Provide pre/post transfer method callbacks for icbbb

clients.

These are helful when making certain drivers work on both Linux
and FreeBSD without changing the code flow too much.

Reviewed by: kib, wlosh
MFC after: 1 month

1 files changed, 38 insertions, 1 deletions

diff --git a/sys/dev/iicbus/iicbb_if.m b/sys/dev/iicbus/iicbb_if.m
index 7d10fe7..5b4ffec 100644
--- a/sys/dev/iicbus/iicbb_if.m
+++ b/sys/dev/iicbus/iicbb_if.m
@@ -31,13 +31,50 @@
 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 {
 	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