USB: gadget: composite device-level suspend/resume hooks

Address one open question in the composite gadget framework:
Yes, we should have device-level suspend/resume callbacks
in addition to the function-level ones.  We have at least one
scenario (with gadget zero in OTG test mode) that's awkward
to handle without it.
Signed-off-by: NDavid Brownell <dbrownell@users.sourceforge.net>
Cc: Felipe Balbi <felipe.balbi@nokia.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

drivers/usb/gadget/composite.c

@@ -1014,7 +1014,7 @@ composite_suspend(struct usb_gadget *gadget)
 	struct usb_composite_dev	*cdev = get_gadget_data(gadget);
 	struct usb_function		*f;
 
-	/* REVISIT:  should we have config and device level
+	/* REVISIT:  should we have config level
 	 * suspend/resume callbacks?
 	 */
 	DBG(cdev, "suspend\n");
@@ -1024,6 +1024,8 @@ composite_suspend(struct usb_gadget *gadget)
 				f->suspend(f);
 		}
 	}
+	if (composite->suspend)
+		composite->suspend(cdev);
 }
 
 static void
@@ -1032,10 +1034,12 @@ composite_resume(struct usb_gadget *gadget)
 	struct usb_composite_dev	*cdev = get_gadget_data(gadget);
 	struct usb_function		*f;
 
-	/* REVISIT:  should we have config and device level
+	/* REVISIT:  should we have config level
 	 * suspend/resume callbacks?
 	 */
 	DBG(cdev, "resume\n");
+	if (composite->resume)
+		composite->resume(cdev);
 	if (cdev->config) {
 		list_for_each_entry(f, &cdev->config->functions, list) {
 			if (f->resume)

include/linux/usb/composite.h

@@ -244,6 +244,10 @@ int usb_add_config(struct usb_composite_dev *,
  *	value; it should return zero on successful initialization.
  * @unbind: Reverses @bind(); called as a side effect of unregistering
  *	this driver.
+ * @suspend: Notifies when the host stops sending USB traffic,
+ *	after function notifications
+ * @resume: Notifies configuration when the host restarts USB traffic,
+ *	before function notifications
  *
  * Devices default to reporting self powered operation.  Devices which rely
  * on bus powered operation should report this in their @bind() method.
@@ -268,6 +272,10 @@ struct usb_composite_driver {
 
 	int			(*bind)(struct usb_composite_dev *);
 	int			(*unbind)(struct usb_composite_dev *);
+
+	/* global suspend hooks */
+	void			(*suspend)(struct usb_composite_dev *);
+	void			(*resume)(struct usb_composite_dev *);
 };
 
 extern int usb_composite_register(struct usb_composite_driver *);