BA0_MIDWP
snd_cs4281_pokeBA0(chip, BA0_MIDWP, byte);
snd_cs4281_pokeBA0(chip, BA0_MIDWP, c);
snd_cs46xx_pokeBA0(chip, BA0_MIDWP, c);
snd_cs46xx_pokeBA0(chip, BA0_MIDWP, byte);