From 57f0f512b273f60d52568b8c6b77e17f5636edc0 Mon Sep 17 00:00:00 2001 From: André Fabian Silva Delgado Date: Wed, 5 Aug 2015 17:04:01 -0300 Subject: Initial import --- .../bindings/input/touchscreen/ti-tsc-adc.txt | 59 ++++++++++++++++++++++ 1 file changed, 59 insertions(+) create mode 100644 Documentation/devicetree/bindings/input/touchscreen/ti-tsc-adc.txt (limited to 'Documentation/devicetree/bindings/input/touchscreen/ti-tsc-adc.txt') diff --git a/Documentation/devicetree/bindings/input/touchscreen/ti-tsc-adc.txt b/Documentation/devicetree/bindings/input/touchscreen/ti-tsc-adc.txt new file mode 100644 index 000000000..6c4fb3482 --- /dev/null +++ b/Documentation/devicetree/bindings/input/touchscreen/ti-tsc-adc.txt @@ -0,0 +1,59 @@ +* TI - TSC ADC (Touschscreen and analog digital converter) +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Required properties: +- child "tsc" + ti,wires: Wires refer to application modes i.e. 4/5/8 wire touchscreen + support on the platform. + ti,x-plate-resistance: X plate resistance + ti,coordinate-readouts: 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. + ti,wire-config: Different boards could have a different order for + connecting wires on touchscreen. We need to provide an + 8 bit number where in the 1st 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 resoectively + is as follows: + AIN0 = 0, AIN1 = 1 and so on till AIN7 = 7. + XP = 0, XN = 1, YP = 2, YN = 3. +- child "adc" + ti,adc-channels: List of analog inputs available for ADC. + AIN0 = 0, AIN1 = 1 and so on till AIN7 = 7. + +Optional properties: +- child "tsc" + ti,charge-delay: 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". + +Example: + tscadc: tscadc@44e0d000 { + compatible = "ti,am3359-tscadc"; + tsc { + ti,wires = <4>; + ti,x-plate-resistance = <200>; + ti,coordiante-readouts = <5>; + ti,wire-config = <0x00 0x11 0x22 0x33>; + ti,charge-delay = <0x400>; + }; + + adc { + ti,adc-channels = <4 5 6 7>; + }; + } -- cgit v1.2.3-54-g00ecf