SPI HW testing (STM32MP157CAA)

[VivekB]

Hi there, 

I have started looking into writing a test program/script to test the functionality of the one of the SPI bus interface (which in the current board called SPI6). Now when I looked into the kernel (the below is the STM kernel we are using at the moment):

# uname -a 
Linux buildroot 5.15.67 #1 SMP PREEMPT Tue Feb 6 16:12:01 GMT 2024 armv7l GNU/Linux

I can see the following: 

# ls -la /sys/bus/spi/devices/spi0.
spi0.0/ spi0.1/ spi0.2/ spi0.3/ spi0.4/

# ls -la /sys/class/spi_master/spi
spi0/ spi1/

# ls -la /sys/class/spi_
spi_master/ spi_slave/

# ls -la /sys/class/spi_master/
total 0
drwxr-xr-x 2 root root 0 Feb 7 08:18 .
drwxr-xr-x 58 root root 0 Feb 7 08:18 ..
lrwxrwxrwx 1 root root 0 Feb 7 10:01 spi0 -> ../../devices/platform/soc/44004000.spi/spi_master/spi0
lrwxrwxrwx 1 root root 0 Feb 7 10:01 spi1 -> ../../devices/platform/soc/5c001000.spi/spi_master/spi1

# ls -la /sys/class/spi_slave/
total 0
drwxr-xr-x 2 root root 0 Feb 7 08:18 .
drwxr-xr-x 58 root root 0 Feb 7 08:18 ..

I checked the .config file we are using and the below config options are present: 

CONFIG_SPI=y
CONFIG_SPI_DEBUG=y
CONFIG_SPI_STM32=m
CONFIG_SPI_STM32_QSPI=y
CONFIG_SPI_SPIDEV=y
CONFIG_SPI_MASTER=y

I can also see the below module:

# lsmod | grep -i spi
spi_stm32 24576 0 

However, I was expecting to see spi nodes under /dev which I cannot:

# ls -la /dev/spi*
ls: /dev/spi*: No such file or directory

I do not have any slave device attached to the bus yet. Can someone please suggest if there is anything I am missing here? Many thanks.

[Erwan SZYMANSKI]

Hello @VivekB ,
What does your device trees' SPI node looks like ? Do you have spi subnodes defined ? 
If you want to make some basic tests, you need to at least declare some spidev subnodes.

Please see an example here in the wiki: https://wiki.st.com/stm32mpu/wiki/How_to_use_SPI_from_Linux_userland_with_spidev#DT_and_kernel_configuration

Kind regards,
Erwan.

[VivekB · Accepted solution]

Hi Erwan, 

Thanks for the reply. I have thankfully resolved the issue with the help from SO. Here is the link if someone is interested in future:

https://stackoverflow.com/questions/77953893/spi-hw-testing-stm32mp157caa?noredirect=1#comment137444496_77953893