CDNC_I2C_ISR
WR2(sc, CDNC_I2C_ISR, CDNC_I2C_ISR_ALL);
status = RD2(sc, CDNC_I2C_ISR) & ~RD2(sc, CDNC_I2C_IMR);
WR2(sc, CDNC_I2C_ISR, status);