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Linux kernel mirror (for testing)
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1* Analog Devices AD7879(-1)/AD7889(-1) touchscreen interface (SPI/I2C)
2
3Required properties:
4- compatible : for SPI slave, use "adi,ad7879"
5 for I2C slave, use "adi,ad7879-1"
6- reg : SPI chipselect/I2C slave address
7 See spi-bus.txt for more SPI slave properties
8- interrupt-parent : the phandle for the interrupt controller
9- interrupts : touch controller interrupt
10- touchscreen-max-pressure : maximum reported pressure
11- adi,resistance-plate-x : total resistance of X-plate (for pressure
12 calculation)
13Optional properties:
14- touchscreen-swapped-x-y : X and Y axis are swapped (boolean)
15- adi,first-conversion-delay : 0-12: In 128us steps (starting with 128us)
16 13 : 2.560ms
17 14 : 3.584ms
18 15 : 4.096ms
19 This property has to be a '/bits/ 8' value
20- adi,acquisition-time : 0: 2us
21 1: 4us
22 2: 8us
23 3: 16us
24 This property has to be a '/bits/ 8' value
25- adi,median-filter-size : 0: disabled
26 1: 4 measurements
27 2: 8 measurements
28 3: 16 measurements
29 This property has to be a '/bits/ 8' value
30- adi,averaging : 0: 2 middle values (1 if median disabled)
31 1: 4 middle values
32 2: 8 middle values
33 3: 16 values
34 This property has to be a '/bits/ 8' value
35- adi,conversion-interval: : 0 : convert one time only
36 1-255: 515us + val * 35us (up to 9.440ms)
37 This property has to be a '/bits/ 8' value
38- gpio-controller : Switch AUX/VBAT/GPIO pin to GPIO mode
39
40Example:
41
42 ad7879@2c {
43 compatible = "adi,ad7879-1";
44 reg = <0x2c>;
45 interrupt-parent = <&gpio1>;
46 interrupts = <13 IRQ_TYPE_EDGE_FALLING>;
47 touchscreen-max-pressure = <4096>;
48 adi,resistance-plate-x = <120>;
49 adi,first-conversion-delay = /bits/ 8 <3>;
50 adi,acquisition-time = /bits/ 8 <1>;
51 adi,median-filter-size = /bits/ 8 <2>;
52 adi,averaging = /bits/ 8 <1>;
53 adi,conversion-interval = /bits/ 8 <255>;
54 };
55
56 ad7879@1 {
57 compatible = "adi,ad7879";
58 spi-max-frequency = <5000000>;
59 reg = <1>;
60 spi-cpol;
61 spi-cpha;
62 gpio-controller;
63 interrupt-parent = <&gpio1>;
64 interrupts = <13 IRQ_TYPE_EDGE_FALLING>;
65 touchscreen-max-pressure = <4096>;
66 adi,resistance-plate-x = <120>;
67 adi,first-conversion-delay = /bits/ 8 <3>;
68 adi,acquisition-time = /bits/ 8 <1>;
69 adi,median-filter-size = /bits/ 8 <2>;
70 adi,averaging = /bits/ 8 <1>;
71 adi,conversion-interval = /bits/ 8 <255>;
72 };