This adds a driver for the SPI controller found on most AT91 and AVR32
chips, implementing the new SPI API.
Changed in v4:
- Update to new API
- Handle zero-length transfers appropriately. The user may send a
zero-length SPI transfer with SPI_XFER_END set in order to
deactivate the chip select after a series of transfers with chip
select active. This is useful e.g. when polling the status
register of DataFlash.
Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
