基于at91rm9200的SPI例程，在linux下的编程,AT91RM9200 based on the SPI routines in programming under linux

linux环境下 AT91RM9200 SPI 驱动程序- High speed frame transmit/receive using the AT91RM9200 s SPIs by pinning down a range of virtual pages from user-space to be able to DMA directly into/out of them, one page (4096 bytes) at a time.