AD7192_CONF_GAIN_MASK
st->conf = FIELD_PREP(AD7192_CONF_GAIN_MASK, 0);
u8 gain = FIELD_GET(AD7192_CONF_GAIN_MASK, st->conf);
st->conf &= ~AD7192_CONF_GAIN_MASK;
st->conf |= FIELD_PREP(AD7192_CONF_GAIN_MASK, i);