USB: xhci: Notify the xHC when a device is reset.

When a USB device is reset, the xHCI hardware must know, in order to match
the device state and disable all endpoints except control endpoint 0.
Issue a Reset Device command after a USB device is successfully reset.
Wait on the command to finish, and then cache or free the disabled
endpoint rings.

There are four different USB device states that the xHCI hardware tracks:
 - disabled/enabled - device connection has just been detected,
 - default - the device has been reset and has an address of 0,
 - addressed - the device has a non-zero address but no configuration has
   been set,
 - configured - a set configuration succeeded.

The USB core may issue a port reset when a device is in any state, but the
Reset Device command will fail for a 0.96 xHC if the device is not in the
addressed or configured state.  Don't consider this failure as an error,
but don't free any endpoint rings if this command fails.

A storage driver may request that the USB device be reset during error
handling, so use GPF_NOIO instead of GPF_KERNEL while allocating memory
for the Reset Device command.

Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 125 insertions, 0 deletions

diff --git a/drivers/usb/host/xhci-hcd.c b/drivers/usb/host/xhci-hcd.c
index 17f1caf2af64..c8573f874ec4 100644
--- a/drivers/usb/host/xhci-hcd.c
+++ b/drivers/usb/host/xhci-hcd.c
@@ -1443,6 +1443,131 @@ void xhci_endpoint_reset(struct usb_hcd *hcd,
 }
 
 /*
+ * This submits a Reset Device Command, which will set the device state to 0,
+ * set the device address to 0, and disable all the endpoints except the default
+ * control endpoint.  The USB core should come back and call
+ * xhci_address_device(), and then re-set up the configuration.  If this is
+ * called because of a usb_reset_and_verify_device(), then the old alternate
+ * settings will be re-installed through the normal bandwidth allocation
+ * functions.
+ *
+ * Wait for the Reset Device command to finish.  Remove all structures
+ * associated with the endpoints that were disabled.  Clear the input device
+ * structure?  Cache the rings?  Reset the control endpoint 0 max packet size?
+ */
+int xhci_reset_device(struct usb_hcd *hcd, struct usb_device *udev)
+{
+        int ret, i;
+        unsigned long flags;
+        struct xhci_hcd *xhci;
+        unsigned int slot_id;
+        struct xhci_virt_device *virt_dev;
+        struct xhci_command *reset_device_cmd;
+        int timeleft;
+        int last_freed_endpoint;
+
+        ret = xhci_check_args(hcd, udev, NULL, 0, __func__);
+        if (ret <= 0)
+                return ret;
+        xhci = hcd_to_xhci(hcd);
+        slot_id = udev->slot_id;
+        virt_dev = xhci->devs[slot_id];
+        if (!virt_dev) {
+                xhci_dbg(xhci, "%s called with invalid slot ID %u\n",
+                                __func__, slot_id);
+                return -EINVAL;
+        }
+
+        xhci_dbg(xhci, "Resetting device with slot ID %u\n", slot_id);
+        /* Allocate the command structure that holds the struct completion.
+         * Assume we're in process context, since the normal device reset
+         * process has to wait for the device anyway.  Storage devices are
+         * reset as part of error handling, so use GFP_NOIO instead of
+         * GFP_KERNEL.
+         */
+        reset_device_cmd = xhci_alloc_command(xhci, false, true, GFP_NOIO);
+        if (!reset_device_cmd) {
+                xhci_dbg(xhci, "Couldn't allocate command structure.\n");
+                return -ENOMEM;
+        }
+
+        /* Attempt to submit the Reset Device command to the command ring */
+        spin_lock_irqsave(&xhci->lock, flags);
+        reset_device_cmd->command_trb = xhci->cmd_ring->enqueue;
+        list_add_tail(&reset_device_cmd->cmd_list, &virt_dev->cmd_list);
+        ret = xhci_queue_reset_device(xhci, slot_id);
+        if (ret) {
+                xhci_dbg(xhci, "FIXME: allocate a command ring segment\n");
+                list_del(&reset_device_cmd->cmd_list);
+                spin_unlock_irqrestore(&xhci->lock, flags);
+                goto command_cleanup;
+        }
+        xhci_ring_cmd_db(xhci);
+        spin_unlock_irqrestore(&xhci->lock, flags);
+
+        /* Wait for the Reset Device command to finish */
+        timeleft = wait_for_completion_interruptible_timeout(
+                        reset_device_cmd->completion,
+                        USB_CTRL_SET_TIMEOUT);
+        if (timeleft <= 0) {
+                xhci_warn(xhci, "%s while waiting for reset device command\n",
+                                timeleft == 0 ? "Timeout" : "Signal");
+                spin_lock_irqsave(&xhci->lock, flags);
+                /* The timeout might have raced with the event ring handler, so
+                 * only delete from the list if the item isn't poisoned.
+                 */
+                if (reset_device_cmd->cmd_list.next != LIST_POISON1)
+                        list_del(&reset_device_cmd->cmd_list);
+                spin_unlock_irqrestore(&xhci->lock, flags);
+                ret = -ETIME;
+                goto command_cleanup;
+        }
+
+        /* The Reset Device command can't fail, according to the 0.95/0.96 spec,
+         * unless we tried to reset a slot ID that wasn't enabled,
+         * or the device wasn't in the addressed or configured state.
+         */
+        ret = reset_device_cmd->status;
+        switch (ret) {
+        case COMP_EBADSLT: /* 0.95 completion code for bad slot ID */
+        case COMP_CTX_STATE: /* 0.96 completion code for same thing */
+                xhci_info(xhci, "Can't reset device (slot ID %u) in %s state\n",
+                                slot_id,
+                                xhci_get_slot_state(xhci, virt_dev->out_ctx));
+                xhci_info(xhci, "Not freeing device rings.\n");
+                /* Don't treat this as an error.  May change my mind later. */
+                ret = 0;
+                goto command_cleanup;
+        case COMP_SUCCESS:
+                xhci_dbg(xhci, "Successful reset device command.\n");
+                break;
+        default:
+                if (xhci_is_vendor_info_code(xhci, ret))
+                        break;
+                xhci_warn(xhci, "Unknown completion code %u for "
+                                "reset device command.\n", ret);
+                ret = -EINVAL;
+                goto command_cleanup;
+        }
+
+        /* Everything but endpoint 0 is disabled, so free or cache the rings. */
+        last_freed_endpoint = 1;
+        for (i = 1; i < 31; ++i) {
+                if (!virt_dev->eps[i].ring)
+                        continue;
+                xhci_free_or_cache_endpoint_ring(xhci, virt_dev, i);
+                last_freed_endpoint = i;
+        }
+        xhci_dbg(xhci, "Output context after successful reset device cmd:\n");
+        xhci_dbg_ctx(xhci, virt_dev->out_ctx, last_freed_endpoint);
+        ret = 0;
+
+command_cleanup:
+        xhci_free_command(xhci, reset_device_cmd);
+        return ret;
+}
+
+/*
  * At this point, the struct usb_device is about to go away, the device has
  * disconnected, and all traffic has been stopped and the endpoints have been
  * disabled.  Free any HC data structures associated with that device.