doc: dt: mtd: add documentation for Mediatek spi-nor controller

Add device tree binding documentation for serial flash with
Mediatek serial flash controller

Signed-off-by: Bayi Cheng <bayi.cheng@mediatek.com>
Acked-by: Rob Herring <robh@kernel.org>
[Brian: fixed up language]
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

diff --git a/Documentation/devicetree/bindings/mtd/mtk-quadspi.txt b/Documentation/devicetree/bindings/mtd/mtk-quadspi.txt
new file mode 100644 (file)
index 0000000..fb314f0
--- /dev/null
+++ b/Documentation/devicetree/bindings/mtd/mtk-quadspi.txt
@@ -0,0 +1,41 @@
+* Serial NOR flash controller for MTK MT81xx (and similar)
+
+Required properties:
+- compatible:    should be "mediatek,mt8173-nor";
+- reg:                   physical base address and length of the controller's register
+- clocks:        the phandle of the clocks needed by the nor controller
+- clock-names:           the names of the clocks
+                 the clocks should be named "spi" and "sf". "spi" is used for spi bus,
+                 and "sf" is used for controller, these are the clocks witch
+                 hardware needs to enabling nor flash and nor flash controller.
+                 See Documentation/devicetree/bindings/clock/clock-bindings.txt for details.
+- #address-cells: should be <1>
+- #size-cells:   should be <0>
+
+The SPI flash must be a child of the nor_flash node and must have a
+compatible property. Also see jedec,spi-nor.txt.
+
+Required properties:
+- compatible:    May include a device-specific string consisting of the manufacturer
+                 and name of the chip. Must also include "jedec,spi-nor" for any
+                 SPI NOR flash that can be identified by the JEDEC READ ID opcode (0x9F).
+- reg :                  Chip-Select number
+
+Example:
+
+nor_flash: spi@1100d000 {
+       compatible = "mediatek,mt8173-nor";
+       reg = <0 0x1100d000 0 0xe0>;
+       clocks = <&pericfg CLK_PERI_SPI>,
+                <&topckgen CLK_TOP_SPINFI_IFR_SEL>;
+       clock-names = "spi", "sf";
+       #address-cells = <1>;
+       #size-cells = <0>;
+       status = "disabled";
+
+       flash@0 {
+               compatible = "jedec,spi-nor";
+               reg = <0>;
+       };
+};
+