I don't know about what might be posted here, I got mine from Freescale as a source bundle.
The iROM protocol is the same, with the same command set, with differences in the initial time out and the watchdog settings.
The "RAM kernel" is specific to the i.MX model, the ATK source has a long list of them.
But the result is the same command set and protocol across all models.
That is two (2) command sets and two (2) protocols total. The iROM command set and protocol and the "RAM kernel" command set and protocol.
Register set-up and dynamic ram setups will also vary.
Freescale has some nice, bit-level, application notes on both the stock source and about making derivative command processors (which is what the "RAM kernel" is, a command processor).
Most of the above is exposed in the *.h files.
Except for the various downloaded "RAM kernels" - those are more than an *.h file.
Which is why I had to get the license terms clear with Freescale last week.
These two pieces (*.h files and command processors) are all that I want to re-use from their sources for a project of my own.
The *.h files do not have distribution restrictions.
The "RAM kernels" (and/or derivates) can be re-distributed in object form as a part of an application for a licensed i.MX machine (which Kindles are).
I.E: You can't ship the "RAM kernels" loose - they have to be embedded in the application.