[PATCH v33 1/5] dt-bindings: i2c: Split AST2600 binding into a new YAML

The AST2600 I2C controller introduces a completely new register layout
with separate controller and target register blocks, unlike the mixed
register layout used by AST2400/AST2500.

Move AST2600 I2C binding from aspeed,i2c.yaml to a dedicated
aspeed,ast2600-i2c.yaml schema.

Besides the split, this also adjusts for AST2600-specific requirements.
- describe two reg regions (controller register block + buffer block);
  the second region is optional (minItems: 1) so existing AST2600 DTs
  that only declare the controller register block continue to validate
- use clock-frequency for bus speed description
- interrupts are required on AST2600
- use correct DTS coding style in example

No compatible strings are changed.

Acked-by: Conor Dooley <[email protected]>
Reviewed-by: Rob Herring (Arm) <[email protected]>
Signed-off-by: Ryan Chen <[email protected]>
---
Changes in v31:
- Commit message body: clarify that the second reg region is optional
  (minItems: 1) rather than required, matching the schema and the v30
  backward-compatibility fix (Sashiko AI review).

Changes in v30:
- Add minItems: 1 to reg so existing AST2600 DTs with a single reg
  region continue to validate (Sashiko AI review)
- Retain bus-frequency as a deprecated property to avoid breaking
  existing AST2600 DTs under unevaluatedProperties: false
  (Sashiko AI review)
Changes in v26:
- commit message: include details of changes from original binding
- fix example property ordering to follow DTS coding style
- use consistent "AST2600" naming
---
 .../bindings/i2c/aspeed,ast2600-i2c.yaml           | 73 ++++++++++++++++++++++
 .../devicetree/bindings/i2c/aspeed,i2c.yaml        |  3 +-
 MAINTAINERS                                        |  1 +
 3 files changed, 75 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/i2c/aspeed,ast2600-i2c.yaml b/Documentation/devicetree/bindings/i2c/aspeed,ast2600-i2c.yaml
new file mode 100644
index 000000000000..abc614315dff
--- /dev/null
+++ b/Documentation/devicetree/bindings/i2c/aspeed,ast2600-i2c.yaml
@@ -0,0 +1,73 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/i2c/aspeed,ast2600-i2c.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: ASPEED I2C on the AST2600 SoCs
+
+maintainers:
+  - Ryan Chen <[email protected]>
+
+allOf:
+  - $ref: /schemas/i2c/i2c-controller.yaml#
+
+properties:
+  compatible:
+    enum:
+      - aspeed,ast2600-i2c-bus
+
+  reg:
+    minItems: 1
+    items:
+      - description: controller registers
+      - description: controller buffer space
+
+  interrupts:
+    maxItems: 1
+
+  clocks:
+    maxItems: 1
+
+  clock-frequency:
+    description: Desired operating frequency of the I2C bus in Hz.
+    minimum: 500
+    maximum: 4000000
+    default: 100000
+
+  bus-frequency:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    deprecated: true
+    description:
+      Legacy name for clock-frequency. Existing AST2600 device trees
+      used this before the binding was split out. New device trees
+      should use the standard clock-frequency property instead.
+    minimum: 500
+    maximum: 4000000
+
+  resets:
+    maxItems: 1
+
+required:
+  - reg
+  - compatible
+  - clocks
+  - resets
+  - interrupts
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/clock/aspeed-clock.h>
+    #include <dt-bindings/interrupt-controller/arm-gic.h>
+    i2c@80 {
+        compatible = "aspeed,ast2600-i2c-bus";
+        reg = <0x80 0x80>, <0xc00 0x20>;
+        #address-cells = <1>;
+        #size-cells = <0>;
+        clocks = <&syscon ASPEED_CLK_APB>;
+        resets = <&syscon ASPEED_RESET_I2C>;
+        clock-frequency = <100000>;
+        interrupts = <GIC_SPI 110 IRQ_TYPE_LEVEL_HIGH>;
+    };
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 <[email protected]>
@@ -17,7 +17,6 @@ properties:
     enum:
       - aspeed,ast2400-i2c-bus
       - aspeed,ast2500-i2c-bus
-      - aspeed,ast2600-i2c-bus
 
   reg:
     minItems: 1
diff --git a/MAINTAINERS b/MAINTAINERS
index 882214b0e7db..f9c929e86e64 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -2596,6 +2596,7 @@ R:	Joel Stanley <[email protected]>
 L:	[email protected]
 L:	[email protected] (moderated for non-subscribers)
 S:	Maintained
+F:	Documentation/devicetree/bindings/i2c/aspeed,ast2600-i2c.yaml
 F:	Documentation/devicetree/bindings/i2c/aspeed,i2c.yaml
 F:	Documentation/devicetree/bindings/interrupt-controller/aspeed,ast2400-i2c-ic.yaml
 F:	drivers/i2c/busses/i2c-aspeed.c

-- 
2.34.1