Documentation/devicetree/bindings/input/touchscreen/ad7879.txt

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