SPI_IOC_MESSAGE
|| _IOC_NR(cmd) != _IOC_NR(SPI_IOC_MESSAGE(0))
&& _IOC_NR(cmd) == _IOC_NR(SPI_IOC_MESSAGE(0))
status = ioctl(fd, SPI_IOC_MESSAGE(2), xfer);
ret = ioctl(fd, SPI_IOC_MESSAGE(1), &tr);