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From: Dumitru Ceclan via B4 Relay <devnull+dumitru.ceclan.analog.com@kernel.org>
Date: Fri, 07 Jun 2024 17:53:07 +0300
Subject: [PATCH v7 1/9] dt-bindings: iio: adc: Add common-mode-channel
 property
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To: Ceclan Dumitru <dumitru.ceclan@analog.com>
Cc: Lars-Peter Clausen <lars@metafoo.de>, 
 Michael Hennerich <Michael.Hennerich@analog.com>, 
 Jonathan Cameron <jic23@kernel.org>, Rob Herring <robh@kernel.org>, 
 Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>, 
 Conor Dooley <conor+dt@kernel.org>, David Lechner <dlechner@baylibre.com>, 
 linux-iio@vger.kernel.org, devicetree@vger.kernel.org, 
 linux-kernel@vger.kernel.org, Dumitru Ceclan <mitrutzceclan@gmail.com>, 
 Conor Dooley <conor.dooley@microchip.com>
Reply-To: dumitru.ceclan@analog.com

From: Dumitru Ceclan <dumitru.ceclan@analog.com>

There are ADCs that are differential but support to measure single-ended
signals on the same channels by connecting a constant voltage to the
negative input pin.

This property allows to properly define a single-ended channel that
requires two inputs to be specified. Software can use the presence of
this property to mark the channel as not differential.

Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Dumitru Ceclan <dumitru.ceclan@analog.com>
---
 Documentation/devicetree/bindings/iio/adc/adc.yaml | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/Documentation/devicetree/bindings/iio/adc/adc.yaml b/Documentation/devicetree/bindings/iio/adc/adc.yaml
index 0a77592f7388..8e7835cf36fd 100644
--- a/Documentation/devicetree/bindings/iio/adc/adc.yaml
+++ b/Documentation/devicetree/bindings/iio/adc/adc.yaml
@@ -46,6 +46,17 @@ properties:
       differential channels). If this and diff-channels are not present reg
       shall be used instead.
 
+  common-mode-channel:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description:
+      Some ADCs have differential input pins that can be used to measure
+      single-ended or pseudo-differential inputs. This property can be used
+      in addition to single-channel to signal software that this channel is
+      not differential but still specify two inputs.
+
+      The input pair is specified by setting single-channel to the positive
+      input pin and common-mode-channel to the negative pin.
+
   settling-time-us:
     description:
       Time between enabling the channel and first stable readings.

-- 
2.43.0