dt-bindings: mailbox: ti,secure-proxy: Convert to json schema

Convert the ti,secure-proxy to yaml for better checks and documentation.
Differences being mostly in the examples:
- Dropped the example usage of mailbox client, it is better done in
tisci node definition.
- Switched reg usage for address-cells and size-cells 1 - aligned with
schema checks as well.
- included header in example for a buildable example.

While at this, lets make sure to support upto 100 rx threads even though
typically upto 1 threads is practically in use.

NOTE: The following checkpatch warning is generated since we do include the header
in the example, but this is a false positive warning.
WARNING: DT binding docs and includes should be a separate patch. See:
Documentation/devicetree/bindings/submitting-patches.rst

Signed-off-by: Nishanth Menon <[e-mail]>
Reviewed-by: Rob Herring <[e-mail]>
Signed-off-by: Jassi Brar <[e-mail]>

Documentation/devicetree/bindings/mailbox/ti,secure-proxy.txt

···
-Texas Instruments' Secure Proxy
-========================================
-
-The Texas Instruments' secure proxy is a mailbox controller that has
-configurable queues selectable at SoC(System on Chip) integration. The
-Message manager is broken up into different address regions that are
-called "threads" or "proxies" - each instance is unidirectional and is
-instantiated at SoC integration level by system controller to indicate
-receive or transmit path.
-
-Message Manager Device Node:
-===========================
-Required properties:
---------------------
-- compatible:		Shall be "ti,am654-secure-proxy"
-- reg-names 		target_data - Map the proxy data region
-			rt - Map the realtime status region
-			scfg - Map the configuration region
-- reg:			Contains the register map per reg-names.
-- #mbox-cells		Shall be 1 and shall refer to the transfer path
-			called thread.
-- interrupt-names:	Contains interrupt names matching the rx transfer path
-			for a given SoC. Receive interrupts shall be of the
-			format: "rx_<PID>".
-- interrupts:		Contains the interrupt information corresponding to
-			interrupt-names property.
-
-Example(AM654):
-------------
-
-	secure_proxy: mailbox@32c00000 {
-		compatible = "ti,am654-secure-proxy";
-		#mbox-cells = <1>;
-		reg-names = "target_data", "rt", "scfg";
-		reg = <0x0 0x32c00000 0x0 0x100000>,
-		      <0x0 0x32400000 0x0 0x100000>,
-		      <0x0 0x32800000 0x0 0x100000>;
-		interrupt-names = "rx_011";
-		interrupts = <GIC_SPI 32 IRQ_TYPE_LEVEL_HIGH>;
-	};
-
-	dmsc: dmsc {
-		[...]
-		mbox-names = "rx", "tx";
-		# RX Thread ID is 11
-		# TX Thread ID is 13
-		mboxes= <&secure_proxy 11>,
-			<&secure_proxy 13>;
-		[...]
-	};

Documentation/devicetree/bindings/mailbox/ti,secure-proxy.yaml

···
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/mailbox/ti,secure-proxy.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Texas Instruments' Secure Proxy
+
+maintainers:
+  - Nishanth Menon <[e-mail]>
+
+description: |
+  The Texas Instruments' secure proxy is a mailbox controller that has
+  configurable queues selectable at SoC(System on Chip) integration. The
+  Message manager is broken up into different address regions that are
+  called "threads" or "proxies" - each instance is unidirectional and is
+  instantiated at SoC integration level by system controller to indicate
+  receive or transmit path.
+
+properties:
+  $nodename:
+    pattern: "^mailbox@[0-9a-f]+$"
+
+  compatible:
+    const: ti,am654-secure-proxy
+
+  "#mbox-cells":
+    const: 1
+    description:
+      Contains the secure proxy thread ID used for the specific transfer path.
+
+  reg-names:
+    items:
+      - const: target_data
+      - const: rt
+      - const: scfg
+
+  reg:
+    minItems: 3
+
+  interrupt-names:
+    minItems: 1
+    maxItems: 100
+    items:
+      pattern: "^rx_[0-9]{3}$"
+    description:
+      Contains the interrupt name information for the Rx interrupt path for
+      secure proxy thread in the form 'rx_<PID>'.
+
+  interrupts:
+    minItems: 1
+    maxItems: 100
+    description:
+      Contains the interrupt information for the Rx interrupt path for secure
+      proxy.
+
+required:
+  - compatible
+  - reg-names
+  - reg
+  - interrupt-names
+  - interrupts
+  - "#mbox-cells"
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/arm-gic.h>
+    secure_proxy: mailbox@32c00000 {
+          compatible = "ti,am654-secure-proxy";
+          #mbox-cells = <1>;
+          reg-names = "target_data", "rt", "scfg";
+          reg = <0x32c00000 0x100000>,
+                <0x32400000 0x100000>,
+                <0x32800000 0x100000>;
+          interrupt-names = "rx_011";
+          interrupts = <GIC_SPI 32 IRQ_TYPE_LEVEL_HIGH>;
+    };