spi_w8r16
ret = spi_w8r16(spi, reg);
ret = spi_w8r16(data->spi_device, MAX31722_REG_TEMP_LSB);
temp = spi_w8r16(st->spi, cmd);
temp = spi_w8r16(st->spi, cmd);
int status = spi_w8r16(spi, reg | READ_CMD);