I2C_IDBR
bus_space_write_4(iot, ioh, I2C_IDBR, (slave<<1) | 0x1);
rv = bus_space_read_4(iot, ioh, I2C_IDBR);
bus_space_write_4(iot, ioh, I2C_IDBR, (slave<<1));
bus_space_write_4(iot, ioh, I2C_IDBR, value);
bus_space_write_4(iot, ioh, I2C_IDBR, (slave<<1) | (rw & 1));
bus_space_write_4(iot, ioh, I2C_IDBR, (slave<<1));
bus_space_write_4(iot, ioh, I2C_IDBR, (value >> 8) & 0xff);
bus_space_write_4(iot, ioh, I2C_IDBR, value & 0xff);
CSR_WRITE_4(sc, I2C_IDBR, (addr << 1) | rd_req);
*bytep = CSR_READ_4(sc, I2C_IDBR);
CSR_WRITE_4(sc, I2C_IDBR, byte);
bus_space_write_4(iot, ioh, I2C_IDBR, data[n]);
bus_space_write_4(iot, ioh, I2C_IDBR, data[n]);
data[n++] = bus_space_read_4(iot, ioh, I2C_IDBR);
*buf = bus_space_read_4(iot, ioh, I2C_IDBR);