dt-bindings: display/msm/gmu: Add GMU wrapper

The "GMU Wrapper" is Qualcomm's name for "let's treat the GPU blocks
we'd normally assign to the GMU as if they were a part of the GMU, even
though they are not". It's a (good) software representation of the GMU_CX
and GMU_GX register spaces within the GPUSS that helps us programatically
treat these de-facto GMU-less parts in a way that's very similar to their
GMU-equipped cousins, massively saving up on code duplication.

The "wrapper" register space was specifically designed to mimic the layout
of a real GMU, though it rather obviously does not have the M3 core et al.

To sum it all up, the GMU wrapper is essentially a register space within
the GPU, which Linux sees as a dumbed-down regular GMU: there's no clocks,
interrupts, multiple reg spaces, iommus and OPP. Document it.
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/542750/Signed-off-by: Rob Clark <robdclark@chromium.org>

Documentation/devicetree/bindings/display/msm/gmu.yaml

@@ -19,16 +19,18 @@ description: |
 
 properties:
   compatible:
-    items:
-      - pattern: '^qcom,adreno-gmu-6[0-9][0-9]\.[0-9]$'
-      - const: qcom,adreno-gmu
+    oneOf:
+      - items:
+          - pattern: '^qcom,adreno-gmu-6[0-9][0-9]\.[0-9]$'
+          - const: qcom,adreno-gmu
+      - const: qcom,adreno-gmu-wrapper
 
   reg:
-    minItems: 3
+    minItems: 1
     maxItems: 4
 
   reg-names:
-    minItems: 3
+    minItems: 1
     maxItems: 4
 
   clocks:
@@ -44,7 +46,6 @@ properties:
       - description: GMU HFI interrupt
       - description: GMU interrupt
 
-
   interrupt-names:
     items:
       - const: hfi
@@ -72,14 +73,8 @@ required:
   - compatible
   - reg
   - reg-names
-  - clocks
-  - clock-names
-  - interrupts
-  - interrupt-names
   - power-domains
   - power-domain-names
-  - iommus
-  - operating-points-v2
 
 additionalProperties: false
 
@@ -218,6 +213,28 @@ allOf:
             - const: axi
             - const: memnoc
 
+  - if:
+      properties:
+        compatible:
+          contains:
+            const: qcom,adreno-gmu-wrapper
+    then:
+      properties:
+        reg:
+          items:
+            - description: GMU wrapper register space
+        reg-names:
+          items:
+            - const: gmu
+    else:
+      required:
+        - clocks
+        - clock-names
+        - interrupts
+        - interrupt-names
+        - iommus
+        - operating-points-v2
+
 examples:
   - |
     #include <dt-bindings/clock/qcom,gpucc-sdm845.h>
@@ -250,3 +267,12 @@ examples:
         iommus = <&adreno_smmu 5>;
         operating-points-v2 = <&gmu_opp_table>;
     };
+
+    gmu_wrapper: gmu@596a000 {
+        compatible = "qcom,adreno-gmu-wrapper";
+        reg = <0x0596a000 0x30000>;
+        reg-names = "gmu";
+        power-domains = <&gpucc GPU_CX_GDSC>,
+                        <&gpucc GPU_GX_GDSC>;
+        power-domain-names = "cx", "gx";
+    };