bu27034_get_gain
ret = bu27034_get_gain(data, channel, &gain);
ret = bu27034_get_gain(data, gains[i].chan, &gains[i].old_gain);
ret = bu27034_get_gain(data, gain.chan, &gain.old_gain);
ret = bu27034_get_gain(data, BU27034_CHAN_DATA0, &gain0);
ret = bu27034_get_gain(data, BU27034_CHAN_DATA1, &gain1);
ret = bu27034_get_gain(data, chan->channel, val);