Adding a zynq board

[Michal Simek]

Hi,

On 6/30/22 19:20, Christopher Bowman wrote:
> Greetings,
> I have a board (Diligent Arty-Z7) for which I have a working U-boot.  I’m not 
> sure I’ve done it right but it does work on my board.  I’d like to contribute 
> this back and get it in U-boot.

Ok. One thing is contributing it back and second maintaining it. This is based 
on zynq chip and TBH I can't see so big value to adding support for these old 
boards unless there is something special on the board.

> I see there is a configuration configs/xilinx_zynq_virt_defconfig which includes 
> several boards.  It would be attractive to simply add the device tree for my 
> board to this list and have a working U-boot.  However, as I understand it, each 
> Zynq board needs to have some initial configuration done and this is done in the 
> ps7_init_gpl.c file which I think is unique to every board.  I don’t understand 
> how the boards in the xilinx_zynq_virt_defconfig configuration are able to share 
> a single ps7_init_gpl.c?  Maybe they don’t?  How do I determine if my board is 
> compatible with the other boards if they’re sharing a ps7_init_gpl.c?  Is it 
> permissible to add a new config for a single zynq board or should I be trying to 
> add it to xilinx_zynq_virt_defconfig?  If someone could provide some perspective 
> here or some direction on adding a new Zynq board that would be great.

Zynq/ZynqMP boards are working in the same way. You add ps7_init_gpl.c to board 
folder and also DT file. When you build u-boot you export DEVICE_TREE variable 
with the board name and based on it the right ps7_init is taken and also default 
value in ITS file can be configured (or hardcoded in SPL at build time).

Normally you take working ps7_init which is also unique to every board.

My biggest problem with these and similar boards is that they don't bring any 
value because they are more or less the same and second it just increasing build.
Are you willing to support this board for 5 years or so? Is it your private board?

Thanks,
Michal