4 files changed, 144 insertions, 0 deletions

diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c
index 823744d80cb9..b2da4753b12e 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 ae6d9db41ca9..d397ecfd5b17 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 9bd26dec7599..3a2e69ec2f29 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 02eb0ef7a4c3..0885d4abdc62 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