spi: qup: Add DMA capabilities

This patch adds DMA capabilities to the spi-qup driver.  If DMA channels are
present, the QUP will use DMA instead of block mode for transfers to/from SPI
peripherals for transactions larger than the length of a block.

Signed-off-by: Andy Gross <agross@codeaurora.org>
Signed-off-by: Stanimir Varbanov <stanimir.varbanov@linaro.org>
Reviewed-by: Ivan T. Ivanov <iivanov@mm-sol.com
Signed-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/spi/qcom,spi-qup.txt

@@ -33,6 +33,11 @@ Optional properties:
 		nodes.  If unspecified, a single SPI device without a chip
 		select can be used.
 
+- dmas:         Two DMA channel specifiers following the convention outlined
+                in bindings/dma/dma.txt
+- dma-names:    Names for the dma channels, if present. There must be at
+                least one channel named "tx" for transmit and named "rx" for
+                receive.
 
 SPI slave nodes must be children of the SPI master node and can contain
 properties described in Documentation/devicetree/bindings/spi/spi-bus.txt
@@ -51,6 +56,9 @@ Example:
 		clocks = <&gcc GCC_BLSP2_QUP2_SPI_APPS_CLK>, <&gcc GCC_BLSP2_AHB_CLK>;
 		clock-names = "core", "iface";
 
+		dmas = <&blsp1_bam 13>, <&blsp1_bam 12>;
+		dma-names = "rx", "tx";
+
 		pinctrl-names = "default";
 		pinctrl-0 = <&spi8_default>;