documentation: networking: add 6lowpan documentation

This patch adds a 6lowpan.txt into the networking documentation
directory. Currently this documentation describes how the lowpan
private data of net devices will be handled.

Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-doc@vger.kernel.org
Suggested-by: Jukka Rissanen <jukka.rissanen@linux.intel.com>
Signed-off-by: Alexander Aring <alex.aring@gmail.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

diff --git a/Documentation/networking/6lowpan.txt b/Documentation/networking/6lowpan.txt
new file mode 100644 (file)
index 0000000..a7dc7e9
--- /dev/null
+++ b/Documentation/networking/6lowpan.txt
@@ -0,0 +1,50 @@
+
+Netdev private dataroom for 6lowpan interfaces:
+
+All 6lowpan able net devices, means all interfaces with ARPHRD_6LOWPAN,
+must have "struct lowpan_priv" placed at beginning of netdev_priv.
+
+The priv_size of each interface should be calculate by:
+
+ dev->priv_size = LOWPAN_PRIV_SIZE(LL_6LOWPAN_PRIV_DATA);
+
+Where LL_PRIV_6LOWPAN_DATA is sizeof linklayer 6lowpan private data struct.
+To access the LL_PRIV_6LOWPAN_DATA structure you can cast:
+
+ lowpan_priv(dev)-priv;
+
+to your LL_6LOWPAN_PRIV_DATA structure.
+
+Before registering the lowpan netdev interface you must run:
+
+ lowpan_netdev_setup(dev, LOWPAN_LLTYPE_FOOBAR);
+
+wheres LOWPAN_LLTYPE_FOOBAR is a define for your 6LoWPAN linklayer type of
+enum lowpan_lltypes.
+
+Example to evaluate the private usually you can do:
+
+static inline sturct lowpan_priv_foobar *
+lowpan_foobar_priv(struct net_device *dev)
+{
+       return (sturct lowpan_priv_foobar *)lowpan_priv(dev)->priv;
+}
+
+switch (dev->type) {
+case ARPHRD_6LOWPAN:
+       lowpan_priv = lowpan_priv(dev);
+       /* do great stuff which is ARPHRD_6LOWPAN related */
+       switch (lowpan_priv->lltype) {
+       case LOWPAN_LLTYPE_FOOBAR:
+               /* do 802.15.4 6LoWPAN handling here */
+               lowpan_foobar_priv(dev)->bar = foo;
+               break;
+       ...
+       }
+       break;
+...
+}
+
+In case of generic 6lowpan branch ("net/6lowpan") you can remove the check
+on ARPHRD_6LOWPAN, because you can be sure that these function are called
+by ARPHRD_6LOWPAN interfaces.

diff --git a/MAINTAINERS b/MAINTAINERS
index 98ede02a96f2bf5666ab2cf14ef4caceb0fdf9cb..5baa91c89b3b9883ca5557828e77c4d2f33aaec1 100644 (file)
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -158,6 +158,7 @@ L:  linux-wpan@vger.kernel.org
 S:     Maintained
 F:     net/6lowpan/
 F:     include/net/6lowpan.h
+F:     Documentation/networking/6lowpan.txt
 
 6PACK NETWORK DRIVER FOR AX.25
 M:     Andreas Koensgen <ajk@comnets.uni-bremen.de>