xhci: add helper to stop endpoint and wait for completion

Expose xhci_stop_endpoint_sync() which is a synchronous variant of
xhci_queue_stop_endpoint(). This is useful for client drivers that are
using the secondary interrupters, and need to stop/clean up the current
session. The stop endpoint command handler will also take care of cleaning
up the ring.

Modifications to repurpose the new API into existing stop endpoint
sequences was implemented by Wesley Cheng.

Signed-off-by: Mathias Nyman <[e-mail]>
Co-developed-by: Wesley Cheng <[e-mail]>
Signed-off-by: Wesley Cheng <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/usb/host/xhci.c

···
 	return -ENOMEM;
 }
 
+/*
+ * Synchronous XHCI stop endpoint helper.  Issues the stop endpoint command and
+ * waits for the command completion before returning.
+ */
+int xhci_stop_endpoint_sync(struct xhci_hcd *xhci, struct xhci_virt_ep *ep, int suspend,
+			    gfp_t gfp_flags)
+{
+	struct xhci_command *command;
+	unsigned long flags;
+	int ret;
+
+	command = xhci_alloc_command(xhci, true, gfp_flags);
+	if (!command)
+		return -ENOMEM;
+
+	spin_lock_irqsave(&xhci->lock, flags);
+	ret = xhci_queue_stop_endpoint(xhci, command, ep->vdev->slot_id,
+				       ep->ep_index, suspend);
+	if (ret < 0) {
+		spin_unlock_irqrestore(&xhci->lock, flags);
+		goto out;
+	}
+
+	xhci_ring_cmd_db(xhci);
+	spin_unlock_irqrestore(&xhci->lock, flags);
+
+	ret = wait_for_completion_timeout(command->completion, msecs_to_jiffies(3000));
+	if (!ret)
+		xhci_warn(xhci, "%s: Unable to stop endpoint.\n",
+				__func__);
+
+	if (command->status == COMP_COMMAND_ABORTED ||
+	    command->status == COMP_COMMAND_RING_STOPPED) {
+		xhci_warn(xhci, "Timeout while waiting for stop endpoint command\n");
+		ret = -ETIME;
+	}
+out:
+	xhci_free_command(xhci, command);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(xhci_stop_endpoint_sync);
 
 /* Issue a configure endpoint command or evaluate context command
  * and wait for it to finish.
···
 	struct xhci_virt_device *vdev;
 	struct xhci_virt_ep *ep;
 	struct xhci_input_control_ctx *ctrl_ctx;
-	struct xhci_command *stop_cmd, *cfg_cmd;
+	struct xhci_command *cfg_cmd;
 	unsigned int ep_index;
 	unsigned long flags;
 	u32 ep_flag;
···
 	if (ep_flag == SLOT_FLAG || ep_flag == EP0_FLAG)
 		return;
 
-	stop_cmd = xhci_alloc_command(xhci, true, GFP_NOWAIT);
-	if (!stop_cmd)
-		return;
-
 	cfg_cmd = xhci_alloc_command_with_ctx(xhci, true, GFP_NOWAIT);
 	if (!cfg_cmd)
 		goto cleanup;
···
 		goto cleanup;
 	}
 
-	err = xhci_queue_stop_endpoint(xhci, stop_cmd, udev->slot_id,
-					ep_index, 0);
+	spin_unlock_irqrestore(&xhci->lock, flags);
+
+	err = xhci_stop_endpoint_sync(xhci, ep, 0, GFP_NOWAIT);
 	if (err < 0) {
-		spin_unlock_irqrestore(&xhci->lock, flags);
-		xhci_free_command(xhci, cfg_cmd);
 		xhci_dbg(xhci, "%s: Failed to queue stop ep command, %d ",
 				__func__, err);
 		goto cleanup;
 	}
 
-	xhci_ring_cmd_db(xhci);
-	spin_unlock_irqrestore(&xhci->lock, flags);
-
-	wait_for_completion(stop_cmd->completion);
-
 	spin_lock_irqsave(&xhci->lock, flags);
-
 	/* config ep command clears toggle if add and drop ep flags are set */
 	ctrl_ctx = xhci_get_input_control_ctx(cfg_cmd->in_ctx);
 	if (!ctrl_ctx) {
···
 
 	xhci_free_command(xhci, cfg_cmd);
 cleanup:
-	xhci_free_command(xhci, stop_cmd);
 	spin_lock_irqsave(&xhci->lock, flags);
 	if (ep->ep_state & EP_SOFT_CLEAR_TOGGLE)
 		ep->ep_state &= ~EP_SOFT_CLEAR_TOGGLE;

drivers/usb/host/xhci.h

···
 void xhci_cleanup_command_queue(struct xhci_hcd *xhci);
 void inc_deq(struct xhci_hcd *xhci, struct xhci_ring *ring);
 unsigned int count_trbs(u64 addr, u64 len);
+int xhci_stop_endpoint_sync(struct xhci_hcd *xhci, struct xhci_virt_ep *ep,
+			    int suspend, gfp_t gfp_flags);
 
 /* xHCI roothub code */
 void xhci_set_link_state(struct xhci_hcd *xhci, struct xhci_port *port,