[PATCH 2/3] dt-bindings: input: touchscreen: add Nsiway NS2009

[Miotsuki Mizuno <founder@crepuse.com>]

Describe the Nsiway NS2009 four-wire resistive touchscreen controller
and the properties used by its polling driver.

The controller returns 12-bit ADC coordinates. Use the common touchscreen
properties for coordinate ranges and orientation, and allow boards to set
the raw Z1 contact threshold through touchscreen-min-pressure. Limit that
threshold to 1..4095 because zero cannot distinguish a released contact.

Document the historical default of 80 and a board override of 150 in the
example. The Z1 threshold is for contact detection, not calibrated
pressure.

Signed-off-by: Mizuno Miotsuki <founder@crepuse.com>
---
 .../input/touchscreen/nsiway,ns2009.yaml      | 64 +++++++++++++++++++
 MAINTAINERS                                   |  6 ++
 2 files changed, 70 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/input/touchscreen/nsiway,ns2009.yaml

diff --git a/Documentation/devicetree/bindings/input/touchscreen/nsiway,ns2009.yaml b/Documentation/devicetree/bindings/input/touchscreen/nsiway,ns2009.yaml
new file mode 100644
index 000000000000..04df7ba66a4a
--- /dev/null
+++ b/Documentation/devicetree/bindings/input/touchscreen/nsiway,ns2009.yaml
@@ -0,0 +1,64 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/input/touchscreen/nsiway,ns2009.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Nsiway NS2009 resistive touchscreen controller
+
+maintainers:
+  - Mizuno Miotsuki <founder@crepuse.com>
+
+description: |
+  The NS2009 is a four-wire resistive touchscreen controller connected over
+  I2C. This binding describes polling operation without a pen interrupt.
+  Coordinates are 12-bit ADC readings, not display pixel coordinates.
+
+allOf:
+  - $ref: touchscreen.yaml#
+
+properties:
+  compatible:
+    const: nsiway,ns2009
+
+  reg:
+    maxItems: 1
+
+  touchscreen-min-pressure:
+    minimum: 1
+    maximum: 4095
+    default: 80
+    description:
+      Minimum raw Z1 reading considered a touch. This is a contact detection
+      threshold, not a calibrated pressure value. Boards may require a higher
+      empirically determined threshold than the historical driver default.
+
+  touchscreen-min-x: true
+  touchscreen-min-y: true
+  touchscreen-size-x: true
+  touchscreen-size-y: true
+  touchscreen-fuzz-x: true
+  touchscreen-fuzz-y: true
+  touchscreen-inverted-x: true
+  touchscreen-inverted-y: true
+  touchscreen-swapped-x-y: true
+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        touchscreen@48 {
+            compatible = "nsiway,ns2009";
+            reg = <0x48>;
+            touchscreen-min-pressure = <150>;
+            touchscreen-inverted-y;
+        };
+    };
diff --git a/MAINTAINERS b/MAINTAINERS
index f53047aa8d3c..696f2badc49c 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -19467,6 +19467,12 @@ S:	Maintained
 F:	Documentation/core-api/symbol-namespaces.rst
 F:	scripts/nsdeps
 
+NSIWAY NS2009 TOUCHSCREEN CONTROLLER
+M:	Mizuno Miotsuki <founder@crepuse.com>
+L:	linux-input@vger.kernel.org
+S:	Maintained
+F:	Documentation/devicetree/bindings/input/touchscreen/nsiway,ns2009.yaml
+
 NTB AMD DRIVER
 M:	Basavaraj Natikar <Basavaraj.Natikar@amd.com>
 M:	Shyam Sundar S K <Shyam-sundar.S-k@amd.com>