[U-Boot] How to support ATF on u-boot

[Andre Przywara]

Hi,

On 13/07/16 13:27, Andreas Färber wrote:
> Hi Kever,
> 
> Am 20.06.2016 um 04:59 schrieb Kever Yang:
>>     I want to upstream a new SoC named RK3399 from Rockchip which is
>> AARCH64/ARMv8, we need to support Arm Trust Firmware base on U-boot.
>>
>>     Right now we are using a miniloader(just like SPL in U-boot) to load
>> ATF/U-boot,
>> and PC jump from miniloader to ATF and then to U-boot(with CPU change to
>> EL2 mode or nsEL1),
>> then U-boot load kernel/rootfs as usual.
>>
>>     The ATF support for RK3399 has already upstream
>>     Could you give your opinion on how to support ATF on U-boot upstream?
>> When I asked Simon Glass offline, he suggest if we can build ATF as part
>> of the
>> U-boot build process, perhaps with a script in U-boot tree,
>>
>> Perhaps something like:
>>
>> make rk3399_board_defconfig
>> make
>> ./scripts/build-atf-image rk3399_board
>> ^^ new script

I am not sure we should trigger an ATF build on building U-Boot. In my
build process for the Pine64 I just point to the compiled binary and
leave it up to the user to take care of compiling that. ATF builds are
really easy and fast, for the Pine64 it's just: "make PLAT=sun50iw1p1
bl31" for instance and takes only a few seconds.

>> In any case, a good README would help.
> 
> I've started looking into RK3368 for my GeekBox, which raises a similar
> issue. Are you working on that as well or just RK3399?
> 
> Personally I think that the approach the HiKey has taken is the best,
> i.e. decouple U-Boot from ATF and just supply a README for how to make
> it work with U-Boot as ATF payload.

Interestingly ATF itself considers U-Boot a payload, as it provides its
own bootstrapping parts which take a similar role as U-Boot's SPL.
So the official ATF build process (at least for Juno) lets you specify
the location of the U-Boot binary to be included in their FIP image.

OTOH, some boards (like the Pine64) only use the runtime component of
ATF, so including it in U-Boot makes more sense (see below). I guess
this is similar for Rockchip?

> Obviously it would help to integrate your loaderimage tool into mkimage.

FWIW, I extended SPL's FIT loading to support loading multiple images.
With this I was able to combine (non-SPL) U-Boot, ATF and multiple DTs
into one FIT image and attach that to the SPL.
I even managed to include a kernel and initrd in there, fwiw.
I will post those patches soonish.

Cheers,
Andre.

> Also, what is the difference between your trust_merger tool and ATF's
> fip_create / fiptool?
> 
> Regards,
> Andreas
>