xhci: move event processing for one interrupter to a separate function

Split the main XHCI interrupt handler into a different API, so that other
potential interrupters can utilize similar event ring handling.  A scenario
would be if a secondary interrupter required to skip pending events in the
event ring, which would warrant a similar set of operations.
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Signed-off-by: Wesley Cheng <quic_wcheng@quicinc.com>
Link: https://lore.kernel.org/r/20240217001017.29969-7-quic_wcheng@quicinc.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/xhci-ring.c

@@ -3069,6 +3069,46 @@ static void xhci_clear_interrupt_pending(struct xhci_hcd *xhci,
 	}
 }
 
+static int xhci_handle_events(struct xhci_hcd *xhci, struct xhci_interrupter *ir)
+{
+	int event_loop = 0;
+	u64 temp;
+
+	xhci_clear_interrupt_pending(xhci, ir);
+
+	if (xhci->xhc_state & XHCI_STATE_DYING ||
+	    xhci->xhc_state & XHCI_STATE_HALTED) {
+		xhci_dbg(xhci, "xHCI dying, ignoring interrupt. Shouldn't IRQs be disabled?\n");
+
+		/* Clear the event handler busy flag (RW1C) */
+		temp = xhci_read_64(xhci, &ir->ir_set->erst_dequeue);
+		xhci_write_64(xhci, temp | ERST_EHB, &ir->ir_set->erst_dequeue);
+		return -ENODEV;
+	}
+
+	while (xhci_handle_event(xhci, ir) > 0) {
+		/*
+		 * If half a segment of events have been handled in one go then
+		 * update ERDP, and force isoc trbs to interrupt more often
+		 */
+		if (event_loop++ > TRBS_PER_SEGMENT / 2) {
+			xhci_update_erst_dequeue(xhci, ir, false);
+
+			if (ir->isoc_bei_interval > AVOID_BEI_INTERVAL_MIN)
+				ir->isoc_bei_interval = ir->isoc_bei_interval / 2;
+
+			event_loop = 0;
+		}
+
+		/* Update SW event ring dequeue pointer */
+		inc_deq(xhci, ir->event_ring);
+	}
+
+	xhci_update_erst_dequeue(xhci, ir, true);
+
+	return 0;
+}
+
 /*
  * xHCI spec says we can get an interrupt, and if the HC has an error condition,
  * we might get bad data out of the event ring.  Section 4.10.2.7 has a list of
@@ -3077,11 +3117,8 @@ static void xhci_clear_interrupt_pending(struct xhci_hcd *xhci,
 irqreturn_t xhci_irq(struct usb_hcd *hcd)
 {
 	struct xhci_hcd *xhci = hcd_to_xhci(hcd);
-	struct xhci_interrupter *ir;
 	irqreturn_t ret = IRQ_NONE;
-	u64 temp_64;
 	u32 status;
-	int event_loop = 0;
 
 	spin_lock(&xhci->lock);
 	/* Check if the xHC generated the interrupt, or the irq is shared */
@@ -3114,50 +3151,10 @@ irqreturn_t xhci_irq(struct usb_hcd *hcd)
 	 */
 	status |= STS_EINT;
 	writel(status, &xhci->op_regs->status);
-
-	/* This is the handler of the primary interrupter */
-	ir = xhci->interrupters[0];
-
-	xhci_clear_interrupt_pending(xhci, ir);
-
-	if (xhci->xhc_state & XHCI_STATE_DYING ||
-	    xhci->xhc_state & XHCI_STATE_HALTED) {
-		xhci_dbg(xhci, "xHCI dying, ignoring interrupt. "
-				"Shouldn't IRQs be disabled?\n");
-		/* Clear the event handler busy flag (RW1C);
-		 * the event ring should be empty.
-		 */
-		temp_64 = xhci_read_64(xhci, &ir->ir_set->erst_dequeue);
-		xhci_write_64(xhci, temp_64 | ERST_EHB,
-				&ir->ir_set->erst_dequeue);
-		ret = IRQ_HANDLED;
-		goto out;
-	}
-
-	/* FIXME this should be a delayed service routine
-	 * that clears the EHB.
-	 */
-	while (xhci_handle_event(xhci, ir) > 0) {
-		/*
-		 * If half a segment of events have been handled in one go then
-		 * update ERDP, and force isoc trbs to interrupt more often
-		 */
-		if (event_loop++ > TRBS_PER_SEGMENT / 2) {
-			xhci_update_erst_dequeue(xhci, ir, false);
-
-			if (ir->isoc_bei_interval > AVOID_BEI_INTERVAL_MIN)
-				ir->isoc_bei_interval = ir->isoc_bei_interval / 2;
-
-			event_loop = 0;
-		}
-
-		/* Update SW event ring dequeue pointer */
-		inc_deq(xhci, ir->event_ring);
-	}
-
-	xhci_update_erst_dequeue(xhci, ir, true);
 	ret = IRQ_HANDLED;
 
+	/* This is the handler of the primary interrupter */
+	xhci_handle_events(xhci, xhci->interrupters[0]);
 out:
 	spin_unlock(&xhci->lock);