--- a/sys/bus/iicbus/iicbus.c	2026-06-29 12:51:18.000000000 +0000
+++ b/sys/bus/iicbus/iicbus.c	2026-10-07 15:58:54.263534670 +0000
@@ -55,6 +55,8 @@
 static int iicbus_attach(device_t);
 static int iicbus_detach(device_t);
 static int iicbus_add_child(device_t dev, int order, const char *name, int unit);
+static int iicbus_read_ivar(device_t, device_t, int, uintptr_t *);
+static int iicbus_write_ivar(device_t, device_t, int, uintptr_t);
 
 static device_method_t iicbus_methods[] = {
         /* device interface */
@@ -66,6 +68,8 @@
         DEVMETHOD(bus_add_child,	iicbus_add_child),
 	DEVMETHOD(bus_driver_added,	bus_generic_driver_added),
         DEVMETHOD(bus_print_child,      bus_generic_print_child),
+        DEVMETHOD(bus_read_ivar,        iicbus_read_ivar),
+        DEVMETHOD(bus_write_ivar,       iicbus_write_ivar),
 
 	DEVMETHOD(iicbus_transfer,	iicbus_transfer_gen),
 
@@ -191,5 +195,43 @@
 	return (IIC_ENOTSUPP);
 }
 
+/*
+ * ivar accessors.  Children of iicbus are created with plain
+ * device_add_child() (no ivars are ever allocated: iicbus_attach()
+ * and iicbus_add_child()), while the generated accessor
+ * iicbus_get_addr() (__BUS_ACCESSOR, sys/sys/bus.h) discards our
+ * error return -- so a failed lookup must still write a sane value
+ * instead of leaving the caller's uninitialized stack in place
+ * (consumed by iic_probe(), sys/bus/iicbus/iic.c:115).
+ */
+static int
+iicbus_read_ivar(device_t dev, device_t child, int index, uintptr_t *result)
+{
+	struct iicbus_ivar *ivar = IICBUS_IVAR(child);
+
+	switch (index) {
+	case IICBUS_IVAR_ADDR:
+		*result = (ivar != NULL) ? ivar->addr : 0;
+		return (0);
+	default:
+		return (ENOENT);
+	}
+}
+
+static int
+iicbus_write_ivar(device_t dev, device_t child, int index, uintptr_t value)
+{
+	struct iicbus_ivar *ivar = IICBUS_IVAR(child);
+
+	switch (index) {
+	case IICBUS_IVAR_ADDR:
+		if (ivar != NULL)
+			ivar->addr = (uint32_t)value;
+		return (0);
+	default:
+		return (ENOENT);
+	}
+}
+
 DRIVER_MODULE(iicbus, iicbb, iicbus_driver, iicbus_devclass, NULL, NULL);
 MODULE_VERSION(iicbus, IICBUS_MODVER);