I2C_INTERRUPT_STATUS_REGISTER
WR4(sc, I2C_INTERRUPT_STATUS_REGISTER, 0xFFFFFFFF);
WR4(sc, I2C_INTERRUPT_STATUS_REGISTER, status);
WR4(sc, I2C_INTERRUPT_STATUS_REGISTER, status);
WR4(sc, I2C_INTERRUPT_STATUS_REGISTER, 0xFFFFFFFF);