CTRL_EXT_I2C_ENA
ctrl_ext |= CTRL_EXT_I2C_ENA;
CSR_WRITE(sc, WMREG_CTRL_EXT, ctrl_ext | CTRL_EXT_I2C_ENA);
reg &= ~CTRL_EXT_I2C_ENA;
reg |= CTRL_EXT_I2C_ENA;