regulator: fixed: provide bindings using power domain

Define bindings for fixed regulator using power domain performance state
to enable/disable corresponding regulator.

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://lore.kernel.org/r/20201023131925.334864-2-dmitry.baryshkov@linaro.org
Signed-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/regulator/fixed-regulator.yaml

@@ -26,12 +26,22 @@ if:
         const: regulator-fixed-clock
   required:
     - clocks
+else:
+  if:
+    properties:
+      compatible:
+        contains:
+          const: regulator-fixed-domain
+    required:
+      - power-domains
+      - required-opps
 
 properties:
   compatible:
     enum:
       - regulator-fixed
       - regulator-fixed-clock
+      - regulator-fixed-domain
 
   regulator-name: true
 
@@ -46,6 +56,20 @@ properties:
       is mandatory if compatible is chosen to regulator-fixed-clock.
     maxItems: 1
 
+  power-domains:
+    description:
+      Power domain to use for enable control. This binding is only
+      available if the compatible is chosen to regulator-fixed-domain.
+    maxItems: 1
+
+  required-opps:
+    description:
+      Performance state to use for enable control. This binding is only
+      available if the compatible is chosen to regulator-fixed-domain. The
+      power-domain binding is mandatory if compatible is chosen to
+      regulator-fixed-domain.
+    maxItems: 1
+
   startup-delay-us:
     description: startup time in microseconds
     $ref: /schemas/types.yaml#/definitions/uint32
@@ -89,4 +113,27 @@ examples:
       gpio-open-drain;
       vin-supply = <&parent_reg>;
     };
+    reg_1v8_clk: regulator-1v8-clk {
+      compatible = "regulator-fixed-clock";
+      regulator-name = "1v8";
+      regulator-min-microvolt = <1800000>;
+      regulator-max-microvolt = <1800000>;
+      clocks = <&clock1>;
+      startup-delay-us = <70000>;
+      enable-active-high;
+      regulator-boot-on;
+      vin-supply = <&parent_reg>;
+    };
+    reg_1v8_domain: regulator-1v8-domain {
+      compatible = "regulator-fixed-domain";
+      regulator-name = "1v8";
+      regulator-min-microvolt = <1800000>;
+      regulator-max-microvolt = <1800000>;
+      power-domains = <&domain1>;
+      required-opps = <&domain1_state1>;
+      startup-delay-us = <70000>;
+      enable-active-high;
+      regulator-boot-on;
+      vin-supply = <&parent_reg>;
+    };
 ...