[PATCH v1 7/8] dt-bindings: mux: add NXP MC33978/MC34978 AMUX

[Oleksij Rempel]

Add device tree binding documentation for the Analog Multiplexer (AMUX)
block of the NXP MC33978/MC34978 Multiple Switch Detection Interface
(MSDI).

The AMUX acts as a 24-to-1 router, allowing an external SoC ADC to
sample the analog voltage of any of the 22 mechanical switch inputs, the
internal silicon temperature diode, or the main battery supply (VBATP).

Signed-off-by: Oleksij Rempel <o.rempel@xxxxxxxxxxxxxx>
---
 .../devicetree/bindings/mfd/nxp,mc33978.yaml  | 11 ++++
 .../bindings/mux/nxp,mc33978-mux.yaml         | 55 +++++++++++++++++++
 2 files changed, 66 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/mux/nxp,mc33978-mux.yaml

diff --git a/Documentation/devicetree/bindings/mfd/nxp,mc33978.yaml b/Documentation/devicetree/bindings/mfd/nxp,mc33978.yaml
index 58fcfe24d415..f86f72cfe230 100644
--- a/Documentation/devicetree/bindings/mfd/nxp,mc33978.yaml
+++ b/Documentation/devicetree/bindings/mfd/nxp,mc33978.yaml
@@ -64,6 +64,12 @@ properties:
     description: |
       Hardware monitoring child node for fault detection.
 
+  mux-controller:
+    type: object
+    $ref: /schemas/mux/nxp,mc33978-mux.yaml#
+    description: |
+      Analog multiplexer (AMUX) controller child node.
+
 required:
   - compatible
   - reg
@@ -104,5 +110,10 @@ examples:
             hwmon {
                 compatible = "nxp,mc33978-hwmon";
             };
+
+            mux-controller {
+                compatible = "nxp,mc33978-mux";
+                #mux-control-cells = <0>;
+            };
         };
     };
diff --git a/Documentation/devicetree/bindings/mux/nxp,mc33978-mux.yaml b/Documentation/devicetree/bindings/mux/nxp,mc33978-mux.yaml
new file mode 100644
index 000000000000..ccb8efb91d8e
--- /dev/null
+++ b/Documentation/devicetree/bindings/mux/nxp,mc33978-mux.yaml
@@ -0,0 +1,55 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/mux/nxp,mc33978-mux.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: NXP MC33978/MC34978 Analog Multiplexer
+
+maintainers:
+  - David Jander <david@xxxxxxxxxxx>
+  - Oleksij Rempel <o.rempel@xxxxxxxxxxxxxx>
+
+description: |
+  The MC33978 and MC34978 include a 24-to-1 analog multiplexer (AMUX) that
+  routes one of the following signals to an external AMUX pin for measurement
+  by an external ADC:
+
+  - Channels 0-13: SG0-SG13 switch input voltages
+  - Channels 14-21: SP0-SP7 switch input voltages
+  - Channel 22: Internal temperature diode
+  - Channel 23: Battery voltage (VBATP)
+
+  The AMUX requires a settling time of up to 200 us for full-scale voltage
+  steps. Consumers (e.g., io-channel-mux) must configure this delay.
+
+properties:
+  compatible:
+    enum:
+      - nxp,mc33978-mux
+      - nxp,mc34978-mux
+
+  '#mux-control-cells':
+    const: 0
+
+required:
+  - compatible
+  - '#mux-control-cells'
+
+additionalProperties: false
+
+examples:
+  - |
+    amux: mux-controller {
+        compatible = "nxp,mc33978-mux";
+        #mux-control-cells = <0>;
+    };
+
+    iio-mux {
+        compatible = "io-channel-mux";
+        io-channels = <&adc 0>;
+        io-channel-names = "parent";
+        mux-controls = <&amux>;
+        settle-time-us = <200>;
+        channels = "sg0", "sg1", "sg2"; /* ... */
+    };
-- 
2.47.3