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 bc8719238793..6194d35ebb97 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