--- /dev/null
+ GNU GENERAL PUBLIC LICENSE
+ Version 2, June 1991
+
+ Copyright (C) 1989, 1991 Free Software Foundation, Inc.,
+ 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+ Preamble
+
+ The licenses for most software are designed to take away your
+freedom to share and change it. By contrast, the GNU General Public
+License is intended to guarantee your freedom to share and change free
+software--to make sure the software is free for all its users. This
+General Public License applies to most of the Free Software
+Foundation's software and to any other program whose authors commit to
+using it. (Some other Free Software Foundation software is covered by
+the GNU Lesser General Public License instead.) You can apply it to
+your programs, too.
+
+ When we speak of free software, we are referring to freedom, not
+price. Our General Public Licenses are designed to make sure that you
+have the freedom to distribute copies of free software (and charge for
+this service if you wish), that you receive source code or can get it
+if you want it, that you can change the software or use pieces of it
+in new free programs; and that you know you can do these things.
+
+ To protect your rights, we need to make restrictions that forbid
+anyone to deny you these rights or to ask you to surrender the rights.
+These restrictions translate to certain responsibilities for you if you
+distribute copies of the software, or if you modify it.
+
+ For example, if you distribute copies of such a program, whether
+gratis or for a fee, you must give the recipients all the rights that
+you have. You must make sure that they, too, receive or can get the
+source code. And you must show them these terms so they know their
+rights.
+
+ We protect your rights with two steps: (1) copyright the software, and
+(2) offer you this license which gives you legal permission to copy,
+distribute and/or modify the software.
+
+ Also, for each author's protection and ours, we want to make certain
+that everyone understands that there is no warranty for this free
+software. If the software is modified by someone else and passed on, we
+want its recipients to know that what they have is not the original, so
+that any problems introduced by others will not reflect on the original
+authors' reputations.
+
+ Finally, any free program is threatened constantly by software
+patents. We wish to avoid the danger that redistributors of a free
+program will individually obtain patent licenses, in effect making the
+program proprietary. To prevent this, we have made it clear that any
+patent must be licensed for everyone's free use or not licensed at all.
+
+ The precise terms and conditions for copying, distribution and
+modification follow.
+
+ GNU GENERAL PUBLIC LICENSE
+ TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
+
+ 0. This License applies to any program or other work which contains
+a notice placed by the copyright holder saying it may be distributed
+under the terms of this General Public License. The "Program", below,
+refers to any such program or work, and a "work based on the Program"
+means either the Program or any derivative work under copyright law:
+that is to say, a work containing the Program or a portion of it,
+either verbatim or with modifications and/or translated into another
+language. (Hereinafter, translation is included without limitation in
+the term "modification".) Each licensee is addressed as "you".
+
+Activities other than copying, distribution and modification are not
+covered by this License; they are outside its scope. The act of
+running the Program is not restricted, and the output from the Program
+is covered only if its contents constitute a work based on the
+Program (independent of having been made by running the Program).
+Whether that is true depends on what the Program does.
+
+ 1. You may copy and distribute verbatim copies of the Program's
+source code as you receive it, in any medium, provided that you
+conspicuously and appropriately publish on each copy an appropriate
+copyright notice and disclaimer of warranty; keep intact all the
+notices that refer to this License and to the absence of any warranty;
+and give any other recipients of the Program a copy of this License
+along with the Program.
+
+You may charge a fee for the physical act of transferring a copy, and
+you may at your option offer warranty protection in exchange for a fee.
+
+ 2. You may modify your copy or copies of the Program or any portion
+of it, thus forming a work based on the Program, and copy and
+distribute such modifications or work under the terms of Section 1
+above, provided that you also meet all of these conditions:
+
+ a) You must cause the modified files to carry prominent notices
+ stating that you changed the files and the date of any change.
+
+ b) You must cause any work that you distribute or publish, that in
+ whole or in part contains or is derived from the Program or any
+ part thereof, to be licensed as a whole at no charge to all third
+ parties under the terms of this License.
+
+ c) If the modified program normally reads commands interactively
+ when run, you must cause it, when started running for such
+ interactive use in the most ordinary way, to print or display an
+ announcement including an appropriate copyright notice and a
+ notice that there is no warranty (or else, saying that you provide
+ a warranty) and that users may redistribute the program under
+ these conditions, and telling the user how to view a copy of this
+ License. (Exception: if the Program itself is interactive but
+ does not normally print such an announcement, your work based on
+ the Program is not required to print an announcement.)
+
+These requirements apply to the modified work as a whole. If
+identifiable sections of that work are not derived from the Program,
+and can be reasonably considered independent and separate works in
+themselves, then this License, and its terms, do not apply to those
+sections when you distribute them as separate works. But when you
+distribute the same sections as part of a whole which is a work based
+on the Program, the distribution of the whole must be on the terms of
+this License, whose permissions for other licensees extend to the
+entire whole, and thus to each and every part regardless of who wrote it.
+
+Thus, it is not the intent of this section to claim rights or contest
+your rights to work written entirely by you; rather, the intent is to
+exercise the right to control the distribution of derivative or
+collective works based on the Program.
+
+In addition, mere aggregation of another work not based on the Program
+with the Program (or with a work based on the Program) on a volume of
+a storage or distribution medium does not bring the other work under
+the scope of this License.
+
+ 3. You may copy and distribute the Program (or a work based on it,
+under Section 2) in object code or executable form under the terms of
+Sections 1 and 2 above provided that you also do one of the following:
+
+ a) Accompany it with the complete corresponding machine-readable
+ source code, which must be distributed under the terms of Sections
+ 1 and 2 above on a medium customarily used for software interchange; or,
+
+ b) Accompany it with a written offer, valid for at least three
+ years, to give any third party, for a charge no more than your
+ cost of physically performing source distribution, a complete
+ machine-readable copy of the corresponding source code, to be
+ distributed under the terms of Sections 1 and 2 above on a medium
+ customarily used for software interchange; or,
+
+ c) Accompany it with the information you received as to the offer
+ to distribute corresponding source code. (This alternative is
+ allowed only for noncommercial distribution and only if you
+ received the program in object code or executable form with such
+ an offer, in accord with Subsection b above.)
+
+The source code for a work means the preferred form of the work for
+making modifications to it. For an executable work, complete source
+code means all the source code for all modules it contains, plus any
+associated interface definition files, plus the scripts used to
+control compilation and installation of the executable. However, as a
+special exception, the source code distributed need not include
+anything that is normally distributed (in either source or binary
+form) with the major components (compiler, kernel, and so on) of the
+operating system on which the executable runs, unless that component
+itself accompanies the executable.
+
+If distribution of executable or object code is made by offering
+access to copy from a designated place, then offering equivalent
+access to copy the source code from the same place counts as
+distribution of the source code, even though third parties are not
+compelled to copy the source along with the object code.
+
+ 4. You may not copy, modify, sublicense, or distribute the Program
+except as expressly provided under this License. Any attempt
+otherwise to copy, modify, sublicense or distribute the Program is
+void, and will automatically terminate your rights under this License.
+However, parties who have received copies, or rights, from you under
+this License will not have their licenses terminated so long as such
+parties remain in full compliance.
