qmk-firmware/keyboards/phantom/phantom.c

#include "phantom.h"
#include "led.h"

__attribute__ ((weak))
void matrix_init_user(void) {
	// leave these blank
};

__attribute__ ((weak))
void matrix_scan_user(void) {
	// leave these blank
};

void matrix_init_kb(void) {
	// put your keyboard start-up code here
	// runs once when the firmware starts up
	matrix_init_user();
	led_init_ports();
};

void matrix_scan_kb(void) {
	// put your looping keyboard code here
	// runs every cycle (a lot)
	matrix_scan_user();
};