If you don't already have a copy, sign-out a copy of: AN3996.pdf from the Freescale site.
(Its one of those free ones that has to be signed for, else I would just post a link to my copy.)
Lots of good information there of the start-up process from power-on-reset through bring up the iROM code.
Such as the SoC setup state.
Interesting things, like there is a single MMU mapping installed, an identity mapping with the four high bits forced to zero giving a virtual memory to physical memory identity map for the lower 32bits of the address space.
You want to access something in the other 60Gbytes of address space, you get to install your own MMU mapping.
Includes a bit-by-bit description of the iROM protocol.
How do they support so many different (usually flash) storage media in the tiny code space used by iROM?
Everything is done "bit serial" and they set the core clock speed to run at the same clock speed of the memory part.
Making synchronous transfers simple. And -
making the user sit there, wondering if anything is happening.
The ATK protocol is in the ATK documentation (they are different).
But your k3flasher info message shows that you already know that.
The only useful thing in this post is the ap-note number.