dt-bindings: iommu: add bindings for sprd IOMMU

This IOMMU module can be used by Unisoc's multimedia devices, such as
display, Image codec(jpeg) and a few signal processors, including
VSP(video), GSP(graphic), ISP(image), and CPP(camera pixel processor), etc.

Signed-off-by: Chunyan Zhang <chunyan.zhang@unisoc.com>
Link: https://lore.kernel.org/r/20210305093216.201897-2-zhang.lyra@gmail.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

Documentation/devicetree/bindings/iommu/sprd,iommu.yaml

@@ -0,0 +1,57 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+# Copyright 2020 Unisoc Inc.
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iommu/sprd,iommu.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Unisoc IOMMU and Multi-media MMU
+
+maintainers:
+  - Chunyan Zhang <zhang.lyra@gmail.com>
+
+properties:
+  compatible:
+    enum:
+      - sprd,iommu-v1
+
+  "#iommu-cells":
+    const: 0
+    description:
+      Unisoc IOMMUs are all single-master IOMMU devices, therefore no
+      additional information needs to associate with its master device.
+      Please refer to the generic bindings document for more details,
+      Documentation/devicetree/bindings/iommu/iommu.txt
+
+  reg:
+    maxItems: 1
+
+  clocks:
+    description:
+      Reference to a gate clock phandle, since access to some of IOMMUs are
+      controlled by gate clock, but this is not required.
+
+required:
+  - compatible
+  - reg
+  - "#iommu-cells"
+
+additionalProperties: false
+
+examples:
+  - |
+    iommu_disp: iommu@63000800 {
+      compatible = "sprd,iommu-v1";
+      reg = <0x63000800 0x80>;
+      #iommu-cells = <0>;
+    };
+
+  - |
+    iommu_jpg: iommu@62300300 {
+      compatible = "sprd,iommu-v1";
+      reg = <0x62300300 0x80>;
+      #iommu-cells = <0>;
+      clocks = <&mm_gate 1>;
+    };
+
+...