+
+ 5. You are not required to accept this License, since you have not
+signed it. However, nothing else grants you permission to modify or
+distribute the Program or its derivative works. These actions are
+prohibited by law if you do not accept this License. Therefore, by
+modifying or distributing the Program (or any work based on the
+Program), you indicate your acceptance of this License to do so, and
+all its terms and conditions for copying, distributing or modifying
+the Program or works based on it.
+
+ 6. Each time you redistribute the Program (or any work based on the
+Program), the recipient automatically receives a license from the
+original licensor to copy, distribute or modify the Program subject to
+these terms and conditions. You may not impose any further
+restrictions on the recipients' exercise of the rights granted herein.
+You are not responsible for enforcing compliance by third parties to
+this License.
+
+ 7. If, as a consequence of a court judgment or allegation of patent
+infringement or for any other reason (not limited to patent issues),
+conditions are imposed on you (whether by court order, agreement or
+otherwise) that contradict the conditions of this License, they do not
+excuse you from the conditions of this License. If you cannot
+distribute so as to satisfy simultaneously your obligations under this
+License and any other pertinent obligations, then as a consequence you
+may not distribute the Program at all. For example, if a patent
+license would not permit royalty-free redistribution of the Program by
+all those who receive copies directly or indirectly through you, then
+the only way you could satisfy both it and this License would be to
+refrain entirely from distribution of the Program.
+
+If any portion of this section is held invalid or unenforceable under
+any particular circumstance, the balance of the section is intended to
+apply and the section as a whole is intended to apply in other
+circumstances.
+
+It is not the purpose of this section to induce you to infringe any
+patents or other property right claims or to contest validity of any
+such claims; this section has the sole purpose of protecting the
+integrity of the free software distribution system, which is
+implemented by public license practices. Many people have made
+generous contributions to the wide range of software distributed
+through that system in reliance on consistent application of that
+system; it is up to the author/donor to decide if he or she is willing
+to distribute software through any other system and a licensee cannot
+impose that choice.
+
+This section is intended to make thoroughly clear what is believed to
+be a consequence of the rest of this License.
+
+ 8. If the distribution and/or use of the Program is restricted in
+certain countries either by patents or by copyrighted interfaces, the
+original copyright holder who places the Program under this License
+may add an explicit geographical distribution limitation excluding
+those countries, so that distribution is permitted only in or among
+countries not thus excluded. In such case, this License incorporates
+the limitation as if written in the body of this License.
+
+ 9. The Free Software Foundation may publish revised and/or new versions
+of the General Public License from time to time. Such new versions will
+be similar in spirit to the present version, but may differ in detail to
+address new problems or concerns.
+
+Each version is given a distinguishing version number. If the Program
+specifies a version number of this License which applies to it and "any
+later version", you have the option of following the terms and conditions
+either of that version or of any later version published by the Free
+Software Foundation. If the Program does not specify a version number of
+this License, you may choose any version ever published by the Free Software
+Foundation.
+
+ 10. If you wish to incorporate parts of the Program into other free
+programs whose distribution conditions are different, write to the author
+to ask for permission. For software which is copyrighted by the Free
+Software Foundation, write to the Free Software Foundation; we sometimes
+make exceptions for this. Our decision will be guided by the two goals
+of preserving the free status of all derivatives of our free software and
+of promoting the sharing and reuse of software generally.
+
+ NO WARRANTY
+
+ 11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY
+FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN
+OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES
+PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED
+OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS
+TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE
+PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING,
+REPAIR OR CORRECTION.
+
+ 12. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
+WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR
+REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES,
+INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING
+OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED
+TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY
+YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER
+PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE
+POSSIBILITY OF SUCH DAMAGES.
+
+ END OF TERMS AND CONDITIONS
+
+ How to Apply These Terms to Your New Programs
+
+ If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+ To do so, attach the following notices to the program. It is safest
+to attach them to the start of each source file to most effectively
+convey the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+ <one line to give the program's name and a brief idea of what it does.>
+ Copyright (C) <year> <name of author>
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License along
+ with this program; if not, write to the Free Software Foundation, Inc.,
+ 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+
+Also add information on how to contact you by electronic and paper mail.
+
+If the program is interactive, make it output a short notice like this
+when it starts in an interactive mode:
+
+ Gnomovision version 69, Copyright (C) year name of author
+ Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
+ This is free software, and you are welcome to redistribute it
+ under certain conditions; type `show c' for details.
+
+The hypothetical commands `show w' and `show c' should show the appropriate
+parts of the General Public License. Of course, the commands you use may
+be called something other than `show w' and `show c'; they could even be
+mouse-clicks or menu items--whatever suits your program.
+
+You should also get your employer (if you work as a programmer) or your
+school, if any, to sign a "copyright disclaimer" for the program, if
+necessary. Here is a sample; alter the names:
+
+ Yoyodyne, Inc., hereby disclaims all copyright interest in the program
+ `Gnomovision' (which makes passes at compilers) written by James Hacker.
+
+ <signature of Ty Coon>, 1 April 1989
+ Ty Coon, President of Vice
+
+This General Public License does not permit incorporating your program into
+proprietary programs. If your program is a subroutine library, you may
+consider it more useful to permit linking proprietary applications with the
+library. If this is what you want to do, use the GNU Lesser General
+Public License instead of this License.
--- /dev/null
+/*
+ * elmcan.c - ELM327 based CAN interface driver
+ * (tty line discipline)
+ *
+ * This file is derived from linux/drivers/net/can/slcan.c
+ *
+ * elmcan.c Author : Max Staudt <elmcan@enpas.org>
+ * slcan.c Author : Oliver Hartkopp <socketcan@hartkopp.net>
+ * slip.c Authors : Laurence Culhane <loz@holmes.demon.co.uk>
+ * Fred N. van Kempen <waltje@uwalt.nl.mugnet.org>
+ *
+ * SPDX-License-Identifier: GPL-2.0
+ *
+ */
+
+#define pr_fmt(fmt) "[elmcan] " fmt
+
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+
+#include <linux/bitops.h>
+#include <linux/errno.h>
+#include <linux/if_ether.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/netdevice.h>
+#include <linux/skbuff.h>
+#include <linux/spinlock.h>
+#include <linux/string.h>
+#include <linux/tty.h>
+#include <linux/workqueue.h>
+
+#include <linux/can.h>
+#include <linux/can/dev.h>
+#include <linux/can/error.h>
+#include <linux/can/led.h>
+
+
+MODULE_ALIAS_LDISC(N_ELMCAN);
+MODULE_DESCRIPTION("ELM327 based CAN interface");
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Max Staudt <max-linux@enpas.org>");
+
+/* Line discipline ID number */
+#ifndef N_ELMCAN
+#define N_ELMCAN 26
+#endif
+
+#define ELM327_CAN_CONFIG_SEND_SFF 0x8000
+#define ELM327_CAN_CONFIG_VARIABLE_DLC 0x4000
+#define ELM327_CAN_CONFIG_RECV_BOTH_SFF_EFF 0x2000
+#define ELM327_CAN_CONFIG_BAUDRATE_MULT_8_7 0x1000
+
+#define ELM327_MAGIC_CHAR 'y'
+#define ELM327_MAGIC_STRING "y"
+
+
+/* Bits in elm->cmds_todo */
+enum ELM_TODO {
+ ELM_TODO_CAN_DATA = 0,
+ ELM_TODO_CANID_11BIT,
+ ELM_TODO_CANID_29BIT_LOW,
+ ELM_TODO_CANID_29BIT_HIGH,
+ ELM_TODO_CAN_CONFIG,
+ ELM_TODO_RESPONSES,
+ ELM_TODO_SILENT_MONITOR,
+ ELM_TODO_INIT
+};
+
+
+struct elmcan {
+ /* This must be the first member when using alloc_candev() */
+ struct can_priv can;
+
+ /* TTY and netdev devices that we're bridging */
+ struct tty_struct *tty;
+ struct net_device *dev;
+
+ int magic;
+
+ /* Per-channel lock */
+ spinlock_t lock;
+
+ /* TTY TX helpers */
+ struct work_struct tx_work; /* Flushes TTY TX buffer */
+ unsigned char txbuf[32];
+ unsigned char *txhead; /* Pointer to next TX byte */
+ int txleft; /* Bytes left to TX */
+
+ /* TTY RX helpers */
+ unsigned char rxbuf[256];
+ int rxfill;
+
+ /* State machine */
+ enum {
+ ELM_NOTINIT = 0,
+ ELM_GETMAGICCHAR,
+ ELM_GETPROMPT,
+ ELM_RECEIVING,
+ } state;
+
+ int drop_next_line;
+
+ /* The CAN frame and config the ELM327 is sending/using,
+ * or will send/use after finishing all cmds_todo */
+ struct can_frame can_frame;
+ unsigned short can_config;
+ unsigned long can_bitrate;
+ unsigned char can_bitrate_divisor;
+ int silent_monitoring;
+
+ /* Things we have yet to send */
+ char **next_init_cmd;
+ unsigned long cmds_todo;
+};
+
+
+static DEFINE_SPINLOCK(elmcan_open_lock);
+
+
+
+
+ /************************************************************************
+ * ELM327: Transmission *
+ ************************************************************************/
+
+static void elm327_send(struct elmcan *elm, const void *buf, size_t len)
+{
+ int actual;
+
+ memcpy(elm->txbuf, buf, len);
+
+ /* Order of next two lines is *very* important.
