dt-bindings: convert mtk-quadspi binding doc for spi-mtk-nor

spi-mtk-nor is a driver to replace mtk-quadspi and they have almost
the same device-tree bindings. Reuse this binding documentation and
convert it for new driver:

1. "Mediatek SoCs" -> "Mediatek ARM SoCs" because MTK MIPS SoCs
   use different controllers.
2. document "interrupts" as a required property because it's
   available on all SoCs with this controller and new driver takes
   advantages of it. It's implemented as optional only to maintain
   backward compatibility.
3. add a dummy interrupt binding in example.

Signed-off-by: Chuanhong Guo <gch981213@gmail.com>
Link: https://lore.kernel.org/r/20200306085052.28258-4-gch981213@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>

1 files changed, 47 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/spi/spi-mtk-nor.txt b/Documentation/devicetree/bindings/spi/spi-mtk-nor.txt
new file mode 100644
index 000000000000..984ae7fd4f94
--- /dev/null
+++ b/Documentation/devicetree/bindings/spi/spi-mtk-nor.txt
@@ -0,0 +1,47 @@
+* Serial NOR flash controller for MediaTek ARM SoCs
+
+Required properties:
+- compatible: 	  For mt8173, compatible should be "mediatek,mt8173-nor",
+		  and it's the fallback compatible for other Soc.
+		  For every other SoC, should contain both the SoC-specific compatible
+		  string and "mediatek,mt8173-nor".
+		  The possible values are:
+		  "mediatek,mt2701-nor", "mediatek,mt8173-nor"
+		  "mediatek,mt2712-nor", "mediatek,mt8173-nor"
+		  "mediatek,mt7622-nor", "mediatek,mt8173-nor"
+		  "mediatek,mt7623-nor", "mediatek,mt8173-nor"
+		  "mediatek,mt7629-nor", "mediatek,mt8173-nor"
+		  "mediatek,mt8173-nor"
+- reg: 		  physical base address and length of the controller's register
+- interrupts:	  Interrupt number used by the controller.
+- 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>
+
+There should be only one spi slave device following generic spi bindings.
+It's not recommended to use this controller for devices other than SPI NOR
+flash due to limited transfer capability of this controller.
+
+Example:
+
+nor_flash: spi@1100d000 {
+	compatible = "mediatek,mt8173-nor";
+	reg = <0 0x1100d000 0 0xe0>;
+	interrupts = <&spi_flash_irq>;
+	clocks = <&pericfg CLK_PERI_SPI>,
+		 <&topckgen CLK_TOP_SPINFI_IFR_SEL>;
+	clock-names = "spi", "sf";
+	#address-cells = <1>;
+	#size-cells = <0>;
+
+	flash@0 {
+		compatible = "jedec,spi-nor";
+		reg = <0>;
+	};
+};
+