correct handling of report ids

[hackapet/Adafruit_Blinka.git] / src / usb_hid.py

diff --git a/src/usb_hid.py b/src/usb_hid.py
index 3f526cc08b556afc15ff0c77f0583c336fd1012f..1bf6c3e273f593709ee1f0704656f4d1cdcde76c 100644 (file)
--- a/src/usb_hid.py
+++ b/src/usb_hid.py
@@ -1,87 +1,298 @@
+"""
+`usb_hid` - support for usb hid devices via usb_gadget driver
+===========================================================
+See `CircuitPython:usb_hid` in CircuitPython for more details.
+For now using report ids in the descriptor
+
+* Author(s): Björn Bösel
+"""
+

 from typing import Sequence
 from pathlib import Path
 from typing import Sequence
 from pathlib import Path

+import os

 import atexit
 
 # https://www.kernel.org/doc/Documentation/usb/gadget_configfs.txt
 
 import atexit
 
 # https://www.kernel.org/doc/Documentation/usb/gadget_configfs.txt
 

-gadget_root = '/sys/kernel/config/usb_gadget/adafruit-blinka'
+gadget_root = "/sys/kernel/config/usb_gadget/adafruit-blinka"
+

 
 

+class Device:
+    """HID Device specification: see https://github.com/adafruit/circuitpython/blob/main/shared-bindings/usb_hid/Device.c"""

 
 

-class Device():
-    def __init__(self, *, descriptor: bytes, usage_page: int, usage: int, report_ids: Sequence[int],
-                 in_report_lengths: Sequence[int], out_report_lengths: Sequence[int]) -> None:
+    def __init__(
+        self,
+        *,
+        descriptor: bytes,
+        usage_page: int,
+        usage: int,
+        report_ids: Sequence[int],
+        in_report_lengths: Sequence[int],
+        out_report_lengths: Sequence[int],
+    ) -> None:

         self.out_report_lengths = out_report_lengths
         self.in_report_lengths = in_report_lengths
         self.report_ids = report_ids
         self.usage = usage
         self.usage_page = usage_page
         self.descriptor = descriptor
         self.out_report_lengths = out_report_lengths
         self.in_report_lengths = in_report_lengths
         self.report_ids = report_ids
         self.usage = usage
         self.usage_page = usage_page
         self.descriptor = descriptor

-        self.handle = ''
+        self._last_received_report = None

 
     def send_report(self, report: bytearray, report_id: int = None):
 
     def send_report(self, report: bytearray, report_id: int = None):

-        device = Path('%s/functions/hid.usb%s/dev' % (gadget_root, report_id or self.report_ids[0])).read_text().strip().split(':')[1]
-        with open('/dev/hidg%s' % device, 'rb+') as fd:
-            fd.write(report)
+        device_path = self.gets_device_path(report_id)
+        with open(device_path, "rb+") as fd:
+            fd.write(bytearray(report_id) + report)
+
+    @property
+    def last_received_report(
+        self,
+    ):
+        device_path = self.gets_device_path(self.report_ids[0])
+        with open(device_path, "rb+") as fd:
+            os.set_blocking(fd.fileno(), False)
+            report = fd.read(self.out_report_lengths[0])
+            if report is not None:
+                self._last_received_report = report
+        return self._last_received_report
+
+    def gets_device_path(self, report_id):
+        device = (
+            Path(
+                "%s/functions/hid.usb%s/dev"
+                % (gadget_root, report_id or self.report_ids[0])
+            )
+            .read_text()
+            .strip()
+            .split(":")[1]
+        )
+        device_path = "/dev/hidg%s" % device
+        return device_path

 
 