+ * When we are sending a little amount of data,
+ * the transfer may be completed inside the ops->write()
+ * routine, because it's running with interrupts enabled.
+ * In this case we *never* got WRITE_WAKEUP event,
+ * if we did not request it before write operation.
+ * 14 Oct 1994 Dmitry Gorodchanin.
+ */
+ set_bit(TTY_DO_WRITE_WAKEUP, &elm->tty->flags);
+ actual = elm->tty->ops->write(elm->tty, elm->txbuf, len);
+ elm->txleft = len - actual;
+ elm->txhead = elm->txbuf + actual;
+}
+
+
+static void elm327_kick_into_cmd_mode(struct elmcan *elm)
+{
+ if (elm->state != ELM_GETMAGICCHAR && elm->state != ELM_GETPROMPT) {
+ elm327_send(elm, ELM327_MAGIC_STRING, 1);
+
+ elm->state = ELM_GETMAGICCHAR;
+ elm->rxfill = 0;
+ }
+}
+
+
+static void elm327_send_frame(struct elmcan *elm, struct can_frame *frame)
+{
+ if (elm->can_frame.can_id != frame->can_id) {
+ /* Set the new CAN ID for transmission. */
+ if ((frame->can_id & CAN_EFF_FLAG) ^ (elm->can_frame.can_id & CAN_EFF_FLAG)) {
+ elm->can_config = (frame->can_id & CAN_EFF_FLAG ? 0 : ELM327_CAN_CONFIG_SEND_SFF)
+ | ELM327_CAN_CONFIG_VARIABLE_DLC
+ | ELM327_CAN_CONFIG_RECV_BOTH_SFF_EFF
+ | elm->can_bitrate_divisor;
+
+ set_bit(ELM_TODO_CAN_CONFIG, &elm->cmds_todo);
+ }
+
+ if (frame->can_id & CAN_EFF_FLAG) {
+ clear_bit(ELM_TODO_CANID_11BIT, &elm->cmds_todo);
+ set_bit(ELM_TODO_CANID_29BIT_LOW, &elm->cmds_todo);
+ set_bit(ELM_TODO_CANID_29BIT_HIGH, &elm->cmds_todo);
+ } else {
+ set_bit(ELM_TODO_CANID_11BIT, &elm->cmds_todo);
+ clear_bit(ELM_TODO_CANID_29BIT_LOW, &elm->cmds_todo);
+ clear_bit(ELM_TODO_CANID_29BIT_HIGH, &elm->cmds_todo);
+ }
+ }
+
+ elm->can_frame = *frame;
+ set_bit(ELM_TODO_CAN_DATA, &elm->cmds_todo);
+
+ elm327_kick_into_cmd_mode(elm);
+}
+
+
+
+ /************************************************************************
+ * ELM327: Initialization sequence *
+ ************************************************************************/
+
+static char *elm327_init_script[] = {
+ "AT WS\r", /* v1.0: Warm Start */
+ "AT PP FF OFF\r", /* v1.0: All Programmable Parameters Off */
+ "AT M0\r", /* v1.0: Memory Off */
+ "AT AL\r", /* v1.0: Allow Long messages */
+ "AT BI\r", /* v1.0: Bypass Initialization */
+ "AT CAF0\r", /* v1.0: CAN Auto Formatting Off */
+ "AT CFC0\r", /* v1.0: CAN Flow Control Off */
+ "AT CF 000\r", /* v1.0: Reset CAN ID Filter */
+ "AT CM 000\r", /* v1.0: Reset CAN ID Mask */
+ "AT E1\r", /* v1.0: Echo On */
+ "AT H1\r", /* v1.0: Headers On */
+ "AT L0\r", /* v1.0: Linefeeds Off */
+ "AT SH 7DF\r", /* v1.0: Set CAN sending ID to 0x7df */
+ "AT ST FF\r", /* v1.0: Set maximum Timeout for response after TX */
+ "AT AT0\r", /* v1.2: Adaptive Timing Off */
+ "AT D1\r", /* v1.3: Print DLC On */
+ "AT S1\r", /* v1.3: Spaces On */
+ "AT TP B\r", /* v1.0: Try Protocol B */
+ NULL
+};
+
+
+static void elm327_init(struct elmcan *elm)
+{
+ elm->state = ELM_NOTINIT;
+ elm->can_frame.can_id = 0x7df;
+ elm->rxfill = 0;
+ elm->drop_next_line = 0;
+
+ /* We can only set the bitrate as a fraction of 500000.
+ * The bit timing constants in elmcan_bittiming_const will
+ * limit the user to the right values.
