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, 14 insertions, 0 deletions

diff --git a/drivers/rapidio/Kconfig b/drivers/rapidio/Kconfig
index bc87192..6194d35 100644
--- a/drivers/rapidio/Kconfig
+++ b/drivers/rapidio/Kconfig
@@ -22,6 +22,20 @@ config RAPIDIO_ENABLE_RX_TX_PORTS
 	  ports for Input/Output direction to allow other traffic
 	  than Maintenance transfers.
 
+config RAPIDIO_DMA_ENGINE
+	bool "DMA Engine support for RapidIO"
+	depends on RAPIDIO
+	select DMADEVICES
+	select DMA_ENGINE
+	help
+	  Say Y here if you want to use DMA Engine frameork for RapidIO data
+	  transfers to/from target RIO devices. RapidIO uses NREAD and
+	  NWRITE (NWRITE_R, SWRITE) requests to transfer data between local
+	  memory and memory on remote target device. You need a DMA controller
+	  capable to perform data transfers to/from RapidIO.
+
+	  If you are unsure about this, say Y here.
+
 config RAPIDIO_DEBUG
 	bool "RapidIO subsystem debug messages"
 	depends on RAPIDIO