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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-27 10:05:51 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-27 10:05:51 +0000 |
commit | 5d1646d90e1f2cceb9f0828f4b28318cd0ec7744 (patch) | |
tree | a94efe259b9009378be6d90eb30d2b019d95c194 /Documentation/devicetree/bindings/input/touchscreen/ti-tsc-adc.txt | |
parent | Initial commit. (diff) | |
download | linux-430c2fc249ea5c0536abd21c23382884005c9093.tar.xz linux-430c2fc249ea5c0536abd21c23382884005c9093.zip |
Adding upstream version 5.10.209.upstream/5.10.209upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'Documentation/devicetree/bindings/input/touchscreen/ti-tsc-adc.txt')
-rw-r--r-- | Documentation/devicetree/bindings/input/touchscreen/ti-tsc-adc.txt | 91 |
1 files changed, 91 insertions, 0 deletions
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..aad5e3496 --- /dev/null +++ b/Documentation/devicetree/bindings/input/touchscreen/ti-tsc-adc.txt @@ -0,0 +1,91 @@ +* TI - TSC ADC (Touschscreen and analog digital converter) +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Required properties: +- mfd + compatible: Should be + "ti,am3359-tscadc" for AM335x/AM437x SoCs + "ti,am654-tscadc", "ti,am3359-tscadc" for AM654 SoCs +- child "tsc" + compatible: Should be "ti,am3359-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" + compatible: Should be + "ti,am3359-adc" for AM335x/AM437x SoCs + "ti,am654-adc", "ti,am3359-adc" for AM654 SoCs + 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". + +- child "adc" + ti,chan-step-opendelay: List of open delays for each channel of + ADC in the order of ti,adc-channels. The + value corresponds to the number of ADC + clock cycles to wait after applying the + step configuration registers and before + sending the start of ADC conversion. + Maximum value is 0x3FFFF. + ti,chan-step-sampledelay: List of sample delays for each channel + of ADC in the order of ti,adc-channels. + The value corresponds to the number of + ADC clock cycles to sample (to hold + start of conversion high). + Maximum value is 0xFF. + ti,chan-step-avg: Number of averages to be performed for each + channel of ADC. If average is 16 then input + is sampled 16 times and averaged to get more + accurate value. This increases the time taken + by ADC to generate a sample. Valid range is 0 + average to 16 averages. Maximum value is 16. + +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>; + ti,chan-step-opendelay = <0x098 0x3ffff 0x098 0x0>; + ti,chan-step-sampledelay = <0xff 0x0 0xf 0x0>; + ti,chan-step-avg = <16 2 4 8>; + }; + } |