+ */
+ elm->can_bitrate_divisor = 500000 / elm->can.bittiming.bitrate;
+ elm->can_config = ELM327_CAN_CONFIG_SEND_SFF
+ | ELM327_CAN_CONFIG_VARIABLE_DLC
+ | ELM327_CAN_CONFIG_RECV_BOTH_SFF_EFF
+ | elm->can_bitrate_divisor;
+
+ /* Configure ELM327 and then start monitoring */
+ elm->next_init_cmd = &elm327_init_script[0];
+ set_bit(ELM_TODO_INIT, &elm->cmds_todo);
+ set_bit(ELM_TODO_SILENT_MONITOR, &elm->cmds_todo);
+ set_bit(ELM_TODO_RESPONSES, &elm->cmds_todo);
+ set_bit(ELM_TODO_CAN_CONFIG, &elm->cmds_todo);
+
+ elm327_kick_into_cmd_mode(elm);
+}
+
+
+
+ /************************************************************************
+ * ELM327: Reception -> netdev glue *
+ ************************************************************************/
+
+static void elm327_feed_frame_to_netdev(struct elmcan *elm, const struct can_frame *frame)
+{
+ struct can_frame *cf;
+ struct sk_buff *skb;
+
+ if (!netif_running(elm->dev)) {
+ return;
+ }
+
+ skb = alloc_can_skb(elm->dev, &cf);
+
+ if (!skb)
+ return;
+
+ memcpy(cf, frame, sizeof(struct can_frame));
+
+ elm->dev->stats.rx_packets++;
+ elm->dev->stats.rx_bytes += frame->can_dlc;
+ netif_rx_ni(skb);
+
+ can_led_event(elm->dev, CAN_LED_EVENT_RX);
+}
+
+
+
+ /************************************************************************
+ * ELM327: Panic handler *
+ ************************************************************************/
+
+static inline void elm327_panic(struct elmcan *elm)
+{
+ struct can_frame frame = {0};
+
+ frame.can_id = CAN_ERR_FLAG | CAN_ERR_RESTARTED;
+ frame.can_dlc = CAN_ERR_DLC;
+ elm327_feed_frame_to_netdev(elm, &frame);
+
+ pr_err("ELM327 misbehaved. Re-initializing.\n");
+
+ elm->can.can_stats.restarts++;
+ elm327_init(elm);
+}
+
+
+
+ /************************************************************************
+ * ELM327: Reception parser *
+ ************************************************************************/
+
+static void elm327_parse_error(struct elmcan *elm, int len)
+{
+ struct can_frame frame = {0};
+
+ frame.can_id = CAN_ERR_FLAG;
+ frame.can_dlc = CAN_ERR_DLC;
+
+ switch(len) {
+ case 17:
+ if (!memcmp(elm->rxbuf, "UNABLE TO CONNECT", 17)) {
+ pr_err("The ELM327 reported UNABLE TO CONNECT. Please check your setup.\n");
+ }
+ break;
+ case 11:
+ if (!memcmp(elm->rxbuf, "BUFFER FULL", 11)) {
+ /* This case will only happen if the last data
+ * line was complete.
+ * Otherwise, elm327_parse_frame() will emit the
+ * error frame instead.
+ */
+ frame.can_id |= CAN_ERR_CRTL;
+ frame.data[1] = CAN_ERR_CRTL_RX_OVERFLOW;
+ }
+ break;
+ case 9:
+ if (!memcmp(elm->rxbuf, "BUS ERROR", 9)) {
+ frame.can_id |= CAN_ERR_BUSERROR;
+ }
+ if (!memcmp(elm->rxbuf, "CAN ERROR", 9)
+ || !memcmp(elm->rxbuf, "<RX ERROR", 9)) {
+ frame.can_id |= CAN_ERR_PROT;
+ }
+ break;
+ case 8:
+ if (!memcmp(elm->rxbuf, "BUS BUSY", 8)) {
+ frame.can_id |= CAN_ERR_PROT;
+ frame.data[2] = CAN_ERR_PROT_OVERLOAD;
+ }
+ if (!memcmp(elm->rxbuf, "FB ERROR", 8)) {
+ frame.can_id |= CAN_ERR_PROT;
+ frame.data[2] = CAN_ERR_PROT_TX;
+ }
+ break;
+ case 5:
+ if (!memcmp(elm->rxbuf, "ERR", 3)) {
+ pr_err("The ELM327 reported an ERR%c%c. Please power it off and on again.\n",
+ elm->rxbuf[3], elm->rxbuf[4]);
+ frame.can_id |= CAN_ERR_CRTL;
+ }
+ break;
+ default:
+ /* Don't emit an error frame if we're unsure */
+ return;
+ }
+
+ elm327_feed_frame_to_netdev(elm, &frame);
+}
+
+
+static int elm327_parse_frame(struct elmcan *elm, int len)
+{
+ struct can_frame frame = {0};
+ int hexlen;
+ int datastart;
+ int i;
+
+ /* Find first non-hex and non-space character:
+ * - In the simplest case, there is none.
+ * - For RTR frames, 'R' is the first non-hex character.
+ * - An error message may replace the end of the data line.
+ */
+ for (hexlen = 0; hexlen <= len; hexlen++) {
+ if (hex_to_bin(elm->rxbuf[hexlen]) < 0
+ && elm->rxbuf[hexlen] != ' ') {
+ break;
+ }
+ }
+
+ /* Use spaces in CAN ID to distinguish 29 or 11 bit address length.
+ * No out-of-bounds access:
+ * We use the fact that we can always read from elm->rxbuf. */
+ if (elm->rxbuf[2] == ' ' && elm->rxbuf[5] == ' '
+ && elm->rxbuf[8] == ' ' && elm->rxbuf[11] == ' '
+ && elm->rxbuf[13] == ' ') {
+ frame.can_id = CAN_EFF_FLAG;
+ datastart = 14;
+ } else if (elm->rxbuf[3] == ' ' && elm->rxbuf[5] == ' ') {
+ frame.can_id = 0;
+ datastart = 6;
+ } else {
+ /* This is not a well-formatted data line.
+ * Assume it's an error message. */
+ return 1;
+ }
+
+ if (hexlen < datastart) {
+ /* The line is too short to be a valid frame hex dump.
+ * Something interrupted the hex dump or it is invalid. */
+ return 1;
+ }
+
+ /* From here on all chars up to buf[hexlen] are hex or spaces,
+ * at well-defined offsets. */
+
+ /* Read CAN data length */
+ frame.can_dlc = (hex_to_bin(elm->rxbuf[datastart - 2]) << 0);
+
+ /* Read CAN ID */
+ if (frame.can_id & CAN_EFF_FLAG) {
+ frame.can_id |= (hex_to_bin(elm->rxbuf[0]) << 28)
+ | (hex_to_bin(elm->rxbuf[1]) << 24)
+ | (hex_to_bin(elm->rxbuf[3]) << 20)
+ | (hex_to_bin(elm->rxbuf[4]) << 16)
+ | (hex_to_bin(elm->rxbuf[6]) << 12)
+ | (hex_to_bin(elm->rxbuf[7]) << 8)
+ | (hex_to_bin(elm->rxbuf[9]) << 4)
+ | (hex_to_bin(elm->rxbuf[10]) << 0);
+ } else {
+ frame.can_id |= (hex_to_bin(elm->rxbuf[0]) << 8)
+ | (hex_to_bin(elm->rxbuf[1]) << 4)
+ | (hex_to_bin(elm->rxbuf[2]) << 0);
+ }
+
+ /* Check for RTR frame */
+ if (elm->rxfill >= hexlen + 3
+ && elm->rxbuf[hexlen + 0] == 'R'
+ && elm->rxbuf[hexlen + 1] == 'T'
+ && elm->rxbuf[hexlen + 2] == 'R') {
+ frame.can_id |= CAN_RTR_FLAG;
+ }
+
+ /* Is the line long enough to hold the advertised payload? */
+ if (!(frame.can_id & CAN_RTR_FLAG) && (hexlen < frame.can_dlc * 3 + datastart)) {
+ /* Incomplete frame. */
+
+ /* Probably the ELM327's RS232 TX buffer was full.
