dt-bindings: dma: Add Loongson-1 APB DMA

Add devicetree binding document for Loongson-1 APB DMA.

Reviewed-by: Conor Dooley <[e-mail]>
Reviewed-by: Jiaxun Yang <[e-mail]>
Signed-off-by: Keguang Zhang <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Vinod Koul <[e-mail]>

Documentation/devicetree/bindings/dma/loongson,ls1b-apbdma.yaml

···
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/dma/loongson,ls1b-apbdma.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Loongson-1 APB DMA Controller
+
+maintainers:
+  - Keguang Zhang <[e-mail]>
+
+description:
+  Loongson-1 APB DMA controller provides 3 independent channels for
+  peripherals such as NAND, audio playback and capture.
+
+properties:
+  compatible:
+    oneOf:
+      - const: loongson,ls1b-apbdma
+      - items:
+          - enum:
+              - loongson,ls1a-apbdma
+              - loongson,ls1c-apbdma
+          - const: loongson,ls1b-apbdma
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    items:
+      - description: NAND interrupt
+      - description: Audio playback interrupt
+      - description: Audio capture interrupt
+
+  interrupt-names:
+    items:
+      - const: ch0
+      - const: ch1
+      - const: ch2
+
+  '#dma-cells':
+    const: 1
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - interrupt-names
+  - '#dma-cells'
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/irq.h>
+    dma-controller@1fd01160 {
+        compatible = "loongson,ls1b-apbdma";
+        reg = <0x1fd01160 0x4>;
+        interrupt-parent = <&intc0>;
+        interrupts = <13 IRQ_TYPE_EDGE_RISING>,
+                     <14 IRQ_TYPE_EDGE_RISING>,
+                     <15 IRQ_TYPE_EDGE_RISING>;
+        interrupt-names = "ch0", "ch1", "ch2";
+        #dma-cells = <1>;
+    };