Diolan DLN2 Linux SPI driver usage

[Michael Tandy <lkml@xxxxxxxxx>]

Hi all,

I have a Diolan DLN2 [1] USB-to-SPI adapter. When I connect it to my
(x86_64) PC, it is recognised, the dln2-spi driver loads successfully,
and /sys/class/spi_master/spi0/ appears. GPIO pins also appear, which
I have successfully interfaced with.

However, I'm at a loss as to what to do next in order to instantiate
an spidev device so I can start sending and receiving data.

Obviously, the normal way to set up spidev would be a devicetree, but
all the articles I can find about that are for embedded processors
like the Raspberry Pi and Beaglebone which have built-in SPI
peripherals, whereas I'm on x86_64. And as the Diolan is a USB device,
it could be plugged into any port. If devicetree can be used in this
situation, I can't find advice saying how to make it work :)

I found an article covering the Diolan's I2C feature [2], involving
boot-time configuration via a new_device file, but spi_master doesn't
seem to have an equivalent file.

I also read about manual driver binding [3] and tried echoing things
like echoing things like "spi0 and "dln2-spi.3.auto" into
/sys/bus/spi/drivers/spidev/bind without success.

I also tried reaching out to the three Diolan driver authors who work
for Intel; unfortunately none of them appear to work there any longer.

I also consulted the mailing list archives [4] and found a question
posted Gaston Gonzalez, unfortunately without a conclusive response.

Can anyone advise me on how to make my diolan device appear as an spidev?

Thanks very much!

[1] https://diolan.com/dln-2
[2] https://kernelsense.wordpress.com/2016/01/22/achievement-unlocked-first-iio-driver/
[3] https://lwn.net/Articles/143397/
[4] https://marc.info/?l=linux-spi&w=2&r=1&s=diolan&q=b