 Device.KEYBOARD = Device(
 
 
 Device.KEYBOARD = Device(

-    descriptor=bytes((
-        0x05, 0x01, 0x09, 0x06, 0xa1, 0x01, 0x05, 0x07, 0x19, 0xe0, 0x29, 0xe7, 0x15, 0x00, 0x25, 0x01, 0x75, 0x01, 0x95, 0x08, 0x81, 0x02, 0x75, 0x08, 0x95, 0x01, 0x81, 0x01, 0x75, 0x01, 0x95, 0x03, 0x05, 0x08, 0x19, 0x01, 0x29, 0x03, 0x91, 0x02, 0x75, 0x01, 0x95, 0x05, 0x91, 0x01, 0x75, 0x08, 0x95, 0x06, 0x15, 0x00, 0x26, 0xff, 0x00, 0x05, 0x07, 0x19, 0x00, 0x2a, 0xff, 0x00, 0x81, 0x00, 0xc0
-    )),
+    descriptor=bytes(
+        (
+            0x05,
+            0x01,  # usage page (generic desktop ctrls)
+            0x09,
+            0x06,  # usage (keyboard)
+            0xA1,
+            0x01,  # collection (application)
+            0x85,
+            0x01,  # Report ID (1)
+            0x05,
+            0x07,  # usage page (kbrd/keypad)
+            0x19,
+            0xE0,  # usage minimum (0xe0)
+            0x29,
+            0xE7,  # usage maximum (0xe7)
+            0x15,
+            0x00,  # logical minimum (0)
+            0x25,
+            0x01,  # logical maximum (1)
+            0x75,
+            0x01,  # report size (1)
+            0x95,
+            0x08,  # report count (8)
+            0x81,
+            0x02,  # input (data,var,abs,no wrap,linear,preferred state,no null position)
+            0x95,
+            0x01,  # report count (1)
+            0x75,
+            0x08,  # report size (8)
+            0x81,
+            0x01,  # input (const,array,abs,no wrap,linear,preferred state,no null position)
+            0x95,
+            0x03,  # report count (3)
+            0x75,
+            0x01,  # report size (1)
+            0x05,
+            0x08,  # usage page (leds)
+            0x19,
+            0x01,  # usage minimum (num lock)
+            0x29,
+            0x05,  # usage maximum (kana)
+            0x91,
+            0x02,  # output (data,var,abs,no wrap,linear,preferred state,no null position,non-volatile)
+            0x95,
+            0x01,  # report count (1)
+            0x75,
+            0x05,  # report size (5)
+            0x91,
+            0x01,  # output (const,array,abs,no wrap,linear,preferred state,no null position,non-volatile)
+            0x95,
+            0x06,  # report count (6)
+            0x75,
+            0x08,  # report size (8)
+            0x15,
+            0x00,  # logical minimum (0)
+            0x26,
+            0xFF,
+            0x00,  # logical maximum (255)
+            0x05,
+            0x07,  # usage page (kbrd/keypad)
+            0x19,
+            0x00,  # usage minimum (0x00)
+            0x2A,
+            0xFF,
+            0x00,  # usage maximum (0xff)
+            0x81,
+            0x00,  # input (data,array,abs,no wrap,linear,preferred state,no null position)
+            0xC0,  # end collection
+        )
+    ),

     usage_page=0x1,
     usage=0x6,
     usage_page=0x1,
     usage=0x6,

-    report_ids=[1],
+    report_ids=[0x1],

     in_report_lengths=[8],
     in_report_lengths=[8],

-    out_report_lengths=[1]
+    out_report_lengths=[1],

 )
 Device.MOUSE = Device(
 )
 Device.MOUSE = Device(

-    descriptor=b"05010906a101050719e029e71500250175019508810275089501810175019503050819012903910275019505910175089506150026ff00050719002aff008100c0",
+    descriptor=bytes(
+        (
+            0x05,
+            0x01,  # Usage Page (Generic Desktop Ctrls)
+            0x09,
+            0x02,  # Usage (Mouse)
+            0xA1,
+            0x01,  # Collection (Application)
+            0x85,
+            0x02,  # Report ID (2)
+            0x09,
+            0x01,  # Usage (Pointer)
+            0xA1,
+            0x00,  # Collection (Physical)
+            0x05,
+            0x09,  # Usage Page (Button)
+            0x19,
+            0x01,  # Usage Minimum (0x01)
+            0x29,
+            0x05,  # Usage Maximum (0x05)
+            0x15,
+            0x00,  # Logical Minimum (0)
+            0x25,
+            0x01,  # Logical Maximum (1)
+            0x95,
+            0x05,  # Report Count (5)
+            0x75,
+            0x01,  # Report Size (1)
+            0x81,
+            0x02,  # Input (Data,Var,Abs,No Wrap,Linear,Preferred State,No Null Position)
+            0x95,
+            0x01,  # Report Count (1)
+            0x75,
+            0x03,  # Report Size (3)
+            0x81,
+            0x01,  # Input (Const,Array,Abs,No Wrap,Linear,Preferred State,No Null Position)
+            0x05,
+            0x01,  # Usage Page (Generic Desktop Ctrls)
+            0x09,
+            0x30,  # Usage (X)
+            0x09,
+            0x31,  # Usage (Y)
+            0x15,
+            0x81,  # Logical Minimum (-127)
+            0x25,
+            0x7F,  # Logical Maximum (127)
+            0x75,
+            0x08,  # Report Size (8)
+            0x95,
+            0x02,  # Report Count (2)
+            0x81,
+            0x06,  # Input (Data,Var,Rel,No Wrap,Linear,Preferred State,No Null Position)
+            0x09,
+            0x38,  # Usage (Wheel)
+            0x15,
+            0x81,  # Logical Minimum (-127)
+            0x25,
+            0x7F,  # Logical Maximum (127)
+            0x75,
+            0x08,  # Report Size (8)
+            0x95,
+            0x01,  # Report Count (1)
+            0x81,
+            0x06,  # Input (Data,Var,Rel,No Wrap,Linear,Preferred State,No Null Position)
+            0xC0,  # End Collection
+            0xC0,  # End Collection
+        )
+    ),

