dt-bindings: trigger-source: add generic PWM trigger source

Add a new binding for using a PWM signal as a trigger source.

The idea here is similar to e.g. "pwm-clock" to allow a trigger source
consumer to use a PWM provider as a trigger source.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: David Lechner <dlechner@baylibre.com>
Link: https://patch.msgid.link/20250207-dlech-mainline-spi-engine-offload-2-v8-3-e48a489be48c@baylibre.com
Signed-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/trigger-source/pwm-trigger.yaml

@@ -0,0 +1,37 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/trigger-source/pwm-trigger.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Generic trigger source using PWM
+
+description: Remaps a PWM channel as a trigger source.
+
+maintainers:
+  - David Lechner <dlechner@baylibre.com>
+
+properties:
+  compatible:
+    const: pwm-trigger
+
+  '#trigger-source-cells':
+    const: 0
+
+  pwms:
+    maxItems: 1
+
+required:
+  - compatible
+  - '#trigger-source-cells'
+  - pwms
+
+additionalProperties: false
+
+examples:
+  - |
+    trigger {
+        compatible = "pwm-trigger";
+        #trigger-source-cells = <0>;
+        pwms = <&pwm 0 1000000 0>;
+    };

MAINTAINERS

@@ -24056,6 +24056,11 @@ W:	https://github.com/srcres258/linux-doc
 T:	git git://github.com/srcres258/linux-doc.git doc-zh-tw
 F:	Documentation/translations/zh_TW/
 
+TRIGGER SOURCE - PWM
+M:	David Lechner <dlechner@baylibre.com>
+S:	Maintained
+F:	Documentation/devicetree/bindings/trigger-source/pwm-trigger.yaml
+
 TRUSTED SECURITY MODULE (TSM) ATTESTATION REPORTS
 M:	Dan Williams <dan.j.williams@intel.com>
 L:	linux-coco@lists.linux.dev