1 ============================================================================
5 Readme file for the Controller Area Network Protocol Family (aka Socket CAN)
9 1 Overview / What is Socket CAN
11 2 Motivation / Why using the socket API
15 3.2 local echo of sent frames
16 3.3 network security issues (capabilities)
17 3.4 network problem notifications
19 4 How to use Socket CAN
20 4.1 RAW protocol sockets with can_filters (SOCK_RAW)
21 4.1.1 RAW socket option CAN_RAW_FILTER
22 4.1.2 RAW socket option CAN_RAW_ERR_FILTER
23 4.1.3 RAW socket option CAN_RAW_ECHO
24 4.1.4 RAW socket option CAN_RAW_RECV_OWN_MSGS
25 4.2 Broadcast Manager protocol sockets (SOCK_DGRAM)
26 4.3 connected transport protocols (SOCK_SEQPACKET)
27 4.4 unconnected transport protocols (SOCK_DGRAM)
29 5 Socket CAN core module
30 5.1 can.ko module params
32 5.3 writing own CAN protocol modules
36 6.2 echo of sent frames
37 6.3 CAN controller hardware filters
38 6.4 currently supported CAN hardware
43 ============================================================================
45 1. Overview / What is Socket CAN
46 --------------------------------
48 The socketcan package is an implementation of CAN protocols
49 (Controller Area Network) for Linux. CAN is a networking technology
50 which has widespread use in automation, embedded devices, and
51 automotive fields. While there have been other CAN implementations
52 for Linux based on character devices, Socket CAN uses the Berkeley
53 socket API, the Linux network stack and implements the CAN device
54 drivers as network interfaces. The CAN socket API has been designed
55 as similar as possible to the TCP/IP protocols to allow programmers,
56 familiar with network programming, to easily learn how to use CAN
59 2. Motivation / Why using the socket API
60 ----------------------------------------
62 There have been CAN implementations for Linux before Socket CAN so the
63 question arises, why we have started another project. Most existing
64 implementations come as a device driver for some CAN hardware, they
65 are based on character devices and provide comparatively little
66 functionality. Usually, there is only a hardware-specific device
67 driver which provides a character device interface to send and
68 receive raw CAN frames, directly to/from the controller hardware.
69 Queueing of frames and higher-level transport protocols like ISO-TP
70 have to be implemented in user space applications. Also, most
71 character-device implementations support only one single process to
72 open the device at a time, similar to a serial interface. Exchanging
73 the CAN controller requires employment of another device driver and
74 often the need for adaption of large parts of the application to the
77 Socket CAN was designed to overcome all of these limitations. A new
78 protocol family has been implemented which provides a socket interface
79 to user space applications and which builds upon the Linux network
80 layer, so to use all of the provided queueing functionality. A device
81 driver for CAN controller hardware registers itself with the Linux
82 network layer as a network device, so that CAN frames from the
83 controller can be passed up to the network layer and on to the CAN
84 protocol family module and also vice-versa. Also, the protocol family
85 module provides an API for transport protocol modules to register, so
86 that any number of transport protocols can be loaded or unloaded
87 dynamically. In fact, the can core module alone does not provide any
88 protocol and cannot be used without loading at least one additional
89 protocol module. Multiple sockets can be opened at the same time,
90 on different or the same protocol module and they can listen/send
91 frames on different or the same CAN IDs. Several sockets listening on
92 the same interface for frames with the same CAN ID are all passed the
93 same received matching CAN frames. An application wishing to
94 communicate using a specific transport protocol, e.g. ISO-TP, just
95 selects that protocol when opening the socket, and then can read and
96 write application data byte streams, without having to deal with
99 Similar functionality visible from user-space could be provided by a
100 character device, too, but this would lead to a technically inelegant
101 solution for a couple of reasons:
103 * Intricate usage. Instead of passing a protocol argument to
104 socket(2) and using bind(2) to select a CAN interface and CAN ID, an
105 application would have to do all these operations using ioctl(2)s.
107 * Code duplication. A character device cannot make use of the Linux
108 network queueing code, so all that code would have to be duplicated
111 * Abstraction. In most existing character-device implementations, the
112 hardware-specific device driver for a CAN controller directly
113 provides the character device for the application to work with.
