rapidio: add DMA engine support for RIO data transfers

Adds DMA Engine framework support into RapidIO subsystem.

Uses DMA Engine DMA_SLAVE interface to generate data transfers to/from
remote RapidIO target devices.

Introduces RapidIO-specific wrapper for prep_slave_sg() interface with an
extra parameter to pass target specific information.

Uses scatterlist to describe local data buffer.  Address flat data buffer
on a remote side.

Signed-off-by: Alexandre Bounine <alexandre.bounine@idt.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Acked-by: Vinod Koul <vinod.koul@linux.intel.com>
Cc: Li Yang <leoli@freescale.com>
Cc: Matt Porter <mporter@kernel.crashing.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 12 insertions, 0 deletions

diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index d3fec584e8c3..56377df39124 100644
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h
@@ -635,6 +635,18 @@ static inline struct dma_async_tx_descriptor *dmaengine_prep_slave_sg(
                                                   dir, flags, NULL);
 }
 
+#ifdef CONFIG_RAPIDIO_DMA_ENGINE
+struct rio_dma_ext;
+static inline struct dma_async_tx_descriptor *dmaengine_prep_rio_sg(
+        struct dma_chan *chan, struct scatterlist *sgl, unsigned int sg_len,
+        enum dma_transfer_direction dir, unsigned long flags,
+        struct rio_dma_ext *rio_ext)
+{
+        return chan->device->device_prep_slave_sg(chan, sgl, sg_len,
+                                                  dir, flags, rio_ext);
+}
+#endif
+
 static inline struct dma_async_tx_descriptor *dmaengine_prep_dma_cyclic(
                 struct dma_chan *chan, dma_addr_t buf_addr, size_t buf_len,
                 size_t period_len, enum dma_transfer_direction dir)