Index: sys/dev/iicbus/iicbb.c
===================================================================
--- sys/dev/iicbus/iicbb.c	(revision 261896)
+++ sys/dev/iicbus/iicbb.c	(working copy)
@@ -75,6 +75,7 @@ static int iicbb_stop(device_t);
 static int iicbb_write(device_t, const char *, int, int *, int);
 static int iicbb_read(device_t, char *, int, int *, int, int);
 static int iicbb_reset(device_t, u_char, u_char, u_char *);
+static int iicbb_transfer(device_t dev, struct iic_msg *msgs, uint32_t nmsgs);
 
 static device_method_t iicbb_methods[] = {
 	/* device interface */
@@ -94,7 +95,7 @@ static device_method_t iicbb_methods[] = {
 	DEVMETHOD(iicbus_write,		iicbb_write),
 	DEVMETHOD(iicbus_read,		iicbb_read),
 	DEVMETHOD(iicbus_reset,		iicbb_reset),
-	DEVMETHOD(iicbus_transfer,	iicbus_transfer_gen),
+	DEVMETHOD(iicbus_transfer,	iicbb_transfer),
 
 	{ 0, 0 }
 };
@@ -413,6 +414,21 @@ iicbb_read(device_t dev, char * buf, int len, int
 	return (0);
 }
 
+static int
+iicbb_transfer(device_t dev, struct iic_msg *msgs, uint32_t nmsgs)
+{
+	int error;
+
+	error = IICBB_PRE_XFER(device_get_parent(dev));
+	if (error)
+		return (error);
+
+	error = iicbus_transfer_gen(dev, msgs, nmsgs);
+
+	IICBB_POST_XFER(device_get_parent(dev));
+	return (error);
+}
+
 DRIVER_MODULE(iicbus, iicbb, iicbus_driver, iicbus_devclass, 0, 0);
 
 MODULE_DEPEND(iicbb, iicbus, IICBUS_MINVER, IICBUS_PREFVER, IICBUS_MAXVER);
Index: sys/dev/iicbus/iicbb_if.m
===================================================================
--- sys/dev/iicbus/iicbb_if.m	(revision 261896)
+++ sys/dev/iicbus/iicbb_if.m	(working copy)
@@ -31,6 +31,29 @@
 INTERFACE iicbb;
 
 #
+# Default implementation of optional methods
+#
+CODE {
+	static int
+	null_pre_xfer(device_t dev)
+	{
+		return 0;
+	}
+
+	static void
+	null_post_xfer(device_t dev)
+
+	{
+	}
+
+	static int
+	null_callback(device_t dev, int index, caddr_t data)
+	{
+		return 0;
+	}
+};
+
+#
 # iicbus callback
 #
 METHOD int callback {
@@ -37,9 +60,23 @@ METHOD int callback {
 	device_t dev;
 	int index;
 	caddr_t data;
-};
+} DEFAULT null_callback;
 
 #
+# Prepare device for I2C transfer
+#
+METHOD int pre_xfer {
+	device_t dev;
+} DEFAULT null_pre_xfer;
+
+#
+# Cleanup device after I2C transfer
+#
+METHOD void post_xfer {
+	device_t dev;
+} DEFAULT null_post_xfer;
+
+#
 # Set I2C bus data line
 #
 METHOD void setsda {