114 This is at least very unusual in Unix systems for both, char and
115 block devices. For example you don't have a character device for a
116 certain UART of a serial interface, a certain sound chip in your
117 computer, a SCSI or IDE controller providing access to your hard
118 disk or tape streamer device. Instead, you have abstraction layers
119 which provide a unified character or block device interface to the
120 application on the one hand, and a interface for hardware-specific
121 device drivers on the other hand. These abstractions are provided
122 by subsystems like the tty layer, the audio subsystem or the SCSI
123 and IDE subsystems for the devices mentioned above.
125 The easiest way to implement a CAN device driver is as a character
126 device without such a (complete) abstraction layer, as is done by most
127 existing drivers. The right way, however, would be to add such a
128 layer with all the functionality like registering for certain CAN
129 IDs, supporting several open file descriptors and (de)multiplexing
130 CAN frames between them, (sophisticated) queueing of CAN frames, and
131 providing an API for device drivers to register with. However, then
132 it would be no more difficult, or may be even easier, to use the
133 networking framework provided by the Linux kernel, and this is what
136 The use of the networking framework of the Linux kernel is just the
137 natural and most appropriate way to implement CAN for Linux.
139 3. Socket CAN concept
140 ---------------------
142 As described in chapter 2 it is the main goal of Socket CAN to
143 provide a socket interface to user space applications which builds
144 upon the Linux network layer. In contrast to the commonly known
145 TCP/IP and ethernet networking, the CAN bus is a broadcast-only(!)
146 medium that has no MAC-layer addressing like ethernet. The CAN-identifier
147 (can_id) is used for arbitration on the CAN-bus. Therefore the CAN-IDs
148 have to be chosen uniquely on the bus. When designing a CAN-ECU
149 network the CAN-IDs are mapped to be sent by a specific ECU.
150 For this reason a CAN-ID can be treated best as a kind of source address.
154 The network transparent access of multiple applications leads to the
155 problem that different applications may be interested in the same
156 CAN-IDs from the same CAN network interface. The Socket CAN core
157 module - which implements the protocol family CAN - provides several
158 high efficient receive lists for this reason. If e.g. a user space
159 application opens a CAN RAW socket, the raw protocol module itself
160 requests the (range of) CAN-IDs from the Socket CAN core that are
161 requested by the user. The subscription and unsubscription of
162 CAN-IDs can be done for specific CAN interfaces or for all(!) known
163 CAN interfaces with the can_rx_(un)register() functions provided to
164 CAN protocol modules by the SocketCAN core (see chapter 5).
165 To optimize the CPU usage at runtime the receive lists are split up
166 into several specific lists per device that match the requested
167 filter complexity for a given use-case.
169 3.2 local echo of sent frames
171 As known from other networking concepts the data exchanging
172 applications may run on the same or different nodes without any
173 change (except for the according addressing information):
175 ___ ___ ___ _______ ___
176 | _ | | _ | | _ | | _ _ | | _ |
177 ||A|| ||B|| ||C|| ||A| |B|| ||C||
178 |___| |___| |___| |_______| |___|
180 -----------------(1)- CAN bus -(2)---------------
182 To ensure that application A receives the same information in the
183 example (2) as it would receive in example (1) there is need for
184 some kind of local echo of the sent CAN frames on the appropriate node.
186 The Linux network devices (by default) just can handle the
187 transmission and reception of media dependent frames. Due to the
188 arbritration on the CAN bus the transmission of a low prio CAN-ID
189 may be delayed by the reception of a high prio CAN frame. To
190 reflect the correct* traffic on the node the local echo of the sent
191 data has to be performed right after a successful transmission. If
192 the CAN network interface is not capable of performing this echo handling
193 for some reason the SocketCAN core can do this task as a fallback solution.
194 See chapter 6.2 for details (recommended).
196 The echo functionality is enabled by default to reflect standard
197 networking behaviour for CAN applications. Due to some requests from
198 the RT-SocketCAN group the local echo optionally may be disabled for each
199 separate socket. See sockopts from the CAN RAW sockets in chapter 4.1.
201 * = you really like to have this when you're running analyser tools
202 like 'candump' or 'cansniffer' on the (same) node.
204 3.3 network security issues (capabilities)
206 The Controller Area Network is a local field bus transmitting only
207 broadcast messages without any routing and security concepts.
208 In the majority of cases the user application has to deal with
209 raw CAN frames. Therefore it might be reasonable NOT to restrict
210 the CAN access only to the user root, as known from other networks.