+ * Emit an error frame and exit. */
+ frame.can_id = CAN_ERR_FLAG | CAN_ERR_CRTL;
+ frame.can_dlc = CAN_ERR_DLC;
+ frame.data[1] = CAN_ERR_CRTL_RX_OVERFLOW;
+ elm327_feed_frame_to_netdev(elm, &frame);
+
+ /* Signal failure to parse.
+ * The line will be re-parsed as an error line, which will fail.
+ * However, this will correctly drop the state machine back into
+ * command mode.
+ */
+ return 2;
+ }
+
+ /* Parse the data nibbles. */
+ for (i = 0; i < frame.can_dlc; i++) {
+ frame.data[i] = (hex_to_bin(elm->rxbuf[datastart+3*i]) << 4)
+ | (hex_to_bin(elm->rxbuf[datastart+3*i+1]) << 0);
+ }
+
+ /* Feed the frame to the network layer. */
+ elm327_feed_frame_to_netdev(elm, &frame);
+
+ return 0;
+}
+
+
+static void elm327_parse_line(struct elmcan *elm, int len)
+{
+ /* Skip empty lines */
+ if (!len) {
+ return;
+ }
+
+ /* Skip echo lines */
+ if (elm->drop_next_line) {
+ elm->drop_next_line = 0;
+ return;
+ } else if (elm->rxbuf[0] == 'A' && elm->rxbuf[1] == 'T') {
+ return;
+ }
+
+ /* Regular parsing */
+ switch(elm->state) {
+ case ELM_RECEIVING:
+ if (elm327_parse_frame(elm, len)) {
+ /* Parse an error line. */
+ elm327_parse_error(elm, len);
+
+ /* After the error line, we expect a prompt. */
+ elm->state = ELM_GETPROMPT;
+ }
+ break;
+ default:
+ break;
+ }
+}
+
+
+static void elm327_handle_prompt(struct elmcan *elm)
+{
+ if (elm->cmds_todo) {
+ struct can_frame *frame = &elm->can_frame;
+ char txbuf[20];
+
+ if (test_bit(ELM_TODO_INIT, &elm->cmds_todo)) {
+ elm327_send(elm, *elm->next_init_cmd, strlen(*elm->next_init_cmd));
+ elm->next_init_cmd++;
+ if (!(*elm->next_init_cmd)) {
+ clear_bit(ELM_TODO_INIT, &elm->cmds_todo);
+ pr_info("%s: Initialization finished.\n", elm->dev->name);
+ }
+
+ /* Some chips are unreliable and need extra time after
+ * init commands, as seen with a clone.
+ * So let's do a dummy get-cmd-prompt dance. */
+ elm->state = ELM_NOTINIT;
+ elm327_kick_into_cmd_mode(elm);
+ } else if (test_and_clear_bit(ELM_TODO_SILENT_MONITOR, &elm->cmds_todo)) {
+ snprintf(txbuf, sizeof(txbuf), "ATCSM%i\r", !(!(elm->can.ctrlmode & CAN_CTRLMODE_LISTENONLY)));
+ } else if (test_and_clear_bit(ELM_TODO_RESPONSES, &elm->cmds_todo)) {
+ snprintf(txbuf, sizeof(txbuf), "ATR%i\r", !(elm->can.ctrlmode & CAN_CTRLMODE_LISTENONLY));
+ } else if (test_and_clear_bit(ELM_TODO_CAN_CONFIG, &elm->cmds_todo)) {
+ snprintf(txbuf, sizeof(txbuf), "ATPB%04X\r", elm->can_config);
+ } else if (test_and_clear_bit(ELM_TODO_CANID_29BIT_HIGH, &elm->cmds_todo)) {
+ snprintf(txbuf, sizeof(txbuf), "ATCP%02X\r", (frame->can_id & CAN_EFF_MASK) >> 24);
+ } else if (test_and_clear_bit(ELM_TODO_CANID_29BIT_LOW, &elm->cmds_todo)) {
+ snprintf(txbuf, sizeof(txbuf), "ATSH%06X\r", frame->can_id & CAN_EFF_MASK & ((1 << 24) - 1));
+ } else if (test_and_clear_bit(ELM_TODO_CANID_11BIT, &elm->cmds_todo)) {
+ snprintf(txbuf, sizeof(txbuf), "ATSH%03X\r", frame->can_id & CAN_SFF_MASK);
+ } else if (test_and_clear_bit(ELM_TODO_CAN_DATA, &elm->cmds_todo)) {
+ if (frame->can_id & CAN_RTR_FLAG) {
+ snprintf(txbuf, sizeof(txbuf), "ATRTR\r");
+ } else {
+ int i;
+
+ for (i = 0; i < frame->can_dlc; i++) {
+ sprintf(&txbuf[2*i], "%02X", frame->data[i]);
+ }
+
+ sprintf(&txbuf[2*i], "\r");
+ }
+
+ elm->drop_next_line = 1;
+ elm->state = ELM_RECEIVING;
+ }
+
+ elm327_send(elm, txbuf, strlen(txbuf));
+ } else {
+ /* Enter CAN monitor mode */
+ elm327_send(elm, "ATMA\r", 5);
+ elm->state = ELM_RECEIVING;
+ }
+}
+
+
+static void elm327_drop_bytes(struct elmcan *elm, int i)
+{
+ memmove(&elm->rxbuf[0], &elm->rxbuf[i], sizeof(elm->rxbuf) - i);
+ elm->rxfill -= i;
+}
+
+
+static void elm327_parse_rxbuf(struct elmcan *elm)
+{
+ int len;
+
+ switch (elm->state) {
+ case ELM_NOTINIT:
+ elm->rxfill = 0;
+ return;
+
+ case ELM_GETMAGICCHAR:
+ {
+ /* Wait for 'y' or '>' */
+ int i;
+
+ for (i = 0; i < elm->rxfill; i++) {
+ if (elm->rxbuf[i] == ELM327_MAGIC_CHAR) {
+ elm327_send(elm, "\r", 1);
+ elm->state = ELM_GETPROMPT;
+ i++;
+ break;
+ } else if (elm->rxbuf[i] == '>') {
+ elm327_send(elm, ELM327_MAGIC_STRING, 1);
+ i++;
+ break;
+ }
+ }
+
+ elm327_drop_bytes(elm, i);
+
+ return;
+ }
+
+ case ELM_GETPROMPT:
+ /* Wait for '>' */
+ if (elm->rxbuf[elm->rxfill - 1] == '>') {
+ elm327_handle_prompt(elm);
+ }
+
+ elm->rxfill = 0;
+ return;
+
+ case ELM_RECEIVING:
+ /* Find <CR> delimiting feedback lines. */
+ for (len = 0;
+ (len < elm->rxfill) && (elm->rxbuf[len] != '\r');
+ len++) {
+ /* empty loop */
+ }
+
+ if (len == sizeof(elm->rxbuf)) {
+ /* Line exceeds buffer. It's probably all garbage.
+ * Did we even connect at the right baud rate? */
+ pr_err("RX buffer overflow. Faulty ELM327 connected?\n");
+ elm327_panic(elm);
+ } else if (len == elm->rxfill) {
+ if (elm->state == ELM_RECEIVING
+ && elm->rxbuf[elm->rxfill - 1] == '>') {
+ /* The ELM327's AT ST response timeout ran out,
+ * so we got a prompt.
