spi: omap2-mcspi: add generic DMA request support to the DT binding

The binding definition is based on the generic DMA request binding
Signed-off-by: Matt Porter <mporter@ti.com>
Signed-off-by: Joel A Fernandes <joelagnel@ti.com>
Signed-off-by: Sourav Poddar <sourav.poddar@ti.com>
Signed-off-by: Mark Brown <broonie@linaro.org>

Documentation/devicetree/bindings/spi/omap-spi.txt

@@ -10,7 +10,18 @@ Required properties:
 			  input. The default is D0 as input and
 			  D1 as output.
 
-Example:
+Optional properties:
+- dmas: List of DMA specifiers with the controller specific format
+	as described in the generic DMA client binding. A tx and rx
+	specifier is required for each chip select.
+- dma-names: List of DMA request names. These strings correspond
+	1:1 with the DMA specifiers listed in dmas. The string naming
+	is to be "rxN" and "txN" for RX and TX requests,
+	respectively, where N equals the chip select number.
+
+Examples:
+
+[hwmod populated DMA resources]
 
 mcspi1: mcspi@1 {
     #address-cells = <1>;
@@ -20,3 +31,17 @@ mcspi1: mcspi@1 {
     ti,spi-num-cs = <4>;
 };
 
+[generic DMA request binding]
+
+mcspi1: mcspi@1 {
+    #address-cells = <1>;
+    #size-cells = <0>;
+    compatible = "ti,omap4-mcspi";
+    ti,hwmods = "mcspi1";
+    ti,spi-num-cs = <2>;
+    dmas = <&edma 42
+	    &edma 43
+	    &edma 44
+	    &edma 45>;
+    dma-names = "tx0", "rx0", "tx1", "rx1";
+};