linux/Documentation/devicetree/bindings/input/lpc32xx-key.txt
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   1NXP LPC32xx Key Scan Interface
   2
   3This binding is based on the matrix-keymap binding with the following
   4changes:
   5
   6Required Properties:
   7- compatible: Should be "nxp,lpc3220-key"
   8- reg: Physical base address of the controller and length of memory mapped
   9  region.
  10- interrupts: The interrupt number to the cpu.
  11- nxp,debounce-delay-ms: Debounce delay in ms
  12- nxp,scan-delay-ms: Repeated scan period in ms
  13- linux,keymap: the key-code to be reported when the key is pressed
  14  and released, see also
  15  Documentation/devicetree/bindings/input/matrix-keymap.txt
  16
  17Note: keypad,num-rows and keypad,num-columns are required, and must be equal
  18since LPC32xx only supports square matrices
  19
  20Example:
  21
  22        key@40050000 {
  23                compatible = "nxp,lpc3220-key";
  24                reg = <0x40050000 0x1000>;
  25                interrupts = <54 0>;
  26                keypad,num-rows = <1>;
  27                keypad,num-columns = <1>;
  28                nxp,debounce-delay-ms = <3>;
  29                nxp,scan-delay-ms = <34>;
  30                linux,keymap = <0x00000002>;
  31        };
  32