tw9900_read_reg
ret = tw9900_read_reg(tw9900->client, TW9900_REG_STD);
ret = tw9900_read_reg(tw9900->client, TW9900_REG_STD);
ret = tw9900_read_reg(tw9900->client, TW9900_REG_CHIP_STATUS);
ret = tw9900_read_reg(client, TW9900_CHIP_ID);