211 Since the currently implemented CAN_RAW and CAN_BCM sockets can only
212 send and receive frames to/from CAN interfaces it does not affect
213 security of others networks to allow all users to access the CAN.
214 To enable non-root users to access CAN_RAW and CAN_BCM protocol
215 sockets the Kconfig options CAN_RAW_USER and/or CAN_BCM_USER may be
216 selected at kernel compile time.
218 3.4 network problem notifications
220 The use of the CAN bus may lead to several problems on the physical
221 and media access control layer. Detecting and logging of these lower
222 layer problems is a vital requirement for CAN users to identify
223 hardware issues on the physical transceiver layer as well as
224 arbitration problems and error frames caused by the different
225 ECUs. The occurrence of detected errors are important for diagnosis
226 and have to be logged together with the exact timestamp. For this
227 reason the CAN interface driver can generate so called Error Frames
228 that can optionally be passed to the user application in the same
229 way as other CAN frames. Whenever an error on the physical layer
230 or the MAC layer is detected (e.g. by the CAN controller) the driver
231 creates an appropriate error frame. Error frames can be requested by
232 the user application using the common CAN filter mechanisms. Inside
233 this filter definition the (interested) type of errors may be
234 selected. The reception of error frames is disabled by default.
236 4. How to use Socket CAN
237 ------------------------
239 Like TCP/IP, you first need to open a socket for communicating over a
240 CAN network. Since Socket CAN implements a new protocol family, you
241 need to pass PF_CAN as the first argument to the socket(2) system
242 call. Currently, there are two CAN protocols to choose from, the raw
243 socket protocol and the broadcast manager (BCM). So to open a socket,
246 s = socket(PF_CAN, SOCK_RAW, CAN_RAW);
250 s = socket(PF_CAN, SOCK_DGRAM, CAN_BCM);
252 respectively. After the successful creation of the socket, you would
253 normally use the bind(2) system call to bind the socket to a CAN
254 interface (which is different from TCP/IP due to different addressing
255 - see chapter 3). After binding (CAN_RAW) or connecting (CAN_BCM)
256 the socket, you can read(2) and write(2) from/to the socket or use
257 send(2), sendto(2), sendmsg(2) and the recv* counterpart operations
258 on the socket as usual. There are also CAN specific socket options
261 The basic CAN frame structure and the sockaddr structure are defined
262 in include/linux/can.h:
265 canid_t can_id; /* 32 bit CAN_ID + EFF/RTR/ERR flags */
266 __u8 can_dlc; /* data length code: 0 .. 8 */
267 __u8 data[8] __attribute__((aligned(8)));
270 The alignment of the (linear) payload data[] to a 64bit boundary
271 allows the user to define own structs and unions to easily access the
272 CAN payload. There is no given byteorder on the CAN bus by
273 default. A read(2) system call on a CAN_RAW socket transfers a
274 struct can_frame to the user space.
276 The sockaddr_can structure has an interface index like the
277 PF_PACKET socket, that also binds to a specific interface:
279 struct sockaddr_can {
280 sa_family_t can_family;
283 struct { canid_t rx_id, tx_id; } tp16;
284 struct { canid_t rx_id, tx_id; } tp20;
285 struct { canid_t rx_id, tx_id; } mcnet;
286 struct { canid_t rx_id, tx_id; } isotp;
290 To determine the interface index an appropriate ioctl() has to
291 be used (example for CAN_RAW sockets without error checking):
294 struct sockaddr_can addr;
297 s = socket(PF_CAN, SOCK_RAW, CAN_RAW);
299 strcpy(ifr.ifr_name, "can0" );
300 ioctl(s, SIOCGIFINDEX, &ifr);
302 addr.can_family = AF_CAN;
303 addr.can_ifindex = ifr.ifr_ifindex;
305 bind(s, (struct sockaddr *)&addr, sizeof(addr));
309 To bind a socket to all(!) CAN interfaces the interface index must
310 be 0 (zero). In this case the socket receives CAN frames from every
311 enabled CAN interface. To determine the originating CAN interface
312 the system call recvfrom(2) may be used instead of read(2). To send
313 on a socket that is bound to 'any' interface sendto(2) is needed to
314 specify the outgoing interface.
