✨ Fan tachometer support (#23086, #23180, #23199)

Co-Authored-By: Scott Lahteine <github@thinkyhead.com>

Marlin/src/gcode/temp/M123.cpp

@@ -0,0 +1,48 @@
+/**
+ * Marlin 3D Printer Firmware
+ * Copyright (c) 2021 MarlinFirmware [https://github.com/MarlinFirmware/Marlin]
+ *
+ * Based on Sprinter and grbl.
+ * Copyright (c) 2011 Camiel Gubbels / Erik van der Zalm
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "../../inc/MarlinConfig.h"
+
+#if HAS_FANCHECK
+
+#include "../gcode.h"
+#include "../../feature/fancheck.h"
+
+/**
+ * M123: Report fan states -or- set interval for auto-report
+ *
+ *   S<seconds> : Set auto-report interval
+ */
+void GcodeSuite::M123() {
+
+  #if ENABLED(AUTO_REPORT_FANS)
+    if (parser.seenval('S')) {
+      fan_check.auto_reporter.set_interval(parser.value_byte());
+      return;
+    }
+  #endif
+
+  fan_check.print_fan_states();
+
+}
+
+#endif // HAS_FANCHECK