USB: Support for addressing a USB device under xHCI

Add host controller driver API and a slot_id variable to struct
usb_device.  This allows the xHCI host controller driver to ask the
hardware to allocate a slot for the device when a struct usb_device is
allocated.  The slot needs to be allocated at that point because the
hardware can run out of internal resources, and we want to know that very
early in the device connection process.  Don't call this new API for root
hubs, since they aren't real devices.

Add HCD API to let the host controller choose the device address.  This is
especially important for xHCI hardware running in a virtualized
environment.  The guests running under the VM don't need to know which
addresses on the bus are taken, because the hardware picks the address for
them.  Announce SuperSpeed USB devices after the address has been assigned
by the hardware.

Don't use the new get descriptor/set address scheme with xHCI.  Unless
special handling is done in the host controller driver, the xHC can't
issue control transfers before you set the device address.  Support for
the older addressing scheme will be added when the xHCI driver supports
the Block Set Address Request (BSR) flag in the Address Device command.
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/core/hcd.h

@@ -226,6 +226,14 @@ struct hc_driver {
 	void	(*relinquish_port)(struct usb_hcd *, int);
 		/* has a port been handed over to a companion? */
 	int	(*port_handed_over)(struct usb_hcd *, int);
+
+	/* xHCI specific functions */
+		/* Called by usb_alloc_dev to alloc HC device structures */
+	int	(*alloc_dev)(struct usb_hcd *, struct usb_device *);
+		/* Called by usb_release_dev to free HC device structures */
+	void	(*free_dev)(struct usb_hcd *, struct usb_device *);
+		/* Returns the hardware-chosen device address */
+	int	(*address_device)(struct usb_hcd *, struct usb_device *udev);
 };
 
 extern int usb_hcd_link_urb_to_ep(struct usb_hcd *hcd, struct urb *urb);

drivers/usb/core/hub.c

@@ -1328,6 +1328,11 @@ EXPORT_SYMBOL_GPL(usb_set_device_state);
  * 0 is reserved by USB for default address; (b) Linux's USB stack
  * uses always #1 for the root hub of the controller. So USB stack's
  * port #1, which is wusb virtual-port #0 has address #2.
+ *
+ * Devices connected under xHCI are not as simple.  The host controller
+ * supports virtualization, so the hardware assigns device addresses and
+ * the HCD must setup data structures before issuing a set address
+ * command to the hardware.
  */
 static void choose_address(struct usb_device *udev)
 {
@@ -1647,6 +1652,9 @@ int usb_new_device(struct usb_device *udev)
 	err = usb_configure_device(udev);	/* detect & probe dev/intfs */
 	if (err < 0)
 		goto fail;
+	dev_dbg(&udev->dev, "udev %d, busnum %d, minor = %d\n",
+			udev->devnum, udev->bus->busnum,
+			(((udev->bus->busnum-1) * 128) + (udev->devnum-1)));
 	/* export the usbdev device-node for libusb */
 	udev->dev.devt = MKDEV(USB_DEVICE_MAJOR,
 			(((udev->bus->busnum-1) * 128) + (udev->devnum-1)));
@@ -2400,19 +2408,29 @@ EXPORT_SYMBOL_GPL(usb_ep0_reinit);
 static int hub_set_address(struct usb_device *udev, int devnum)
 {
 	int retval;
+	struct usb_hcd *hcd = bus_to_hcd(udev->bus);
 
-	if (devnum <= 1)
+	/*
+	 * The host controller will choose the device address,
+	 * instead of the core having chosen it earlier
+	 */
+	if (!hcd->driver->address_device && devnum <= 1)
 		return -EINVAL;
 	if (udev->state == USB_STATE_ADDRESS)
 		return 0;
 	if (udev->state != USB_STATE_DEFAULT)
 		return -EINVAL;
+	if (hcd->driver->address_device) {
+		retval = hcd->driver->address_device(hcd, udev);
+	} else {
 		retval = usb_control_msg(udev, usb_sndaddr0pipe(),
 				USB_REQ_SET_ADDRESS, 0, devnum, 0,
 				NULL, 0, USB_CTRL_SET_TIMEOUT);
+		if (retval == 0)
+			update_address(udev, devnum);
+	}
 	if (retval == 0) {
 		/* Device now using proper address. */
-		update_address(udev, devnum);
 		usb_set_device_state(udev, USB_STATE_ADDRESS);
 		usb_ep0_reinit(udev);
 	}
@@ -2525,7 +2543,8 @@ hub_port_init (struct usb_hub *hub, struct usb_device *udev, int port1,
 				break;
 	default: 		speed = "?";	break;
 	}
-	dev_info (&udev->dev,
+	if (udev->speed != USB_SPEED_SUPER)
+		dev_info(&udev->dev,
 				"%s %s speed %sUSB device using %s and address %d\n",
 				(udev->config) ? "reset" : "new", speed, type,
 				udev->bus->controller->driver->name, devnum);
@@ -2553,7 +2572,11 @@ hub_port_init (struct usb_hub *hub, struct usb_device *udev, int port1,
 	 * value.
 	 */
 	for (i = 0; i < GET_DESCRIPTOR_TRIES; (++i, msleep(100))) {
-		if (USE_NEW_SCHEME(retry_counter)) {
+		/*
+		 * An xHCI controller cannot send any packets to a device until
+		 * a set address command successfully completes.
+		 */
+		if (USE_NEW_SCHEME(retry_counter) && !(hcd->driver->flags & HCD_USB3)) {
 			struct usb_device_descriptor *buf;
 			int r = 0;
 
