SCARA support in homeaxis

Marlin/Marlin_main.cpp

 #define HOMEAXIS(LETTER) homeaxis(LETTER##_AXIS)
 
 static void homeaxis(AxisEnum axis) {
-  #define CAN_HOME(A) \
-    (axis == A##_AXIS && ((A##_MIN_PIN > -1 && A##_HOME_DIR < 0) || (A##_MAX_PIN > -1 && A##_HOME_DIR > 0)))
 
-  if (!CAN_HOME(X) && !CAN_HOME(Y) && !CAN_HOME(Z)) return;
+  #if IS_SCARA
+    // Only Z homing (with probe) is permitted
+    if (axis != Z_AXIS) { BUZZ(100, 880); return; }
+  #else
+    #define CAN_HOME(A) \
+      (axis == A##_AXIS && ((A##_MIN_PIN > -1 && A##_HOME_DIR < 0) || (A##_MAX_PIN > -1 && A##_HOME_DIR > 0)))
+    if (!CAN_HOME(X) && !CAN_HOME(Y) && !CAN_HOME(Z)) return;
+  #endif
 
   #if ENABLED(DEBUG_LEVELING_FEATURE)
     if (DEBUGGING(LEVELING)) {
     } // Z_AXIS
   #endif
 
-  // Delta has already moved all three towers up in G28
-  // so here it re-homes each tower in turn.
-  // Delta homing treats the axes as normal linear axes.
-  #if ENABLED(DELTA)
+  #if IS_SCARA
+
+    set_axis_is_at_home(axis);
+    SYNC_PLAN_POSITION_KINEMATIC();
+
+  #elif ENABLED(DELTA)
+
+    // Delta has already moved all three towers up in G28
+    // so here it re-homes each tower in turn.
+    // Delta homing treats the axes as normal linear axes.
 
     // retrace by the amount specified in endstop_adj
     if (endstop_adj[axis] * Z_HOME_DIR < 0) {