tree 00680c39dde5cefa549028532347902d9f714b4c
parent 631e61b7ca12ef14c834f99f8948e410c539f585
author Steven King <sfking@fdwdc.com> 1264020584 -0700
committer Grant Likely <grant.likely@secretlab.ca> 1264020584 -0700

spi: Add Freescale/Motorola Coldfire QSPI driver

Add support for the QSPI controller found some on Freescale/Motorola
Coldfire MCUs.

Full duplex, active high cs, spi modes 0-3 and word sizes 8-16 bits are
supported.  The hardware drives the MISO, MOSI and SCLK lines, but the chip
selects are managed via GPIO and must be configured by the board code.

The QSPI controller has an 80 byte buffer which allows us to transfer up to 16
words at a time.  For transfers longer than 16 words, we split the buffer in
half so we can update in one half while the controller is operating on the
other half.  Interrupt latencies then ultimately limits our sustained thru-put
to something less than half the maximum speed supported by the part.

Signed-off-by: Steven King <sfking@fdwdc.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>