[PATCH v4 1/2] dt-bindings: mux: gpio-mux: add enable-gpios support

[Antoniu Miclaus <antoniu.miclaus@analog.com>]

Add support for an optional enable GPIO that allows the multiplexer
to be disabled before changing address lines and re-enabled after,
preventing glitches during channel transitions.

This is useful for devices like the Analog Devices ADG2404 (4:1 mux)
that benefit from enable control to ensure clean channel switching.

Signed-off-by: Antoniu Miclaus <antoniu.miclaus@analog.com>
---
Changes in v4:
 * Add ADG2404 to binding description for discoverability
 * Add dedicated ADG2404 example showing enable-gpios usage
 * Update commit message to reference ADG2404 as use case

---
 .../devicetree/bindings/mux/gpio-mux.yaml     | 25 +++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/Documentation/devicetree/bindings/mux/gpio-mux.yaml b/Documentation/devicetree/bindings/mux/gpio-mux.yaml
index ef7e33ec85d4..2d9f32012127 100644
--- a/Documentation/devicetree/bindings/mux/gpio-mux.yaml
+++ b/Documentation/devicetree/bindings/mux/gpio-mux.yaml
@@ -17,6 +17,9 @@ description: |+
   multiplexer GPIO pins, where the first pin is the least significant
   bit. An active pin is a binary 1, an inactive pin is a binary 0.
 
+  This binding supports GPIO-controlled multiplexers such as the Analog
+  Devices ADG2404 (4:1 mux with enable control).
+
 properties:
   compatible:
     const: gpio-mux
@@ -25,6 +28,13 @@ properties:
     description:
       List of gpios used to control the multiplexer, least significant bit first.
 
+  enable-gpios:
+    description:
+      Optional GPIO to enable the multiplexer. When present, the mux will be
+      disabled before changing address lines and re-enabled after to prevent
+      glitches. Required for MUX_IDLE_DISCONNECT idle-state.
+    maxItems: 1
+
   mux-supply:
     description:
       Regulator to power on the multiplexer.
@@ -100,4 +110,19 @@ examples:
             };
         };
     };
+
+  - |
+    /* Analog Devices ADG2404 4:1 multiplexer with enable control */
+    #include <dt-bindings/gpio/gpio.h>
+
+    mux-controller {
+        compatible = "gpio-mux";
+        #mux-control-cells = <0>;
+
+        mux-gpios = <&gpio 1 GPIO_ACTIVE_HIGH>,
+                    <&gpio 2 GPIO_ACTIVE_HIGH>;
+        enable-gpios = <&gpio 3 GPIO_ACTIVE_HIGH>;
+
+        idle-state = <0>;
+    };
 ...
-- 
2.43.0