dt-bindings: dmaengine: Document qcom,gpi dma binding

Add devicetree binding documentation for GPI DMA controller
implemented on Qualcomm SoCs
Reviewed-by: NRob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20201109085450.24843-2-vkoul@kernel.orgSigned-off-by: NVinod Koul <vkoul@kernel.org>

Documentation/devicetree/bindings/dma/qcom,gpi.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/dma/qcom,gpi.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Qualcomm Technologies Inc GPI DMA controller
+
+maintainers:
+  - Vinod Koul <vkoul@kernel.org>
+
+description: |
+  QCOM GPI DMA controller provides DMA capabilities for
+  peripheral buses such as I2C, UART, and SPI.
+
+allOf:
+  - $ref: "dma-controller.yaml#"
+
+properties:
+  compatible:
+    enum:
+      - qcom,sdm845-gpi-dma
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    description:
+      Interrupt lines for each GPI instance
+    maxItems: 13
+
+  "#dma-cells":
+    const: 3
+    description: >
+      DMA clients must use the format described in dma.txt, giving a phandle
+      to the DMA controller plus the following 3 integer cells:
+      - channel: if set to 0xffffffff, any available channel will be allocated
+        for the client. Otherwise, the exact channel specified will be used.
+      - seid: serial id of the client as defined in the SoC documentation.
+      - client: type of the client as defined in dt-bindings/dma/qcom-gpi.h
+
+  iommus:
+    maxItems: 1
+
+  dma-channels:
+    maximum: 31
+
+  dma-channel-mask:
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - "#dma-cells"
+  - iommus
+  - dma-channels
+  - dma-channel-mask
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/arm-gic.h>
+    #include <dt-bindings/dma/qcom-gpi.h>
+    gpi_dma0: dma-controller@800000 {
+        compatible = "qcom,gpi-dma";
+        #dma-cells = <3>;
+        reg = <0x00800000 0x60000>;
+        iommus = <&apps_smmu 0x0016 0x0>;
+        dma-channels = <13>;
+        dma-channel-mask = <0xfa>;
+        interrupts = <GIC_SPI 244 IRQ_TYPE_LEVEL_HIGH>,
+                     <GIC_SPI 245 IRQ_TYPE_LEVEL_HIGH>,
+                     <GIC_SPI 246 IRQ_TYPE_LEVEL_HIGH>,
+                     <GIC_SPI 247 IRQ_TYPE_LEVEL_HIGH>,
+                     <GIC_SPI 248 IRQ_TYPE_LEVEL_HIGH>,
+                     <GIC_SPI 249 IRQ_TYPE_LEVEL_HIGH>,
+                     <GIC_SPI 250 IRQ_TYPE_LEVEL_HIGH>,
+                     <GIC_SPI 251 IRQ_TYPE_LEVEL_HIGH>,
+                     <GIC_SPI 252 IRQ_TYPE_LEVEL_HIGH>,
+                     <GIC_SPI 253 IRQ_TYPE_LEVEL_HIGH>,
+                     <GIC_SPI 254 IRQ_TYPE_LEVEL_HIGH>,
+                     <GIC_SPI 255 IRQ_TYPE_LEVEL_HIGH>,
+                     <GIC_SPI 256 IRQ_TYPE_LEVEL_HIGH>;
+    };
+
+...

include/dt-bindings/dma/qcom-gpi.h

+/* SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause */
+/* Copyright (c) 2020, Linaro Ltd.  */
+
+#ifndef __DT_BINDINGS_DMA_QCOM_GPI_H__
+#define __DT_BINDINGS_DMA_QCOM_GPI_H__
+
+#define QCOM_GPI_SPI		1
+#define QCOM_GPI_UART		2
+#define QCOM_GPI_I2C		3
+
+#endif /* __DT_BINDINGS_DMA_QCOM_GPI_H__ */