[PATCH 1/3] dt-bindings: counter: add gpio-quadrature-encoder binding

[Wadim Mueller <wafgo01@gmail.com>]

Add devicetree binding documentation for the GPIO-based quadrature
encoder counter driver. The driver reads A/B quadrature signals and
an optional index pulse via edge-triggered GPIO interrupts, supporting
X1, X2, X4 quadrature decoding and pulse-direction mode.

This is useful on SoCs that lack a dedicated hardware quadrature
decoder or where the encoder is wired to generic GPIO pins.

Signed-off-by: Wadim Mueller <wafgo01@gmail.com>
---
 .../counter/gpio-quadrature-encoder.yaml      | 69 +++++++++++++++++++
 1 file changed, 69 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/counter/gpio-quadrature-encoder.yaml

diff --git a/Documentation/devicetree/bindings/counter/gpio-quadrature-encoder.yaml b/Documentation/devicetree/bindings/counter/gpio-quadrature-encoder.yaml
new file mode 100644
index 000000000..a52deaab6
--- /dev/null
+++ b/Documentation/devicetree/bindings/counter/gpio-quadrature-encoder.yaml
@@ -0,0 +1,69 @@
+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/counter/gpio-quadrature-encoder.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: GPIO-based Quadrature Encoder
+
+maintainers:
+  - Wadim Mueller <wadim.mueller@cmblu.de>
+
+description: |
+  A generic GPIO-based quadrature encoder counter.  Reads A/B quadrature
+  signals and an optional index pulse via edge-triggered GPIO interrupts.
+  Supports X1, X2, X4 quadrature decoding and pulse-direction mode.
+
+  This driver is useful on SoCs that lack a dedicated hardware quadrature
+  decoder (eQEP, QEI, etc.) or where the encoder is wired to generic GPIO
+  pins rather than to a dedicated peripheral.
+
+properties:
+  compatible:
+    const: gpio-quadrature-encoder
+
+  encoder-a-gpios:
+    maxItems: 1
+    description:
+      GPIO connected to the encoder's A (phase A) output.
+
+  encoder-b-gpios:
+    maxItems: 1
+    description:
+      GPIO connected to the encoder's B (phase B) output.
+
+  encoder-index-gpios:
+    maxItems: 1
+    description:
+      Optional GPIO connected to the encoder's index (Z) output.
+      When the index input is enabled via sysfs, the count resets
+      to zero on each index pulse.
+
+required:
+  - compatible
+  - encoder-a-gpios
+  - encoder-b-gpios
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+
+    quadrature-encoder-0 {
+        compatible = "gpio-quadrature-encoder";
+        encoder-a-gpios = <&gpio0 10 GPIO_ACTIVE_HIGH>;
+        encoder-b-gpios = <&gpio0 11 GPIO_ACTIVE_HIGH>;
+    };
+
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+
+    quadrature-encoder-1 {
+        compatible = "gpio-quadrature-encoder";
+        encoder-a-gpios = <&gpio0 10 GPIO_ACTIVE_LOW>;
+        encoder-b-gpios = <&gpio0 11 GPIO_ACTIVE_LOW>;
+        encoder-index-gpios = <&gpio0 12 GPIO_ACTIVE_LOW>;
+    };
+
+...
-- 
2.52.0