ACPI mode then it is possible
to use ACPI to instantiate the touchpad in the kernel without
needing to have a platform level driver to do the binding.

This is the "new way" of describing on-board I2C devices and the
upstream kernel is starting to add ACPI IDs to drivers so they can
be used in this fashion.  For the Cypress touchpad use a generic
ACPI ID of "CYPA0000" to describe it.

In order to support the proper scoping of the touchpad device under
the appropriate I2C controller device the mainboard.asl file needs
to be included after pch.asl so the I2C device exists.

Change-Id: I81e053d27be478f3a19b6f9b13cd2b4fabcb88c0
Signed-off-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-on: http://review.coreboot.org/5194
Tested-by: build bot (Jenkins)
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

src/mainboard/google/falco/acpi/mainboard.asl

@@ -108,3 +108,37 @@ Scope (\_SB)
 		}
 	}
 }
+
+Scope (\_SB.PCI0.I2C0)
+{
+	Device (CYPA)
+	{
+		Name (_HID, "CYPA0000")
+		Name (_DDN, "Cypress Touchpad")
+		Name (_UID, 1)
+
+		Name (_CRS, ResourceTemplate()
+		{
+			I2cSerialBus (
+				BOARD_TRACKPAD_I2C_ADDR,  // SlaveAddress
+				ControllerInitiated,      // SlaveMode
+				400000,                   // ConnectionSpeed
+				AddressingMode7Bit,       // AddressingMode
+				"\\_SB.PCI0.I2C0",        // ResourceSource
+			)
+			Interrupt (ResourceConsumer, Edge, ActiveLow)
+			{
+				BOARD_TRACKPAD_IRQ
+			}
+		})
+
+		Method (_STA)
+		{
+			If (LEqual (\S1EN, 1)) {
+				Return (0xF)
+			} Else {
+				Return (0x0)
+			}
+		}
+	}
+}

src/mainboard/google/falco/dsdt.asl

@@ -31,7 +31,6 @@ DefinitionBlock(
 {
 	// Some generic macros
 	#include "acpi/platform.asl"
-	#include "acpi/mainboard.asl"
 
 	// global NVS and variables
 	#include <southbridge/intel/lynxpoint/acpi/globalnvs.asl>
@@ -50,6 +49,9 @@ DefinitionBlock(
 		}
 	}
 
+	// Mainboard specific
+	#include "acpi/mainboard.asl"
+
 	// Thermal handler
 	#include "acpi/thermal.asl"