     # Omitted for brevity.
     usage_page=0x1,
     usage=0x02,
     report_ids=[2],
     # Omitted for brevity.
     usage_page=0x1,
     usage=0x02,
     report_ids=[2],

-    in_report_lengths=[8],
-    out_report_lengths=[1],
+    in_report_lengths=[4],
+    out_report_lengths=[0],

 )
 
 Device.CONSUMER_CONTROL = Device(
 )
 
 Device.CONSUMER_CONTROL = Device(

-    descriptor=b"05010906a101050719e029e71500250175019508810275089501810175019503050819012903910275019505910175089506150026ff00050719002aff008100c0",
+    descriptor=bytes(
+        (
+            0x05,
+            0x0C,  # Usage Page (Consumer)
+            0x09,
+            0x01,  # Usage (Consumer Control)
+            0xA1,
+            0x01,  # Collection (Application)
+            0x85,
+            0x03,  # Report ID (3)
+            0x75,
+            0x10,  # Report Size (16)
+            0x95,
+            0x01,  # Report Count (1)
+            0x15,
+            0x01,  # Logical Minimum (1)
+            0x26,
+            0x8C,
+            0x02,  # Logical Maximum (652)
+            0x19,
+            0x01,  # Usage Minimum (Consumer Control)
+            0x2A,
+            0x8C,
+            0x02,  # Usage Maximum (AC Send)
+            0x81,
+            0x00,  # Input (Data,Array,Abs,No Wrap,Linear,Preferred State,No Null Position)
+            0xC0,  # End Collection
+        )
+    ),

     # Omitted for brevity.
     usage_page=0x0C,
     usage=0x01,
     report_ids=[3],
     # Omitted for brevity.
     usage_page=0x0C,
     usage=0x01,
     report_ids=[3],

-    in_report_lengths=[1],
-    out_report_lengths=[8],
+    in_report_lengths=[2],
+    out_report_lengths=[0],

 )
 devices = [Device.KEYBOARD, Device.MOUSE, Device.CONSUMER_CONTROL]
 
 
 def disable() -> None:
     try:
 )
 devices = [Device.KEYBOARD, Device.MOUSE, Device.CONSUMER_CONTROL]
 
 
 def disable() -> None:
     try:

-        Path('%s/UDC' % gadget_root).write_text('')
+        Path("%s/UDC" % gadget_root).write_text("")

     except FileNotFoundError:
         pass
     except FileNotFoundError:
         pass

-    for symlink in Path(gadget_root).glob('configs/**/hid.usb*'):
+    for symlink in Path(gadget_root).glob("configs/**/hid.usb*"):

         symlink.unlink()
 
         symlink.unlink()
 

-    for strings_file in Path(gadget_root).rglob('configs/*/strings/*/*'):
+    for strings_file in Path(gadget_root).rglob("configs/*/strings/*/*"):

         if strings_file.is_dir():
             strings_file.rmdir()
 
         if strings_file.is_dir():
             strings_file.rmdir()
 