316 Reading CAN frames from a bound CAN_RAW socket (see above) consists
317 of reading a struct can_frame:
319 struct can_frame frame;
321 nbytes = read(s, &frame, sizeof(struct can_frame));
324 perror("can raw socket read");
328 /* paraniod check ... */
329 if (nbytes < sizeof(struct can_frame)) {
330 fprintf(stderr, "read: incomplete CAN frame\n");
334 /* do something with the received CAN frame */
336 Writing CAN frames can be done similarly, with the write(2) system call:
338 nbytes = write(s, &frame, sizeof(struct can_frame));
340 When the CAN interface is bound to 'any' existing CAN interface
341 (addr.can_ifindex = 0) it is recommended to use recvfrom(2) if the
342 information about the originating CAN interface is needed:
344 struct sockaddr_can addr;
346 socklen_t len = sizeof(addr);
347 struct can_frame frame;
349 nbytes = recvfrom(s, &frame, sizeof(struct can_frame),
350 0, (struct sockaddr*)&addr, &len);
352 /* get interface name of the received CAN frame */
353 ifr.ifr_ifindex = addr.can_ifindex;
354 ioctl(s, SIOCGIFNAME, &ifr);
355 printf("Received a CAN frame from interface %s", ifr.ifr_name);
357 To write CAN frames on sockets bound to 'any' CAN interface the
358 outgoing interface has to be defined certainly.
360 strcpy(ifr.ifr_name, "can0");
361 ioctl(s, SIOCGIFINDEX, &ifr);
362 addr.can_ifindex = ifr.ifr_ifindex;
363 addr.can_family = AF_CAN;
365 nbytes = sendto(s, &frame, sizeof(struct can_frame),
366 0, (struct sockaddr*)&addr, sizeof(addr));
368 4.1 RAW protocol sockets with can_filters (SOCK_RAW)
370 Using CAN_RAW sockets is extensively comparable to the commonly
371 known access to CAN character devices. To meet the new possibilities
372 provided by the multi user SocketCAN approach, some reasonable
373 defaults are set at RAW socket binding time:
375 - The filters are set to exactly one filter receiving everything
376 - The socket only receives valid data frames (=> no error frames)
377 - The local echo of sent CAN frames is enabled (see chapter 3.2)
378 - The socket does not receive its own sent and echoed frames
380 These default settings may be changed before or after binding the socket.
381 To use the referenced definitions of the socket options for CAN_RAW
382 sockets, include <linux/can/raw.h>.
384 4.1.1 RAW socket option CAN_RAW_FILTER
386 The reception of CAN frames using CAN_RAW sockets can be controlled
387 by defining 0 .. n filters with the CAN_RAW_FILTER socket option.
389 The CAN filter structure is defined in include/linux/can.h:
396 A filter matches, when
398 <received_can_id> & mask == can_id & mask
400 which is analogous to known CAN controllers hardware filter semantics.
401 The filter can be inverted in this semantic, when the CAN_INV_FILTER
402 bit is set in can_id element of the can_filter structure. In
403 contrast to CAN controller hardware filters the user may set 0 .. n
404 receive filters for each open socket separately:
406 struct can_filter rfilter[2];
408 rfilter[0].can_id = 0x123;
409 rfilter[0].can_mask = CAN_SFF_MASK;
410 rfilter[1].can_id = 0x200;
411 rfilter[1].can_mask = 0x700;
413 setsockopt(s, SOL_CAN_RAW, CAN_RAW_FILTER, &rfilter, sizeof(rfilter));
415 To disable the reception of CAN frames on the selected CAN_RAW socket:
417 setsockopt(s, SOL_CAN_RAW, CAN_RAW_FILTER, NULL, 0);
419 To set the filters to zero filters is quite obsolete as not read
420 data causes the raw socket to discard the received CAN frames. But
421 having this 'send only' use-case we may remove the receive list in the
422 Kernel to save a little (really a very little!) CPU usage.
424 4.1.2 RAW socket option CAN_RAW_ERR_FILTER
426 As described in chapter 3.4 the CAN interface driver can generate so
427 called Error Frames that can optionally be passed to the user
428 application in the same way as other CAN frames. The possible
429 errors are divided into different error classes that may be filtered
430 using the appropriate error mask. To register for every possible
431 error condition CAN_ERR_MASK can be used as value for the error mask.
