dt-bindings: sram: Merge Allwinner SRAM bindings into generic

The Allwinner SRAM bindings list only compatible so integrate them into
generic SRAM bindings schema.

Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/sram/sram.yaml

@@ -65,6 +65,7 @@ patternProperties:
           Should contain a vendor specific string in the form
           <vendor>,[<device>-]<usage>
         enum:
+          - allwinner,sun9i-a80-smp-sram
           - amlogic,meson8-smp-sram
           - amlogic,meson8b-smp-sram
           - renesas,smp-sram
@@ -215,3 +216,27 @@ examples:
             reg = <0x10080000 0x50>;
         };
     };
+
+  - |
+    // Allwinner's A80 SoC uses part of the secure sram for hotplugging of the
+    // primary core (cpu0). Once the core gets powered up it checks if a magic
+    // value is set at a specific location. If it is then the BROM will jump
+    // to the software entry address, instead of executing a standard boot.
+    //
+    // Also there are no "secure-only" properties. The implementation should
+    // check if this SRAM is usable first.
+    sram@20000 {
+        // 256 KiB secure SRAM at 0x20000
+        compatible = "mmio-sram";
+        reg = <0x00020000 0x40000>;
+        #address-cells = <1>;
+        #size-cells = <1>;
+        ranges = <0 0x00020000 0x40000>;
+
+        smp-sram@1000 {
+            // This is checked by BROM to determine if
+            // cpu0 should jump to SMP entry vector
+            compatible = "allwinner,sun9i-a80-smp-sram";
+            reg = <0x1000 0x8>;
+        };
+    };