platform/oaktrail: ACPI EC Extra driver for Oaktrail

This driver implements an Extra ACPI EC driver for products based on Intel
Oaktrail platform.

This driver does below things:
1. registers itself in the Linux backlight control in
   /sys/class/backlight/intel_oaktrail/

2. registers in the rfkill subsystem here: /sys/class/rfkill/rfkillX/
   for these components: wifi, bluetooth, wwan (3g), gps

Signed-off-by: Yin Kangkai <kangkai.yin@linux.intel.com>

[Extracted from a bigger patch by Yin Kangkai, this version leaves out some
 sysfs bits that probably want to be driver managed, and ACPI i2c enumeration]

Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Matthew Garrett <mjg@redhat.com>

drivers/platform/x86/Kconfig

@@ -760,4 +760,13 @@ config MXM_WMI
           MXM is a standard for laptop graphics cards, the WMI interface
 	  is required for switchable nvidia graphics machines
 
+config INTEL_OAKTRAIL
+	tristate "Intel Oaktrail Platform Extras"
+	depends on ACPI
+	depends on RFKILL && BACKLIGHT_CLASS_DEVICE && ACPI
+	---help---
+	  Intel Oaktrail platform need this driver to provide interfaces to
+	  enable/disable the Camera, WiFi, BT etc. devices. If in doubt, say Y
+	  here; it will only load on supported platforms.
+
 endif # X86_PLATFORM_DEVICES