Function write_pull_selection 

pub unsafe fn write_pull_selection(
    pin_num: u64,
    pull_selection: PullSelection,
) -> Result<()>

Sets the pull selection for a GPIO pin.

The logic was entirely reverse-engineered from the ql_peripheral library. The code contains inline comments that explain the corresponding C code.

Safety

This function is safe if the pin_num is a valid GPIO pin number.