DDR3: Add utilities for creating MRS commands

MRS commands are used to tell the DRAM chip what timing and what
termination and drive strength to use, along with other parameters.
The MRS commands are defined by the DDR3 specification [1]. This
makes MRS commands hardware-independent.

MRS command creation is duplicated in various shapes and forms in any
chipset that does DDR3. This is an effort to create a generic MRS API
that can be used with any chipset.

This is used in the VX900 branch.

[1] www.jedec.org/sites/default/files/docs/JESD79-3E.pdf

Change-Id: Ia8bb593e3e28a5923a866042327243d798c3b793
Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
Reviewed-on: http://review.coreboot.org/3354
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
2 files changed