What:		/sys/class/tty/console/active
Date:		Nov 2010
Contact:	Kay Sievers <kay.sievers@vrfy.org>
Description:
		 Shows the list of currently configured
		 console devices, like 'tty1 ttyS0'.
		 The last entry in the file is the active
		 device connected to /dev/console.
		 The file supports poll() to detect virtual
		 console switches.

What:		/sys/class/tty/tty0/active
Date:		Nov 2010
Contact:	Kay Sievers <kay.sievers@vrfy.org>
Description:
		 Shows the currently active virtual console
		 device, like 'tty1'.
		 The file supports poll() to detect virtual
		 console switches.

What:		/sys/class/tty/ttyS0/uartclk
Date:		Sep 2012
Contact:	Tomas Hlavacek <tmshlvck@gmail.com>
Description:
		 Shows the current uartclk value associated with the
		 UART port in serial_core, that is bound to TTY like ttyS0.
		 uartclk = 16 * baud_base