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authorSascha Hauer <s.hauer@pengutronix.de>2021-11-17 07:36:09 +0100
committerSascha Hauer <s.hauer@pengutronix.de>2021-11-17 07:36:09 +0100
commit3f2f5980d517b6a71ffe54e615bd3a4b58b1c295 (patch)
treeeb5a7bfce811d20e58dd0eb1add0f6cf0e6b86e0 /dts/Bindings/input/touchscreen/ti-tsc-adc.txt
parent81ceab95360295cef146e89a1cd1cd5e590aa75e (diff)
downloadbarebox-3f2f5980d517b6a71ffe54e615bd3a4b58b1c295.tar.gz
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dts: update to v5.16-rc1
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
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-* 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>;
- };
- }