I2C_BUSY
sc->sc_flags &= ~I2C_BUSY;
while (sc->sc_flags & I2C_BUSY) {
sc->sc_flags |= I2C_BUSY;
sc->sc_flags &= ~I2C_BUSY;
while (sc->sc_flags & I2C_BUSY) {
sc->sc_flags |= I2C_BUSY;