Adding upstream version 4.19.249.upstream/4.19.249upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 83 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
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+* 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".
+
+- 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>;
+		};
+	}