Questions about userspace SPI async IO support

[Jesse T <mr.bossman075@xxxxxxxxx>]

Hello,

As far as I know, the SPI userspace API has "no async I/O support;
everything is purely synchronous."
https://docs.kernel.org/spi/spidev.html

I would like to add support for userspace SPI async IO.
Why hasn't it been added?

Is it not as simple as adding the async equivalent of SPI_IOC_MESSAGE
to ioctl, or is that not a valid way to accomplish this?

Thanks,
Jesse Taube