dt-bindings: iommu: add DART iommu bindings

DART (Device Address Resolution Table) is the iommu found on Apple
ARM SoCs such as the M1.

Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Signed-off-by: Sven Peter <sven@svenpeter.dev>
Link: https://lore.kernel.org/r/20210803121651.61594-3-sven@svenpeter.dev
Signed-off-by: Joerg Roedel <jroedel@suse.de>

Documentation/devicetree/bindings/iommu/apple,dart.yaml

@@ -0,0 +1,81 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iommu/apple,dart.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Apple DART IOMMU
+
+maintainers:
+  - Sven Peter <sven@svenpeter.dev>
+
+description: |+
+  Apple SoCs may contain an implementation of their Device Address
+  Resolution Table which provides a mandatory layer of address
+  translations for various masters.
+
+  Each DART instance is capable of handling up to 16 different streams
+  with individual pagetables and page-level read/write protection flags.
+
+  This DART IOMMU also raises interrupts in response to various
+  fault conditions.
+
+properties:
+  compatible:
+    const: apple,t8103-dart
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  clocks:
+    description:
+      Reference to the gate clock phandle if required for this IOMMU.
+      Optional since not all IOMMUs are attached to a clock gate.
+
+  '#iommu-cells':
+    const: 1
+    description:
+      Has to be one. The single cell describes the stream id emitted by
+      a master to the IOMMU.
+
+required:
+  - compatible
+  - reg
+  - '#iommu-cells'
+  - interrupts
+
+additionalProperties: false
+
+examples:
+  - |+
+    dart1: iommu@82f80000 {
+      compatible = "apple,t8103-dart";
+      reg = <0x82f80000 0x4000>;
+      interrupts = <1 781 4>;
+      #iommu-cells = <1>;
+    };
+
+    master1 {
+      iommus = <&dart1 0>;
+    };
+
+  - |+
+    dart2a: iommu@82f00000 {
+      compatible = "apple,t8103-dart";
+      reg = <0x82f00000 0x4000>;
+      interrupts = <1 781 4>;
+      #iommu-cells = <1>;
+    };
+    dart2b: iommu@82f80000 {
+      compatible = "apple,t8103-dart";
+      reg = <0x82f80000 0x4000>;
+      interrupts = <1 781 4>;
+      #iommu-cells = <1>;
+    };
+
+    master2 {
+      iommus = <&dart2a 0>, <&dart2b 1>;
+    };

MAINTAINERS

@@ -1262,6 +1262,12 @@ L:	linux-input@vger.kernel.org
 S:	Odd fixes
 F:	drivers/input/mouse/bcm5974.c
 
+APPLE DART IOMMU DRIVER
+M:	Sven Peter <sven@svenpeter.dev>
+L:	iommu@lists.linux-foundation.org
+S:	Maintained
+F:	Documentation/devicetree/bindings/iommu/apple,dart.yaml
+
 APPLE SMC DRIVER
 M:	Henrik Rydberg <rydberg@bitmath.org>
 L:	linux-hwmon@vger.kernel.org