+ * Clear RX buffer and restart listening. */
+ elm->rxfill = 0;
+
+ elm327_handle_prompt(elm);
+ return;
+ } else {
+ /* We haven't received a full line yet. Wait for more data. */
+ return;
+ }
+ }
+
+ /* We have a full line to parse. */
+ elm327_parse_line(elm, len);
+
+ /* Remove parsed data from RX buffer. */
+ elm327_drop_bytes(elm, len+1);
+
+ /* More data to parse? */
+ if (elm->rxfill) {
+ elm327_parse_rxbuf(elm);
+ }
+ }
+}
+
+
+
+
+
+ /************************************************************************
+ * netdev *
+ ************************************************************************/
+
+/* Netdevice DOWN -> UP routine */
+static int elmcan_netdev_open(struct net_device *dev)
+{
+ struct elmcan *elm = netdev_priv(dev);
+ int err;
+
+ spin_lock_bh(&elm->lock);
+ if (elm->tty == NULL) {
+ spin_unlock_bh(&elm->lock);
+ return -ENODEV;
+ }
+
+ /* open_candev() checks for elm->can.bittiming.bitrate != 0 */
+ err = open_candev(dev);
+ if (err) {
+ spin_unlock_bh(&elm->lock);
+ return err;
+ }
+
+ /* Initialize the ELM327 */
+ elm327_init(elm);
+ spin_unlock_bh(&elm->lock);
+
+ can_led_event(dev, CAN_LED_EVENT_OPEN);
+ elm->can.state = CAN_STATE_ERROR_ACTIVE;
+ netif_start_queue(dev);
+
+ return 0;
+}
+
+/* Netdevice UP -> DOWN routine */
+static int elmcan_netdev_close(struct net_device *dev)
+{
+ struct elmcan *elm = netdev_priv(dev);
+
+ spin_lock_bh(&elm->lock);
+ if (elm->tty) {
+ /* TTY discipline is running. */
+
+ /* Interrupt whatever we're doing right now */
+ elm327_send(elm, ELM327_MAGIC_STRING, 1);
+
+ /* Clear the wakeup bit, as the netdev will be down and thus
+ * the wakeup handler won't clear it
+ */
+ clear_bit(TTY_DO_WRITE_WAKEUP, &elm->tty->flags);
+
+ spin_unlock_bh(&elm->lock);
+
+ flush_work(&elm->tx_work);
+ } else {
+ spin_unlock_bh(&elm->lock);
+ }
+
+ elm->can.state = CAN_STATE_STOPPED;
+ netif_stop_queue(dev);
+ close_candev(dev);
+ can_led_event(dev, CAN_LED_EVENT_STOP);
+
+ return 0;
+}
+
+/* Send a can_frame to a TTY queue. */
+static netdev_tx_t elmcan_netdev_start_xmit(struct sk_buff *skb, struct net_device *dev)
+{
+ struct elmcan *elm = netdev_priv(dev);
+ struct can_frame *frame = (struct can_frame *) skb->data;
+
+ if (skb->len != sizeof(struct can_frame))
+ goto out;
+
+ if (!netif_running(dev)) {
+ pr_warn("%s: xmit: iface is down\n", dev->name);
+ goto out;
+ }
+
+ /* BHs are already disabled, so no spin_lock_bh().
+ * See Documentation/networking/netdevices.txt
+ */
+ spin_lock(&elm->lock);
+ if (elm->tty == NULL
+ || elm->can.ctrlmode & CAN_CTRLMODE_LISTENONLY) {
+ spin_unlock(&elm->lock);
+ goto out;
+ }
+
+ netif_stop_queue(dev);
+
+ elm327_send_frame(elm, frame);
+ spin_unlock(&elm->lock);
+
+ dev->stats.tx_packets++;
+ dev->stats.tx_bytes += frame->can_dlc;
+
+ can_led_event(dev, CAN_LED_EVENT_TX);
+
+out:
+ kfree_skb(skb);
+ return NETDEV_TX_OK;
+}
+
+static int elmcan_netdev_change_mtu(struct net_device *dev, int new_mtu)
+{
+ return -EINVAL;
+}
+
+static const struct net_device_ops elmcan_netdev_ops = {
+ .ndo_open = elmcan_netdev_open,
+ .ndo_stop = elmcan_netdev_close,
+ .ndo_start_xmit = elmcan_netdev_start_xmit,
+ .ndo_change_mtu = elmcan_netdev_change_mtu,
+};
+
+
+
+
+
+ /************************************************************************
+ * Line discipline *
+ ************************************************************************/
+
+/*
+ * Handle the 'receiver data ready' interrupt.
+ * This function is called by the 'tty_io' module in the kernel when
+ * a block of ELM327 CAN data has been received, which can now be parsed
+ * and sent on to some IP layer for further processing. This will not
+ * be re-entered while running but other ldisc functions may be called
+ * in parallel
+ */
+static void elmcan_ldisc_rx(struct tty_struct *tty,
+ const unsigned char *cp, char *fp, int count)
+{
+ struct elmcan *elm = (struct elmcan *) tty->disc_data;
+
+ if (!elm)
+ return;
+
+ /* Read the characters out of the buffer */
+ while (count-- && elm->rxfill < sizeof(elm->rxbuf)) {
+ if (fp && *fp++) {
+ pr_err("Error in received character stream. Check your wiring.");
+
+ spin_lock_bh(&elm->lock);
+ elm327_panic(elm);
+ spin_unlock_bh(&elm->lock);
+ return;
+ }
+ if (*cp != 0) {
+ elm->rxbuf[elm->rxfill++] = *cp;
+ }
+ cp++;
+ }
+
+ if (count >= 0) {
+ pr_err("Receive buffer overflowed. Bad chip or wiring?");
+
+ spin_lock_bh(&elm->lock);
+ elm327_panic(elm);
+ spin_unlock_bh(&elm->lock);
+ return;
+ }
+
+ spin_lock_bh(&elm->lock);
+ elm327_parse_rxbuf(elm);
+ spin_unlock_bh(&elm->lock);
+}
+
+/* Write out remaining transmit buffer.
+ * Scheduled when TTY is writable.
+ */
+static void elmcan_ldisc_tx_worker(struct work_struct *work)
+{
+ struct elmcan *elm = container_of(work, struct elmcan, tx_work);
+ ssize_t actual;
+
+ spin_lock_bh(&elm->lock);
+ /* First make sure we're connected. */
+ if (!elm->tty || !netif_running(elm->dev)) {
+ spin_unlock_bh(&elm->lock);
+ return;
+ }
+
+ if (elm->txleft <= 0) {
+ /* Our TTY write buffer is empty:
+ * We can start transmission of another packet
+ */
+ clear_bit(TTY_DO_WRITE_WAKEUP, &elm->tty->flags);
+ spin_unlock_bh(&elm->lock);
+ netif_wake_queue(elm->dev);
+ return;
+ }
+
+ actual = elm->tty->ops->write(elm->tty, elm->txhead, elm->txleft);
+ if (actual < 0) {
+ pr_err("Failed to write to tty for %s.\n", elm->dev->name);
+ elm327_panic(elm);
+ }
+
+ elm->txleft -= actual;
+ elm->txhead += actual;
+ spin_unlock_bh(&elm->lock);
+}
+
+
+/*
+ * Called by the driver when there's room for more data.
