usbd: Add support for configuration open and reset callbacks.

Implement by overriding USBInterface.handle_open or handle_reset.

Signed-off-by: Angus Gratton <angus@redyak.com.au>

Author: projectgus

micropython/usbd/device.py

@@ -78,7 +78,8 @@ def __init__(self):
             descriptor_device_cb=self._descriptor_device_cb,
             descriptor_config_cb=self._descriptor_config_cb,
             descriptor_string_cb=self._descriptor_string_cb,
-            open_driver_cb=self._open_driver_cb,
+            open_cb=self._open_cb,
+            reset_cb=self._reset_cb,
             control_xfer_cb=self._control_xfer_cb,
             xfer_cb=self._xfer_cb,
         )
@@ -286,9 +287,37 @@ def _descriptor_string_cb(self, index):
         except IndexError:
             return None
 
-    def _open_driver_cb(self, interface_desc_view):
-        # Singleton callback from TinyUSB custom class driver
-        pass
+    def _open_cb(self, interface_desc_view):
+        # Singleton callback from TinyUSB custom class driver, when USB host does
+        # Set Configuration. The "runtime class device" accepts all interfaces that
+        # it has sent in descriptors, and calls this callback.
+
+        # Walk the view of the "claimed" descriptor data provided in the
+        # callback and call handle_open() on each claimed interface
+        #
+        # ... this may be unnecessary at the moment, as only one configuration is supported so we
+        # can probably assume all the interfaces will be included.
+        i = 0
+        while i < len(interface_desc_view):
+            # descriptor length, type, and index (if it's an interface descriptor)
+            dl, dt, di = interface_desc_view[i:i+3]
+            if dt == _STD_DESC_INTERFACE_TYPE:
+                if di >= self._usbd.static.itf_max:
+                    di -= self._usbd.static.itf_max
+                self._itfs[di].handle_open()
+            i += dl
+            assert dl
+
+    def _reset_cb(self):
+        # Callback when the USB device is reset by the host
+
+        # Cancel outstanding transfer callbacks
+        for k in self._ep_cbs.keys():
+            self._ep_cbs[k] = None
+
+        # Allow interfaces to respond to the reset
+        for itf in self._itfs:
+            itf.handle_reset()
 
     def _submit_xfer(self, ep_addr, data, done_cb=None):
         # Singleton function to submit a USB transfer (of any type except control).
@@ -387,6 +416,7 @@ def __init__(
         self.bInterfaceSubClass = bInterfaceSubClass
         self.bInterfaceProtocol = bInterfaceProtocol
         self.interface_str = interface_str
+        self._open = False
 
     def get_itf_descriptor(self, num_eps, itf_idx, str_idx):
         # Return the interface descriptor binary data and associated other
@@ -466,6 +496,27 @@ def get_endpoint_descriptors(self, ep_addr, str_idx):
         #   start from ep_addr, optionally with the utils.EP_IN_FLAG bit set.)
         return (b"", [], [])
 
+    def handle_open(self):
+        # Callback called when the USB host accepts the device configuration.
+        #
+        # Override this function to initiate any operations that the USB interface
+        # should do when the USB device is configured to the host.
+        self._open = True
+
+    def handle_reset(self):
+        # Callback called on every registered interface when the USB device is
+        # reset by the host. This can happen when the USB device is unplugged,
+        # or if the host triggers a reset for some other reason.
+        #
+        # At this point, no USB functionality is available - handle_open() will
+        # be called later if/when the USB host re-enumerates and configures the
+        # interface.
+        self._open = False
+
+    def is_open(self):
+        # Returns True if the interface is in use
+        return self._open
+
     def handle_device_control_xfer(self, stage, request):
         # Control transfer callback. Override to handle a non-standard device
         # control transfer where bmRequestType Recipient is Device, Type is
@@ -486,11 +537,11 @@ def handle_device_control_xfer(self, stage, request):
         # The function can call split_bmRequestType() to split bmRequestType into
         # (Recipient, Type, Direction).
         #
-        # Result:
+        # Result, any of:
         #
-        # - True to continue the request False to STALL the endpoint A buffer
-        # - interface object to provide a buffer to the host as part of the
-        # - transfer, if possible.
+        # - True to continue the request, False to STALL the endpoint.
+        # - Buffer interface object to provide a buffer to the host as part of the
+        #   transfer, if possible.
         return False
 
     def handle_interface_control_xfer(self, stage, request):
@@ -512,7 +563,8 @@ def handle_interface_control_xfer(self, stage, request):
     def handle_endpoint_control_xfer(self, stage, request):
         # Control transfer callback. Override to handle a device
         # control transfer where bmRequestType Recipient is Endpoint and
-        # the lower byte of wIndex indicates an endpoint address associated with this interface.
+        # the lower byte of wIndex indicates an endpoint address associated
+        # with this interface.
         #
         # bmRequestType Type will generally have any value except
         # utils.REQ_TYPE_STANDARD, as Standard endpoint requests are handled by
@@ -546,4 +598,6 @@ def submit_xfer(self, ep_addr, data, done_cb=None):
         #
         # Note that done_cb may be called immediately, possibly before this
         # function has returned to the caller.
+        if not self._open:
+            raise RuntimeError()
         return get_usbdevice()._submit_xfer(ep_addr, data, done_cb)