original development tree for Linux kernel GTP module; now long in mainline.
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Device tree bindings for TI's ADS7843, ADS7845, ADS7846, ADS7873, TSC2046
SPI driven touch screen controllers.
The node for this driver must be a child node of a SPI controller, hence
all mandatory properties described in
must be specified.
Additional required properties:
compatible Must be one of the following, depending on the
interrupts An interrupt node describing the IRQ line the chip's
!PENIRQ pin is connected to.
vcc-supply A regulator node for the supply voltage.
Optional properties:
ti,vref-delay-usecs vref supply delay in usecs, 0 for
external vref (u16).
ti,vref-mv The VREF voltage, in millivolts (u16).
ti,keep-vref-on set to keep vref on for differential
measurements as well
ti,swap-xy swap x and y axis
ti,settle-delay-usec Settling time of the analog signals;
a function of Vcc and the capacitance
on the X/Y drivers. If set to non-zero,
two samples are taken with settle_delay
us apart, and the second one is used.
~150 uSec with 0.01uF caps (u16).
ti,penirq-recheck-delay-usecs If set to non-zero, after samples are
taken this delay is applied and penirq
is rechecked, to help avoid false
events. This value is affected by the
material used to build the touch layer
ti,x-plate-ohms Resistance of the X-plate,
in Ohms (u16).
ti,y-plate-ohms Resistance of the Y-plate,
in Ohms (u16).
ti,x-min Minimum value on the X axis (u16).
ti,y-min Minimum value on the Y axis (u16).
ti,x-max Maximum value on the X axis (u16).
ti,y-max Minimum value on the Y axis (u16).
ti,pressure-min Minimum reported pressure value
(threshold) - u16.
ti,pressure-max Maximum reported pressure value (u16).
ti,debounce-max Max number of additional readings per
sample (u16).
ti,debounce-tol Tolerance used for filtering (u16).
ti,debounce-rep Additional consecutive good readings
required after the first two (u16).
ti,pendown-gpio-debounce Platform specific debounce time for the
pendown-gpio (u32).
pendown-gpio GPIO handle describing the pin the !PENIRQ
line is connected to.
linux,wakeup use any event on touchscreen as wakeup event.
Example for a TSC2046 chip connected to an McSPI controller of an OMAP SoC::
spi_controller {
tsc2046@0 {
reg = <0>; /* CS0 */
compatible = "ti,tsc2046";
interrupt-parent = <&gpio1>;
interrupts = <8 0>; /* BOOT6 / GPIO 8 */
spi-max-frequency = <1000000>;
pendown-gpio = <&gpio1 8 0>;
vcc-supply = <&reg_vcc3>;
ti,x-min = /bits/ 16 <0>;
ti,x-max = /bits/ 16 <8000>;
ti,y-min = /bits/ 16 <0>;
ti,y-max = /bits/ 16 <4800>;
ti,x-plate-ohms = /bits/ 16 <40>;
ti,pressure-max = /bits/ 16 <255>;