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 - 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)
  13 Optional 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
  40 Example:
  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         };