talos-op-linux/include/linux/spi/sh_msiof.h, branch v3.4Talos™ II Linux sources for OpenPOWERhttps://git.raptorcs.com/git/talos-op-linux/atom?h=v3.42009-12-13T07:48:27+00:00spi: SuperH MSIOF SPI Master driver V22009-12-13T07:48:27+00:00Magnus Dammdamm@opensource.se2009-11-26T11:10:05+00:00urn:sha1:8051effcbced8478119167b93b0e9554cb82d28e
This patch is V2 of SPI Master support for the SuperH MSIOF.
Full duplex, spi mode 0-3, active high cs, 3-wire and lsb
first should all be supported, but the driver has so far
only been tested with "mmc_spi".
The MSIOF hardware comes with 32-bit FIFOs for receive and
transmit, and this driver simply breaks the SPI messages
into FIFO-sized chunks. The MSIOF hardware manages the pins
for clock, receive and transmit (sck/miso/mosi), but the chip
select pin is managed by software and must be configured as
a regular GPIO pin by the board code.
Performance wise there is still room for improvement, but
on a Ecovec board with the built-in sh7724 MSIOF0 this driver
gets Mini-sd read speeds of about half a megabyte per second.
Future work include better clock setup and merging of 8-bit
transfers into 32-bit words to reduce interrupt load and
improve throughput.
Signed-off-by: Magnus Damm <damm@opensource.se>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>