I2C_CTRL
HWRITE4(sc, I2C_CTRL, sc->sc_ctrl);
HWRITE4(sc, I2C_CTRL, 0);
HWRITE4(sc, I2C_CTRL, sc->sc_ctrl | I2C_CTRL_STA);
HWRITE4(sc, I2C_CTRL, sc->sc_ctrl | I2C_CTRL_STO);
HWRITE4(sc, I2C_CTRL, 0);
HWRITE4(sc, I2C_CTRL, sc->sc_ctrl);
HWRITE4(sc, I2C_CTRL, sc->sc_ctrl | ack);
HWRITE4(sc, I2C_CTRL, sc->sc_ctrl);
ctrl = HREAD4(sc, I2C_CTRL);