4 files changed, 144 insertions, 0 deletions

diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c
index 823744d80cb..b2da4753b12 100644
--- a/drivers/usb/core/hcd.c
+++ b/drivers/usb/core/hcd.c
@@ -1560,6 +1560,92 @@ rescan:
 	}
 }
 
+/* Check whether a new configuration or alt setting for an interface
+ * will exceed the bandwidth for the bus (or the host controller resources).
+ * Only pass in a non-NULL config or interface, not both!
+ * Passing NULL for both new_config and new_intf means the device will be
+ * de-configured by issuing a set configuration 0 command.
+ */
+int usb_hcd_check_bandwidth(struct usb_device *udev,
+		struct usb_host_config *new_config,
+		struct usb_interface *new_intf)
+{
+	int num_intfs, i, j;
+	struct usb_interface_cache *intf_cache;
+	struct usb_host_interface *alt = 0;
+	int ret = 0;
+	struct usb_hcd *hcd;
+	struct usb_host_endpoint *ep;
+
+	hcd = bus_to_hcd(udev->bus);
+	if (!hcd->driver->check_bandwidth)
+		return 0;
+
+	/* Configuration is being removed - set configuration 0 */
+	if (!new_config && !new_intf) {
+		for (i = 1; i < 16; ++i) {
+			ep = udev->ep_out[i];
+			if (ep)
+				hcd->driver->drop_endpoint(hcd, udev, ep);
+			ep = udev->ep_in[i];
+			if (ep)
+				hcd->driver->drop_endpoint(hcd, udev, ep);
+		}
+		hcd->driver->check_bandwidth(hcd, udev);
+		return 0;
+	}
+	/* Check if the HCD says there's enough bandwidth.  Enable all endpoints
+	 * each interface's alt setting 0 and ask the HCD to check the bandwidth
+	 * of the bus.  There will always be bandwidth for endpoint 0, so it's
+	 * ok to exclude it.
+	 */
+	if (new_config) {
+		num_intfs = new_config->desc.bNumInterfaces;
+		/* Remove endpoints (except endpoint 0, which is always on the
+		 * schedule) from the old config from the schedule
+		 */
+		for (i = 1; i < 16; ++i) {
+			ep = udev->ep_out[i];
+			if (ep) {
+				ret = hcd->driver->drop_endpoint(hcd, udev, ep);
+				if (ret < 0)
+					goto reset;
+			}
+			ep = udev->ep_in[i];
+			if (ep) {
+				ret = hcd->driver->drop_endpoint(hcd, udev, ep);
+				if (ret < 0)
+					goto reset;
+			}
+		}
+		for (i = 0; i < num_intfs; ++i) {
+
+			/* Dig the endpoints for alt setting 0 out of the
+			 * interface cache for this interface
+			 */
+			intf_cache = new_config->intf_cache[i];
+			for (j = 0; j < intf_cache->num_altsetting; j++) {
+				if (intf_cache->altsetting[j].desc.bAlternateSetting == 0)
+					alt = &intf_cache->altsetting[j];
+			}
+			if (!alt) {
+				printk(KERN_DEBUG "Did not find alt setting 0 for intf %d\n", i);
+				continue;
+			}
+			for (j = 0; j < alt->desc.bNumEndpoints; j++) {
+				ret = hcd->driver->add_endpoint(hcd, udev, &alt->endpoint[j]);
+				if (ret < 0)
+					goto reset;
+			}
+		}
+	}
+	ret = hcd->driver->check_bandwidth(hcd, udev);
+reset:
+	if (ret < 0)
+		hcd->driver->reset_bandwidth(hcd, udev);
+	return ret;
+}
+
 /* Disables the endpoint: synchronizes with the hcd to make sure all
  * endpoint state is gone from hardware.  usb_hcd_flush_endpoint() must
  * have been called previously.  Use for set_configuration, set_interface,
diff --git a/drivers/usb/core/hcd.h b/drivers/usb/core/hcd.h
index ae6d9db41ca..d397ecfd5b1 100644
--- a/drivers/usb/core/hcd.h
+++ b/drivers/usb/core/hcd.h
@@ -232,6 +232,35 @@ struct hc_driver {
 	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 *);
+
+	/* Bandwidth computation functions */
+	/* Note that add_endpoint() can only be called once per endpoint before
+	 * check_bandwidth() or reset_bandwidth() must be called.
+	 * drop_endpoint() can only be called once per endpoint also.
+	 * A call to xhci_drop_endpoint() followed by a call to xhci_add_endpoint() will
+	 * add the endpoint to the schedule with possibly new parameters denoted by a
+	 * different endpoint descriptor in usb_host_endpoint.
+	 * A call to xhci_add_endpoint() followed by a call to xhci_drop_endpoint() is
+	 * not allowed.
+	 */
+		/* Allocate endpoint resources and add them to a new schedule */
+	int 	(*add_endpoint)(struct usb_hcd *, struct usb_device *, struct usb_host_endpoint *);
+		/* Drop an endpoint from a new schedule */
+	int 	(*drop_endpoint)(struct usb_hcd *, struct usb_device *, struct usb_host_endpoint *);
+		/* Check that a new hardware configuration, set using
+		 * endpoint_enable and endpoint_disable, does not exceed bus
+		 * bandwidth.  This must be called before any set configuration
+		 * or set interface requests are sent to the device.
+		 */
+	int	(*check_bandwidth)(struct usb_hcd *, struct usb_device *);
+		/* Reset the device schedule to the last known good schedule,
+		 * which was set from a previous successful call to
+		 * check_bandwidth().  This reverts any add_endpoint() and
+		 * drop_endpoint() calls since that last successful call.
+		 * Used for when a check_bandwidth() call fails due to resource
+		 * or bandwidth constraints.
+		 */
+	void	(*reset_bandwidth)(struct usb_hcd *, struct usb_device *);
 		/* Returns the hardware-chosen device address */
 	int	(*address_device)(struct usb_hcd *, struct usb_device *udev);
 };
@@ -252,6 +281,9 @@ extern void usb_hcd_disable_endpoint(struct usb_device *udev,
 extern void usb_hcd_reset_endpoint(struct usb_device *udev,
 		struct usb_host_endpoint *ep);
 extern void usb_hcd_synchronize_unlinks(struct usb_device *udev);
+extern int usb_hcd_check_bandwidth(struct usb_device *udev,
+		struct usb_host_config *new_config,
+		struct usb_interface *new_intf);
 extern int usb_hcd_get_frame_number(struct usb_device *udev);
 
