Developed a major enhancement for the Zephyr repository by expanding DMA support in the SAM0 SPI driver to include synchronous transfers. This work unified the DMA path for both blocking and non-blocking SPI operations, allowing the driver to leverage DMA for improved efficiency. By reducing CPU overhead during SPI transactions, the changes enabled higher throughput and lower latency on SAM0-based embedded systems. The implementation focused on C programming and driver development, with careful attention to code maintainability and portability. All contributions were properly signed off and aligned SPI driver behavior across synchronous and asynchronous paths, supporting scalable embedded applications.