PORT_MODE_REG
ret = i2c_smbus_read_byte_data(client, PORT_MODE_REG);
ret = i2c_smbus_read_byte_data(client, PORT_MODE_REG);
ret = i2c_smbus_write_byte_data(client, PORT_MODE_REG, val);
ret = i2c_smbus_read_byte_data(client, PORT_MODE_REG);
ret = i2c_smbus_write_byte_data(client, PORT_MODE_REG, val);