-    for strings_file in Path(gadget_root).rglob('configs/*/strings/*'):
+    for strings_file in Path(gadget_root).rglob("configs/*/strings/*"):

         if strings_file.is_dir():
             strings_file.rmdir()
         if strings_file.is_dir():
             strings_file.rmdir()

-    for config_dir in Path(gadget_root).rglob('configs/*'):
+    for config_dir in Path(gadget_root).rglob("configs/*"):

         if config_dir.is_dir():
             config_dir.rmdir()
         if config_dir.is_dir():
             config_dir.rmdir()

-    for function_dir in Path(gadget_root).rglob('functions/*'):
+    for function_dir in Path(gadget_root).rglob("functions/*"):

         if function_dir.is_dir():
             function_dir.rmdir()
     try:
         Path(gadget_root).rmdir()
     except:
         pass
         if function_dir.is_dir():
             function_dir.rmdir()
     try:
         Path(gadget_root).rmdir()
     except:
         pass

-atexit.register(disable)
+
+
+# atexit.register(disable)
+

 
 def enable(devices: Sequence[Device], boot_device: int = 0) -> None:
     if len(devices) == 0:
 
 def enable(devices: Sequence[Device], boot_device: int = 0) -> None:
     if len(devices) == 0:


@@ -90,106 +301,112 @@ def enable(devices: Sequence[Device], boot_device: int = 0) -> None:
     """
     1. Creating the gadgets
     -----------------------
     """
     1. Creating the gadgets
     -----------------------

-    
+

     For each gadget to be created its corresponding directory must be created::
     For each gadget to be created its corresponding directory must be created::

-    
+

         $ mkdir $CONFIGFS_HOME/usb_gadget/<gadget name>
         $ mkdir $CONFIGFS_HOME/usb_gadget/<gadget name>

-    
+

     e.g.::
     e.g.::

-    
+

         $ mkdir $CONFIGFS_HOME/usb_gadget/g1
         $ mkdir $CONFIGFS_HOME/usb_gadget/g1

-    
+

         ...
         ...
         ...
         ...
         ...
         ...

-    
+

         $ cd $CONFIGFS_HOME/usb_gadget/g1
         $ cd $CONFIGFS_HOME/usb_gadget/g1

-    
+

     Each gadget needs to have its vendor id <VID> and product id <PID> specified::
     Each gadget needs to have its vendor id <VID> and product id <PID> specified::

-    
+

         $ echo <VID> > idVendor
         $ echo <PID> > idProduct
         $ echo <VID> > idVendor
         $ echo <PID> > idProduct

-    
+

     A gadget also needs its serial number, manufacturer and product strings.
     In order to have a place to store them, a strings subdirectory must be created
     for each language, e.g.::
     A gadget also needs its serial number, manufacturer and product strings.
     In order to have a place to store them, a strings subdirectory must be created
     for each language, e.g.::

-    
+

         $ mkdir strings/0x409
         $ mkdir strings/0x409

-    
+

     Then the strings can be specified::
     Then the strings can be specified::

-    
+

         $ echo <serial number> > strings/0x409/serialnumber
         $ echo <manufacturer> > strings/0x409/manufacturer
         $ echo <product> > strings/0x409/product
     """
         $ echo <serial number> > strings/0x409/serialnumber
         $ echo <manufacturer> > strings/0x409/manufacturer
         $ echo <product> > strings/0x409/product
     """

