dt-bindings: uniphier: add bindings for UniPhier SoC family

Document the list of SoCs and boards of UniPhier platform.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/arm/socionext/uniphier.txt

+Socionext UniPhier SoC family
+-----------------------------
+
+Required properties in the root node:
+  - compatible: should contain board and SoC compatible strings
+
+SoC and board compatible strings:
+  (sorted chronologically)
+
+  - LD4 SoC:  "socionext,uniphier-ld4"
+      - Reference Board: "socionext,uniphier-ld4-ref"
+
+  - Pro4 SoC: "socionext,uniphier-pro4"
+      - Reference Board: "socionext,uniphier-pro4-ref"
+      - Ace Board:       "socionext,uniphier-pro4-ace"
+      - Sanji Board:     "socionext,uniphier-pro4-sanji"
+
+  - sLD8 SoC: "socionext,uniphier-sld8"
+      - Reference Board: "socionext,uniphier-sld8-ref"
+
+  - PXs2 SoC: "socionext,uniphier-pxs2"
+      - Gentil Board:    "socionext,uniphier-pxs2-gentil"
+      - Vodka Board:     "socionext,uniphier-pxs2-vodka"
+
+  - LD6b SoC: "socionext,uniphier-ld6b"
+      - Reference Board: "socionext,uniphier-ld6b-ref"
+
+  - LD11 SoC: "socionext,uniphier-ld11"
+      - Reference Board: "socionext,uniphier-ld11-ref"
+      - Global Board:    "socionext,uniphier-ld11-global"
+
+  - LD20 SoC: "socionext,uniphier-ld20"
+      - Reference Board: "socionext,uniphier-ld20-ref"
+      - Global Board:    "socionext,uniphier-ld20-global"
+
+  - PXs3 SoC: "socionext,uniphier-pxs3"
+      - Reference Board: "socionext,uniphier-pxs3-ref"
+
+Example:
+
+/dts-v1/;
+
+/ {
+	compatible = "socionext,uniphier-ld20-ref", "socionext,uniphier-ld20";
+
+	...
+};

MAINTAINERS

@@ -2247,6 +2247,7 @@ M:	Masahiro Yamada <yamada.masahiro@socionext.com>
 L:	linux-arm-kernel@lists.infradead.org (moderated for non-subscribers)
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-uniphier.git
 S:	Maintained
+F:	Documentation/devicetree/bindings/arm/socionext/uniphier.txt
 F:	Documentation/devicetree/bindings/gpio/gpio-uniphier.txt
 F:	Documentation/devicetree/bindings/pinctrl/socionext,uniphier-pinctrl.txt
 F:	arch/arm/boot/dts/uniphier*