dt-bindings: touchscreen: ti,am3359-tsc: New yaml description

This touchscreen controller is already described in a text file:
Documentation/devicetree/bindings/input/touchscreen/ti-tsc-adc.txt

After introducing a proper description of the MFD, this is the second
step. The file cannot be removed yet as it also contains an ADC
description.
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20211015081506.933180-4-miquel.raynal@bootlin.com

Documentation/devicetree/bindings/input/touchscreen/ti,am3359-tsc.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/input/touchscreen/ti,am3359-tsc.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: TI AM3359 Touchscreen controller
+
+maintainers:
+  - Miquel Raynal <miquel.raynal@bootlin.com>
+
+properties:
+  compatible:
+    const: ti,am3359-tsc
+
+  ti,wires:
+    description: Wires refer to application modes i.e. 4/5/8 wire touchscreen
+      support on the platform.
+    $ref: /schemas/types.yaml#/definitions/uint32
+    enum: [4, 5, 8]
+
+  ti,x-plate-resistance:
+    description: X plate resistance
+    $ref: /schemas/types.yaml#/definitions/uint32
+
+  ti,coordinate-readouts:
+    description: The sequencer supports a total of 16 programmable steps. Each
+      step is used to read a single coordinate. A single readout is enough but
+      multiple reads can increase the quality. A value of 5 means, 5 reads for
+      X, 5 for Y and 2 for Z (always). This utilises 12 of the 16 software steps
+      available. The remaining 4 can be used by the ADC.
+    $ref: /schemas/types.yaml#/definitions/uint32
+    minimum: 1
+    maximum: 6
+
+  ti,wire-config:
+    description: Different boards could have a different order for connecting
+      wires on touchscreen. We need to provide an 8-bit number where the
+      first four bits represent the analog lines and the next 4 bits represent
+      positive/negative terminal on that input line. Notations to represent the
+      input lines and terminals respectively are as follows, AIN0 = 0, AIN1 = 1
+      and so on until AIN7 = 7. XP = 0, XN = 1, YP = 2, YN = 3.
+    $ref: /schemas/types.yaml#/definitions/uint32-array
+    minItems: 4
+    maxItems: 8
+
+  ti,charge-delay:
+    description: Length of touch screen charge delay step in terms of ADC clock
+      cycles. Charge delay value should be large in order to avoid false pen-up
+      events. This value effects the overall sampling speed, hence need to be
+      kept as low as possible, while avoiding false pen-up event. Start from a
+      lower value, say 0x400, and increase value until false pen-up events are
+      avoided. The pen-up detection happens immediately after the charge step,
+      so this does in fact function as a hardware knob for adjusting the amount
+      of "settling time".
+    $ref: /schemas/types.yaml#/definitions/uint32
+
+required:
+  - compatible
+  - ti,wires
+  - ti,x-plate-resistance
+  - ti,coordinate-readouts
+  - ti,wire-config
+
+additionalProperties: false
+
+examples:
+  - |
+    tsc {
+        compatible = "ti,am3359-tsc";
+        ti,wires = <4>;
+        ti,x-plate-resistance = <200>;
+        ti,coordinate-readouts = <5>;
+        ti,wire-config = <0x00 0x11 0x22 0x33>;
+        ti,charge-delay = <0x400>;
+    };