[RFC] rockchip: Reset to bootrom download mode on hang

[Quentin Schulz]

Hi Jonas,

On 2/2/24 01:12, Jonas Karlman wrote:
> Add support to reset to bootrom download mode on hang in U-Boot SPL and
> proper. ROCKCHIP_HANG_TO_BROM can be used to enable this feature.
> 
> Example when SPL cannot load FIT:
> 
>    U-Boot SPL 2024.04-rc1 (Feb 01 2024 - 23:01:12 +0000)
>    Trying to boot from MMC1
>    mmc_load_image_raw_sector: mmc block read error
>    Trying to boot from MMC2
>    Card did not respond to voltage select! : -110
>    spl: mmc init failed with error: -95
>    Trying to boot from MMC1
>    mmc_load_image_raw_sector: mmc block read error
>    SPL: failed to boot from all boot devices
>    ### ERROR ### Please RESET the board ###
>    entering download mode ...
>    resetting ...
> 
> Procedure to start bootrom download mode:
> - U-Boot SPL or proper write 0xEF08A53C to BOOT_MODE_REG and then reset
> - Bootrom loads and run boot code (TPL) from e.g. SPI > eMMC > SD-card
> - TPL check for 0xEF08A53C in BOOT_MODE_REG very early, i.e. Rockchip
>    TPL blobs check for this value directly at start
> - TPL return to bootrom with a return value != 0
> - Bootrom enter download mode
> 
> This also fixes an issue where the BOOT_MODE_REG is reset to 0 when
> board is reset on RK35xx after TF-A has been loaded. To fix this the
> SOC_CON1 reg value is reset prior to issuing a global reset.
> 
> The RK356x TF-A blobs will clear SOC_CON1 as part of a PSCI reset,
> however the RK3588 TF-A blobs does not seem to clear SOC_CON1.
> 
> Signed-off-by: Jonas Karlman <jonas at kwiboo.se>

I'm wondering if there isn't a simpler way to do this?

board_boot_order() could parse u-boot,spl-boot-order for e.g. "bootrom", 
the same way it does for "same-as-spl" for example.

If it is set, then add BOOT_DEVICE_BOOTROM to spl_boot_list.

Then this would call spl_return_to_bootrom() from 
common/spl/spl_bootrom.c which in turns would call 
board_return_to_bootrom() and back_to_bootrom().

What do you think?

Cheers,
Quentin