ADC108S102: ADC108S102

Hi Satyajit,

Welcome to our forum!  Are you using the ti-adc108s102.c file or the full driver linked at the bottom of the original thread?

Hi, I am using below driver:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/iio/adc/ti-adc108s102.c

Thanks for verifying.  I do not see anything in the .c file that seems to relate to the /CS pin of the ADC108S102, so I can't tell where its being asserted.

Hi Satyajit,

What I found out is that this is an IIO driver that uses SPI interface. It makes calls to the linux SPI driver to drive the signals. The linux SPI peripheral must be configured with CS at DTS level. All our driver is supposed to do is issue SPI reads and writes. The SPI driver is supposed to trigger the chip select on read and write with the SPI transfer calls.

 https://www.kernel.org/doc/html/v4.15/driver-api/iio/intro.html

https://www.kernel.org/doc/html/v4.15/driver-api/spi.html

In the DTS, we map the SPI interface to this driver, as shown in:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/devicetree/bindings/iio/adc/ti,adc108s102.yaml

 In short, our driver does not handle the SPI transfers itself nor driving CS.

Yes that analysis I already know. How to configure in device tree or other areas to toggle CS line. It is the requirement. Do you have any other application to do it from user space using spidev device? or any way perhaps bitbang using GPIO driver and an userspace application?

Unfortunately not, the CS control is at the board level.  

www.kernel.org/.../spi.html

I checked even after the  transaction, the CS remains low and there is no CLK as well.

I understand the CLK from Master helps in ADC data acquisation, so no CLK means ADC does not do conversion even if CS remains low.

Am I correct?

Yes, that is correct.  Without a clock, there are no conversions going on.