dt-bindings: timer: convert bcm2835-system-timer bindings to YAML

Convert the DT binding document for bcm2835-system-timer from .txt
to YAML.

Signed-off-by: Stefan Wahren <[e-mail]>
Reviewed-by: Conor Dooley <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Florian Fainelli <[e-mail]>

Documentation/devicetree/bindings/timer/brcm,bcm2835-system-timer.txt

···
-BCM2835 System Timer
-
-The System Timer peripheral provides four 32-bit timer channels and a
-single 64-bit free running counter. Each channel has an output compare
-register, which is compared against the 32 least significant bits of the
-free running counter values, and generates an interrupt.
-
-Required properties:
-
-- compatible : should be "brcm,bcm2835-system-timer"
-- reg : Specifies base physical address and size of the registers.
-- interrupts : A list of 4 interrupt sinks; one per timer channel.
-- clock-frequency : The frequency of the clock that drives the counter, in Hz.
-
-Example:
-
-timer {
-	compatible = "brcm,bcm2835-system-timer";
-	reg = <0x7e003000 0x1000>;
-	interrupts = <1 0>, <1 1>, <1 2>, <1 3>;
-	clock-frequency = <1000000>;
-};

Documentation/devicetree/bindings/timer/brcm,bcm2835-system-timer.yaml

···
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/timer/brcm,bcm2835-system-timer.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: BCM2835 System Timer
+
+maintainers:
+  - Stefan Wahren <[e-mail]>
+  - Raspberry Pi Kernel Maintenance <[e-mail]>
+
+description:
+  The System Timer peripheral provides four 32-bit timer channels and a
+  single 64-bit free running counter. Each channel has an output compare
+  register, which is compared against the 32 least significant bits of the
+  free running counter values, and generates an interrupt.
+
+properties:
+  compatible:
+    const: brcm,bcm2835-system-timer
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    items:
+      - description: System Timer Compare 0 match (used by VideoCore GPU)
+      - description: System Timer Compare 1 match (usable for ARM core)
+      - description: System Timer Compare 2 match (used by VideoCore GPU)
+      - description: System Timer Compare 3 match (usable for ARM core)
+
+  clock-frequency: true
+
+required:
+  - compatible
+  - reg
+  - interrupts
+
+additionalProperties: false
+
+examples:
+  - |
+    timer@7e003000 {
+      compatible = "brcm,bcm2835-system-timer";
+      reg = <0x7e003000 0x1000>;
+      interrupts = <1 0>, <1 1>, <1 2>, <1 3>;
+      clock-frequency = <1000000>;
+    };
+...