usb: raw-gadget: report suspend, resume, reset, and disconnect events

Update USB_RAW_IOCTL_EVENT_FETCH to also report suspend, resume, reset,
and disconnect events.

This allows the code that emulates a USB device via Raw Gadget to handle
these events. For example, the device can restart enumeration when it
gets reset.

Also do not print a WARNING when the event queue overflows. With these new
events being queued, the queue might overflow if the device emulation code
stops fetching events.

Also print debug messages when a non-control event is received.

Signed-off-by: Andrey Konovalov <[e-mail]>
Link: https://lore.kernel.org/r/d6[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/usb/gadget/legacy/raw_gadget.c

···
 	struct usb_raw_event *event;
 
 	spin_lock_irqsave(&queue->lock, flags);
-	if (WARN_ON(queue->size >= RAW_EVENT_QUEUE_SIZE)) {
+	if (queue->size >= RAW_EVENT_QUEUE_SIZE) {
 		spin_unlock_irqrestore(&queue->lock, flags);
 		return -ENOMEM;
 	}
···
 	dev->eps_num = i;
 	spin_unlock_irqrestore(&dev->lock, flags);
 
+	dev_dbg(&gadget->dev, "gadget connected\n");
 	ret = raw_queue_event(dev, USB_RAW_EVENT_CONNECT, 0, NULL);
 	if (ret < 0) {
-		dev_err(&gadget->dev, "failed to queue event\n");
+		dev_err(&gadget->dev, "failed to queue connect event\n");
 		set_gadget_data(gadget, NULL);
 		return ret;
 	}
···
 
 	ret = raw_queue_event(dev, USB_RAW_EVENT_CONTROL, sizeof(*ctrl), ctrl);
 	if (ret < 0)
-		dev_err(&gadget->dev, "failed to queue event\n");
+		dev_err(&gadget->dev, "failed to queue control event\n");
 	goto out;
 
 out_unlock:
···
 	return ret;
 }
 
-/* These are currently unused but present in case UDC driver requires them. */
-static void gadget_disconnect(struct usb_gadget *gadget) { }
-static void gadget_suspend(struct usb_gadget *gadget) { }
-static void gadget_resume(struct usb_gadget *gadget) { }
-static void gadget_reset(struct usb_gadget *gadget) { }
+static void gadget_disconnect(struct usb_gadget *gadget)
+{
+	struct raw_dev *dev = get_gadget_data(gadget);
+	int ret;
+
+	dev_dbg(&gadget->dev, "gadget disconnected\n");
+	ret = raw_queue_event(dev, USB_RAW_EVENT_DISCONNECT, 0, NULL);
+	if (ret < 0)
+		dev_err(&gadget->dev, "failed to queue disconnect event\n");
+}
+static void gadget_suspend(struct usb_gadget *gadget)
+{
+	struct raw_dev *dev = get_gadget_data(gadget);
+	int ret;
+
+	dev_dbg(&gadget->dev, "gadget suspended\n");
+	ret = raw_queue_event(dev, USB_RAW_EVENT_SUSPEND, 0, NULL);
+	if (ret < 0)
+		dev_err(&gadget->dev, "failed to queue suspend event\n");
+}
+static void gadget_resume(struct usb_gadget *gadget)
+{
+	struct raw_dev *dev = get_gadget_data(gadget);
+	int ret;
+
+	dev_dbg(&gadget->dev, "gadget resumed\n");
+	ret = raw_queue_event(dev, USB_RAW_EVENT_RESUME, 0, NULL);
+	if (ret < 0)
+		dev_err(&gadget->dev, "failed to queue resume event\n");
+}
+static void gadget_reset(struct usb_gadget *gadget)
+{
+	struct raw_dev *dev = get_gadget_data(gadget);
+	int ret;
+
+	dev_dbg(&gadget->dev, "gadget reset\n");
+	ret = raw_queue_event(dev, USB_RAW_EVENT_RESET, 0, NULL);
+	if (ret < 0)
+		dev_err(&gadget->dev, "failed to queue reset event\n");
+}
 
 /*----------------------------------------------------------------------*/
 

include/uapi/linux/usb/raw_gadget.h

···
 	/* This event is queued when a new control request arrived to ep0. */
 	USB_RAW_EVENT_CONTROL = 2,
 
+	/*
+	 * These events are queued when the gadget driver is suspended,
+	 * resumed, reset, or disconnected. Note that some UDCs (e.g. dwc2)
+	 * report a disconnect event instead of a reset.
+	 */
+	USB_RAW_EVENT_SUSPEND = 3,
+	USB_RAW_EVENT_RESUME = 4,
+	USB_RAW_EVENT_RESET = 5,
+	USB_RAW_EVENT_DISCONNECT = 6,
+
 	/* The list might grow in the future. */
 };
 
···
  *     actual length of the fetched event data.
  * @data: A buffer to store the fetched event data.
  *
- * Currently the fetched data buffer is empty for USB_RAW_EVENT_CONNECT,
- * and contains struct usb_ctrlrequest for USB_RAW_EVENT_CONTROL.
+ * The fetched event data buffer contains struct usb_ctrlrequest for
+ * USB_RAW_EVENT_CONTROL and is empty for other events.
  */
 struct usb_raw_event {
 	__u32		type;