qmk_firmware/keyboards/touchpad/touchpad.h

#pragma once
#include "quantum.h"

#define LAYOUT_ortho_6x6( \
    K00, K01, K02, K03, K04, K05, \
    K10, K11, K12, K13, K14, K15, \
    K20, K21, K22, K23, K24, K25, \
    K30, K31, K32, K33, K34, K35, \
    K40, K41, K42, K43, K44, K45, \
    K50, K51, K52, K53, K54, K55  \
) \
{ \
    { K00, K01, K02, K03, K04, K05 }, \
    { K10, K11, K12, K13, K14, K15 }, \
    { K20, K21, K22, K23, K24, K25 }, \
    { K30, K31, K32, K33, K34, K35 }, \
    { K40, K41, K42, K43, K44, K45 }, \
    { K50, K51, K52, K53, K54, K55 }  \
}