Move dwell to gcode

Marlin/src/gcode/control/M3-M5.h

@@ -52,10 +52,10 @@
  */
 
 // Wait for spindle to come up to speed
-inline void delay_for_power_up() { dwell(SPINDLE_LASER_POWERUP_DELAY); }
+inline void delay_for_power_up() { gcode.dwell(SPINDLE_LASER_POWERUP_DELAY); }
 
 // Wait for spindle to stop turning
-inline void delay_for_power_down() { dwell(SPINDLE_LASER_POWERDOWN_DELAY); }
+inline void delay_for_power_down() { gcode.dwell(SPINDLE_LASER_POWERDOWN_DELAY); }
 
 /**
  * ocr_val_mode() is used for debugging and to get the points needed to compute the RPM vs ocr_val line

Marlin/src/gcode/gcode.cpp

@@ -31,12 +31,13 @@ GcodeSuite gcode;
 #include "parser.h"
 #include "queue.h"
 #include "../module/motion.h"
-#include "../module/printcounter.h"
 
 #if ENABLED(PRINTCOUNTER)
   #include "../module/printcounter.h"
 #endif
 
+#include "../Marlin.h" // for idle()
+
 uint8_t GcodeSuite::target_extruder;
 millis_t GcodeSuite::previous_cmd_ms;
 
@@ -99,6 +100,15 @@ void GcodeSuite::get_destination_from_command() {
   #endif
 }
 
+/**
+ * Dwell waits immediately. It does not synchronize. Use M400 instead of G4
+ */
+void GcodeSuite::dwell(millis_t time) {
+  refresh_cmd_timeout();
+  time += previous_cmd_ms;
+  while (PENDING(millis(), time)) idle();
+}
+
 //
 // Placeholders for non-migrated codes
 //

Marlin/src/gcode/gcode.h

@@ -299,6 +299,8 @@ public:
     #define KEEPALIVE_STATE(n) NOOP
   #endif
 
+  void dwell(millis_t time);
+
 private:
 
   static void G0_G1(

Marlin/src/gcode/lcd/M0_M1.h

@@ -67,7 +67,7 @@ void gcode_M0_M1() {
   gcode.refresh_cmd_timeout();
 
   if (ms > 0) {
-    ms += previous_cmd_ms;  // wait until this time for a click
+    ms += gcode.previous_cmd_ms;  // wait until this time for a click
     while (PENDING(millis(), ms) && wait_for_user) idle();
   }
   else {

Marlin/src/gcode/motion/G4.h

@@ -33,5 +33,5 @@ void gcode_G4() {
 
   if (!lcd_hasstatus()) LCD_MESSAGEPGM(MSG_DWELL);
 
-  dwell(dwell_ms);
+  gcode.dwell(dwell_ms);
 }