[tools] Improvements to BlackMagicProbe tool

- Added a missing import to `modm_tools/bmp.py`
- Changed `guess_serial_port()` to use `/dev/ttyBmpGdb` when guessing a BMP port

tools/modm_tools/bmp.py

@@ -73,6 +73,7 @@ def add_subparser(subparser):
 # -----------------------------------------------------------------------------
 if __name__ == "__main__":
     import argparse
+    import os.path
 
     parser = argparse.ArgumentParser(
         description='Program ELF file or reset device via Black Magic Probe')

tools/modm_tools/utils.py

@@ -50,7 +50,18 @@ def guess_serial_port(port_hint=None):
         else:
             ports = glob.glob('/dev/tty.usb*')
     else:
-        ports = glob.glob('/dev/tty[A-Za-z]*')
+        if port_hint == 'bmp':
+            import os.path
+            # Symlink created by BMP udev rules
+            # https://github.com/blackmagic-debug/blackmagic/blob/main/driver/99-blackmagic-plugdev.rules
+            if os.path.exists('/dev/ttyBmpGdb'):
+                ports = ['/dev/ttyBmpGdb']
+            elif os.path.exists('/dev/ttyACM0'):
+                ports = ['/dev/ttyACM0']
+            else:
+                ports = [None]
+        else:
+            ports = glob.glob('/dev/tty[A-Za-z]*')
     return next(iter(ports), None)