That looks perfect thank you for this.
I have followed through the wiki to set up the power-button.dtbo and double checked myself today, but I'm having a problem.
When booting the power button is not loading. It is looking for ' /boot/dtb/overlay/armada-388-helios4-fixup.scr' which is missing.
Applying user provided DT overlay power-button.dtbo
** File not found /boot/dtb/overlay/armada-388-helios4-fixup.scr **
The address of the fdt is 0x2040000
** Bad device specification 0:1 /boot/overlay-user/power-button **
** Bad device specification 0:1 /boot/overlay-user/power-button **
## Loading init Ramdisk from Legacy Image at 02880000 ...
This may be unrelated / unimportant, but I had this come up when creating the dtbo
admin@helios4:~$ ./dtc -I dts -O dtb -o power-button.dtbo power-button.dts
power-button.dtbo: Warning (unit_address_vs_reg): Node /fragment@0 has a unit name, but no reg property