dmaengine: DMA engine driver for Marvell XOR engine

The XOR engine found in Marvell's SoCs and system controllers
provides XOR and DMA operation, iSCSI CRC32C calculation, memory
initialization, and memory ECC error cleanup operation support.

This driver implements the DMA engine API and supports the following
capabilities:
- memcpy
- xor
- memset

The XOR engine can be used by DMA engine clients implemented in the
kernel, one of those clients is the RAID module.  In that case, I
observed 20% improvement in the raid5 write throughput, and 40%
decrease in the CPU utilization when doing array construction, those
results obtained on an 5182 running at 500Mhz.

When enabling the NET DMA client, the performance decreased, so
meanwhile it is recommended to keep this client off.

Signed-off-by: Saeed Bishara <saeed@marvell.com>
Signed-off-by: Lennert Buytenhek <buytenh@marvell.com>
Signed-off-by: Nicolas Pitre <nico@marvell.com>
Acked-by: Maciej Sosnowski <maciej.sosnowski@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

drivers/dma/Kconfig

@@ -47,6 +47,14 @@ config FSL_DMA
 	  MPC8560/40, MPC8555, MPC8548 and MPC8641 processors.
 	  The MPC8349, MPC8360 is also supported.
 
+config MV_XOR
+	bool "Marvell XOR engine support"
+	depends on PLAT_ORION
+	select ASYNC_CORE
+	select DMA_ENGINE
+	---help---
+	  Enable support for the Marvell XOR engine.
+
 config DMA_ENGINE
 	bool
 

drivers/dma/Makefile

@@ -4,3 +4,4 @@ obj-$(CONFIG_INTEL_IOATDMA) += ioatdma.o
 ioatdma-objs := ioat.o ioat_dma.o ioat_dca.o
 obj-$(CONFIG_INTEL_IOP_ADMA) += iop-adma.o
 obj-$(CONFIG_FSL_DMA) += fsldma.o
+obj-$(CONFIG_MV_XOR) += mv_xor.o