dt-bindings: clock: convert rockchip,rk3308-cru.txt to YAML

Convert rockchip,rk3308-cru.txt to YAML.

Changes against original bindings:
 - Add clocks and clock-names because the device has to have
   at least one input clock.

Signed-off-by: Johan Jonker <jbx6244@gmail.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20220329184339.1134-1-jbx6244@gmail.com
Signed-off-by: Heiko Stuebner <heiko@sntech.de>

Author: Johan Jonker

Documentation/devicetree/bindings/clock/rockchip,rk3308-cru.txt

@@ -0,0 +1,76 @@
+# SPDX-License-Identifier: GPL-2.0
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/clock/rockchip,rk3308-cru.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Rockchip RK3308 Clock and Reset Unit (CRU)
+
+maintainers:
+  - Elaine Zhang <zhangqing@rock-chips.com>
+  - Heiko Stuebner <heiko@sntech.de>
+
+description: |
+  The RK3308 clock controller generates and supplies clocks to various
+  controllers within the SoC and also implements a reset controller for SoC
+  peripherals.
+  Each clock is assigned an identifier and client nodes can use this identifier
+  to specify the clock which they consume. All available clocks are defined as
+  preprocessor macros in the dt-bindings/clock/rk3308-cru.h headers and can be
+  used in device tree sources. Similar macros exist for the reset sources in
+  these files.
+  There are several clocks that are generated outside the SoC. It is expected
+  that they are defined using standard clock bindings with following
+  clock-output-names:
+    - "xin24m"                               - crystal input      - required
+    - "xin32k"                               - rtc clock          - optional
+    - "mclk_i2s0_8ch_in", "mclk_i2s1_8ch_in",
+      "mclk_i2s2_8ch_in", "mclk_i2s3_8ch_in",
+      "mclk_i2s0_2ch_in", "mclk_i2s1_2ch_in" - external I2S or
+                                               SPDIF clock        - optional
+    - "mac_clkin"                            - external MAC clock - optional
+
+properties:
+  compatible:
+    enum:
+      - rockchip,rk3308-cru
+
+  reg:
+    maxItems: 1
+
+  "#clock-cells":
+    const: 1
+
+  "#reset-cells":
+    const: 1
+
+  clocks:
+    maxItems: 1
+
+  clock-names:
+    const: xin24m
+
+  rockchip,grf:
+    $ref: /schemas/types.yaml#/definitions/phandle
+    description:
+      Phandle to the syscon managing the "general register files" (GRF),
+      if missing pll rates are not changeable, due to the missing pll
+      lock status.
+
+required:
+  - compatible
+  - reg
+  - "#clock-cells"
+  - "#reset-cells"
+
+additionalProperties: false
+
+examples:
+  - |
+    cru: clock-controller@ff500000 {
+      compatible = "rockchip,rk3308-cru";
+      reg = <0xff500000 0x1000>;
+      rockchip,grf = <&grf>;
+      #clock-cells = <1>;
+      #reset-cells = <1>;
+    };