+ * Schedule the transmit.
+ */
+static void elmcan_ldisc_tx_wakeup(struct tty_struct *tty)
+{
+ struct elmcan *elm = tty->disc_data;
+
+ schedule_work(&elm->tx_work);
+}
+
+
+
+/* Some fake bit timings to allow bitrate setting */
+static const struct can_bittiming_const elmcan_bittiming_const = {
+ .name = "elmcan",
+ .tseg1_min = 1,
+ .tseg1_max = 1,
+ .tseg2_min = 0,
+ .tseg2_max = 0,
+ .sjw_max = 1,
+ .brp_min = 1,
+ .brp_max = 500,
+ .brp_inc = 1,
+};
+
+/*
+ * Open the high-level part of the elmcan channel.
+ * This function is called by the TTY module when the
+ * elmcan line discipline is called for.
+ *
+ * Called in process context serialized from other ldisc calls.
+ */
+static int elmcan_ldisc_open(struct tty_struct *tty)
+{
+ struct net_device *dev;
+ struct elmcan *elm;
+ int err;
+
+ if (!capable(CAP_NET_ADMIN))
+ return -EPERM;
+
+ if (!tty->ops->write)
+ return -EOPNOTSUPP;
+
+ elm = tty->disc_data;
+
+ /* First make sure we're not already connected.
+ * Also, protect against simlutaneous open calls. */
+ spin_lock_bh(&elmcan_open_lock);
+ if (elm) {
+ spin_unlock_bh(&elmcan_open_lock);
+ return -EEXIST;
+ }
+ spin_unlock_bh(&elmcan_open_lock);
+
+ /* OK. Find a free elmcan channel to use. */
+ dev = alloc_candev(sizeof(struct elmcan), 0);
+ if (!dev)
+ return -ENFILE;
+ elm = netdev_priv(dev);
+
+ /* Configure TTY interface */
+ tty->receive_room = 65536; /* We don't flow control */
+ elm->txleft = 0; /* Clear TTY TX buffer */
+ spin_lock_init(&elm->lock);
+ INIT_WORK(&elm->tx_work, elmcan_ldisc_tx_worker);
+
+ /* Configure CAN metadata */
+ elm->can.state = CAN_STATE_STOPPED;
+ elm->can.clock.freq = 1000000;
+ elm->can.bittiming_const = &elmcan_bittiming_const;
+ elm->can.ctrlmode_supported = CAN_CTRLMODE_LISTENONLY;
+
+ /* Configure netlink interface */
+ elm->dev = dev;
+ dev->netdev_ops = &elmcan_netdev_ops;
+
+ /* Mark ldisc channel as alive */
+ elm->tty = tty;
+ tty->disc_data = elm;
+
+ devm_can_led_init(elm->dev);
+
+ /* Let 'er rip */
+ err = register_candev(elm->dev);
+ if (err) {
+ free_candev(elm->dev);
+ return err;
+ }
+
+ return 0;
+}
+
+/*
+ * Close down an elmcan channel.
+ * This means flushing out any pending queues, and then returning. This
+ * call is serialized against other ldisc functions.
+ *
+ * We also use this method for a hangup event.
+ */
+static void elmcan_ldisc_close(struct tty_struct *tty)
+{
+ struct elmcan *elm = (struct elmcan *) tty->disc_data;
+
+ /* First make sure we're connected. */
+ if (!elm)
+ return;
+
+ /* Flush network side */
+ unregister_candev(elm->dev);
+
+ /* Mark channel as dead */
+ spin_lock_bh(&elm->lock);
+ tty->disc_data = NULL;
+ elm->tty = NULL;
+ spin_unlock_bh(&elm->lock);
+
+ /* Flush TTY side */
+ flush_work(&elm->tx_work);
+
+ /* Free our memory */
+ free_candev(elm->dev);
+}
+
+static int elmcan_ldisc_hangup(struct tty_struct *tty)
+{
+ elmcan_ldisc_close(tty);
+ return 0;
+}
+
+/* Perform I/O control on an active elmcan channel. */
+static int elmcan_ldisc_ioctl(struct tty_struct *tty, struct file *file,
+ unsigned int cmd, unsigned long arg)
+{
+ struct elmcan *elm = (struct elmcan *) tty->disc_data;
+ unsigned int tmp;
+
+ /* First make sure we're connected. */
+ if (!elm)
+ return -EINVAL;
+
+ switch (cmd) {
+ case SIOCGIFNAME:
+ tmp = strlen(elm->dev->name) + 1;
+ if (copy_to_user((void __user *)arg, elm->dev->name, tmp))
+ return -EFAULT;
+ return 0;
+
+ case SIOCSIFHWADDR:
+ return -EINVAL;
+
+ default:
+ return tty_mode_ioctl(tty, file, cmd, arg);
+ }
+}
+
+static struct tty_ldisc_ops elmcan_ldisc = {
+ .owner = THIS_MODULE,
+ .magic = TTY_LDISC_MAGIC,
+ .name = "elmcan",
+ .receive_buf = elmcan_ldisc_rx,
+ .write_wakeup = elmcan_ldisc_tx_wakeup,
+ .open = elmcan_ldisc_open,
+ .close = elmcan_ldisc_close,
+ .hangup = elmcan_ldisc_hangup,
+ .ioctl = elmcan_ldisc_ioctl,
+};
+
+
+
+
+
+ /************************************************************************
+ * Module init/exit *
+ ************************************************************************/
+
+static int __init elmcan_init(void)
+{
+ int status;
+
+ pr_info("ELM327 based best-effort CAN interface driver\n");
+ pr_info("This device is severely limited as a CAN interface, see documentation.\n");
+
+ /* Fill in our line protocol discipline, and register it */
+ status = tty_register_ldisc(N_ELMCAN, &elmcan_ldisc);
+ if (status) {
+ pr_err("can't register line discipline\n");
+ }
+ return status;
+}
+
+static void __exit elmcan_exit(void)
+{
+ /* This will only be called when all channels have been closed by
+ * userspace - tty_ldisc.c takes care of the module's refcount.
+ */
+ int status;
+
+ status = tty_unregister_ldisc(N_ELMCAN);
+ if (status) {
+ pr_err("Can't unregister line discipline (error: %d)\n", status);
+ }
+}
+
+module_init(elmcan_init);
+module_exit(elmcan_exit);
--- /dev/null
+Linux SocketCAN driver for ELM327
+==================================
+
+Authors
+--------
+
+Max Staudt <elmcan@enpas.org>
+
+
+
+Motivation
+-----------
+
+CAN adapters are expensive, few, and far between.
+ELM327 interfaces are cheap and plentiful.
+
+This driver aims to lower the initial cost for hackers interested in
+working with CAN buses.
+
+
+
+Introduction
+-------------
+
+This driver is an effort to turn abundant ELM327 based OBD interfaces
+into full-fledged (as far as possible) CAN interfaces.
+
+Since the ELM327 was never meant to be a stand-alone CAN controller,
+the driver has to switch between its modes asa quickly as possible in
+order to approximate full-duplex operation.
+
+As such, elmcan is a best-effort driver. However, this is more than
+enough to implement simple request-response protocols (such as OBD II),
+and to monitor broadcast messages on a bus (such as in a vehicle).
