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, 9 insertions, 0 deletions

diff --git a/include/linux/rio_drv.h b/include/linux/rio_drv.h
index 7f07470e1ed9..31ad146be316 100644
--- a/include/linux/rio_drv.h
+++ b/include/linux/rio_drv.h
@@ -377,6 +377,15 @@ void rio_unregister_driver(struct rio_driver *);
 struct rio_dev *rio_dev_get(struct rio_dev *);
 void rio_dev_put(struct rio_dev *);
 
+#ifdef CONFIG_RAPIDIO_DMA_ENGINE
+extern struct dma_chan *rio_request_dma(struct rio_dev *rdev);
+extern void rio_release_dma(struct dma_chan *dchan);
+extern struct dma_async_tx_descriptor *rio_dma_prep_slave_sg(
+                struct rio_dev *rdev, struct dma_chan *dchan,
+                struct rio_dma_data *data,
+                enum dma_transfer_direction direction, unsigned long flags);
+#endif
+
 /**
  * rio_name - Get the unique RIO device identifier
  * @rdev: RIO device