dt-bindings: mtd: Add Cadence NAND controller driver

Document the bindings used by Cadence NAND controller driver

Signed-off-by: Piotr Sroka <piotrs@cadence.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>

Documentation/devicetree/bindings/mtd/cadence-nand-controller.txt

+* Cadence NAND controller
+
+Required properties:
+  - compatible : "cdns,hp-nfc"
+  - reg : Contains two entries, each of which is a tuple consisting of a
+	  physical address and length. The first entry is the address and
+	  length of the controller register set. The second entry is the
+	  address and length of the Slave DMA data port.
+  - reg-names: should contain "reg" and "sdma"
+  - #address-cells: should be 1. The cell encodes the chip select connection.
+  - #size-cells : should be 0.
+  - interrupts : The interrupt number.
+  - clocks: phandle of the controller core clock (nf_clk).
+
+Optional properties:
+  - dmas: shall reference DMA channel associated to the NAND controller
+  - cdns,board-delay-ps : Estimated Board delay. The value includes the total
+    round trip delay for the signals and is used for deciding on values
+    associated with data read capture. The example formula for SDR mode is
+    the following:
+    board delay = RE#PAD delay + PCB trace to device + PCB trace from device
+    + DQ PAD delay
+
+Child nodes represent the available NAND chips.
+
+Required properties of NAND chips:
+  - reg: shall contain the native Chip Select ids from 0 to max supported by
+    the cadence nand flash controller
+
+See Documentation/devicetree/bindings/mtd/nand.txt for more details on
+generic bindings.
+
+Example:
+
+nand_controller: nand-controller@60000000 {
+	  compatible = "cdns,hp-nfc";
+	  #address-cells = <1>;
+	  #size-cells = <0>;
+	  reg = <0x60000000 0x10000>, <0x80000000 0x10000>;
+	  reg-names = "reg", "sdma";
+	  clocks = <&nf_clk>;
+	  cdns,board-delay-ps = <4830>;
+	  interrupts = <2 0>;
+	  nand@0 {
+	      reg = <0>;
+	      label = "nand-1";
+	  };
+	  nand@1 {
+	      reg = <1>;
+	      label = "nand-2";
+	  };
+
+};

MAINTAINERS

@@ -3603,6 +3603,7 @@ M:	Piotr Sroka <piotrs@cadence.com>
 L:	linux-mtd@lists.infradead.org
 S:	Maintained
 F:	drivers/mtd/nand/raw/cadence-nand-controller.c
+F:	Documentation/devicetree/bindings/mtd/cadence-nand-controller.txt
 CADET FM/AM RADIO RECEIVER DRIVER
 M:	Hans Verkuil <hverkuil@xs4all.nl>