dt-bindings: rtc: Convert snps,dw-apb-timer to DT schema

Modern device tree bindings are supposed to be created as YAML-files
in accordance with DT schema. This commit replaces Synopsys DW Timer
legacy bare text binding with YAML file. As before the binding file
states that the corresponding dts node is supposed to be compatible
with generic DW APB Timer indicated by the "snps,dw-apb-timer"
compatible string and to provide a mandatory registers memory range,
one timer interrupt, either reference clock source or a fixed clock
rate value. It may also have an optional APB bus reference clock
phandle specified.

Signed-off-by: Serge Semin <[email protected]>
Reviewed-by: Rob Herring <[email protected]>
Cc: Alexey Malahov <[email protected]>
Cc: Thomas Bogendoerfer <[email protected]>
Cc: Paul Burton <[email protected]>
Cc: Ralf Baechle <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Daniel Lezcano <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: [email protected]
Signed-off-by: Daniel Lezcano <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

Author: fancer

Documentation/devicetree/bindings/rtc/dw-apb.txt

@@ -0,0 +1,88 @@
+# SPDX-License-Identifier: GPL-2.0-only
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/rtc/snps,dw-apb-timer.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Synopsys DesignWare APB Timer
+
+maintainers:
+  - Daniel Lezcano <[email protected]>
+
+properties:
+  compatible:
+    oneOf:
+      - const: snps,dw-apb-timer
+      - enum:
+          - snps,dw-apb-timer-sp
+          - snps,dw-apb-timer-osc
+        deprecated: true
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  clocks:
+    minItems: 1
+    items:
+       - description: Timer ticks reference clock source
+       - description: APB interface clock source
+
+  clock-names:
+    minItems: 1
+    items:
+      - const: timer
+      - const: pclk
+
+  clock-frequency: true
+
+  clock-freq:
+    $ref: "/schemas/types.yaml#/definitions/uint32"
+    description: |
+      Has the same meaning as the 'clock-frequency' property - timer clock
+      frequency in HZ, but is defined only for the backwards compatibility
+      with the picoxcell platform.
+
+unevaluatedProperties: false
+
+required:
+  - compatible
+  - reg
+  - interrupts
+
+oneOf:
+  - required:
+      - clocks
+      - clock-names
+  - required:
+      - clock-frequency
+  - required:
+      - clock-freq
+
+examples:
+  - |
+    timer@ffe00000 {
+      compatible = "snps,dw-apb-timer";
+      interrupts = <0 170 4>;
+      reg = <0xffe00000 0x1000>;
+      clocks = <&timer_clk>, <&timer_pclk>;
+      clock-names = "timer", "pclk";
+    };
+  - |
+    timer@ffe00000 {
+      compatible = "snps,dw-apb-timer";
+      interrupts = <0 170 4>;
+      reg = <0xffe00000 0x1000>;
+      clocks = <&timer_clk>;
+      clock-names = "timer";
+    };
+  - |
+    timer@ffe00000 {
+      compatible = "snps,dw-apb-timer";
+      interrupts = <0 170 4>;
+      reg = <0xffe00000 0x1000>;
+      clock-frequency = <25000000>;
+    };
+...