Add M524 to abort SD printing (#12155)

Marlin/src/gcode/gcode.cpp

@@ -584,6 +584,10 @@ void GcodeSuite::process_parsed_command(
         case 504: M504(); break;                                  // M504: Validate EEPROM contents
       #endif
 
+      #if ENABLED(SDSUPPORT)
+        case 524: M524(); break;                                   // M524: Abort the current SD print job
+      #endif
+      
       #if ENABLED(ABORT_ON_ENDSTOP_HIT_FEATURE_ENABLED)
         case 540: M540(); break;                                  // M540: Set abort on endstop hit for SD printing
       #endif

Marlin/src/gcode/gcode.h

@@ -202,6 +202,7 @@
  * M501 - Restore parameters from EEPROM. (Requires EEPROM_SETTINGS)
  * M502 - Revert to the default "factory settings". ** Does not write them to EEPROM! **
  * M503 - Print the current settings (in memory): "M503 S<verbose>". S0 specifies compact output.
+ * M524 - Abort the current SD print job (started with M24)
  * M540 - Enable/disable SD card abort on endstop hit: "M540 S<state>". (Requires ABORT_ON_ENDSTOP_HIT_FEATURE_ENABLED)
  * M600 - Pause for filament change: "M600 X<pos> Y<pos> Z<raise> E<first_retract> L<later_retract>". (Requires ADVANCED_PAUSE_FEATURE)
  * M603 - Configure filament change: "M603 T<tool> U<unload_length> L<load_length>". (Requires ADVANCED_PAUSE_FEATURE)
@@ -719,6 +720,10 @@ private:
     static void M504();
   #endif
 
+  #if ENABLED(SDSUPPORT)
+    static void M524();
+  #endif
+    
   #if ENABLED(ABORT_ON_ENDSTOP_HIT_FEATURE_ENABLED)
     static void M540();
   #endif

Marlin/src/gcode/sdcard/M20-M30_M32-M34_M524_M928.cpp

@@ -244,6 +244,13 @@ void GcodeSuite::M32() {
 
 #endif // SDCARD_SORT_ALPHA && SDSORT_GCODE
 
+/**
+ * M524: Abort the current SD print job (started with M24)
+ */
+void GcodeSuite::M524() {
+  if (IS_SD_PRINTING()) card.abort_sd_printing = true;
+}
+
 /**
  * M928: Start SD Write
  */