-    Path('%s/functions' % gadget_root).mkdir(parents=True, exist_ok=True)
-    Path('%s/configs' % gadget_root).mkdir(parents=True, exist_ok=True)
-    Path('%s/bcdDevice' % gadget_root).write_text('%s' % 1)  # Version 1.0.0
-    Path('%s/bcdUSB' % gadget_root).write_text('%s' % 0x0200)  # USB 2.0
-    Path('%s/bDeviceClass' % gadget_root).write_text('%s' % 0xEF)  # multipurpose i guess?
-    Path('%s/bDeviceProtocol' % gadget_root).write_text('%s' % 0x01)
-    Path('%s/bDeviceSubClass' % gadget_root).write_text('%s' % 0x02)
-    Path('%s/bMaxPacketSize0' % gadget_root).write_text('%s' % 0x08)
-    Path('%s/idProduct' % gadget_root).write_text('%s' % 0x0104)  # Multifunction Composite Gadget
-    Path('%s/idVendor' % gadget_root).write_text('%s' % 0x1d6b)  # Linux Foundation
+    Path("%s/functions" % gadget_root).mkdir(parents=True, exist_ok=True)
+    Path("%s/configs" % gadget_root).mkdir(parents=True, exist_ok=True)
+    Path("%s/bcdDevice" % gadget_root).write_text("%s" % 1)  # Version 1.0.0
+    Path("%s/bcdUSB" % gadget_root).write_text("%s" % 0x0200)  # USB 2.0
+    Path("%s/bDeviceClass" % gadget_root).write_text(
+        "%s" % 0x00
+    )  # multipurpose i guess?
+    Path("%s/bDeviceProtocol" % gadget_root).write_text("%s" % 0x00)
+    Path("%s/bDeviceSubClass" % gadget_root).write_text("%s" % 0x00)
+    Path("%s/bMaxPacketSize0" % gadget_root).write_text("%s" % 0x08)
+    Path("%s/idProduct" % gadget_root).write_text(
+        "%s" % 0x0104
+    )  # Multifunction Composite Gadget
+    Path("%s/idVendor" % gadget_root).write_text("%s" % 0x1D6B)  # Linux Foundation

     """
     2. Creating the configurations
     ------------------------------
     """
     2. Creating the configurations
     ------------------------------

-    
+

     Each gadget will consist of a number of configurations, their corresponding
     directories must be created:
     Each gadget will consist of a number of configurations, their corresponding
     directories must be created:

-    
+

     $ mkdir configs/<name>.<number>
     $ mkdir configs/<name>.<number>

-    
+

     where <name> can be any string which is legal in a filesystem and the
     <number> is the configuration's number, e.g.::
     where <name> can be any string which is legal in a filesystem and the
     <number> is the configuration's number, e.g.::

-    
+

         $ mkdir configs/c.1
         $ mkdir configs/c.1

-    
+

         ...
         ...
         ...
         ...
         ...
         ...

-    
+

     Each configuration also needs its strings, so a subdirectory must be created
     for each language, e.g.::
     Each configuration also needs its strings, so a subdirectory must be created
     for each language, e.g.::

-    
+

         $ mkdir configs/c.1/strings/0x409
         $ mkdir configs/c.1/strings/0x409

-    
+

     Then the configuration string can be specified::
     Then the configuration string can be specified::

-    
+

         $ echo <configuration> > configs/c.1/strings/0x409/configuration
         $ echo <configuration> > configs/c.1/strings/0x409/configuration

-    
+

     Some attributes can also be set for a configuration, e.g.::
     Some attributes can also be set for a configuration, e.g.::

-    
+

         $ echo 120 > configs/c.1/MaxPower
         """
 
     for i, device in enumerate(devices):
         $ echo 120 > configs/c.1/MaxPower
         """
 
     for i, device in enumerate(devices):

-        config_root = '%s/configs/device.%s' % (gadget_root, i + 1)
-        Path('%s/' % config_root).mkdir(parents=True, exist_ok=True)
-        Path('%s/strings/0x409' % config_root).mkdir(parents=True, exist_ok=True)
-        Path('%s/strings/0x409/configuration' % config_root).write_text('my configuration')
-        Path('%s/MaxPower' % config_root).write_text('150')
-        Path('%s/bmAttributes' % config_root).write_text('%s' % 0x080)

 
 

+        config_root = "%s/configs/device.%s" % (gadget_root, 1)
+        Path("%s/" % config_root).mkdir(parents=True, exist_ok=True)
+        Path("%s/strings/0x409" % config_root).mkdir(parents=True, exist_ok=True)
+        Path("%s/strings/0x409/configuration" % config_root).write_text(
+            "my configuration"
+        )
+        Path("%s/MaxPower" % config_root).write_text("150")
+        Path("%s/bmAttributes" % config_root).write_text("%s" % 0x080)

         """
         3. Creating the functions
         -------------------------
         """
         3. Creating the functions
         -------------------------

-        
+

         The gadget will provide some functions, for each function its corresponding
         directory must be created::
         The gadget will provide some functions, for each function its corresponding
         directory must be created::

-        
+

             $ mkdir functions/<name>.<instance name>
             $ mkdir functions/<name>.<instance name>

-        
+

         where <name> corresponds to one of allowed function names and instance name
         is an arbitrary string allowed in a filesystem, e.g.::
         where <name> corresponds to one of allowed function names and instance name
         is an arbitrary string allowed in a filesystem, e.g.::

-        
+

           $ mkdir functions/ncm.usb0 # usb_f_ncm.ko gets loaded with request_module()
           $ mkdir functions/ncm.usb0 # usb_f_ncm.ko gets loaded with request_module()

-        
+

           ...
           ...
           ...
           ...
           ...
           ...

