Hi Jiri, 

I'm was planning a SPI driver for the SAM4S and later on the SAMe70. 
I have sufficient boards to test the SPI driver, with displays, flash, IMU and transceivers on them to push its boundries. I can add the IRQ and DMA also, as I was using both with another RTOS before. 

Perhaps we can combine effort for this. 

Kind regards,
Vincent