AD7124_GAIN
ret = ad_sd_read_reg(&st->sd, AD7124_GAIN(0), 3,
ret = ad_sd_read_reg(&st->sd, AD7124_GAIN(0), 3,
ret = ad_sd_write_reg(&st->sd, AD7124_GAIN(cfg_slot), 3,
ret = ad_sd_read_reg(&st->sd, AD7124_GAIN(0), 3, &st->gain_default);