Add device tree binding documentation for the Realtek SYSTIMER, a 64-bit
timer that can be used as a tick broadcast timer on multi-core Realtek
SoCs.

The SYSTIMER remains active during deep CPU idle states where local
timers are powered off, allowing all CPUs to enter power-cut idle states
simultaneously for improved power efficiency. The timer operates at a
fixed 1MHz frequency and supports oneshot mode for tick broadcast
functionality.

Signed-off-by: Hao-Wen Ting <haowen.ting@realtek.com>
---
 .../bindings/timer/realtek,systimer.yaml      | 48 +++++++++++++++++++
 1 file changed, 48 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/timer/realtek,systimer.yaml

diff --git a/Documentation/devicetree/bindings/timer/realtek,systimer.yaml b/Documentation/devicetree/bindings/timer/realtek,systimer.yaml
new file mode 100644
index 000000000000..8e68158c68f8
--- /dev/null
+++ b/Documentation/devicetree/bindings/timer/realtek,systimer.yaml
@@ -0,0 +1,48 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/timer/realtek,systimer.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Realtek System Timer
+
+maintainers:
+  - Hao-Wen Ting <haowen.ting@realtek.com>
+
+description: |
+  The Realtek SYSTIMER (System Timer) is a 64-bit timer that can be used as
+  a tick broadcast timer on multi-core Realtek SoCs. It remains active during
+  deep CPU idle states where local timers are powered off, allowing all CPUs
+  to enter power-cut idle states simultaneously for better power efficiency.
+
+  The timer operates at a fixed 1MHz frequency and supports oneshot mode
+  for tick broadcast functionality.
+
+properties:
+  compatible:
+    enum:
+      - realtek,rtd1625-systimer
+      - realtek,rtd1635-systimer
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+  - interrupts
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/arm-gic.h>
+
+    timer@89420 {
+        compatible = "realtek,rtd1625-systimer";
+        reg = <0x89420 0x18>;
+        interrupts = <GIC_SPI 112 IRQ_TYPE_LEVEL_HIGH>;
+    };
-- 
2.34.1

On 14/11/2025 10:04, Hao-Wen Ting wrote:
> Add device tree binding documentation for the Realtek SYSTIMER, a 64-bit
> timer that can be used as a tick broadcast timer on multi-core Realtek
> SoCs.
> 
> The SYSTIMER remains active during deep CPU idle states where local
> timers are powered off, allowing all CPUs to enter power-cut idle states
> simultaneously for improved power efficiency. The timer operates at a
> fixed 1MHz frequency and supports oneshot mode for tick broadcast
> functionality.
> 
> Signed-off-by: Hao-Wen Ting <haowen.ting@realtek.com>
> ---
>  .../bindings/timer/realtek,systimer.yaml      | 48 +++++++++++++++++++
>  1 file changed, 48 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/timer/realtek,systimer.yaml
> 
> diff --git a/Documentation/devicetree/bindings/timer/realtek,systimer.yaml b/Documentation/devicetree/bindings/timer/realtek,systimer.yaml
> new file mode 100644
> index 000000000000..8e68158c68f8
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/timer/realtek,systimer.yaml

Filename matching compatible, see writing bindings doc. I already asked
to read that doc.

A nit, subject: drop second/last, redundant "binding". The "dt-bindings"
prefix is already stating that these are bindings.
See also:
https://elixir.bootlin.com/linux/v6.17-rc3/source/Documentation/devicetree/bindings/submitting-patches.rst#L18


> @@ -0,0 +1,48 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/timer/realtek,systimer.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Realtek System Timer
> +
> +maintainers:
> +  - Hao-Wen Ting <haowen.ting@realtek.com>
> +
> +description: |
> +  The Realtek SYSTIMER (System Timer) is a 64-bit timer that can be used as
> +  a tick broadcast timer on multi-core Realtek SoCs. It remains active during
> +  deep CPU idle states where local timers are powered off, allowing all CPUs
> +  to enter power-cut idle states simultaneously for better power efficiency.
> +
> +  The timer operates at a fixed 1MHz frequency and supports oneshot mode
> +  for tick broadcast functionality.
> +
> +properties:
> +  compatible:
> +    enum:
> +      - realtek,rtd1625-systimer
> +      - realtek,rtd1635-systimer

You don't use this compatible which raises questions, maybe you wanted
to express compatibility.


Best regards,
Krzysztof