-        
+

         Each function provides its specific set of attributes, with either read-only
         or read-write access. Where applicable they need to be written to as
         appropriate.
         Each function provides its specific set of attributes, with either read-only
         or read-write access. Where applicable they need to be written to as
         appropriate.


@@ -199,48 +416,50 @@ def enable(devices: Sequence[Device], boot_device: int = 0) -> None:
 
         # create functions
         for report_index, report_id in enumerate(device.report_ids):
 
         # create functions
         for report_index, report_id in enumerate(device.report_ids):

-            function_root = '%s/functions/hid.usb%s' % (gadget_root, report_id)
+            function_root = "%s/functions/hid.usb%s" % (gadget_root, report_id)

             try:
             try:

-                Path('%s/' % function_root).mkdir(parents=True)
+                Path("%s/" % function_root).mkdir(parents=True)

             except FileExistsError:
                 continue
             except FileExistsError:
                 continue

-            Path('%s/protocol' % function_root).write_text('%s' % 1)
-            Path('%s/report_length' % function_root).write_text('%s' % device.in_report_lengths[report_index])
-            Path('%s/subclass' % function_root).write_text('%s' % 1)
-            Path('%s/report_desc' % function_root).write_bytes(device.descriptor)
+            Path("%s/protocol" % function_root).write_text("%s" % report_id)
+            Path("%s/report_length" % function_root).write_text(
+                "%s" % device.in_report_lengths[report_index]
+            )
+            Path("%s/subclass" % function_root).write_text("%s" % 1)
+            Path("%s/report_desc" % function_root).write_bytes(device.descriptor)

             """
             4. Associating the functions with their configurations
             ------------------------------------------------------
             """
             4. Associating the functions with their configurations
             ------------------------------------------------------

-            
+

             At this moment a number of gadgets is created, each of which has a number of
             configurations specified and a number of functions available. What remains
             is specifying which function is available in which configuration (the same
             function can be used in multiple configurations). This is achieved with
             creating symbolic links::
             At this moment a number of gadgets is created, each of which has a number of
             configurations specified and a number of functions available. What remains
             is specifying which function is available in which configuration (the same
             function can be used in multiple configurations). This is achieved with
             creating symbolic links::

-            
+

                 $ ln -s functions/<name>.<instance name> configs/<name>.<number>
                 $ ln -s functions/<name>.<instance name> configs/<name>.<number>

-            
+

             e.g.::
             e.g.::

-            
+

                 $ ln -s functions/ncm.usb0 configs/c.1
             """
 
                 $ ln -s functions/ncm.usb0 configs/c.1
             """
 

-            Path('%s/hid.usb%s' % (config_root, report_id)).symlink_to(function_root)
+            Path("%s/hid.usb%s" % (config_root, report_id)).symlink_to(function_root)

     """
     5. Enabling the gadget
     ----------------------
     Such a gadget must be finally enabled so that the USB host can enumerate it.
     """
     5. Enabling the gadget
     ----------------------
     Such a gadget must be finally enabled so that the USB host can enumerate it.

-    
+

     In order to enable the gadget it must be bound to a UDC (USB Device
     Controller)::
     In order to enable the gadget it must be bound to a UDC (USB Device
     Controller)::

-    
+

         $ echo <udc name> > UDC
         $ echo <udc name> > UDC

-    
+

     where <udc name> is one of those found in /sys/class/udc/*
     e.g.::
 
     $ echo s3c-hsotg > UDC
 
     """
     where <udc name> is one of those found in /sys/class/udc/*
     e.g.::
 
     $ echo s3c-hsotg > UDC
 
     """

-    udc = next(Path('/sys/class/udc/').glob('*'))
-    Path('%s/UDC' % gadget_root).write_text('%s' % udc.name)
+    udc = next(Path("/sys/class/udc/").glob("*"))
+    Path("%s/UDC" % gadget_root).write_text("%s" % udc.name)