linux-imx

dma: edma: Add support for Cyclic DMA

Using the PaRAM configuration function that we split for reuse by the
different DMA types, we implement Cyclic DMA support.
For the cyclic case, we pass different configuration parameters to this
function, and handle all the Cyclic-specific functionality separately.

Callbacks to the DMA users are handled using vchan_cyclic_callback in
the virt-dma layer. Linking is handled the same way as the slave SG case
except for the last slot where we link it back to the first one in a
cyclic fashion.

For continuity, we check for cases where no.of periods is great than the
MAX number of slots the driver can allocate for a particular descriptor
and error out on such cases.

Signed-off-by: Joel Fernandes <joelf@ti.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>