linux/Documentation/devicetree/bindings/input/gpio-matrix-keypad.txt

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* GPIO driven matrix keypad device tree bindings
GPIO driven matrix keypad is used to interface a SoC with a matrix keypad.
The matrix keypad supports multiple row and column lines, a key can be
placed at each intersection of a unique row and a unique column. The matrix
keypad can sense a key-press and key-release by means of GPIO lines and
report the event using GPIO interrupts to the cpu.
Required Properties:
- compatible: Should be "gpio-matrix-keypad"
- row-gpios: List of gpios used as row lines. The gpio specifier
for this property depends on the gpio controller to
which these row lines are connected.
- col-gpios: List of gpios used as column lines. The gpio specifier
for this property depends on the gpio controller to
which these column lines are connected.
- linux,keymap: The definition can be found at
bindings/input/matrix-keymap.txt
Optional Properties:
- linux,no-autorepeat: do no enable autorepeat feature.
- wakeup-source: use any event on keypad as wakeup event.
(Legacy property supported: "linux,wakeup")
- debounce-delay-ms: debounce interval in milliseconds
- col-scan-delay-us: delay, measured in microseconds, that is needed
before we can scan keypad after activating column gpio
- drive-inactive-cols: drive inactive columns during scan,
default is to turn inactive columns into inputs.
Example:
matrix-keypad {
compatible = "gpio-matrix-keypad";
debounce-delay-ms = <5>;
col-scan-delay-us = <2>;
row-gpios = <&gpio2 25 0
&gpio2 26 0
&gpio2 27 0>;
col-gpios = <&gpio2 21 0
&gpio2 22 0>;
linux,keymap = <0x0000008B
0x0100009E
0x02000069
0x0001006A
0x0101001C
0x0201006C>;
};