432 The values for the error mask are defined in linux/can/error.h .
434 can_err_mask_t err_mask = ( CAN_ERR_TX_TIMEOUT | CAN_ERR_BUSOFF );
436 setsockopt(s, SOL_CAN_RAW, CAN_RAW_ERR_FILTER,
437 &err_mask, sizeof(err_mask));
439 4.1.3 RAW socket option CAN_RAW_ECHO
441 To meet multi user needs the local echo is enabled by default
442 (see chapter 3.2 for details). But in some embedded use-cases
443 (e.g. when only one application uses the CAN bus) this echo
444 functionality can be disabled (separately for each socket):
446 int echo = 0; /* 0 = disabled, 1 = enabled (default) */
448 setsockopt(s, SOL_CAN_RAW, CAN_RAW_ECHO, &echo, sizeof(echo));
450 4.1.4 RAW socket option CAN_RAW_RECV_OWN_MSGS
452 When the local echo is enabled, all the sent CAN frames are
453 looped back to the open CAN sockets that registered for the CAN
454 frames' CAN-ID on this given interface to meet the multi user
455 needs. The reception of the CAN frames on the same socket that was
456 sending the CAN frame is assumed to be unwanted and therefore
457 disabled by default. This default behaviour may be changed on
460 int recv_own_msgs = 1; /* 0 = disabled (default), 1 = enabled */
462 setsockopt(s, SOL_CAN_RAW, CAN_RAW_RECV_OWN_MSGS,
463 &recv_own_msgs, sizeof(recv_own_msgs));
465 4.2 Broadcast Manager protocol sockets (SOCK_DGRAM)
466 4.3 connected transport protocols (SOCK_SEQPACKET)
467 4.4 unconnected transport protocols (SOCK_DGRAM)
470 5. Socket CAN core module
471 -------------------------
473 The Socket CAN core module implements the protocol family
474 PF_CAN. CAN protocol modules are loaded by the core module at
475 runtime. The core module provides an interface for CAN protocol
476 modules to subscribe needed CAN IDs (see chapter 3.1).
478 5.1 can.ko module params
480 - stats_timer: To calculate the Socket CAN core statistics
481 (e.g. current/maximum frames per second) this 1 second timer is
482 invoked at can.ko module start time by default. This timer can be
483 disabled by using stattimer=0 on the module comandline.
485 - debug: When the Kconfig option CONFIG_CAN_DEBUG_CORE is set at
486 compile time, the debug output code is compiled into the module.
487 debug = 0x01 => print general debug information
488 debug = 0x02 => print content of processed CAN frames
489 debug = 0x04 => print content of processed socket buffers
491 It is possible to use ORed values e.g. 3 or 7 for an output of
492 all available debug information. Using 0x02 and 0x04 may flood
493 your kernel log - so be careful.
497 As described in chapter 3.1 the Socket CAN core uses several filter
498 lists to deliver received CAN frames to CAN protocol modules. These
499 receive lists, their filters and the count of filter matches can be
500 checked in the appropriate receive list. All entries contain the
501 device and a protocol module identifier:
503 foo@bar:~$ cat /proc/net/can/rcvlist_all
505 receive list 'rx_all':
509 device can_id can_mask function userdata matches ident
510 vcan0 000 00000000 f88e6370 f6c6f400 0 raw
513 In this example an application requests any CAN traffic from vcan0.
515 rcvlist_all - list for unfiltered entries (no filter operations)
516 rcvlist_eff - list for single extended frame (EFF) entries
517 rcvlist_err - list for error frames masks
518 rcvlist_fil - list for mask/value filters
519 rcvlist_inv - list for mask/value filters (inverse semantic)
520 rcvlist_sff - list for single standard frame (SFF) entries
522 Additional procfs files in /proc/net/can
524 stats - Socket CAN core statistics (rx/tx frames, match ratios, ...)
525 reset_stats - manual statistic reset
526 version - prints the Socket CAN core version and the ABI version
528 5.3 writing own CAN protocol modules
530 To implement a new protocol in the protocol family PF_CAN a new
531 protocol has to be defined in include/linux/can.h .
532 The prototypes and definitions to use the Socket CAN core can be
533 accessed by including include/linux/can/core.h .
