linux/Documentation/devicetree/bindings/input/matrix-keymap.txt
<<
>>
Prefs
   1A simple common binding for matrix-connected key boards. Currently targeted at
   2defining the keys in the scope of linux key codes since that is a stable and
   3standardized interface at this time.
   4
   5Required properties:
   6- linux,keymap: an array of packed 1-cell entries containing the equivalent
   7  of row, column and linux key-code. The 32-bit big endian cell is packed
   8  as:
   9        row << 24 | column << 16 | key-code
  10
  11Optional properties:
  12Properties for the number of rows and columns are optional because some
  13drivers will use fixed values for these.
  14- keypad,num-rows: Number of row lines connected to the keypad controller.
  15- keypad,num-columns: Number of column lines connected to the keypad
  16  controller.
  17
  18Some users of this binding might choose to specify secondary keymaps for
  19cases where there is a modifier key such as a Fn key. Proposed names
  20for said properties are "linux,fn-keymap" or with another descriptive
  21word for the modifier other from "Fn".
  22
  23Example:
  24        linux,keymap = < 0x00030012
  25                         0x0102003a >;
  26        keypad,num-rows = <2>;
  27        keypad,num-columns = <8>;
  28