IOEXP_BACKLIGHT_ON
output_init_value |= IOEXP_BACKLIGHT_ON;
output_init_value &= ~IOEXP_BACKLIGHT_ON;
uint8_t bkreg = ioexp_gpio_pin_get(sc, IOEXP_BACKLIGHT_ON);
ioexp_gpio_pin_write(sc, IOEXP_BACKLIGHT_ON,
ioexp_gpio_pin_write(sc, IOEXP_BACKLIGHT_ON,