Cache flushing and Invalidation

I plan on writing a network driver that activates a chip performing DMA.
The Buffers I intend to send are in cache, the cache is a WB cache and no
coherency/snooping is
supported by the processor/system thus I need to use cache flush and cache
invalidate when
transmitting or receiving packets respectively.

My question: what are the commands QNX provide the driver with for these
cache operations ?

Moti H