@@ -2632,13 +2655,20 @@ hub_port_init (struct usb_hub *hub, struct usb_device *udev, int port1,
 					devnum, retval);
 				goto fail;
 			}
+			if (udev->speed == USB_SPEED_SUPER) {
+				devnum = udev->devnum;
+				dev_info(&udev->dev,
+						"%s SuperSpeed USB device using %s and address %d\n",
+						(udev->config) ? "reset" : "new",
+						udev->bus->controller->driver->name, devnum);
+			}
 
 			/* cope with hardware quirkiness:
 			 *  - let SET_ADDRESS settle, some device hardware wants it
 			 *  - read ep0 maxpacket even for high and low speed,
 			 */
 			msleep(10);
-			if (USE_NEW_SCHEME(retry_counter))
+			if (USE_NEW_SCHEME(retry_counter) && !(hcd->driver->flags & HCD_USB3))
 				break;
   		}
 
@@ -2877,13 +2907,6 @@ static void hub_port_connect_change(struct usb_hub *hub, int port1,
 		udev->level = hdev->level + 1;
 		udev->wusb = hub_is_wusb(hub);
 
-		/* set the address */
-		choose_address(udev);
-		if (udev->devnum <= 0) {
-			status = -ENOTCONN;	/* Don't retry */
-			goto loop;
-		}
-
 		/*
 		 * USB 3.0 devices are reset automatically before the connect
 		 * port status change appears, and the root hub port status
@@ -2901,6 +2924,19 @@ static void hub_port_connect_change(struct usb_hub *hub, int port1,
 		else
 			udev->speed = USB_SPEED_UNKNOWN;
 
+		/*
+		 * xHCI needs to issue an address device command later
+		 * in the hub_port_init sequence for SS/HS/FS/LS devices.
+		 */
+		if (!(hcd->driver->flags & HCD_USB3)) {
+			/* set the address */
+			choose_address(udev);
+			if (udev->devnum <= 0) {
+				status = -ENOTCONN;	/* Don't retry */
+				goto loop;
+			}
+		}
+
 		/* reset (non-USB 3.0 devices) and get descriptor */
 		status = hub_port_init(hub, udev, port1, i);
 		if (status < 0)

drivers/usb/core/usb.c

@@ -184,11 +184,16 @@ EXPORT_SYMBOL_GPL(usb_find_interface);
 static void usb_release_dev(struct device *dev)
 {
 	struct usb_device *udev;
+	struct usb_hcd *hcd;
 
 	udev = to_usb_device(dev);
+	hcd = bus_to_hcd(udev->bus);
 
 	usb_destroy_configuration(udev);
-	usb_put_hcd(bus_to_hcd(udev->bus));
+	/* Root hubs aren't real devices, so don't free HCD resources */
+	if (hcd->driver->free_dev && udev->parent)
+		hcd->driver->free_dev(hcd, udev);
+	usb_put_hcd(hcd);
 	kfree(udev->product);
 	kfree(udev->manufacturer);
 	kfree(udev->serial);
@@ -348,6 +353,13 @@ struct usb_device *usb_alloc_dev(struct usb_device *parent,
 		kfree(dev);
 		return NULL;
 	}
+	/* Root hubs aren't true devices, so don't allocate HCD resources */
+	if (usb_hcd->driver->alloc_dev && parent &&
+		!usb_hcd->driver->alloc_dev(usb_hcd, dev)) {
+		usb_put_hcd(bus_to_hcd(bus));
+		kfree(dev);
+		return NULL;
+	}
 
 	device_initialize(&dev->dev);
 	dev->dev.bus = &usb_bus_type;

include/linux/usb.h

@@ -420,6 +420,7 @@ struct usb_tt;
  * @skip_sys_resume: skip the next system resume
  * @wusb_dev: if this is a Wireless USB device, link to the WUSB
  *	specific data for the device.
+ * @slot_id: Slot ID assigned by xHCI
  *
  * Notes:
  * Usbcore drivers should not set usbdev->state directly.  Instead use
@@ -504,6 +505,7 @@ struct usb_device {
 	unsigned skip_sys_resume:1;
 #endif
 	struct wusb_dev *wusb_dev;
+	int slot_id;
 };
 #define	to_usb_device(d) container_of(d, struct usb_device, dev)