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Subject[PATCH v2 1/3] dt-bindings: iio: adc: stm32: add support for diff channels
Date
STM32H7 ADC channels may be configured either as single-ended or
differential.
Add 'st,adc-diff-channels' property to support differential channels.
Differential channels are defined as a pair of positive and negative
inputs: vinp & vinn.

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
---
Changes in v2:
- Add differential channels example
- Add a note on mixed single-ended / differential channels
---
.../devicetree/bindings/iio/adc/st,stm32-adc.txt | 24 ++++++++++++++++++++++
1 file changed, 24 insertions(+)

diff --git a/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.txt b/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.txt
index 48bfcaa3..e8bb824 100644
--- a/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.txt
+++ b/Documentation/devicetree/bindings/iio/adc/st,stm32-adc.txt
@@ -62,6 +62,15 @@ Required properties:
- st,adc-channels: List of single-ended channels muxed for this ADC.
It can have up to 16 channels on stm32f4 or 20 channels on stm32h7, numbered
from 0 to 15 or 19 (resp. for in0..in15 or in0..in19).
+- st,adc-diff-channels: List of differential channels muxed for this ADC.
+ Depending on part used, some channels can be configured as differential
+ instead of single-ended (e.g. stm32h7). List here positive and negative
+ inputs pairs as <vinp vinn>, <vinp vinn>,... vinp and vinn are numbered
+ from 0 to 19 on stm32h7)
+ Note: At least one of "st,adc-channels" or "st,adc-diff-channels" is required.
+ Both properties can be used together. Some channels can be used as
+ single-ended and some other ones as differential (mixed). But channels
+ can't be configured both as single-ended and differential (invalid).
- #io-channel-cells = <1>: See the IIO bindings section "IIO consumers" in
Documentation/devicetree/bindings/iio/iio-bindings.txt

@@ -111,3 +120,18 @@ Example:
...
other adc child nodes follow...
};
+
+Example to setup:
+- channel 1 as single-ended
+- channels 2 & 3 as differential (with resp. 6 & 7 negative inputs)
+
+ adc: adc@40022000 {
+ compatible = "st,stm32h7-adc-core";
+ ...
+ adc1: adc@0 {
+ compatible = "st,stm32h7-adc";
+ ...
+ st,adc-channels = <1>;
+ st,adc-diff-channels = <2 6>, <3 7>;
+ };
+ };
--
1.9.1
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