add python handler

README.md

@@ -62,4 +62,7 @@ https://github.com/torvalds/linux/blob/master/drivers/usb/core/quirks.c
 
 https://docs.kernel.org/admin-guide/reporting-issues.html
 
-https://kernel.org/category/faq.html
+https://kernel.org/category/faq.html
+
+https://bugzilla.kernel.org/show_bug.cgi?id=220422
+

src/dymott.py

@@ -1,6 +1,50 @@
 import usb.core
 import usb.util
 
-dymo_vid = 0x0922
-dymo_tt_pid = 0x0018
+dymo_vid = 0x0922       # Dymo vendor ID
+dymo_tt_pid = 0x0018    # Dymo Twin Turbo Product ID
+dymo_450_pid = 0x0020   # Dymo 450 Product ID
+
+dymo_tt = usb.core.find(idVendor=dymo_vid, idProduct=dymo_tt_pid)
+dymo_450 = usb.core.find(idVendor=dymo_vid, idProduct=dymo_450_pid)
+
+#dymo_tt.serial_number    # Prints device unique ID
+#dymo_tt.langids          # Returns language IDs (1033,) for english
+
+# Get descriptor for serial number
+# fields: dymo_tt - reference to device to get the data from
+#         254 - max buffer for received data (254 max, 30 expected for serial number)
+#         0x03 - Data type - 0x03 = string data
+#         dymo_tt.iSerialNumber - index of serial number data (0x03)
+#         dymo_tt.langids[0] - First item from supported languages (1033)
+#usb.control.get_descriptor(dymo_tt, 254, 0x03, dymo_tt.iSerialNumber, dymo_tt.langids[0])
+#usb.control.get_descriptor(dymo_450, 254, 0x03, dymo_450.iSerialNumber, dymo_450.langids[0])
+dymo_tt_serialdata = usb.control.get_descriptor(dymo_tt, 30, 0x03, 0x03, 1033)
+dymo_450_serialdata = usb.control.get_descriptor(dymo_450, 30, 0x03, 0x03, 1033)
+
+#print(dymo_tt_serialdata.hex())
+#print(dymo_450_serialdata.hex())
+
+# returns the string representation of the serial number received from the device
+#print(dymo_tt_serialdata[2:len(dymo_tt_serialdata)].decode('utf-16-le'))
+#print(dymo_450_serialdata[2:30].decode('utf-16-le'))
+
+# returns raw bytes representation of encoded data
+#print(dymo_tt_serialdata[2:30].decode('utf-8'))
+#print(dymo_450_serialdata[2:30].decode('utf-8'))
+
+def get_serial_raw(dev):
+    return usb.control.get_descriptor(dev, 254, usb.DT_STRING, dev.iSerialNumber, dev.langids[0])
+
+def get_serial(dev):
+    rawserial = get_serial_raw(dev)
+    # Return just the data portion of the descriptor data
+    # First byte is length of returned data, second byte is type of returned data (30 and 3 expected)
+    rawserial = rawserial[2:len(rawserial)].tobytes()
+    if dev.idVendor == 0x0922 and dev.idProduct == 0x0018:
+        # Because the Twin Turbo returns invalid serial data, we drop the first 2 bytes
+        # and decode the remainder as utf-16-be (big-endian)
+        return rawserial[2:len(rawserial)].decode('utf-16-be')
+    else:
+        return rawserial.decode('utf-16-le')