Re: [PATCH v3 2/2] dt-bindings: dma: hisi: Add bindings for Hisi Ascend sdma

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在 2023/8/24 15:15, Krzysztof Kozlowski 写道:
On 24/08/2023 06:00, Guo Mengqi wrote:
Add device-tree binding documentation for the Hisi Ascend sdma

Signed-off-by: Guo Mengqi <guomengqi3@xxxxxxxxxx>
  .../bindings/dma/hisi,ascend-sdma.yaml        | 75 +++++++++++++++++++
  1 file changed, 75 insertions(+)
  create mode 100644 Documentation/devicetree/bindings/dma/hisi,ascend-sdma.yaml
Filename matching compatible, so hisilicon,ascend-sdma.yaml. hisi, is a
deprecated prefix, so don't use it.
OK, will change it in next patch.

diff --git a/Documentation/devicetree/bindings/dma/hisi,ascend-sdma.yaml b/Documentation/devicetree/bindings/dma/hisi,ascend-sdma.yaml
new file mode 100644
index 000000000000..87b6132c1b4b
--- /dev/null
+++ b/Documentation/devicetree/bindings/dma/hisi,ascend-sdma.yaml
@@ -0,0 +1,75 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+title: HISI Ascend System DMA (SDMA) controller
What is HISI? HiSilicon?
Yes, It is short for HiSilicon.
+description: |
+  The Ascend SDMA controller is used for transferring data
+  in system memory. It utilizes IOMMU SVA feature and accepts
+  virtual address from user process.
+  - Guo Mengqi <guomengqi3@xxxxxxxxxx>
+  - $ref: dma-controller.yaml#
+  compatible:
+    enum:
+      - hisilicon,ascend310-sdma
+      - hisilicon,ascend910-sdma
+  reg:
+    maxItems: 1
+  '#dma-cells':
+    const: 1
+    description:
+      Clients specify a single cell with channel number.
+  hisilicon,ascend-sdma-channel-map:
+    description: |
+      bitmap, each bit stands for a channel that is allowed to
+      use by this system. Maximum 64 bits.
+    $ref: /schemas/types.yaml#/definitions/uint64
Why some channels would not be allowed to be used on some board with
ascend310? Who decides on this?
This is because the SoC runs more than one operating system. So from the perspective of any user OS, dma hardware is a shared resource.
+  iommus:
+    maxItems: 1
+  pasid-num-bits:
+    description: |
+      sdma utilizes iommu sva feature to transfer user space data.
+      It acts as a basic dma controller if not bound to user space.
+    const: 0x10

Best regards,


Best regards,

Guo Mengqi

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