How to enter maskrom boot for emmc flashing, from software instead of using button?

[grixm]

Hi. I have Rock Pi S0 boards that I install in an enclosure.
It works, but it is conceivable that some critical bug or change with the image is discovered in the future so that customers later need to flash a new image to the emmc. But for them to do this, they would have to open the enclosure and locate the maskrom button, very inconvenient.
Is there a way to trigger rebooting into maskrom from software instead of pushing the button?
Apparently this is possible on the official radxa OS image by running command "reboot loader" instead of just "reboot", but not on armbian it seems.

After investigating I see linux patches made by the rockchip team for kernel modules like “syscon-reboot-mode” and from the code I see something like that it’s supposed to write the value 0x5242C301 to the RK3308’s GRF OS register 0, and I guess this is supposed to be read by the bootloader to direct the boot to bootmask mode instead of the OS? But the armbian distribution is already built with this kernel module by default, and I even tried to manually write this value to the appropriate registers and then rebooting, and yet nothing works, it just boots to Linux like usual. Anyone have any ideas?