util/blobtool: Add new tool for compiling/decompiling data blobs

Given a specification of bitfields defined e.g. as follows:

	specfile:
		{
			"field1" : 8,
			"field2" : 4,
			"field3" : 4
		}
and a set of values for setting defaults:
	setterfile:
		{
			"field1" = 0xff,
			"field2" = 0xf,
			"field3" = 0xf
		}

You can generate a binary packed blob as follows:
	./blobtool specfile setterfile binaryoutput
	binaryoutput:	ff ff

The reverse is also possible, i.e. you can regenerate the setter:
	./blobtool -d specfile binaryoutput setterorig
	setterorig:
		# AUTOGENERATED SETTER BY BLOBTOOL
		{
			"field1" = 0xff,
			"field2" = 0xf,
			"field3" = 0xf
		}

This tool comes with spec/set files for X200 flash descriptor
and ICH9M GbE region, and can be extended or used to decompile
other data blobs with known specs.

Change-Id: I744d6b421003feb4fc460133603af7e6bd80b1d6
Signed-off-by: Damien Zammit <damien@zamaudio.com>
Reviewed-on: https://review.coreboot.org/17445
Tested-by: build bot (Jenkins)
Reviewed-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Reviewed-by: Martin Roth <martinroth@google.com>
8 files changed