Add support for the AD4880, a dual-channel 20-bit 40MSPS SAR ADC
with integrated fully differential amplifiers (FDA).

The AD4880 has two independent ADC channels, each with its own SPI
configuration interface. This requires:
- Two entries in reg property for primary and secondary channel
  chip selects
- Two io-backends entries for the two data channels

Signed-off-by: Antoniu Miclaus <antoniu.miclaus@analog.com>
---
Changes in v3:
  - Add items descriptions for io-backends entries
  - Fix reg example format: reg = <0 1> -> reg = <0>, <1>

 .../bindings/iio/adc/adi,ad4080.yaml          | 54 ++++++++++++++++++-
 1 file changed, 52 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/iio/adc/adi,ad4080.yaml b/Documentation/devicetree/bindings/iio/adc/adi,ad4080.yaml
index ccd6a0ac1539..871bbdd7e1ce 100644
--- a/Documentation/devicetree/bindings/iio/adc/adi,ad4080.yaml
+++ b/Documentation/devicetree/bindings/iio/adc/adi,ad4080.yaml
@@ -18,7 +18,11 @@ description: |
   service a wide variety of precision, wide bandwidth data acquisition
   applications.
 
+  The AD4880 is a dual-channel variant with two independent ADC channels,
+  each with its own SPI configuration interface.
+
   https://www.analog.com/media/en/technical-documentation/data-sheets/ad4080.pdf
+  https://www.analog.com/media/en/technical-documentation/data-sheets/ad4880.pdf
 
 $ref: /schemas/spi/spi-peripheral-props.yaml#
 
@@ -31,9 +35,15 @@ properties:
       - adi,ad4084
       - adi,ad4086
       - adi,ad4087
+      - adi,ad4880
 
   reg:
-    maxItems: 1
+    minItems: 1
+    maxItems: 2
+    description:
+      SPI chip select(s). For single-channel devices, one chip select.
+      For multi-channel devices like AD4880, two chip selects are required
+      as each channel has its own SPI configuration interface.
 
   spi-max-frequency:
     description: Configuration of the SPI bus.
@@ -57,7 +67,11 @@ properties:
   vrefin-supply: true
 
   io-backends:
-    maxItems: 1
+    minItems: 1
+    maxItems: 2
+    items:
+      - description: Backend for channel A (primary)
+      - description: Backend for channel B (secondary)
 
   adi,lvds-cnv-enable:
     description: Enable the LVDS signal type on the CNV pin. Default is CMOS.
@@ -78,6 +92,25 @@ required:
   - vdd33-supply
   - vrefin-supply
 
+allOf:
+  - if:
+      properties:
+        compatible:
+          contains:
+            const: adi,ad4880
+    then:
+      properties:
+        reg:
+          minItems: 2
+        io-backends:
+          minItems: 2
+    else:
+      properties:
+        reg:
+          maxItems: 1
+        io-backends:
+          maxItems: 1
+
 additionalProperties: false
 
 examples:
@@ -98,4 +131,21 @@ examples:
           io-backends = <&iio_backend>;
         };
     };
+  - |
+    spi {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        adc@0 {
+          compatible = "adi,ad4880";
+          reg = <0>, <1>;
+          spi-max-frequency = <10000000>;
+          vdd33-supply = <&vdd33>;
+          vddldo-supply = <&vddldo>;
+          vrefin-supply = <&vrefin>;
+          clocks = <&cnv>;
+          clock-names = "cnv";
+          io-backends = <&iio_backend_cha>, <&iio_backend_chb>;
+        };
+    };
 ...
-- 
2.43.0

On 13/02/2026 15:47, Antoniu Miclaus wrote:
> Add support for the AD4880, a dual-channel 20-bit 40MSPS SAR ADC
> with integrated fully differential amplifiers (FDA).
> 
> The AD4880 has two independent ADC channels, each with its own SPI
> configuration interface. This requires:
> - Two entries in reg property for primary and secondary channel
>   chip selects
> - Two io-backends entries for the two data channels
> 
> Signed-off-by: Antoniu Miclaus <antoniu.miclaus@analog.com>
> ---
> Changes in v3:
>   - Add items descriptions for io-backends entries
>   - Fix reg example format: reg = <0 1> -> reg = <0>, <1>

Not tested.

Best regards,
Krzysztof

On Fri, 13 Feb 2026 16:47:36 +0200, Antoniu Miclaus wrote:
> Add support for the AD4880, a dual-channel 20-bit 40MSPS SAR ADC
> with integrated fully differential amplifiers (FDA).
> 
> The AD4880 has two independent ADC channels, each with its own SPI
> configuration interface. This requires:
> - Two entries in reg property for primary and secondary channel
>   chip selects
> - Two io-backends entries for the two data channels
> 
> Signed-off-by: Antoniu Miclaus <antoniu.miclaus@analog.com>
> ---
> Changes in v3:
>   - Add items descriptions for io-backends entries
>   - Fix reg example format: reg = <0 1> -> reg = <0>, <1>
> 
>  .../bindings/iio/adc/adi,ad4080.yaml          | 54 ++++++++++++++++++-
>  1 file changed, 52 insertions(+), 2 deletions(-)
> 

My bot found errors running 'make dt_binding_check' on your patch:

yamllint warnings/errors:

dtschema/dtc warnings/errors:
/builds/robherring/dt-review-ci/linux/Documentation/devicetree/bindings/iio/adc/adi,ad4080.yaml: properties:io-backends: {'minItems': 1, 'maxItems': 2, 'items': [{'description': 'Backend for channel A (primary)'}, {'description': 'Backend for channel B (secondary)'}]} should not be valid under {'required': ['maxItems']}
	hint: "maxItems" is not needed with an "items" list
	from schema $id: http://devicetree.org/meta-schemas/items.yaml

doc reference errors (make refcheckdocs):

See https://patchwork.kernel.org/project/devicetree/patch/20260213144742.16394-5-antoniu.miclaus@analog.com

The base for the series is generally the latest rc1. A different dependency
should be noted in *this* patch.

If you already ran 'make dt_binding_check' and didn't see the above
error(s), then make sure 'yamllint' is installed and dt-schema is up to
date:

pip3 install dtschema --upgrade

Please check and re-submit after running the above command yourself. Note
that DT_SCHEMA_FILES can be set to your schema file to speed up checking
your schema. However, it must be unset to test all examples with your schema.