534 In addition to functions that register the CAN protocol and the
535 CAN device notifier chain there are functions to subscribe CAN
536 frames received by CAN interfaces and to send CAN frames:
538 can_rx_register - subscribe CAN frames from a specific interface
539 can_rx_unregister - unsubscribe CAN frames from a specific interface
540 can_send - transmit a CAN frame (optional with local echo)
542 For details see the kerneldoc documentation in net/can/af_can.c or
543 the source code of net/can/raw.c or net/can/bcm.c .
545 6. CAN network drivers
546 ----------------------
548 Writing a CAN network device driver is much easier than writing a
549 CAN character device driver. Similar to other known network device
550 drivers you mainly have to deal with:
552 - TX: Put the CAN frame from the socket buffer to the CAN controller.
553 - RX: Put the CAN frame from the CAN controller to the socket buffer.
555 See e.g. at Documentation/networking/netdevices.txt . The differences
556 for writing CAN network device driver are described below:
560 dev->type = ARPHRD_CAN; /* the netdevice hardware type */
561 dev->flags = IFF_NOARP; /* CAN has no arp */
563 dev->mtu = sizeof(struct can_frame);
565 The struct can_frame is the payload of each socket buffer in the
566 protocol family PF_CAN.
568 6.2 echo of sent frames
570 As described in chapter 3.2 the CAN network device driver should
571 support a local echo functionality. In this case the driver flag
572 IFF_ECHO has to be set to cause the PF_CAN core to not perform the
573 local echo as fallback solution:
575 dev->flags = (IFF_NOARP | IFF_ECHO);
577 6.3 CAN controller hardware filters
579 To reduce the interrupt load on deep embedded systems some CAN
580 controllers support the filtering of CAN IDs or ranges of CAN IDs.
581 These hardware filter capabilities vary from controller to
582 controller and have to be identified as not feasible in a multi-user
583 networking approach. The use of the very controller specific
584 hardware filters could make sense in a very dedicated use-case, as a
585 filter on driver level would affect all users in the multi-user
586 system. The high efficient filter sets inside the PF_CAN core allow
587 to set different multiple filters for each socket separately.
588 Therefore the use of hardware filters goes to the category 'handmade
589 tuning on deep embedded systems'. The author is running a MPC603e
590 @133MHz with four SJA1000 CAN controllers from 2002 under heavy bus
591 load without any problems ...
593 6.4 currently supported CAN hardware (May 2007)
595 On the project website http://developer.berlios.de/projects/socketcan
596 there are different drivers available:
598 vcan: Virtual CAN interface driver (if no real hardware is available)
599 sja1000: Philips SJA1000 CAN controller (recommended)
600 i82527: Intel i82527 CAN controller
601 mscan: Motorola/Freescale CAN controller (e.g. inside SOC MPC5200)
602 slcan: For a bunch of CAN adaptors that are attached via a
603 serial line ASCII protocol (for serial / USB adaptors)
605 Additionally the different CAN adaptors (ISA/PCI/PCMCIA/USB/Parport)
606 from PEAK Systemtechnik support the CAN netdevice driver model
607 since Linux driver v6.0: http://www.peak-system.com/linux/index.htm
609 Please check the Mailing Lists on the berlios OSS project website.
611 6.5 todo (September 2007)
613 The configuration interface for CAN network drivers is still an open
614 issue that has not been finalized in the socketcan project. Also the
615 idea of having a library module (candev.ko) that holds functions
616 that are needed by all CAN netdevices is not ready to ship.
617 Your contribution is welcome.
622 Oliver Hartkopp (PF_CAN core, filters, drivers, bcm)
623 Urs Thuermann (PF_CAN core, kernel integration, socket interfaces, raw, vcan)
624 Jan Kizka (RT-SocketCAN core, Socket-API reconciliation)
625 Wolfgang Grandegger (RT-SocketCAN core & drivers, Raw Socket-API reviews)
626 Robert Schwebel (design reviews, PTXdist integration)
627 Marc Kleine-Budde (design reviews, Kernel 2.6 cleanups, drivers)
628 Benedikt Spranger (reviews)
629 Thomas Gleixner (LKML reviews, coding style, posting hints)
630 Andrey Volkov (kernel subtree structure, ioctls, mscan driver)
631 Matthias Brukner (first SJA1000 CAN netdevice implementation Q2/2003)
632 Klaus Hitschler (PEAK driver integration)
633 Uwe Koppe (CAN netdevices with PF_PACKET approach)
634 Michael Schulze (driver layer echo requirement, RT CAN drivers review)