Re: bf537 SPI Bus: To use Kernel, Userspace, or Bitbang control by ADIApproved
There is no strict standards for the SPI baudrate, theoretically it would work, you are going to have a try. Assign the baudrate you want in the board file.
If you are going to use GPIO as the chip select, take a look at the following code line in arch/blackfin/mach-bf537/boards/stamp.c as example:
.chip_select = GPIO_PF10 + MAX_CTRL_CS, /* GPIO controlled SSEL */
and it's implementation is in function bfin_spi_cs_active in spi-bfin5xx.c