Index: sys/dev/gpio/gpiobus.c
===================================================================
--- sys/dev/gpio/gpiobus.c
+++ sys/dev/gpio/gpiobus.c
@@ -96,7 +96,8 @@
 	gpio_data->gpio_pin_flags = pin->flags;
 	gpio_data->gpio_intr_mode = intr_mode;
 
-	irq = intr_map_irq(pin->dev, 0, (struct intr_map_data *)gpio_data);
+	irq = intr_map_irq(pin->dev, XREF_NONE,
+	    (struct intr_map_data *)gpio_data);
 	res = bus_alloc_resource(consumer_dev, SYS_RES_IRQ, rid, irq, irq, 1,
 	    alloc_flags);
 	if (res == NULL) {
Index: sys/kern/subr_intr.c
===================================================================
--- sys/kern/subr_intr.c
+++ sys/kern/subr_intr.c
@@ -104,6 +104,7 @@
 /* Interrupt controller definition. */
 struct intr_pic {
 	SLIST_ENTRY(intr_pic)	pic_next;
+#define XREF_INVALID	-1
 	intptr_t		pic_xref;	/* hardware identification */
 	device_t		pic_dev;
 /* Only one of FLAG_PIC or FLAG_MSI may be set */
@@ -697,8 +698,10 @@
 
 	mtx_assert(&pic_list_lock, MA_OWNED);
 
-	if (dev == NULL && xref == 0)
-		return (NULL);
+	KASSERT(dev != NULL || xref != XREF_INVALID,
+	    ("pic_lookup_locked: Either the device or the xref must be valid"));
+	KASSERT(dev != NULL || xref != XREF_NONE,
+	    ("pic_lookup_locked: A device is required when there is no xref"));
 
 	/* Note that pic->pic_dev is never NULL on registered PIC. */
 	SLIST_FOREACH(pic, &pic_list, pic_next) {
@@ -706,14 +709,18 @@
 		    (flags & FLAG_TYPE_MASK))
 			continue;
 
-		if (dev == NULL) {
+		if (dev == NULL && xref != XREF_NONE) {
+			/* No dev, check the xref */
 			if (xref == pic->pic_xref)
 				return (pic);
-		} else if (xref == 0 || pic->pic_xref == 0) {
+		} else if (xref == XREF_INVALID) {
+			/* No xref, check the dev */
 			if (dev == pic->pic_dev)
 				return (pic);
-		} else if (xref == pic->pic_xref && dev == pic->pic_dev)
-				return (pic);
+		} else if (xref == pic->pic_xref && dev == pic->pic_dev) {
+			/* Have both, check both */
+			return (pic);
+		}
 	}
 	return (NULL);
 }
@@ -740,6 +747,8 @@
 {
 	struct intr_pic *pic;
 
+	KASSERT(xref != XREF_INVALID, ("%s: Invalid xref", __func__));
+
 	mtx_lock(&pic_list_lock);
 	pic = pic_lookup_locked(dev, xref, flags);
 	if (pic != NULL) {
@@ -769,6 +778,8 @@
 {
 	struct intr_pic *pic;
 
+	KASSERT(xref != XREF_INVALID, ("%s: Invalid xref", __func__));
+
 	mtx_lock(&pic_list_lock);
 	pic = pic_lookup_locked(dev, xref, flags);
 	if (pic == NULL) {
@@ -828,6 +839,7 @@
 {
 	struct intr_pic *pic;
 
+	KASSERT(xref != XREF_INVALID, ("%s: Invalid xref", __func__));
 	pic = pic_lookup(dev, xref, FLAG_PIC);
 	if (pic == NULL) {
 		device_printf(dev, "not registered\n");
@@ -877,7 +889,7 @@
 #endif
 
 	/* Find the parent PIC */
-	parent_pic = pic_lookup(parent, 0, FLAG_PIC);
+	parent_pic = pic_lookup(parent, XREF_INVALID, FLAG_PIC);
 	if (parent_pic == NULL)
 		return (NULL);
 
@@ -911,6 +923,7 @@
 	if (data == NULL)
 		return (EINVAL);
 
+	KASSERT(xref != XREF_INVALID, ("%s: Invalid xref", __func__));
 	pic = pic_lookup(dev, xref,
 	    (data->type == INTR_MAP_DATA_MSI) ? FLAG_MSI : FLAG_PIC);
 	if (pic == NULL)
@@ -1290,6 +1303,7 @@
 	struct intr_map_data_msi *msi;
 	int err, i;
 
+	KASSERT(xref != XREF_INVALID, ("%s: Invalid xref", __func__));
 	pic = pic_lookup(NULL, xref, FLAG_MSI);
 	if (pic == NULL)
 		return (ESRCH);
@@ -1327,6 +1341,7 @@
 	struct intr_map_data_msi *msi;
 	int i, err;
 
+	KASSERT(xref != XREF_INVALID, ("%s: Invalid xref", __func__));
 	pic = pic_lookup(NULL, xref, FLAG_MSI);
 	if (pic == NULL)
 		return (ESRCH);
@@ -1366,6 +1381,7 @@
 	struct intr_map_data_msi *msi;
 	int err;
 
+	KASSERT(xref != XREF_INVALID, ("%s: Invalid xref", __func__));
 	pic = pic_lookup(NULL, xref, FLAG_MSI);
 	if (pic == NULL)
 		return (ESRCH);
@@ -1394,6 +1410,7 @@
 	struct intr_map_data_msi *msi;
 	int err;
 
+	KASSERT(xref != XREF_INVALID, ("%s: Invalid xref", __func__));
 	pic = pic_lookup(NULL, xref, FLAG_MSI);
 	if (pic == NULL)
 		return (ESRCH);
@@ -1427,6 +1444,7 @@
 	struct intr_pic *pic;
 	int err;
 
+	KASSERT(xref != XREF_INVALID, ("%s: Invalid xref", __func__));
 	pic = pic_lookup(NULL, xref, FLAG_MSI);
 	if (pic == NULL)
 		return (ESRCH);
Index: sys/sys/intr.h
===================================================================
--- sys/sys/intr.h
+++ sys/sys/intr.h
@@ -106,6 +106,8 @@
 int intr_isrc_dispatch(struct intr_irqsrc *, struct trapframe *);
 u_int intr_irq_next_cpu(u_int current_cpu, cpuset_t *cpumask);
 
+/* The device has no xref */
+#define	XREF_NONE	-2
 struct intr_pic *intr_pic_register(device_t, intptr_t);
 int intr_pic_deregister(device_t, intptr_t);
 int intr_pic_claim_root(device_t, intptr_t, intr_irq_filter_t *, void *, u_int);