[PATCH v5 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 v5:
 - Expand enable-gpios description to explain high-impedance (high-Z)
   behavior when mux is disabled
 - Describe analog multiplexer use case where downstream capacitance
   maintains signal level during brief disconnection
 - Remove separate ADG2404 example, add enable-gpios to existing example
---
 .../devicetree/bindings/mux/gpio-mux.yaml        | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/Documentation/devicetree/bindings/mux/gpio-mux.yaml b/Documentation/devicetree/bindings/mux/gpio-mux.yaml
index ef7e33ec85d4..798e0a73d77b 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 +28,18 @@ 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 is
+      disabled before changing address lines and re-enabled after. This
+      prevents glitches where an unintended channel could be briefly activated
+      during address line transitions. When disabled, all outputs enter a
+      high-impedance (high-Z) state rather than holding their previous value.
+      This is suitable for analog multiplexers where downstream capacitance
+      maintains the signal level during the brief disconnection.
+      Required for MUX_IDLE_DISCONNECT idle-state.
+    maxItems: 1
+
   mux-supply:
     description:
       Regulator to power on the multiplexer.
@@ -59,6 +74,7 @@ examples:
 
         mux-gpios = <&pioA 0 GPIO_ACTIVE_HIGH>,
               <&pioA 1 GPIO_ACTIVE_HIGH>;
+        enable-gpios = <&pioA 2 GPIO_ACTIVE_HIGH>;
     };
 
     adc-mux {
-- 
2.43.0