STM32H747i-DISCO - Added initially U-Boot support

[krotti42]

Hi ST community members!

For a long time ago with another nick (but lost the account access), I have wanted to add U-Boot support for this board. Now I have done this but not released a patch series yet (only on my local Git repo) in the U-Boot mailing list. Also must do some tests on real hardware.

Short question:

Does somebody need support for this board or is it useless? I know the board has less RAM, but some ST maintainers on the U-Boot list where interested in the past. But unfortunately I haven't finally done this, because of an illness. Also when it's useless for other users, it was a fun project for me. :)

[krotti42]

Tests succeed  (runs now):

U-Boot 2025.07-rc1-00141-g48db49b0977c-dirty (May 08 2025 - 19:22:08 +0200)

Model: STMicroelectronics STM32H747i-Discovery board
DRAM:  32 MiB
Core:  30 devices, 16 uclasses, devicetree: separate
MMC:   STM32 SD/MMC: 0
Loading Environment from nowhere... OK
In:    serial@40011000
Out:   serial@40011000
Err:   serial@40011000
Hit SPACE in 30 seconds to stop autoboot.
U-Boot >

Had must add some SoC specific code, because I used the preexisting source from board STM32H743-DISCO. And without this SoC specific code a had a deadlock from the board, because of the missing early initialization from the PWR register from the SoC.

Also I have must changed the stm32h7-pinctrl device tree to get a serial output. Was mapped to other pins for USART1.