Add support for nexus map `power-domain-map` to be able to support
hierarchical power domains for providers with #power-domain-cells > 0.

Suggested-by: Rob Herring <robh@kernel.org>
Signed-off-by: Kevin Hilman <khilman@baylibre.com>
---
 Documentation/devicetree/bindings/power/power-domain.yaml | 35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/Documentation/devicetree/bindings/power/power-domain.yaml b/Documentation/devicetree/bindings/power/power-domain.yaml
index 8fdb529d560b..9f099d326aee 100644
--- a/Documentation/devicetree/bindings/power/power-domain.yaml
+++ b/Documentation/devicetree/bindings/power/power-domain.yaml
@@ -68,6 +68,15 @@ properties:
       by the given provider should be subdomains of the domain specified
       by this binding.
 
+  power-domains-map:
+    $ref: /schemas/types.yaml#/definitions/uint32-array
+    description:
+      Nexus node mapping property that establishes parent-child relationships
+      for PM domains using the format defined in the Device Tree specification
+      section 2.5.1. Each map entry consists of child domain specifier,
+      parent phandle, and optional parent specifier arguments. This property
+      is only supported for onecell providers (#power-domain-cells = 1).
+
 required:
   - "#power-domain-cells"
 
@@ -133,3 +142,29 @@ examples:
             min-residency-us = <7000>;
         };
     };
+
+  - |
+    // Example using power-domains-map for Nexus mapping
+    main_pd: power-controller@12370000 {
+        compatible = "foo,power-controller";
+        reg = <0x12370000 0x1000>;
+        #power-domain-cells = <0>;
+    };
+
+    wkup_pd: power-controller@12380000 {
+        compatible = "foo,power-controller";
+        reg = <0x12380000 0x1000>;
+        #power-domain-cells = <0>;
+    };
+
+    scmi_pds protocol@11 {
+        compatible = "arm,scmi-power-domain";
+        reg = <0x11>;
+        #power-domain-cells = <1>;
+        power-domains-map = <15 &main_pd>,
+                            <19 &wkup_pd>;
+    };
+
+    // In this example using Nexus node mapping:
+    // - Child domain 15 (scmi_pds 15) becomes a subdomain of main_pd
+    // - Child domain 19 (scmi_pds 19) becomes a subdomain of wkup_pd

-- 
2.49.0

On Fri, 13 Jun 2025 15:39:27 -0700, Kevin Hilman wrote:
> Add support for nexus map `power-domain-map` to be able to support
> hierarchical power domains for providers with #power-domain-cells > 0.
> 
> Suggested-by: Rob Herring <robh@kernel.org>
> Signed-off-by: Kevin Hilman <khilman@baylibre.com>
> ---
>  Documentation/devicetree/bindings/power/power-domain.yaml | 35 +++++++++++++++++++++++++++++++++++
>  1 file changed, 35 insertions(+)
> 

My bot found errors running 'make dt_binding_check' on your patch:

yamllint warnings/errors:

dtschema/dtc warnings/errors:
Error: Documentation/devicetree/bindings/power/power-domain.example.dts:136.18-19 syntax error
FATAL ERROR: Unable to parse input tree
make[2]: *** [scripts/Makefile.dtbs:131: Documentation/devicetree/bindings/power/power-domain.example.dtb] Error 1
make[2]: *** Waiting for unfinished jobs....
make[1]: *** [/builds/robherring/dt-review-ci/linux/Makefile:1519: dt_binding_check] Error 2
make: *** [Makefile:248: __sub-make] Error 2

doc reference errors (make refcheckdocs):

See https://patchwork.ozlabs.org/project/devicetree-bindings/patch/20250613-pmdomain-hierarchy-onecell-v3-1-5c770676fce7@baylibre.com

The base for the series is generally the latest rc1. A different dependency
should be noted in *this* patch.

If you already ran 'make dt_binding_check' and didn't see the above
error(s), then make sure 'yamllint' is installed and dt-schema is up to
date:

pip3 install dtschema --upgrade

Please check and re-submit after running the above command yourself. Note
that DT_SCHEMA_FILES can be set to your schema file to speed up checking
your schema. However, it must be unset to test all examples with your schema.