The AST2600 I2C controller supports three transfer modes (byte, buffer,
DMA). Add "aspeed,transfer-mode" so DT can select the preferred transfer
method per controller instance. Also add the "aspeed,global-regs"
phandle to reference the AST2600 global registers syscon/regmap used by
the controller.

These properties apply only to the AST2600 binding and are not part of
the legacy binding, which uses a mixed controller/target register layout
and does not have the split register blocks or these new configuration
registers. Legacy DTs remain unchanged.

Signed-off-by: Ryan Chen <ryan_chen@aspeedtech.com>
---
Changes in v27:
- change aspeed,transfer-mode to aspeed,enable-dma.
---
 .../devicetree/bindings/i2c/aspeed,ast2600-i2c.yaml     | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/Documentation/devicetree/bindings/i2c/aspeed,ast2600-i2c.yaml b/Documentation/devicetree/bindings/i2c/aspeed,ast2600-i2c.yaml
index de2c359037da..38da6fc6424f 100644
--- a/Documentation/devicetree/bindings/i2c/aspeed,ast2600-i2c.yaml
+++ b/Documentation/devicetree/bindings/i2c/aspeed,ast2600-i2c.yaml
@@ -37,6 +37,21 @@ properties:
   resets:
     maxItems: 1
 
+  aspeed,enable-dma:
+    type: boolean
+    description: |
+      I2C bus enable dma mode transfer.
+
+      ASPEED ast2600 platform equipped with 16 I2C controllers that share a
+      single DMA engine. DTS files can specify the data transfer mode to/from
+      the device, either DMA or programmed I/O.
+
+  aspeed,global-regs:
+    $ref: /schemas/types.yaml#/definitions/phandle
+    description:
+      Phandle reference to the i2c global syscon node, containing the
+      SoC-common i2c register set.
+
 required:
   - reg
   - compatible
@@ -59,4 +74,6 @@ examples:
         resets = <&syscon ASPEED_RESET_I2C>;
         clock-frequency = <100000>;
         interrupts = <GIC_SPI 110 IRQ_TYPE_LEVEL_HIGH>;
+        aspeed,global-regs = <&i2c_global>;
+        aspeed,transfer-mode = "buffer";
     };

-- 
2.34.1

On Tue, 24 Mar 2026 11:06:27 +0800, Ryan Chen wrote:
> The AST2600 I2C controller supports three transfer modes (byte, buffer,
> DMA). Add "aspeed,transfer-mode" so DT can select the preferred transfer
> method per controller instance. Also add the "aspeed,global-regs"
> phandle to reference the AST2600 global registers syscon/regmap used by
> the controller.
> 
> These properties apply only to the AST2600 binding and are not part of
> the legacy binding, which uses a mixed controller/target register layout
> and does not have the split register blocks or these new configuration
> registers. Legacy DTs remain unchanged.
> 
> Signed-off-by: Ryan Chen <ryan_chen@aspeedtech.com>
> ---
> Changes in v27:
> - change aspeed,transfer-mode to aspeed,enable-dma.
> ---
>  .../devicetree/bindings/i2c/aspeed,ast2600-i2c.yaml     | 17 +++++++++++++++++
>  1 file changed, 17 insertions(+)
> 

My bot found errors running 'make dt_binding_check' on your patch:

yamllint warnings/errors:

dtschema/dtc warnings/errors:
/builds/robherring/dt-review-ci/linux/Documentation/devicetree/bindings/i2c/aspeed,ast2600-i2c.example.dtb: i2c@80 (aspeed,ast2600-i2c-bus): Unevaluated properties are not allowed ('aspeed,transfer-mode' was unexpected)
	from schema $id: http://devicetree.org/schemas/i2c/aspeed,ast2600-i2c.yaml

doc reference errors (make refcheckdocs):

See https://patchwork.kernel.org/project/devicetree/patch/20260324-upstream_i2c-v27-2-f19b511c8c28@aspeedtech.com

The base for the series is generally the latest rc1. A different dependency
should be noted in *this* patch.

If you already ran 'make dt_binding_check' and didn't see the above
error(s), then make sure 'yamllint' is installed and dt-schema is up to
date:

pip3 install dtschema --upgrade

Please check and re-submit after running the above command yourself. Note
that DT_SCHEMA_FILES can be set to your schema file to speed up checking
your schema. However, it must be unset to test all examples with your schema.

Hi Ryan,

> The AST2600 I2C controller supports three transfer modes (byte, buffer,
> DMA). Add "aspeed,transfer-mode" so DT can select the preferred transfer
> method per controller instance.

This patch does not add an aspeed,transfer-mode property.

> Also add the "aspeed,global-regs"
> phandle to reference the AST2600 global registers syscon/regmap used by
> the controller.
> 
> These properties apply only to the AST2600 binding and are not part of
> the legacy binding, which uses a mixed controller/target register layout
> and does not have the split register blocks or these new configuration
> registers. Legacy DTs remain unchanged.
> 
> Signed-off-by: Ryan Chen <ryan_chen@aspeedtech.com>
> ---
> Changes in v27:
> - change aspeed,transfer-mode to aspeed,enable-dma.

What about all the previous changes?

> ---
>  .../devicetree/bindings/i2c/aspeed,ast2600-i2c.yaml     | 17 +++++++++++++++++
>  1 file changed, 17 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/i2c/aspeed,ast2600-i2c.yaml b/Documentation/devicetree/bindings/i2c/aspeed,ast2600-i2c.yaml
> index de2c359037da..38da6fc6424f 100644
> --- a/Documentation/devicetree/bindings/i2c/aspeed,ast2600-i2c.yaml
> +++ b/Documentation/devicetree/bindings/i2c/aspeed,ast2600-i2c.yaml
> @@ -37,6 +37,21 @@ properties:
>    resets:
>      maxItems: 1
>  
> +  aspeed,enable-dma:
> +    type: boolean
> +    description: |
> +      I2C bus enable dma mode transfer.
> +
> +      ASPEED ast2600 platform equipped with 16 I2C controllers that share a
> +      single DMA engine. DTS files can specify the data transfer mode to/from
> +      the device, either DMA or programmed I/O.

As we had discussed: this does not define the transfer mode, only
whether DMA is available to the peripheral.

Why mention the 16 i2c controllers here?

Please keep this description simple and relevant to the specific purpose
of the property.

> +
> +  aspeed,global-regs:
> +    $ref: /schemas/types.yaml#/definitions/phandle
> +    description:
> +      Phandle reference to the i2c global syscon node, containing the
> +      SoC-common i2c register set.
> +
>  required:
>    - reg
>    - compatible
> @@ -59,4 +74,6 @@ examples:
>          resets = <&syscon ASPEED_RESET_I2C>;
>          clock-frequency = <100000>;
>          interrupts = <GIC_SPI 110 IRQ_TYPE_LEVEL_HIGH>;
> +        aspeed,global-regs = <&i2c_global>;
> +        aspeed,transfer-mode = "buffer";

This example does not match the binding.

Cheers,


Jeremy