dt-bindings: arm: Document Broadcom SoCs 'secondary-boot-reg'

Consolidate and move the 'secondary-boot-reg' property from the 3
existing binding documents into the main cpus.yaml documentation, also
make sure that the property is enforced when relevant.
Acked-by: Maxime Ripard <mripard@kernel.org>
Acked-by: Scott Branden <scott.branden@broadcom.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>

Documentation/devicetree/bindings/arm/bcm/brcm,bcm11351-cpu-method.txt

-Broadcom Kona Family CPU Enable Method
---------------------------------------
-This binding defines the enable method used for starting secondary
-CPUs in the following Broadcom SoCs:
-  BCM11130, BCM11140, BCM11351, BCM28145, BCM28155, BCM21664
-
-The enable method is specified by defining the following required
-properties in the "cpu" device tree node:
-  - enable-method = "brcm,bcm11351-cpu-method";
-  - secondary-boot-reg = <...>;
-
-The secondary-boot-reg property is a u32 value that specifies the
-physical address of the register used to request the ROM holding pen
-code release a secondary CPU.  The value written to the register is
-formed by encoding the target CPU id into the low bits of the
-physical start address it should jump to.
-
-Example:
-	cpus {
-		#address-cells = <1>;
-		#size-cells = <0>;
-
-		cpu0: cpu@0 {
-			device_type = "cpu";
-			compatible = "arm,cortex-a9";
-			reg = <0>;
-		};
-
-		cpu1: cpu@1 {
-			device_type = "cpu";
-			compatible = "arm,cortex-a9";
-			reg = <1>;
-			enable-method = "brcm,bcm11351-cpu-method";
-			secondary-boot-reg = <0x3500417c>;
-		};
-	};

Documentation/devicetree/bindings/arm/bcm/brcm,bcm23550-cpu-method.txt

-Broadcom Kona Family CPU Enable Method
---------------------------------------
-This binding defines the enable method used for starting secondary
-CPUs in the following Broadcom SoCs:
-  BCM23550
-
-The enable method is specified by defining the following required
-properties in the "cpu" device tree node:
-  - enable-method = "brcm,bcm23550";
-  - secondary-boot-reg = <...>;
-
-The secondary-boot-reg property is a u32 value that specifies the
-physical address of the register used to request the ROM holding pen
-code release a secondary CPU.  The value written to the register is
-formed by encoding the target CPU id into the low bits of the
-physical start address it should jump to.
-
-Example:
-	cpus {
-		#address-cells = <1>;
-		#size-cells = <0>;
-
-		cpu0: cpu@0 {
-			device_type = "cpu";
-			compatible = "arm,cortex-a9";
-			reg = <0>;
-		};
-
-		cpu1: cpu@1 {
-			device_type = "cpu";
-			compatible = "arm,cortex-a9";
-			reg = <1>;
-			enable-method = "brcm,bcm23550";
-			secondary-boot-reg = <0x3500417c>;
-		};
-	};

Documentation/devicetree/bindings/arm/bcm/brcm,nsp-cpu-method.txt

-Broadcom Northstar Plus SoC CPU Enable Method
----------------------------------------------
-This binding defines the enable method used for starting secondary
-CPU in the following Broadcom SoCs:
-  BCM58522, BCM58525, BCM58535, BCM58622, BCM58623, BCM58625, BCM88312
-
-The enable method is specified by defining the following required
-properties in the corresponding secondary "cpu" device tree node:
-  - enable-method = "brcm,bcm-nsp-smp";
-  - secondary-boot-reg = <...>;
-
-The secondary-boot-reg property is a u32 value that specifies the
-physical address of the register which should hold the common
-entry point for a secondary CPU. This entry is cpu node specific
-and should be added per cpu. E.g., in case of NSP (BCM58625) which
-is a dual core CPU SoC, this entry should be added to cpu1 node.
-
-
-Example:
-	cpus {
-		#address-cells = <1>;
-		#size-cells = <0>;
-
-		cpu0: cpu@0 {
-			device_type = "cpu";
-			compatible = "arm,cortex-a9";
-			next-level-cache = <&L2>;
-			reg = <0>;
-		};
-
-		cpu1: cpu@1 {
-			device_type = "cpu";
-			compatible = "arm,cortex-a9";
-			next-level-cache = <&L2>;
-			enable-method = "brcm,bcm-nsp-smp";
-			secondary-boot-reg = <0xffff042c>;
-			reg = <1>;
-		};
-	};

Documentation/devicetree/bindings/arm/cpus.yaml

@@ -287,6 +287,39 @@ properties:
       While optional, it is the preferred way to get access to
       the cpu-core power-domains.
 
+  secondary-boot-reg:
+    $ref: '/schemas/types.yaml#/definitions/uint32'
+    description: |
+      Required for systems that have an "enable-method" property value of
+      "brcm,bcm11351-cpu-method", "brcm,bcm23550" or "brcm,bcm-nsp-smp".
+
+      This includes the following SoCs: |
+      BCM11130, BCM11140, BCM11351, BCM28145, BCM28155, BCM21664, BCM23550
+      BCM58522, BCM58525, BCM58535, BCM58622, BCM58623, BCM58625, BCM88312
+
+      The secondary-boot-reg property is a u32 value that specifies the
+      physical address of the register used to request the ROM holding pen
+      code release a secondary CPU. The value written to the register is
+      formed by encoding the target CPU id into the low bits of the
+      physical start address it should jump to.
+
+if:
+  # If the enable-method property contains one of those values
+  properties:
+    enable-method:
+      contains:
+        enum:
+          - brcm,bcm11351-cpu-method
+          - brcm,bcm23550
+          - brcm,bcm-nsp-smp
+  # and if enable-method is present
+  required:
+    - enable-method
+
+then:
+   required:
+     - secondary-boot-reg
+
 required:
   - device_type
   - reg