display: Add initial support for LCD screens attached to an MCU

Add support for displaying basic status information on ST7920 and
HD44780 based LCDs that are attached directly to a micro-controller.

Signed-off-by: Marcio Teixeira <marcio@alephobjects.com>
Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

klippy/extras/virtual_sdcard.py

@@ -35,6 +35,11 @@ class VirtualSD:
         except:
             logging.exception("virtual_sdcard get_file_list")
             raise self.gcode.error("Unable to get file list")
+    def get_status(self, eventtime):
+        progress = 0.
+        if self.work_timer is not None and self.file_size:
+            progress = float(self.file_position) / self.file_size
+        return {'progress': progress}
     # G-Code commands
     def cmd_error(self, params):
         raise self.gcode.error("SD write not supported")