kernel-ark/Documentation/networking/6lowpan.txt
Alexander Aring ea9eb698b2 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>
2015-08-11 22:05:36 +02:00

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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.