tjh.dev
Linux kernel mirror (for testing)
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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 interrupts An interrupt node describing the IRQ line the chip's
22 !PENIRQ pin is connected to.
23 vcc-supply A regulator node for the supply voltage.
24
25
26Optional properties:
27
28 ti,vref-delay-usecs vref supply delay in usecs, 0 for
29 external vref (u16).
30 ti,vref-mv The VREF voltage, in millivolts (u16).
31 Set to 0 to use internal references
32 (ADS7846).
33 ti,keep-vref-on set to keep vref on for differential
34 measurements as well
35 ti,swap-xy swap x and y axis
36 ti,settle-delay-usec Settling time of the analog signals;
37 a function of Vcc and the capacitance
38 on the X/Y drivers. If set to non-zero,
39 two samples are taken with settle_delay
40 us apart, and the second one is used.
41 ~150 uSec with 0.01uF caps (u16).
42 ti,penirq-recheck-delay-usecs If set to non-zero, after samples are
43 taken this delay is applied and penirq
44 is rechecked, to help avoid false
45 events. This value is affected by the
46 material used to build the touch layer
47 (u16).
48 ti,x-plate-ohms Resistance of the X-plate,
49 in Ohms (u16).
50 ti,y-plate-ohms Resistance of the Y-plate,
51 in Ohms (u16).
52 ti,x-min Minimum value on the X axis (u16).
53 ti,y-min Minimum value on the Y axis (u16).
54 ti,x-max Maximum value on the X axis (u16).
55 ti,y-max Minimum value on the Y axis (u16).
56 ti,pressure-min Minimum reported pressure value
57 (threshold) - u16.
58 ti,pressure-max Maximum reported pressure value (u16).
59 ti,debounce-max Max number of additional readings per
60 sample (u16).
61 ti,debounce-tol Tolerance used for filtering (u16).
62 ti,debounce-rep Additional consecutive good readings
63 required after the first two (u16).
64 ti,pendown-gpio-debounce Platform specific debounce time for the
65 pendown-gpio (u32).
66 pendown-gpio GPIO handle describing the pin the !PENIRQ
67 line is connected to.
68 wakeup-source use any event on touchscreen as wakeup event.
69 (Legacy property support: "linux,wakeup")
70
71
72Example for a TSC2046 chip connected to an McSPI controller of an OMAP SoC::
73
74 spi_controller {
75 tsc2046@0 {
76 reg = <0>; /* CS0 */
77 compatible = "ti,tsc2046";
78 interrupt-parent = <&gpio1>;
79 interrupts = <8 0>; /* BOOT6 / GPIO 8 */
80 spi-max-frequency = <1000000>;
81 pendown-gpio = <&gpio1 8 0>;
82 vcc-supply = <®_vcc3>;
83
84 ti,x-min = /bits/ 16 <0>;
85 ti,x-max = /bits/ 16 <8000>;
86 ti,y-min = /bits/ 16 <0>;
87 ti,y-max = /bits/ 16 <4800>;
88 ti,x-plate-ohms = /bits/ 16 <40>;
89 ti,pressure-max = /bits/ 16 <255>;
90
91 wakeup-source;
92 };
93 };