[PATCH v21 01/39] xhci: add helper to stop endpoint and wait for completion

[Wesley Cheng <quic_wcheng@xxxxxxxxxxx>]

From: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>

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.

Signed-off-by: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>
Signed-off-by: Wesley Cheng <quic_wcheng@xxxxxxxxxxx>
---
 drivers/usb/host/xhci.c | 39 +++++++++++++++++++++++++++++++++++++++
 drivers/usb/host/xhci.h |  2 ++
 2 files changed, 41 insertions(+)

diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index 37eb37b0affa..3a051ed32907 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -2784,6 +2784,45 @@ static int xhci_reserve_bandwidth(struct xhci_hcd *xhci,
 	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);
+
+	wait_for_completion(command->completion);
+
+	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.
diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
index 30415158ed3c..1c6126ed55b0 100644
--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h
@@ -1914,6 +1914,8 @@ void xhci_ring_doorbell_for_active_rings(struct xhci_hcd *xhci,
 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,