Has anyone had any luck in getting the general purpose SPI port to work on the M4? The documentation I have found so far is a little vague, suggesting that the device tree needs to be changed along with the kernel configuration. As best I can tell, .config has all the appropriate flags set (CONFIG_SPI, CONFIG_SPI_DEBUG, CONFIG_SPI_MASTER, CONFIG_SPI_BITBANG, CONFIG_SPI_SPIDEV and CONFIG_SPI_RTK129X), and the kernel build reports success. However, none of the corresponding kernel objects are being built, and none seem to exist in the stock image for the M4, although they are in the stock image for the BPI-64. I have seen a number of other questions about SPI on this forum, but none of the answers seem helpful for this situation and none are specifically for the M4.
this is BPI-W2 gpio ,you can reference this
Please help me understand this answer. My entire issue is that all pins appear to be in GPIO mode and none of the SPI support modules appear to be compiling with a kernel build. The script at https://github.com/BPI-SINOVOIP/BPI-files/blob/master/others/logfile/bpi-w2/20181017/bpi-w2-gpio40-led.sh appears to only cycle the GPIO, particularly the pin attached to the user LED. It does not appear to address SPI in any way. Did I miss something?
BPI-M4 GPIO demo:
That is a very nice video of GPIO being used as GPIO. It shows nothing about the pins being used for their SPI function. Are you trying to explain with minimum words that GPIO works, but that you either don’t know whether SPI works or that it does not work and you would rather not say so?