[PATCH] USB dummy_hcd: Partial OTG emulation

Partial OTG support for dummy_hcd, mostly as a framework for further work.
It emulates the new OTG flags in the host and peripheral frameworks, if
that option is configured.  But it's incomplete:

  - Resetting the peripheral needs to clear the OTG state bits;
    a second enumeration won't work correctly.

  - This stops modeling HNP right when roles should switch the first time.
    It should probably disconnect, then set the usb_bus.is_b_host and
    usb_gadget.is_a_peripheral flags; then it'd enumerate almost normally,
    except for the role reversal.  Roles could then switch a second time,
    back to "normal" (with those flags cleared).

  - SRP should be modeled as "resume from port-unpowered", which is
    a state that usbcore doesn't yet use.

HNP can be triggered by enabling the OTG whitelist and configuring a
gadget driver that's not in that list; or by configuring Gadget Zero
to identify itself as the HNP test device.
Sent-by: David Brownell <david-b@pacbell.net>
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/gadget/dummy_hcd.c

@@ -601,8 +601,10 @@ static int dummy_wakeup (struct usb_gadget *_gadget)
 	struct dummy	*dum;
 
 	dum = gadget_to_dummy (_gadget);
-	if ((dum->devstatus & (1 << USB_DEVICE_REMOTE_WAKEUP)) == 0
-			|| !(dum->port_status & (1 << USB_PORT_FEAT_SUSPEND)))
+	if (!(dum->port_status & (1 << USB_PORT_FEAT_SUSPEND))
+			|| !(dum->devstatus &
+				( (1 << USB_DEVICE_B_HNP_ENABLE)
+				| (1 << USB_DEVICE_REMOTE_WAKEUP))))
 		return -EINVAL;
 
 	/* hub notices our request, issues downstream resume, etc */
@@ -713,6 +715,9 @@ usb_gadget_register_driver (struct usb_gadget_driver *driver)
 	dum->gadget.ops = &dummy_ops;
 	dum->gadget.is_dualspeed = 1;
 
+	/* maybe claim OTG support, though we won't complete HNP */
+	dum->gadget.is_otg = (dummy_to_hcd(dum)->self.otg_port != 0);
+
 	dum->devstatus = 0;
 	dum->resuming = 0;
 
@@ -1215,6 +1220,16 @@ restart:
 					switch (setup.wValue) {
 					case USB_DEVICE_REMOTE_WAKEUP:
 						break;
+					case USB_DEVICE_B_HNP_ENABLE:
+						dum->gadget.b_hnp_enable = 1;
+						break;
+					case USB_DEVICE_A_HNP_SUPPORT:
+						dum->gadget.a_hnp_support = 1;
+						break;
+					case USB_DEVICE_A_ALT_HNP_SUPPORT:
+						dum->gadget.a_alt_hnp_support
+							= 1;
+						break;
 					default:
 						value = -EOPNOTSUPP;
 					}
@@ -1533,6 +1548,13 @@ static int dummy_hub_control (
 					spin_unlock (&dum->lock);
 					dum->driver->suspend (&dum->gadget);
 					spin_lock (&dum->lock);
+					/* HNP would happen here; for now we
+					 * assume b_bus_req is always true.
+					 */
+					if (((1 << USB_DEVICE_B_HNP_ENABLE)
+							& dum->devstatus) != 0)
+						dev_dbg (dummy_dev(dum),
+							"no HNP yet!\n");
 				}
 			}
 			break;
@@ -1648,6 +1670,10 @@ static int dummy_start (struct usb_hcd *hcd)
 	hcd->power_budget = 8;
 	hcd->state = HC_STATE_RUNNING;
 
+#ifdef CONFIG_USB_OTG
+	hcd->self.otg_port = 1;
+#endif
+
 	/* FIXME 'urbs' should be a per-device thing, maybe in usbcore */
 	device_create_file (dummy_dev(dum), &dev_attr_urbs);
 	return 0;