 extern struct usb_hcd *usb_create_hcd(const struct hc_driver *driver,
diff --git a/drivers/usb/core/message.c b/drivers/usb/core/message.c
index 9bd26dec759..3a2e69ec2f2 100644
--- a/drivers/usb/core/message.c
+++ b/drivers/usb/core/message.c
@@ -510,6 +510,10 @@ EXPORT_SYMBOL_GPL(usb_sg_init);
  * could be transferred.  That capability is less useful for low or full
  * speed interrupt endpoints, which allow at most one packet per millisecond,
  * of at most 8 or 64 bytes (respectively).
+ *
+ * It is not necessary to call this function to reserve bandwidth for devices
+ * under an xHCI host controller, as the bandwidth is reserved when the
+ * configuration or interface alt setting is selected.
  */
 void usb_sg_wait(struct usb_sg_request *io)
 {
@@ -1653,6 +1657,21 @@ free_interfaces:
 	if (ret)
 		goto free_interfaces;
 
+	/* Make sure we have bandwidth (and available HCD resources) for this
+	 * configuration.  Remove endpoints from the schedule if we're dropping
+	 * this configuration to set configuration 0.  After this point, the
+	 * host controller will not allow submissions to dropped endpoints.  If
+	 * this call fails, the device state is unchanged.
+	 */
+	if (cp)
+		ret = usb_hcd_check_bandwidth(dev, cp, NULL);
+	else
+		ret = usb_hcd_check_bandwidth(dev, NULL, NULL);
+	if (ret < 0) {
+		usb_autosuspend_device(dev);
+		goto free_interfaces;
+	}
+
 	/* if it's already configured, clear out old state first.
 	 * getting rid of old interfaces means unbinding their drivers.
 	 */
@@ -1675,6 +1694,7 @@ free_interfaces:
 	dev->actconfig = cp;
 	if (!cp) {
 		usb_set_device_state(dev, USB_STATE_ADDRESS);
+		usb_hcd_check_bandwidth(dev, NULL, NULL);
 		usb_autosuspend_device(dev);
 		goto free_interfaces;
 	}
diff --git a/drivers/usb/core/urb.c b/drivers/usb/core/urb.c
index 02eb0ef7a4c..0885d4abdc6 100644
--- a/drivers/usb/core/urb.c
+++ b/drivers/usb/core/urb.c
@@ -241,6 +241,12 @@ EXPORT_SYMBOL_GPL(usb_unanchor_urb);
  * If the USB subsystem can't allocate sufficient bandwidth to perform
  * the periodic request, submitting such a periodic request should fail.
  *
+ * For devices under xHCI, the bandwidth is reserved at configuration time, or
+ * when the alt setting is selected.  If there is not enough bus bandwidth, the
+ * configuration/alt setting request will fail.  Therefore, submissions to
+ * periodic endpoints on devices under xHCI should never fail due to bandwidth
+ * constraints.
+ *
  * Device drivers must explicitly request that repetition, by ensuring that
  * some URB is always on the endpoint's queue (except possibly for short
  * periods during completion callacks).  When there is no longer an urb