dt/bindings: qcom_nandc: Add DT bindings

Add DT bindings document for the Qualcomm NAND controller driver.

Reviewed-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Archit Taneja <architt@codeaurora.org>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

Documentation/devicetree/bindings/mtd/qcom_nandc.txt

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+* Qualcomm NAND controller
+
+Required properties:
+- compatible:		should be "qcom,ipq806x-nand"
+- reg:			MMIO address range
+- clocks:		must contain core clock and always on clock
+- clock-names:		must contain "core" for the core clock and "aon" for the
+			always on clock
+- dmas:			DMA specifier, consisting of a phandle to the ADM DMA
+			controller node and the channel number to be used for
+			NAND. Refer to dma.txt and qcom_adm.txt for more details
+- dma-names:		must be "rxtx"
+- qcom,cmd-crci:	must contain the ADM command type CRCI block instance
+			number specified for the NAND controller on the given
+			platform
+- qcom,data-crci:	must contain the ADM data type CRCI block instance
+			number specified for the NAND controller on the given
+			platform
+- #address-cells:	<1> - subnodes give the chip-select number
+- #size-cells:		<0>
+
+* NAND chip-select
+
+Each controller may contain one or more subnodes to represent enabled
+chip-selects which (may) contain NAND flash chips. Their properties are as
+follows.
+
+Required properties:
+- compatible:		should contain "qcom,nandcs"
+- reg:			a single integer representing the chip-select
+			number (e.g., 0, 1, 2, etc.)
+- #address-cells:	see partition.txt
+- #size-cells:		see partition.txt
+- nand-ecc-strength:	see nand.txt
+- nand-ecc-step-size:	must be 512. see nand.txt for more details.
+
+Optional properties:
+- nand-bus-width:	see nand.txt
+
+Each nandcs device node may optionally contain a 'partitions' sub-node, which
+further contains sub-nodes describing the flash partition mapping. See
+partition.txt for more detail.
+
+Example:
+
+nand@1ac00000 {
+	compatible = "qcom,ebi2-nandc";
+	reg = <0x1ac00000 0x800>;
+
+	clocks = <&gcc EBI2_CLK>,
+		 <&gcc EBI2_AON_CLK>;
+	clock-names = "core", "aon";
+
+	dmas = <&adm_dma 3>;
+	dma-names = "rxtx";
+	qcom,cmd-crci = <15>;
+	qcom,data-crci = <3>;
+
+	#address-cells = <1>;
+	#size-cells = <0>;
+
+	nandcs@0 {
+		compatible = "qcom,nandcs";
+		reg = <0>;
+
+		nand-ecc-strength = <4>;
+		nand-ecc-step-size = <512>;
+		nand-bus-width = <8>;
+
+		partitions {
+			compatible = "fixed-partitions";
+			#address-cells = <1>;
+			#size-cells = <1>;
+
+			partition@0 {
+				label = "boot-nand";
+				reg = <0 0x58a0000>;
+			};
+
+			partition@58a0000 {
+				label = "fs-nand";
+				reg = <0x58a0000 0x4000000>;
+			};
+		};
+	};
+};