[PATCH v3 1/2] dt-bindings: timer: Add Realtek SYSTIMER

Hao-Wen Ting
2025-11-17T07:34:28Z

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>
---
.../timer/realtek,rtd1625-systimer.yaml | 55 +++++++++++++++++++
1 file changed, 55 insertions(+)
create mode 100644 Documentation/devicetree/bindings/timer/realtek,rtd1625-systimer.yaml

diff --git a/Documentation/devicetree/bindings/timer/realtek,rtd1625-systimer.yaml b/Documentation/devicetree/bindings/timer/realtek,rtd1625-systimer.yaml
new file mode 100644
index 000000000000..b7702ba52437
--- /dev/null
+++ b/Documentation/devicetree/bindings/timer/realtek,rtd1625-systimer.yaml
@@ -0,0 +1,55 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/timer/realtek,rtd1625-systimer.yaml#
+$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.
+
+ The SYSTIMER hardware for both RTD1625 and RTD1635 SoCs has identical register
+ layout and IRQ configuration. The driver therefore matches both compatibles
+ without special handling.
+
+properties:
+ compatible:
+ items:
+ - enum:
+ - realtek,rtd1625-systimer
+ - realtek,rtd1635-systimer
+ - const: realtek,rtd1625-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,rtd1635-systimer",
+ "realtek,rtd1625-systimer";
+ reg = <0x89420 0x18>;
+ interrupts = <GIC_SPI 112 IRQ_TYPE_LEVEL_HIGH>;
+ };
--
2.34.1