Re: [PATCH 2/3] dt-bindings: dma: loongson: Add Loongson-2K0300 DMA mux support

The DMA mux on Loongson-2K0300 is not a standalone hardware block. It is
implemented as part of the chip configuration registers CHIP_CTRL13/14/15,
which route peripheral DMA requests to the physical channels of the CMC
DMA controller.

Document this as a DMA router. The #dma-cells = <3> specifier contains
the peripheral request ID, the target CMC DMA channel, and channel
configuration flags forwarded to the parent DMA controller.

Signed-off-by: Binbin Zhou <zhoubinbin@loongson.cn>
---
 .../dma/loongson,ls2k0300-dmamux.yaml         | 49 +++++++++++++++++++
 MAINTAINERS                                   |  1 +
 2 files changed, 50 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/dma/loongson,ls2k0300-dmamux.yaml

diff --git a/Documentation/devicetree/bindings/dma/loongson,ls2k0300-dmamux.yaml b/Documentation/devicetree/bindings/dma/loongson,ls2k0300-dmamux.yaml
new file mode 100644
index 000000000000..12b8f8af51e9
--- /dev/null
+++ b/Documentation/devicetree/bindings/dma/loongson,ls2k0300-dmamux.yaml

@@ -0,0 +1,49 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/dma/loongson,ls2k0300-dmamux.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Loongson-2 APB DMA MUX (DMA request router)
+
+maintainers:
+  - Binbin Zhou <zhoubinbin@loongson.cn>
+
+allOf:
+  - $ref: /schemas/dma/dma-router.yaml#
+
+properties:
+  compatible:
+    const: loongson,ls2k0300-dmamux
+
+  reg:
+    maxItems: 1
+
+  '#dma-cells':
+    const: 3
+    description: |
+      Each cell represents the following:
+      1. The peripheral request id (see
+         include/dt-bindings/dma/loongson,ls2k-dmamux.h)
+      2. The physical CMC DMA channel (0-7) that is passed to the real
+         DMA controller

+      3. Bitfield representing DMA channel configuration that is passed
+         to the real DMA controller
+
+required:
+  - compatible
+  - reg
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/dma/loongson,ls2k-dmamux.h>
+    dma-router@16000134 {
+        compatible = "loongson,ls2k0300-dmamux";
+        reg = <0x16000134 0xc>;
+        #dma-cells = <3>;
+        dma-masters = <&dma>;
+        dma-requests = <22>;
+    };
+...

diff --git a/MAINTAINERS b/MAINTAINERS
index b021fb623446..dc976938c58c 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS

@@ -15344,6 +15344,7 @@ M:	Binbin Zhou <zhoubinbin@loongson.cn>
 L:	dmaengine@vger.kernel.org
 S:	Maintained
 F:	Documentation/devicetree/bindings/dma/loongson,ls2k0300-dma.yaml
+F:	Documentation/devicetree/bindings/dma/loongson,ls2k0300-dmamux.yaml
 F:	Documentation/devicetree/bindings/dma/loongson,ls2x-apbdma.yaml
 F:	drivers/dma/loongson/loongson2-apb-cmc-dma.c
 F:	drivers/dma/loongson/loongson2-apb-dma.c
--

2.52.0