iop-adma: P+Q support for iop13xx adma engines
iop33x support is not included because that engine is a bit more awkward
to handle in that it can either be in xor mode or pq mode. The
dmaengine/async_tx layers currently only comprehend static capabilities.
Note iop13xx does not support hardware PQ continuation so the driver
must handle the DMA_PREP_CONTINUE flag for operations across > 16
sources. From the comment for dma_maxpq:
/* When an engine does not support native continuation we need 3 extra
* source slots to reuse P and Q with the following coefficients:
* 1/ {00} * P : remove P from Q', but use it as a source for P'
* 2/ {01} * Q : use Q to continue Q' calculation
* 3/ {00} * Q : subtract Q from P' to cancel (2)
*/
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
4 files changed