LXR linux/Documentation/devicetree/bindings/input/ads7846.txt

   1Device tree bindings for TI's ADS7843, ADS7845, ADS7846, ADS7873, TSC2046
   2SPI driven touch screen controllers.
   3
   4The node for this driver must be a child node of a SPI controller, hence
   5all mandatory properties described in
   6
   7        Documentation/devicetree/bindings/spi/spi-bus.txt
   8
   9must be specified.
  10
  11Additional required properties:
  12
  13        compatible              Must be one of the following, depending on the
  14                                model:
  15                                        "ti,tsc2046"
  16                                        "ti,ads7843"
  17                                        "ti,ads7845"
  18                                        "ti,ads7846"
  19                                        "ti,ads7873"
  20
  21        interrupt-parent
  22        interrupts              An interrupt node describing the IRQ line the chip's
  23                                !PENIRQ pin is connected to.
  24        vcc-supply              A regulator node for the supply voltage.
  25
  26
  27Optional properties:
  28
  29        ti,vref-delay-usecs             vref supply delay in usecs, 0 for
  30                                        external vref (u16).
  31        ti,vref-mv                      The VREF voltage, in millivolts (u16).
  32        ti,keep-vref-on                 set to keep vref on for differential
  33                                        measurements as well
  34        ti,swap-xy                      swap x and y axis
  35        ti,settle-delay-usec            Settling time of the analog signals;
  36                                        a function of Vcc and the capacitance
  37                                        on the X/Y drivers.  If set to non-zero,
  38                                        two samples are taken with settle_delay
  39                                        us apart, and the second one is used.
  40                                        ~150 uSec with 0.01uF caps (u16).
  41        ti,penirq-recheck-delay-usecs   If set to non-zero, after samples are
  42                                        taken this delay is applied and penirq
  43                                        is rechecked, to help avoid false
  44                                        events.  This value is affected by the
  45                                        material used to build the touch layer
  46                                        (u16).
  47        ti,x-plate-ohms                 Resistance of the X-plate,
  48                                        in Ohms (u16).
  49        ti,y-plate-ohms                 Resistance of the Y-plate,
  50                                        in Ohms (u16).
  51        ti,x-min                        Minimum value on the X axis (u16).
  52        ti,y-min                        Minimum value on the Y axis (u16).
  53        ti,x-max                        Maximum value on the X axis (u16).
  54        ti,y-max                        Minimum value on the Y axis (u16).
  55        ti,pressure-min                 Minimum reported pressure value
  56                                        (threshold) - u16.
  57        ti,pressure-max                 Maximum reported pressure value (u16).
  58        ti,debounce-max                 Max number of additional readings per
  59                                        sample (u16).
  60        ti,debounce-tol                 Tolerance used for filtering (u16).
  61        ti,debounce-rep                 Additional consecutive good readings
  62                                        required after the first two (u16).
  63        ti,pendown-gpio-debounce        Platform specific debounce time for the
  64                                        pendown-gpio (u32).
  65        pendown-gpio                    GPIO handle describing the pin the !PENIRQ
  66                                        line is connected to.
  67        linux,wakeup                    use any event on touchscreen as wakeup event.
  68
  69
  70Example for a TSC2046 chip connected to an McSPI controller of an OMAP SoC::
  71
  72        spi_controller {
  73                tsc2046@0 {
  74                        reg = <0>;      /* CS0 */
  75                        compatible = "ti,tsc2046";
  76                        interrupt-parent = <&gpio1>;
  77                        interrupts = <8 0>;     /* BOOT6 / GPIO 8 */
  78                        spi-max-frequency = <1000000>;
  79                        pendown-gpio = <&gpio1 8 0>;
  80                        vcc-supply = <&reg_vcc3>;
  81
  82                        ti,x-min = /bits/ 16 <0>;
  83                        ti,x-max = /bits/ 16 <8000>;
  84                        ti,y-min = /bits/ 16 <0>;
  85                        ti,y-max = /bits/ 16 <4800>;
  86                        ti,x-plate-ohms = /bits/ 16 <40>;
  87                        ti,pressure-max = /bits/ 16 <255>;
  88
  89                        linux,wakeup;
  90                };
  91        };
  92