[U-Boot] What if ATF can be part of U-Boot source, like SPL?

[Jagan Teki]

In terms of code maintenance and development feasibility it is always
a better approach to have out-of-tree code or binary to be part of
in-house source tree.

This is what exactly it was done for SPL, if I'm not wrong. So can we
do the same thing for ATF on ARM64 SoCs?

We are using ATF (on Allwinner) to switch EL3 to EL2 for start loading
U-Boot proper and minimal PSCI, PMIC initialization. So assuming the
functionality of ATF (like here) is limited so the code it require can
be limited too, so why can't this code to be part of U-Boot tree?

This would ultimately avoid out-off-tree ATF builds with associated
variable exporting during u-boot builds.

More over this idea would also help to design a single-step bootloader
where it can't depends on out-of-tree sources.

Code sync from ATF source to U-Boot can be possible in-terms licensing
point-of-view since ATF licensed under BSD-3-Clause.

I'm thinking this can be a worth-idea to look at it and I'm sure It
may require some hard changes and other things to consider but just
posted to understand how hard or feasible or meaningful it is?

Feel free for any comments?

Jagan,
Amarula Solutions India.