The AST2600 I2C controller is a new hardware design compared to the
I2C controllers in previous ASPEED SoCs (e.g., AST2400, AST2500).

It introduces new features such as:
 - A redesigned register layout
 - Separation between controller and target mode registers
 - Transfer mode selection (byte, buffer, DMA)
 - Support for a shared global register block for configuration

Due to these fundamental differences, maintaining a separate
devicetree binding file for AST2600 helps to clearly distinguish
the hardware capabilities and configuration options from the older
controllers.

Signed-off-by: Ryan Chen <ryan_chen@aspeedtech.com>
---
 .../devicetree/bindings/i2c/aspeed,i2c.yaml   |  3 +-
 .../devicetree/bindings/i2c/ast2600-i2c.yaml  | 67 +++++++++++++++++++
 2 files changed, 68 insertions(+), 2 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/i2c/ast2600-i2c.yaml

diff --git a/Documentation/devicetree/bindings/i2c/aspeed,i2c.yaml b/Documentation/devicetree/bindings/i2c/aspeed,i2c.yaml
index 5b9bd2feda3b..d4e4f412feba 100644
--- a/Documentation/devicetree/bindings/i2c/aspeed,i2c.yaml
+++ b/Documentation/devicetree/bindings/i2c/aspeed,i2c.yaml
@@ -4,7 +4,7 @@
 $id: http://devicetree.org/schemas/i2c/aspeed,i2c.yaml#
 $schema: http://devicetree.org/meta-schemas/core.yaml#
 
-title: ASPEED I2C on the AST24XX, AST25XX, and AST26XX SoCs
+title: ASPEED I2C on the AST24XX, AST25XX SoCs
 
 maintainers:
   - Rayn Chen <rayn_chen@aspeedtech.com>
@@ -17,7 +17,6 @@ properties:
     enum:
       - aspeed,ast2400-i2c-bus
       - aspeed,ast2500-i2c-bus
-      - aspeed,ast2600-i2c-bus
 
   reg:
     minItems: 1
diff --git a/Documentation/devicetree/bindings/i2c/ast2600-i2c.yaml b/Documentation/devicetree/bindings/i2c/ast2600-i2c.yaml
new file mode 100644
index 000000000000..2dcddb0ecc2e
--- /dev/null
+++ b/Documentation/devicetree/bindings/i2c/ast2600-i2c.yaml
@@ -0,0 +1,67 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/i2c/aspeed,i2c.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: ASPEED I2C on the AST26XX SoCs
+
+maintainers:
+  - Ryan Chen <ryan_chen@aspeedtech.com>
+
+allOf:
+  - $ref: /schemas/i2c/i2c-controller.yaml#
+
+properties:
+  compatible:
+    enum:
+      - aspeed,ast2600-i2c-bus
+
+  reg:
+    minItems: 1
+    maxItems: 2
+    items:
+      - description: address offset and range of bus
+      - description: address offset and range of bus buffer
+
+  interrupts:
+    maxItems: 1
+
+  clocks:
+    maxItems: 1
+    description:
+      root clock of bus, should reference the APB
+      clock in the second cell
+
+  resets:
+    maxItems: 1
+
+  bus-frequency:
+    minimum: 500
+    maximum: 4000000
+    default: 100000
+    description: frequency of the bus clock in Hz defaults to 100 kHz when not
+      specified
+
+required:
+  - reg
+  - compatible
+  - clocks
+  - resets
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/clock/aspeed-clock.h>
+    i2c@40 {
+      #address-cells = <1>;
+      #size-cells = <0>;
+      compatible = "aspeed,ast2600-i2c-bus";
+      reg = <0x40 0x40>;
+      clocks = <&syscon ASPEED_CLK_APB>;
+      resets = <&syscon ASPEED_RESET_I2C>;
+      bus-frequency = <100000>;
+      interrupts = <0>;
+      interrupt-parent = <&i2c_ic>;
+    };
-- 
2.34.1

On Mon, 20 Oct 2025 09:31:57 +0800, Ryan Chen wrote:
> The AST2600 I2C controller is a new hardware design compared to the
> I2C controllers in previous ASPEED SoCs (e.g., AST2400, AST2500).
> 
> It introduces new features such as:
>  - A redesigned register layout
>  - Separation between controller and target mode registers
>  - Transfer mode selection (byte, buffer, DMA)
>  - Support for a shared global register block for configuration
> 
> Due to these fundamental differences, maintaining a separate
> devicetree binding file for AST2600 helps to clearly distinguish
> the hardware capabilities and configuration options from the older
> controllers.
> 
> Signed-off-by: Ryan Chen <ryan_chen@aspeedtech.com>
> ---
>  .../devicetree/bindings/i2c/aspeed,i2c.yaml   |  3 +-
>  .../devicetree/bindings/i2c/ast2600-i2c.yaml  | 67 +++++++++++++++++++
>  2 files changed, 68 insertions(+), 2 deletions(-)
>  create mode 100644 Documentation/devicetree/bindings/i2c/ast2600-i2c.yaml
> 

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/ast2600-i2c.yaml: warning: ignoring duplicate '$id' value 'http://devicetree.org/schemas/i2c/aspeed,i2c.yaml#'
/builds/robherring/dt-review-ci/linux/Documentation/devicetree/bindings/i2c/ast2600-i2c.yaml: properties:reg: {'minItems': 1, 'maxItems': 2, 'items': [{'description': 'address offset and range of bus'}, {'description': 'address offset and range of bus buffer'}]} should not be valid under {'required': ['maxItems']}
	hint: "maxItems" is not needed with an "items" list
	from schema $id: http://devicetree.org/meta-schemas/items.yaml#
/builds/robherring/dt-review-ci/linux/Documentation/devicetree/bindings/i2c/ast2600-i2c.yaml: $id: Cannot determine base path from $id, relative path/filename doesn't match actual path or filename
 	 $id: http://devicetree.org/schemas/i2c/aspeed,i2c.yaml
 	file: /builds/robherring/dt-review-ci/linux/Documentation/devicetree/bindings/i2c/ast2600-i2c.yaml
Documentation/devicetree/bindings/i2c/ast2600-i2c.example.dtb: /example-0/i2c@40: failed to match any schema with compatible: ['aspeed,ast2600-i2c-bus']

doc reference errors (make refcheckdocs):

See https://patchwork.ozlabs.org/project/devicetree-bindings/patch/20251020013200.1858325-2-ryan_chen@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.