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List:       linux-usb-devel
Subject:    [linux-usb-devel] [PATCH as519] dummy_hcd: Partial OTG emulation
From:       Alan Stern <stern () rowland ! harvard ! edu>
Date:       2005-04-29 20:26:17
Message-ID: Pine.LNX.4.44L0.0504291621150.8297-100000 () iolanthe ! rowland ! org
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Greg:

This patch was written by David; I have merely regenerated it against the
current source with appropriate modifications.

Alan Stern



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>


Index: usb-2.6/drivers/usb/gadget/dummy_hcd.c
==================================================================--- \
                usb-2.6.orig/drivers/usb/gadget/dummy_hcd.c
+++ usb-2.6/drivers/usb/gadget/dummy_hcd.c
@@ -601,8 +601,10 @@ static int dummy_wakeup (struct usb_gadg
 	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_g
 	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->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;
Index: usb-2.6/drivers/usb/gadget/Kconfig
==================================================================--- \
                usb-2.6.orig/drivers/usb/gadget/Kconfig
+++ usb-2.6/drivers/usb/gadget/Kconfig
@@ -203,6 +203,15 @@ config USB_GADGET_DUMMY_HCD
 	  dynamically linked module called "dummy_hcd" and force all
 	  gadget drivers to also be dynamically linked.

+config USB_OTG
+	boolean "OTG support for Dummy HCD (DEVELOPMENT)"
+	depends on USB_GADGET_DUMMY_HCD
+	help
+	  Say "y" build the dummy HCD with API support for USB OTG.  This
+	  is incomplete, because the "A-Peripheral" and "B-Host" devices
+	  are not yet emulated ... only "A-Host" and "B-Peripheral", which
+	  behaves as if OTG weren't active at all.
+
 config USB_DUMMY_HCD
 	tristate
 	depends on USB_GADGET_DUMMY_HCD



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