Allow initVariant()

cores/rp2040/main.cpp

@@ -24,11 +24,18 @@
 extern void setup();
 extern void loop();
 
+
+// Weak empty variant initialization. May be redefined by variant files.
+void initVariant() __attribute__((weak));
+void initVariant() { }
+
 extern "C" int main() {
 #if F_CPU != 125000000
     set_sys_clock_khz(F_CPU / 1000, true);
 #endif
 
+    initVariant();
+
 #ifndef DISABLE_USB_SERIAL
     // Enable serial port for reset/upload always
     Serial.begin();
@@ -37,6 +44,7 @@ extern "C" int main() {
 #if defined DEBUG_RP2040_PORT
     DEBUG_RP2040_PORT.begin();
 #endif
+
     setup();
     while (1) {
         loop();