What:		/sys/kernel/debug/moxtet/input
Date:		March 2019
KernelVersion:	5.3
Contact:	Marek Behún <marek.behun@nic.cz>
Description:	(R) Read input from the shift registers, in hexadecimal.
		Returns N+1 bytes, where N is the number of Moxtet connected
		modules. The first byte is from the CPU board itself.
		Example: 101214
			 10: CPU board with SD card
			 12: 2 = PCIe module, 1 = IRQ not active
			 14: 4 = Peridot module, 1 = IRQ not active

What:		/sys/kernel/debug/moxtet/output
Date:		March 2019
KernelVersion:	5.3
Contact:	Marek Behún <marek.behun@nic.cz>
Description:	(RW) Read last written value to the shift registers, in
		hexadecimal, or write values to the shift registers, also
		in hexadecimal.
		Example: 0102
			 01: 01 was last written, or is to be written, to the
			     first module's shift register
			 02: the same for second module