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Sergey Lapin02cf2282009-06-08 12:18:50 +00001
2 Linux IEEE 802.15.4 implementation
3
4
5Introduction
6============
Masanari Iidac17cb8b2013-10-30 16:46:15 +09007The IEEE 802.15.4 working group focuses on standardization of bottom
Stefan Huber3d9738a2013-06-05 12:24:34 +02008two layers: Medium Access Control (MAC) and Physical (PHY). And there
alex.bluesman.smirnov@gmail.comdd456d42012-05-15 20:50:31 +00009are mainly two options available for upper layers:
10 - ZigBee - proprietary protocol from ZigBee Alliance
11 - 6LowPAN - IPv6 networking over low rate personal area networks
Sergey Lapin02cf2282009-06-08 12:18:50 +000012
13The Linux-ZigBee project goal is to provide complete implementation
alex.bluesman.smirnov@gmail.comdd456d42012-05-15 20:50:31 +000014of IEEE 802.15.4 and 6LoWPAN protocols. IEEE 802.15.4 is a stack
Sergey Lapin02cf2282009-06-08 12:18:50 +000015of protocols for organizing Low-Rate Wireless Personal Area Networks.
16
alex.bluesman.smirnov@gmail.comdd456d42012-05-15 20:50:31 +000017The stack is composed of three main parts:
18 - IEEE 802.15.4 layer; We have chosen to use plain Berkeley socket API,
19 the generic Linux networking stack to transfer IEEE 802.15.4 messages
20 and a special protocol over genetlink for configuration/management
21 - MAC - provides access to shared channel and reliable data delivery
22 - PHY - represents device drivers
Sergey Lapin02cf2282009-06-08 12:18:50 +000023
24
25Socket API
26==========
27
28int sd = socket(PF_IEEE802154, SOCK_DGRAM, 0);
29.....
30
31The address family, socket addresses etc. are defined in the
Dmitry Baryshkov48a2f112009-08-07 02:58:39 +000032include/net/af_ieee802154.h header or in the special header
Lennert Buytenhekb251d4d2015-05-25 15:38:29 +030033in the userspace package (see either http://wpan.cakelab.org/ or the
34git tree at https://github.com/linux-wpan/wpan-tools).
Sergey Lapin02cf2282009-06-08 12:18:50 +000035
36One can use SOCK_RAW for passing raw data towards device xmit function. YMMV.
37
38
Sergey Lapin02cf2282009-06-08 12:18:50 +000039Kernel side
40=============
41
42Like with WiFi, there are several types of devices implementing IEEE 802.15.4.
431) 'HardMAC'. The MAC layer is implemented in the device itself, the device
44 exports MLME and data API.
452) 'SoftMAC' or just radio. These types of devices are just radio transceivers
46 possibly with some kinds of acceleration like automatic CRC computation and
47 comparation, automagic ACK handling, address matching, etc.
48
49Those types of devices require different approach to be hooked into Linux kernel.
50
51
52HardMAC
53=======
54
Dmitry Baryshkov48a2f112009-08-07 02:58:39 +000055See the header include/net/ieee802154_netdev.h. You have to implement Linux
Sergey Lapin02cf2282009-06-08 12:18:50 +000056net_device, with .type = ARPHRD_IEEE802154. Data is exchanged with socket family
Dmitry Eremin-Solenikova0aea572009-08-19 18:53:39 +040057code via plain sk_buffs. On skb reception skb->cb must contain additional
58info as described in the struct ieee802154_mac_cb. During packet transmission
59the skb->cb is used to provide additional data to device's header_ops->create
Masanari Iidac17cb8b2013-10-30 16:46:15 +090060function. Be aware that this data can be overridden later (when socket code
Dmitry Eremin-Solenikova0aea572009-08-19 18:53:39 +040061submits skb to qdisc), so if you need something from that cb later, you should
62store info in the skb->data on your own.
Sergey Lapin02cf2282009-06-08 12:18:50 +000063
64To hook the MLME interface you have to populate the ml_priv field of your
Werner Almesberger56aa0912013-04-04 06:32:35 +000065net_device with a pointer to struct ieee802154_mlme_ops instance. The fields
66assoc_req, assoc_resp, disassoc_req, start_req, and scan_req are optional.
67All other fields are required.
