dt-bindings: dma: Add Apple ADMAC

Apple's Audio DMA Controller (ADMAC) is used to fetch and store audio
samples on SoCs from the "Apple Silicon" family.
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Martin Povišer <povik+lin@cutebit.org>
Link: https://lore.kernel.org/r/20220531213615.7822-2-povik+lin@cutebit.orgSigned-off-by: Vinod Koul <vkoul@kernel.org>

Documentation/devicetree/bindings/dma/apple,admac.yaml

+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/dma/apple,admac.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Apple Audio DMA Controller (ADMAC)
+
+description: |
+  Apple's Audio DMA Controller (ADMAC) is used to fetch and store audio samples
+  on SoCs from the "Apple Silicon" family.
+
+  The controller has been seen with up to 24 channels. Even-numbered channels
+  are TX-only, odd-numbered are RX-only. Individual channels are coupled to
+  fixed device endpoints.
+
+maintainers:
+  - Martin Povišer <povik+lin@cutebit.org>
+
+allOf:
+  - $ref: "dma-controller.yaml#"
+
+properties:
+  compatible:
+    items:
+      - enum:
+          - apple,t6000-admac
+          - apple,t8103-admac
+      - const: apple,admac
+
+  reg:
+    maxItems: 1
+
+  '#dma-cells':
+    const: 1
+    description:
+      Clients specify a single cell with channel number.
+
+  dma-channels:
+    maximum: 24
+
+  interrupts:
+    minItems: 4
+    maxItems: 4
+    description:
+      Interrupts that correspond to the 4 IRQ outputs of the controller. Usually
+      only one of the controller outputs will be connected as an usable interrupt
+      source. The remaining interrupts will be left without a valid value, e.g.
+      in an interrupts-extended list the disconnected positions will contain
+      an empty phandle reference <0>.
+
+required:
+  - compatible
+  - reg
+  - '#dma-cells'
+  - dma-channels
+  - interrupts
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/apple-aic.h>
+    #include <dt-bindings/interrupt-controller/irq.h>
+
+    admac: dma-controller@238200000 {
+      compatible = "apple,t8103-admac", "apple,admac";
+      reg = <0x38200000 0x34000>;
+      dma-channels = <24>;
+      interrupts-extended = <0>,
+                            <&aic AIC_IRQ 626 IRQ_TYPE_LEVEL_HIGH>,
+                            <0>,
+                            <0>;
+      #dma-cells = <1>;
+    };