What:		/sys/class/extcon/.../
Date:		December 2011
Contact:	MyungJoo Ham <myungjoo.ham@samsung.com>
Description:
		Provide a place in sysfs for the extcon objects.
		This allows accessing extcon specific variables.
		The name of extcon object denoted as ... is the name given
		with extcon_dev_register.

		One extcon device denotes a single external connector
		port. An external connector may have multiple cables
		attached simultaneously. Many of docks, cradles, and
		accessory cables have such capability. For example,
		the 30-pin port of Nuri board (/arch/arm/mach-exynos)
		may have both HDMI and Charger attached, or analog audio,
		video, and USB cables attached simulteneously.

		If there are cables mutually exclusive with each other,
		such binary relations may be expressed with extcon_dev's
		mutually_exclusive array.

What:		/sys/class/extcon/.../name
Date:		December 2011
Contact:	MyungJoo Ham <myungjoo.ham@samsung.com>
Description:
		The /sys/class/extcon/.../name shows the name of the extcon
		object. If the extcon object has an optional callback
		"show_name" defined, the callback will provide the name with
		this sysfs node.

What:		/sys/class/extcon/.../state
Date:		December 2011
Contact:	MyungJoo Ham <myungjoo.ham@samsung.com>
Description:
		The /sys/class/extcon/.../state shows and stores the cable
		attach/detach information of the corresponding extcon object.
		If the extcon objecct has an optional callback "show_state"
		defined, the showing function is overriden with the optional
		callback.

		If the default callback for showing function is used, the
		format is like this:
		# cat state
		USB_OTG=1
		HDMI=0
		TA=1
		EAR_JACK=0
		#
		In this example, the extcon device have USB_OTG and TA
		cables attached and HDMI and EAR_JACK cables detached.

		There are two methods to update state of extcon.
		Method 1.
		  echo CABLE_NAME [0|1] > state
		Method 2.
		  echo 0xHEX > state

		Method 1 updates the state (0 or 1) of the
		corresponding cable (either the name or index of the cable).
		Method 2 updates the whole state of the extcon dev.
		Inputs of all the methods are required to meet the
		mutually_exclusive contidions if they exist.

What:		/sys/class/extcon/.../mutually_exclusive
Date:		December 2011
Contact:	MyungJoo Ham <myungjoo.ham@samsung.com>
Description:
		Shows the relations of mutually exclusiveness. For example,
		if the mutually_exclusive array of extcon_dev is
		{0x3, 0x5, 0xC, 0x0}, the, the output is:
		# cat mutually_exclusive
		0x3
		0x5
		0xC
		#