Sergey Lapin02cf2282009-06-08 12:18:50 +000068
Sergey Lapin02cf2282009-06-08 12:18:50 +000069
70SoftMAC
71=======
72
alex.bluesman.smirnov@gmail.comdd456d42012-05-15 20:50:31 +000073The MAC is the middle layer in the IEEE 802.15.4 Linux stack. This moment it
74provides interface for drivers registration and management of slave interfaces.
75
76NOTE: Currently the only monitor device type is supported - it's IEEE 802.15.4
77stack interface for network sniffers (e.g. WireShark).
78
79This layer is going to be extended soon.
Sergey Lapin02cf2282009-06-08 12:18:50 +000080
Lennert Buytenhekb251d4d2015-05-25 15:38:29 +030081See header include/net/mac802154.h and several drivers in
82drivers/net/ieee802154/.
Dmitry Eremin-Solenikova0aea572009-08-19 18:53:39 +040083
alex.bluesman.smirnov@gmail.comdd456d42012-05-15 20:50:31 +000084
85Device drivers API
86==================
87
88The include/net/mac802154.h defines following functions:
89 - struct ieee802154_dev *ieee802154_alloc_device
90 (size_t priv_size, struct ieee802154_ops *ops):
91 allocation of IEEE 802.15.4 compatible device
92
93 - void ieee802154_free_device(struct ieee802154_dev *dev):
94 freeing allocated device
95
96 - int ieee802154_register_device(struct ieee802154_dev *dev):
97 register PHY in the system
98
99 - void ieee802154_unregister_device(struct ieee802154_dev *dev):
100 freeing registered PHY
101
102Moreover IEEE 802.15.4 device operations structure should be filled.
103
104Fake drivers
105============
106
Lennert Buytenhekb251d4d2015-05-25 15:38:29 +0300107In addition there is a driver available which simulates a real device with
108SoftMAC (fakelb - IEEE 802.15.4 loopback driver) interface. This option
109provides possibility to test and debug stack without usage of real hardware.
alex.bluesman.smirnov@gmail.comdd456d42012-05-15 20:50:31 +0000110
Lennert Buytenhekb251d4d2015-05-25 15:38:29 +0300111See sources in drivers/net/ieee802154 folder for more details.
alex.bluesman.smirnov@gmail.comdd456d42012-05-15 20:50:31 +0000112
113
alex.bluesman.smirnov@gmail.com63ce40e2011-11-10 07:41:11 +00001146LoWPAN Linux implementation
115============================
116
Lennert Buytenhekb251d4d2015-05-25 15:38:29 +0300117The IEEE 802.15.4 standard specifies an MTU of 127 bytes, yielding about 80
alex.bluesman.smirnov@gmail.com63ce40e2011-11-10 07:41:11 +0000118octets of actual MAC payload once security is turned on, on a wireless link
119with a link throughput of 250 kbps or less. The 6LoWPAN adaptation format
120[RFC4944] was specified to carry IPv6 datagrams over such constrained links,
121taking into account limited bandwidth, memory, or energy resources that are
122expected in applications such as wireless Sensor Networks. [RFC4944] defines
123a Mesh Addressing header to support sub-IP forwarding, a Fragmentation header
124to support the IPv6 minimum MTU requirement [RFC2460], and stateless header
125compression for IPv6 datagrams (LOWPAN_HC1 and LOWPAN_HC2) to reduce the
126relatively large IPv6 and UDP headers down to (in the best case) several bytes.
127
128In Semptember 2011 the standard update was published - [RFC6282].
129It deprecates HC1 and HC2 compression and defines IPHC encoding format which is
130used in this Linux implementation.
131
Lennert Buytenhekb251d4d2015-05-25 15:38:29 +0300132All the code related to 6lowpan you may find in files: net/6lowpan/*
133and net/ieee802154/6lowpan/*
alex.bluesman.smirnov@gmail.com63ce40e2011-11-10 07:41:11 +0000134
135To setup 6lowpan interface you need (busybox release > 1.17.0):
1361. Add IEEE802.15.4 interface and initialize PANid;
1372. Add 6lowpan interface by command like:
138 # ip link add link wpan0 name lowpan0 type lowpan
1393. Set MAC (if needs):
140 # ip link set lowpan0 address de:ad:be:ef:ca:fe:ba:be
1414. Bring up 'lowpan0' interface