What:		/sys/devices/platform/<i2c-demux-name>/available_masters
Date:		January 2016
KernelVersion:	4.6
Contact:	Wolfram Sang <wsa@the-dreams.de>
Description:
		Reading the file will give you a list of masters which can be
		selected for a demultiplexed bus. The format is
		"<index>:<name>". Example from a Renesas Lager board:

		0:/i2c@e6500000 1:/i2c@e6508000

What:		/sys/devices/platform/<i2c-demux-name>/current_master
Date:		January 2016
KernelVersion:	4.6
Contact:	Wolfram Sang <wsa@the-dreams.de>
Description:
		This file selects/shows the active I2C master for a demultiplexed
		bus. It uses the <index> value from the file 'available_masters'.