+
+Most ELM327s come as nondescript serial devices, attached via USB or
+Bluetooth. The driver cannot recognize them by itself, and as such it
+is up to the user to attach it in form of a TTY line discipline
+(similar to PPP, SLIP, slcan, ...).
+
+This driver is meant for ELM327 versions 1.4b and up, see below for
+known limitations in older controllers and clones.
+
+
+
+Data sheet
+-----------
+
+The official data sheets can be found at ELM electronics' home page:
+
+ https://www.elmelectronics.com/
+
+
+
+How to check the controller version
+------------------------------------
+
+Use a terminal program to attach to the controller.
+
+After issuing the "``AT WS``" command, the controller will respond with
+its version::
+
+ >AT WS
+
+
+ ELM327 v1.4b
+
+ >
+
+
+
+How to attach the line discipline
+----------------------------------
+
+Every ELM327 chip is factory programmed to operate at a serial setting
+of 38400 baud/s, 8 data bits, no parity, 1 stopbit.
+
+The line discipline can be attached on a command prompt as follows::
+
+ sudo ldattach \
+ --debug \
+ --speed 38400 \
+ --eightbits \
+ --noparity \
+ --onestopbit \
+ --iflag -ICRNL,INLCR,-IXOFF \
+ 26 \
+ /dev/ttyUSB0
+
+To change the ELM327's serial settings, please refer to its data
+sheet. This needs to be done before attaching the line discipline.
+
+
+
+Known limitations of the controller
+------------------------------------
+
+- All versions
+
+ No automatic full duplex operation is supported. The driver will
+ switch between input/output mode as quickly as possible.
+
+ The length of outgoing RTR frames cannot be set. In fact, some
+ clones (tested with one identifying as "``v1.5``") are unable to
+ send RTR frames at all.
+
+ We don't have a way to get real-time notifications on CAN errors.
+ While there is a command (``AT CS``) to retrieve some basic stats,
+ we don't poll it as it would force us to interrupt reception mode.
+
+
+- Versions prior to 1.4b
+
+ These versions do not send CAN ACKs when in monitoring mode (AT MA).
+ However, they do send ACKs while waiting for a reply immediately
+ after sending a frame. The driver maximizes this time to make the
+ controller as useful as possible.
+
+ Starting with version 1.4b, the ELM327 supports the "``AT CSM``"
+ command, and the "listen-only" CAN option will take effect.
+
+
+- Versions prior to 1.4
+
+ These chips do not support the "``AT PB``" command, and thus cannot
+ change bitrate or SFF/EFF mode on-the-fly. This will have to be
+ programmed by the user before attaching the line discipline. See the
+ data sheet for details.
+
+
+- Versions prior to 1.3
+
+ These chips cannot be used at all with elmcan. They do not support
+ the "``AT D1``", which is necessary to avoid parsing conflicts on
+ incoming data, as well as distinction of RTR frame lengths.
+
+ Specifically, this allows for easy distinction of SFF and EFF
+ frames, and to check whether frames are complete. While it is possible
+ to deduce the type and length from the length of the line the ELM327
+ sends us, this method fails when the ELM327's UART output buffer
+ overruns. It may abort sending in the middle of the line, which will
+ then be mistaken for something else.
+
+
+
+Known limitations of the driver
+--------------------------------
+
+- No 8/7 timing.
+
+ ELM327 can only set CAN bitrates that are of the form 500000/n, where
+ n is an integer divisor.
+ However there is an exception: With a separate flag, it may set the
+ speed to be 8/7 of the speed indicated by the divisor.
+ This mode is not currently implemented.
+
+- No evaluation of command responses.
+
+ The ELM327 will reply with OK when a command is understood, and with ?
+ when it is not. The driver does not currently check this, and simply
+ assumes that the chip understands every command.
+ The driver is built such that functionality degrades gracefully
+ nevertheless. See the section on known limitations of the controller.
+
+- No use of hardware CAN ID filtering
+
+ An ELM327's UART sending buffer will easily overflow on heavy CAN bus
+ load, resulting in the "``BUFFER FULL``" message. Using the hardware
+ filters available through "``AT CF xxx``" and "``AT CM xxx``" would be
+ helpful here, however SocketCAN does not currently provide a facility
+ to make use of such hardware features.
+
+- No BUS-OFF state and automatic restart
+
+ We currently reset the ELM327 and generate error frames manually.
+ In the future, we may be able to use ``can_bus_off()`` and its siblings.
+
+
+
+Communication example
+----------------------
+
+This is a short and incomplete introduction on how to talk to an ELM327.
+
+
+The ELM327 has two modes:
+
+- Command mode
+- Reception mode
+
+In command mode, it expects one command per line, terminated by CR.
+By default, the prompt is a "``>``", after which a command can be
+entered::
+
+ >ATE1
+ OK
+ >
+
+The init script in the driver switches off several configuration options
+that are only meaningful in the original OBD scenario the chip is meant
+for, and are actually a hindrance for elmcan.
+
+
+When a command is not recognized, such as by an older version of the
+ELM327, a question mark is printed as a response instead of OK::
+
+ >ATUNKNOWN
+ ?
+ >
+
+At present, elmcan does not evaluate this response and silently assumes
+that all commands are recognized. It is structured such that it will
+degrade gracefully when a command is unknown. See the sections above on
+known limitations for details.
+
+
+When a CAN frame is to be sent, the target address is configured, after
+which the frame is sent as a command that consists of the data's hex
+dump::
+
+ >ATSH123
+ OK
+ >DEADBEEF12345678
+ OK
+ >
+
+The above interaction sends the frame "``DE AD BE EF 12 34 56 78``" with
+the 11 bit CAN ID ``0x123``.
+For this to function, the controller must be configured for 11 bit CAN
+ID sending mode (using "``AT PB``", see code or datasheet).
+
+
+Once a frame has been sent and wait-for-reply mode is on (ATR1,
+configured on listen-only=off), or when the reply timeout expires and
+the driver sets the controller into monitoring mode (``ATMA``), the ELM327
+will send one line for each received CAN frame, consisting of CAN ID,
+DLC, and data::
+
+ 123 8 DEADBEEF12345678
+
+For 29 bit CAN frames, the address format is slightly different, which
+elmcan uses to tell the two apart::
+
+ 12 34 56 78 8 DEADBEEF12345678
+
+The ELM327 will receive both 11 and 29 bit frames - the current CAN
+config (``ATPB``) does not matter.
+
+
+If the ELM327's internal UART sending buffer runs full, it will abort
+the monitoring mode, print "BUFFER FULL" and drop back into command
+mode. Note that in this case, unlike with other error messages, the
+error message may appear on the same line as the last (usually
+incomplete) data frame::
+
+ 12 34 56 78 8 DEADBEEF123 BUFFER FULL
+
+
+
+To Do list for future development
+----------------------------------
+
+- Handle ``write()`` error
+
+- Rename ``elm327_panic()``
+
+- No auto-restart in ``elm327_panic()``?
+
+- Stop current function when in ``elm327_panic()``
+
+- ``if (!elm)``: Race with ``ldisc_close()``
+
+- ``elm->dev``: Race in ``ldisc_ioctl()``
+
+- DMA capable rx/tx buffers
+
+- fixup constants, constant for '``>``'
+
+- flushing of ``tx_work`` is too late in ``ldisc_close()``
projects / elmcan.git / commitdiff