Thank you for your feedback,
So I discovered after some research in the source files that there is a file "spi-gpio-custom".
So in fact the atheros only has one SPI that is already used to read flash memory.
The second SPI is virtual and obtained by GPIO status changes.
This explains that system calls "ioctl" can not configure the speed of the SPI ...
So I created a github, not yet updated, on SPI or UART communication between arduino and atheros ...
Best regards.