dt-bindings: i2c: spacemit: add support for K1 SoC

The I2C of K1 supports fast-speed-mode and high-speed-mode,
and supports FIFO transmission.

Signed-off-by: Troy Mitchell <[e-mail]>
Reviewed-by: Conor Dooley <[e-mail]>
Signed-off-by: Andi Shyti <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

Documentation/devicetree/bindings/i2c/spacemit,k1-i2c.yaml

···
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/i2c/spacemit,k1-i2c.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: I2C controller embedded in SpacemiT's K1 SoC
+
+maintainers:
+  - Troy Mitchell <[e-mail]>
+
+properties:
+  compatible:
+    const: spacemit,k1-i2c
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  clocks:
+    items:
+      - description: I2C Functional Clock
+      - description: APB Bus Clock
+
+  clock-names:
+    items:
+      - const: func
+      - const: bus
+
+  clock-frequency:
+    description: |
+      K1 support three different modes which running different frequencies
+      standard speed mode: up to 100000 (100Hz)
+      fast speed mode    : up to 400000 (400Hz)
+      high speed mode    : up to 3300000 (3.3Mhz)
+    default: 400000
+    maximum: 3300000
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - clocks
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    i2c@d4010800 {
+        compatible = "spacemit,k1-i2c";
+        reg = <0xd4010800 0x38>;
+        interrupt-parent = <&plic>;
+        interrupts = <36>;
+        clocks =<&ccu 32>, <&ccu 84>;
+        clock-names = "func", "bus";
+        clock-frequency = <100000>;
+    };
+
+...