dt-bindings: mmc: synopsys-dw-mshc: integrate Altera and Imagination

The bindings for Altera and Imagination extensions are the same as for
the original Synopsys Designware Mobile Storage Host Controller.
Integrate them into Synopsys bindings to have dtschema coverage.
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Link: https://lore.kernel.org/r/20211227133558.135185-3-krzysztof.kozlowski@canonical.comSigned-off-by: Ulf Hansson <ulf.hansson@linaro.org>

Documentation/devicetree/bindings/mmc/img-dw-mshc.txt

-* Imagination specific extensions to the Synopsys Designware Mobile Storage
-  Host Controller
-
-The Synopsys designware mobile storage host controller is used to interface
-a SoC with storage medium such as eMMC or SD/MMC cards. This file documents
-differences between the core Synopsys dw mshc controller properties described
-by synopsys-dw-mshc.txt and the properties used by the Imagination specific
-extensions to the Synopsys Designware Mobile Storage Host Controller.
-
-Required Properties:
-
-* compatible: should be
-	- "img,pistachio-dw-mshc": for Pistachio SoCs
-
-Example:
-
-	mmc@18142000 {
-		compatible = "img,pistachio-dw-mshc";
-		reg = <0x18142000 0x400>;
-		interrupts = <GIC_SHARED 39 IRQ_TYPE_LEVEL_HIGH>;
-
-		clocks = <&system_clk>, <&sdhost_clk>;
-		clock-names = "biu", "ciu";
-
-		fifo-depth = <0x20>;
-		bus-width = <4>;
-		disable-wp;
-	};

Documentation/devicetree/bindings/mmc/socfpga-dw-mshc.txt

-* Altera SOCFPGA specific extensions to the Synopsys Designware Mobile
-  Storage Host Controller
-
-The Synopsys designware mobile storage host controller is used to interface
-a SoC with storage medium such as eMMC or SD/MMC cards. This file documents
-differences between the core Synopsys dw mshc controller properties described
-by synopsys-dw-mshc.txt and the properties used by the Altera SOCFPGA specific
-extensions to the Synopsys Designware Mobile Storage Host Controller.
-
-Required Properties:
-
-* compatible: should be
-	- "altr,socfpga-dw-mshc": for Altera's SOCFPGA platform
-
-Example:
-
-	mmc: dwmmc0@ff704000 {
-		compatible = "altr,socfpga-dw-mshc";
-		reg = <0xff704000 0x1000>;
-		interrupts = <0 129 4>;
-		#address-cells = <1>;
-		#size-cells = <0>;
-	};

Documentation/devicetree/bindings/mmc/synopsys-dw-mshc.yaml

@@ -15,7 +15,10 @@ maintainers:
 # Everything else is described in the common file
 properties:
   compatible:
-    const: snps,dw-mshc
+    enum:
+      - altr,socfpga-dw-mshc
+      - img,pistachio-dw-mshc
+      - snps,dw-mshc
 
   reg:
     maxItems: 1