dt-bindings: firmware: Add bindings for xilinx firmware

Add documentation to describe Xilinx firmware driver bindings.
Firmware driver provides an interface to firmware APIs.
Interface APIs can be used by any driver to communicate
to Platform Management Unit.

Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Nava kishore Manne <nava.manne@xilinx.com>
Link: https://lore.kernel.org/r/20210626155248.5004-4-nava.manne@xilinx.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/devicetree/bindings/firmware/xilinx/xlnx,zynqmp-firmware.yaml

@@ -0,0 +1,89 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/firmware/xilinx/xlnx,zynqmp-firmware.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Xilinx firmware driver
+
+maintainers:
+  - Nava kishore Manne <nava.manne@xilinx.com>
+
+description: The zynqmp-firmware node describes the interface to platform
+  firmware. ZynqMP has an interface to communicate with secure firmware.
+  Firmware driver provides an interface to firmware APIs. Interface APIs
+  can be used by any driver to communicate to PMUFW(Platform Management Unit).
+  These requests include clock management, pin control, device control,
+  power management service, FPGA service and other platform management
+  services.
+
+properties:
+  compatible:
+    oneOf:
+      - description: For implementations complying for Zynq Ultrascale+ MPSoC.
+        const: xlnx,zynqmp-firmware
+
+      - description: For implementations complying for Versal.
+        const: xlnx,versal-firmware
+
+  method:
+    description: |
+                 The method of calling the PM-API firmware layer.
+                 Permitted values are.
+                 - "smc" : SMC #0, following the SMCCC
+                 - "hvc" : HVC #0, following the SMCCC
+
+    $ref: /schemas/types.yaml#/definitions/string-array
+    enum:
+      - smc
+      - hvc
+
+  versal_fpga:
+    $ref: /schemas/fpga/xlnx,versal-fpga.yaml#
+    description: Compatible of the FPGA device.
+    type: object
+
+  zynqmp-aes:
+    $ref: /schemas/crypto/xlnx,zynqmp-aes.yaml#
+    description: The ZynqMP AES-GCM hardened cryptographic accelerator is
+      used to encrypt or decrypt the data with provided key and initialization
+      vector.
+    type: object
+
+  clock-controller:
+    $ref: /schemas/clock/xlnx,versal-clk.yaml#
+    description: The clock controller is a hardware block of Xilinx versal
+      clock tree. It reads required input clock frequencies from the devicetree
+      and acts as clock provider for all clock consumers of PS clocks.list of
+      clock specifiers which are external input clocks to the given clock
+      controller.
+    type: object
+
+required:
+  - compatible
+
+additionalProperties: false
+
+examples:
+  - |
+    versal-firmware {
+      compatible = "xlnx,versal-firmware";
+      method = "smc";
+
+      versal_fpga: versal_fpga {
+        compatible = "xlnx,versal-fpga";
+      };
+
+      xlnx_aes: zynqmp-aes {
+        compatible = "xlnx,zynqmp-aes";
+      };
+
+      versal_clk: clock-controller {
+        #clock-cells = <1>;
+        compatible = "xlnx,versal-clk";
+        clocks = <&ref>, <&alt_ref>, <&pl_alt_ref>;
+        clock-names = "ref", "alt_ref", "pl_alt_ref";
+      };
+    };
+
+...