1 # SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
2 %YAML 1.2
3 ---
4 $id: http://devicetree.org/schemas/input/touchscreen/ti,am3359-tsc.yaml#
5 $schema: http://devicetree.org/meta-schemas/core.yaml#
6
7 title: TI AM3359 Touchscreen controller
8
9 maintainers:
10 - Miquel Raynal <miquel.raynal@bootlin.com>
11
12 properties:
13 compatible:
14 const: ti,am3359-tsc
15
16 ti,wires:
17 description: Wires refer to application modes i.e. 4/5/8 wire touchscreen
18 support on the platform.
19 $ref: /schemas/types.yaml#/definitions/uint32
20 enum: [4, 5, 8]
21
22 ti,x-plate-resistance:
23 description: X plate resistance
24 $ref: /schemas/types.yaml#/definitions/uint32
25
26 ti,coordinate-readouts:
27 description: The sequencer supports a total of 16 programmable steps. Each
28 step is used to read a single coordinate. A single readout is enough but
29 multiple reads can increase the quality. A value of 5 means, 5 reads for
30 X, 5 for Y and 2 for Z (always). This utilises 12 of the 16 software steps
31 available. The remaining 4 can be used by the ADC.
32 $ref: /schemas/types.yaml#/definitions/uint32
33 minimum: 1
34 maximum: 6
35
36 ti,wire-config:
37 description: Different boards could have a different order for connecting
38 wires on touchscreen. We need to provide an 8-bit number where the
39 first four bits represent the analog lines and the next 4 bits represent
40 positive/negative terminal on that input line. Notations to represent the
41 input lines and terminals respectively are as follows, AIN0 = 0, AIN1 = 1
42 and so on until AIN7 = 7. XP = 0, XN = 1, YP = 2, YN = 3.
43 $ref: /schemas/types.yaml#/definitions/uint32-array
44 minItems: 4
45 maxItems: 8
46
47 ti,charge-delay:
48 description: Length of touch screen charge delay step in terms of ADC clock
49 cycles. Charge delay value should be large in order to avoid false pen-up
50 events. This value effects the overall sampling speed, hence need to be
51 kept as low as possible, while avoiding false pen-up event. Start from a
52 lower value, say 0x400, and increase value until false pen-up events are
53 avoided. The pen-up detection happens immediately after the charge step,
54 so this does in fact function as a hardware knob for adjusting the amount
55 of "settling time".
56 $ref: /schemas/types.yaml#/definitions/uint32
57
58 required:
59 - compatible
60 - ti,wires
61 - ti,x-plate-resistance
62 - ti,coordinate-readouts
63 - ti,wire-config
64
65 additionalProperties: false
66
67 examples:
68 - |
69 tsc {
70 compatible = "ti,am3359-tsc";
71 ti,wires = <4>;
72 ti,x-plate-resistance = <200>;
73 ti,coordinate-readouts = <5>;
74 ti,wire-config = <0x00 0x11 0x22 0x33>;
75 ti,charge-delay = <0x400>;
76 };
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