USB: xhci: Re-purpose xhci_quiesce().

xhci_quiesce() is basically a no-op right now.  It's only called if
HC_IS_RUNNING() is true, and the body of the function consists of a
BUG_ON if HC_IS_RUNNING() is false.  For the new xHCI watchdog timer, we
need a new function that clears the xHCI running bit in the command
register, but doesn't wait for the halt status to show up in the status
register.  Re-purpose xhci_quiesce() to do that.
Signed-off-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/host/xhci-hcd.c

@@ -67,22 +67,14 @@ static int handshake(struct xhci_hcd *xhci, void __iomem *ptr,
 }
 
 /*
- * Force HC into halt state.
- *
- * Disable any IRQs and clear the run/stop bit.
- * HC will complete any current and actively pipelined transactions, and
- * should halt within 16 microframes of the run/stop bit being cleared.
- * Read HC Halted bit in the status register to see when the HC is finished.
- * XXX: shouldn't we set HC_STATE_HALT here somewhere?
+ * Disable interrupts and begin the xHCI halting process.
  */
-int xhci_halt(struct xhci_hcd *xhci)
+void xhci_quiesce(struct xhci_hcd *xhci)
 {
 	u32 halted;
 	u32 cmd;
 	u32 mask;
 
-	xhci_dbg(xhci, "// Halt the HC\n");
-	/* Disable all interrupts from the host controller */
 	mask = ~(XHCI_IRQS);
 	halted = xhci_readl(xhci, &xhci->op_regs->status) & STS_HALT;
 	if (!halted)
@@ -91,6 +83,21 @@ int xhci_halt(struct xhci_hcd *xhci)
 	cmd = xhci_readl(xhci, &xhci->op_regs->command);
 	cmd &= mask;
 	xhci_writel(xhci, cmd, &xhci->op_regs->command);
+}
+
+/*
+ * Force HC into halt state.
+ *
+ * Disable any IRQs and clear the run/stop bit.
+ * HC will complete any current and actively pipelined transactions, and
+ * should halt within 16 microframes of the run/stop bit being cleared.
+ * Read HC Halted bit in the status register to see when the HC is finished.
+ * XXX: shouldn't we set HC_STATE_HALT here somewhere?
+ */
+int xhci_halt(struct xhci_hcd *xhci)
+{
+	xhci_dbg(xhci, "// Halt the HC\n");
+	xhci_quiesce(xhci);
 
 	return handshake(xhci, &xhci->op_regs->status,
 			STS_HALT, STS_HALT, XHCI_MAX_HALT_USEC);
@@ -124,28 +131,6 @@ int xhci_reset(struct xhci_hcd *xhci)
 	return handshake(xhci, &xhci->op_regs->command, CMD_RESET, 0, 250 * 1000);
 }
 
-/*
- * Stop the HC from processing the endpoint queues.
- */
-static void xhci_quiesce(struct xhci_hcd *xhci)
-{
-	/*
-	 * Queues are per endpoint, so we need to disable an endpoint or slot.
-	 *
-	 * To disable a slot, we need to insert a disable slot command on the
-	 * command ring and ring the doorbell.  This will also free any internal
-	 * resources associated with the slot (which might not be what we want).
-	 *
-	 * A Release Endpoint command sounds better - doesn't free internal HC
-	 * memory, but removes the endpoints from the schedule and releases the
-	 * bandwidth, disables the doorbells, and clears the endpoint enable
-	 * flag.  Usually used prior to a set interface command.
-	 *
-	 * TODO: Implement after command ring code is done.
-	 */
-	BUG_ON(!HC_IS_RUNNING(xhci_to_hcd(xhci)->state));
-	xhci_dbg(xhci, "Finished quiescing -- code not written yet\n");
-}
 
 #if 0
 /* Set up MSI-X table for entry 0 (may claim other entries later) */
@@ -490,8 +475,6 @@ void xhci_stop(struct usb_hcd *hcd)
 	struct xhci_hcd *xhci = hcd_to_xhci(hcd);
 
 	spin_lock_irq(&xhci->lock);
-	if (HC_IS_RUNNING(hcd->state))
-		xhci_quiesce(xhci);
 	xhci_halt(xhci);
 	xhci_reset(xhci);
 	spin_unlock_irq(&xhci->lock);

drivers/usb/host/xhci.h

@@ -1223,6 +1223,7 @@ void xhci_unregister_pci(void);
 #endif
 
 /* xHCI host controller glue */
+void xhci_quiesce(struct xhci_hcd *xhci);
 int xhci_halt(struct xhci_hcd *xhci);
 int xhci_reset(struct xhci_hcd *xhci);
 int xhci_init(struct usb_hcd *hcd);