[PATCH v5 7/8] dt-bindings: touchscreen: resistive-adc-touch: add support for z1 and z2 channels

Oleksij Rempel
2021-05-21T04:46:17Z

For pressure calculation based on plates resistance we need some additional
properties:
- z1 and z2 channels with additional measurements between plates
- actual resistance of the touchscreen. Currently we use only
X-resistance.

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Reviewed-by: Rob Herring <robh@kernel.org>
---
.../input/touchscreen/resistive-adc-touch.yaml | 16 ++++++++++++++++
1 file changed, 16 insertions(+)

diff --git a/Documentation/devicetree/bindings/input/touchscreen/resistive-adc-touch.yaml b/Documentation/devicetree/bindings/input/touchscreen/resistive-adc-touch.yaml
index 38b4cbee9429..7fc22a403d48 100644
--- a/Documentation/devicetree/bindings/input/touchscreen/resistive-adc-touch.yaml
+++ b/Documentation/devicetree/bindings/input/touchscreen/resistive-adc-touch.yaml
@@ -27,6 +27,8 @@ properties:
- description: x
- description: y
- description: pressure (optional)
+ - description: z1 (optional)
+ - description: z2 (optional)

io-channel-names:
oneOf:
@@ -37,6 +39,11 @@ properties:
- enum: [x, y, pressure]
- enum: [x, y, pressure]
- enum: [x, y, pressure]
+ - items:
+ - enum: [x, y, z1, z2]
+ - enum: [x, y, z1, z2]
+ - enum: [x, y, z1, z2]
+ - enum: [x, y, z1, z2]

touchscreen-size-x: true
touchscreen-size-y: true
@@ -46,6 +53,7 @@ properties:
touchscreen-inverted-y: true
touchscreen-swapped-x-y: true
touchscreen-min-pressure: true
+ touchscreen-x-plate-ohms: true

additionalProperties: false

@@ -68,3 +76,11 @@ examples:
io-channels = <&adc 24>, <&adc 25>, <&adc 26>;
io-channel-names = "y", "pressure", "x";
};
+ - |
+ touchscreen {
+ compatible = "resistive-adc-touch";
+ touchscreen-min-pressure = <50000>;
+ io-channels = <&adc 1>, <&adc 2>, <&adc 3>, <&adc 4>;
+ io-channel-names = "x", "z1", "z2", "y";
+ touchscreen-x-plate-ohms = <800>;
+ };
--
2.29.2