nRF52 Delete bonds while in Bootloader

[Zami]

I'm working on a custom board that uses an nRF52832 module. It has a single button that is used to power the device On/Off and a  >= 5sec  long press from Off to force enter the bootloader (my fail-case backup). The bootloader can also be entered by the buttonless DFU.

I would like to delete bond data when entering the bootloader by the long-press since I cannot provide a separate button for it. I also don't want to use BLE command to do it in case of app failure.

I added a bootloader entry case for the long press in static bool dfu_enter_check(void)  in  nrf_bootloader.c  and I would like to delete bonds here, shown below:

static bool dfu_enter_check(void)
{
    // If power button is held for >= 5 seconds, then enter DFU
    uint32_t timeout_ticks = nrf_bootloader_dfu_timer_counter_get() + NRF_BOOTLOADER_MS_TO_TICKS(5000);
    while (0 == nrf_gpio_pin_read(PIN_PB_OUT))
    {
      if(nrf_bootloader_dfu_timer_counter_get() >= timeout_ticks)
      {
        NRF_LOG_DEBUG("DFU mode requested via timed button press.");
        
        delete_bonds(); // <-- This
        
        return true;
      }
    }
    
    ...
    
    return false;
}

My question is, is there a quick and dirty way to do this in the bootloader without having to pull in the entire peer manager?

[Zami]

I suppose one way I could do this is setting a delete-bonds-flag in GPREGRET2. Then if the app is valid it would read the flag, delete bonds, and reset GPREGRET2.  ..I'll try this first but I'm open to more suggestions.

EDIT: So I got it working but I had to change the bootloader behavior when the power button is pressed as follows:

button pressed < 5sec run bootloader normally

button pressed >= 5sec set the delete-bonds flag in GPREGRET2 and let the bootloader run normally when released, ie if valid app then it will jump to it.

button pressed >= 10sec then stay in the bootloader (delete-bonds flag still set)