X-Git-Url: https://git.enpas.org/?a=blobdiff_plain;ds=sidebyside;f=module%2Felmcan.c;h=3d35821fae7d34e0b707d96d8f80146af942ba55;hb=8b5dee0e36334412500b1ba41dca51fd10cbb56e;hp=acb605781c6d4387e50e0f4a6d7eece20afa47ae;hpb=9a173e976bc0dbd77ceecb4202298c75dbcff891;p=elmcan.git diff --git a/module/elmcan.c b/module/elmcan.c index acb6057..3d35821 100644 --- a/module/elmcan.c +++ b/module/elmcan.c @@ -1,24 +1,9 @@ // SPDX-License-Identifier: GPL-2.0 -/* elmcan.c - ELM327 based CAN interface driver - * (tty line discipline) +/* ELM327 based CAN interface driver (tty line discipline) * * This driver started as a derivative of linux/drivers/net/can/slcan.c - * and my thanks go to the original authors for their inspiration. - * - * elmcan.c Author : Max Staudt - * slcan.c Author : Oliver Hartkopp - * slip.c Authors : Laurence Culhane - * Fred N. van Kempen - * - * This code barely bears any resemblance to slcan anymore, and whatever - * may be left is Linux specific boilerplate anyway, however I am leaving - * the GPL-2.0 identifier at the top just to be sure. - * - * Please feel free to use my own code, especially the ELM327 communication - * logic, in accordance with SPDX-License-Identifier BSD-3-Clause to port - * this driver to other systems. - * - Max - * + * and my thanks go to the original authors for their inspiration, even + * after almost none of their code is left. */ #define pr_fmt(fmt) "[elmcan] " fmt @@ -57,15 +42,6 @@ MODULE_DESCRIPTION("ELM327 based CAN interface"); MODULE_LICENSE("GPL"); MODULE_AUTHOR("Max Staudt "); -/* If this is enabled, we'll try to make the best of the situation - * even if we receive unexpected characters on the line. - * No guarantees. - * Handle with care, it's likely your hardware is unreliable! - */ -static bool accept_flaky_uart; -module_param_named(accept_flaky_uart, accept_flaky_uart, bool, 0444); -MODULE_PARM_DESC(accept_flaky_uart, "Don't bail at the first invalid character. Behavior undefined."); - /* Line discipline ID number */ #ifndef N_ELMCAN #define N_ELMCAN 29 @@ -168,12 +144,7 @@ static DEFINE_SPINLOCK(elmcan_discdata_lock); static inline void elm327_hw_failure(struct elmcan *elm); - /*********************************************************************** - * ELM327: Transmission * - * * - * (all functions assume elm->lock taken) * - ***********************************************************************/ - +/* Assumes elm->lock taken. */ static void elm327_send(struct elmcan *elm, const void *buf, size_t len) { int actual; @@ -209,6 +180,8 @@ static void elm327_send(struct elmcan *elm, const void *buf, size_t len) * We send ELM327_MAGIC_CHAR which will either abort any running * operation, or be echoed back to us in case we're already in command * mode. + * + * Assumes elm->lock taken. */ static void elm327_kick_into_cmd_mode(struct elmcan *elm) { @@ -219,7 +192,10 @@ static void elm327_kick_into_cmd_mode(struct elmcan *elm) } } -/* Schedule a CAN frame and necessary config changes to be sent to the TTY. */ +/* Schedule a CAN frame and necessary config changes to be sent to the TTY. + * + * Assumes elm->lock taken. + */ static void elm327_send_frame(struct elmcan *elm, struct can_frame *frame) { /* Schedule any necessary changes in ELM327's CAN configuration */ @@ -255,12 +231,10 @@ static void elm327_send_frame(struct elmcan *elm, struct can_frame *frame) elm327_kick_into_cmd_mode(elm); } - /*********************************************************************** - * ELM327: Initialization sequence * - * * - * (assumes elm->lock taken) * - ***********************************************************************/ - +/* ELM327 initialization sequence. + * + * Assumes elm->lock taken. + */ static char *elm327_init_script[] = { "AT WS\r", /* v1.0: Warm Start */ "AT PP FF OFF\r", /* v1.0: All Programmable Parameters Off */ @@ -310,12 +284,7 @@ static void elm327_init(struct elmcan *elm) elm327_kick_into_cmd_mode(elm); } - /*********************************************************************** - * ELM327: Reception -> netdev glue * - * * - * (assumes elm->lock taken) * - ***********************************************************************/ - +/* Assumes elm->lock taken. */ static void elm327_feed_frame_to_netdev(struct elmcan *elm, const struct can_frame *frame) { @@ -344,13 +313,9 @@ static void elm327_feed_frame_to_netdev(struct elmcan *elm, #endif } - /*********************************************************************** - * ELM327: "Panic" handler * - * * - * (assumes elm->lock taken) * - ***********************************************************************/ - -/* Called when we're out of ideas and just want it all to end. */ +/* Called when we're out of ideas and just want it all to end. + * Assumes elm->lock taken. + */ static inline void elm327_hw_failure(struct elmcan *elm) { struct can_frame frame; @@ -369,12 +334,13 @@ static inline void elm327_hw_failure(struct elmcan *elm) can_bus_off(elm->dev); } - /*********************************************************************** - * ELM327: Reception parser * - * * - * (assumes elm->lock taken) * - ***********************************************************************/ +/* Compare a buffer to a fixed string */ +static int _memstrcmp(const u8 *mem, const char *str) +{ + return memcmp(mem, str, strlen(str)); +} +/* Assumes elm->lock taken. */ static void elm327_parse_error(struct elmcan *elm, int len) { struct can_frame frame; @@ -383,15 +349,16 @@ static void elm327_parse_error(struct elmcan *elm, int len) frame.can_id = CAN_ERR_FLAG; frame.can_dlc = CAN_ERR_DLC; + /* Filter possible error messages based on length of RX'd line */ switch (len) { case 17: - if (!memcmp(elm->rxbuf, "UNABLE TO CONNECT", 17)) { + if (!_memstrcmp(elm->rxbuf, "UNABLE TO CONNECT")) { netdev_err(elm->dev, "ELM327 reported UNABLE TO CONNECT. Please check your setup.\n"); } break; case 11: - if (!memcmp(elm->rxbuf, "BUFFER FULL", 11)) { + if (!_memstrcmp(elm->rxbuf, "BUFFER FULL")) { /* This case will only happen if the last data * line was complete. * Otherwise, elm327_parse_frame() will heuristically @@ -402,33 +369,36 @@ static void elm327_parse_error(struct elmcan *elm, int len) } break; case 9: - if (!memcmp(elm->rxbuf, "BUS ERROR", 9)) + if (!_memstrcmp(elm->rxbuf, "BUS ERROR")) frame.can_id |= CAN_ERR_BUSERROR; - if (!memcmp(elm->rxbuf, "CAN ERROR", 9)) + if (!_memstrcmp(elm->rxbuf, "CAN ERROR")) frame.can_id |= CAN_ERR_PROT; - if (!memcmp(elm->rxbuf, "rxbuf, "rxbuf, "BUS BUSY", 8)) { + if (!_memstrcmp(elm->rxbuf, "BUS BUSY")) { frame.can_id |= CAN_ERR_PROT; frame.data[2] = CAN_ERR_PROT_OVERLOAD; } - if (!memcmp(elm->rxbuf, "FB ERROR", 8)) { + if (!_memstrcmp(elm->rxbuf, "FB ERROR")) { frame.can_id |= CAN_ERR_PROT; frame.data[2] = CAN_ERR_PROT_TX; } break; - case 5: - if (!memcmp(elm->rxbuf, "ERR", 3)) { + case 5: /* ERR is followed by two digits, hence line length 5 */ + if (!_memstrcmp(elm->rxbuf, "ERR")) { netdev_err(elm->dev, "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; + /* Something else has happened. + * Maybe garbage on the UART line. + * Emit a generic error frame. + */ + break; } elm327_feed_frame_to_netdev(elm, &frame); @@ -445,6 +415,8 @@ static void elm327_parse_error(struct elmcan *elm, int len) * Instead of a payload, RTR indicates a remote request. * * We will use the spaces and line length to guess the format. + * + * Assumes elm->lock taken. */ static int elm327_parse_frame(struct elmcan *elm, int len) { @@ -467,12 +439,10 @@ static int elm327_parse_frame(struct elmcan *elm, int len) } } - /* If we accept stray characters coming in: - * Check for stray characters on a payload line. - * No idea what causes this. + /* Sanity check whether the line is really a clean hexdump, + * or terminated by an error message, or contains garbage. */ - if (accept_flaky_uart && - hexlen < len && + if (hexlen < len && !isdigit(elm->rxbuf[hexlen]) && !isupper(elm->rxbuf[hexlen]) && '<' != elm->rxbuf[hexlen] && @@ -480,7 +450,6 @@ static int elm327_parse_frame(struct elmcan *elm, int len) /* The line is likely garbled anyway, so bail. * The main code will restart listening. */ - elm327_kick_into_cmd_mode(elm); return -ENODATA; } @@ -535,7 +504,7 @@ static int elm327_parse_frame(struct elmcan *elm, int len) /* Check for RTR frame */ if (elm->rxfill >= hexlen + 3 && - !memcmp(&elm->rxbuf[hexlen], "RTR", 3)) { + !_memstrcmp(&elm->rxbuf[hexlen], "RTR")) { frame.can_id |= CAN_RTR_FLAG; } @@ -574,6 +543,7 @@ static int elm327_parse_frame(struct elmcan *elm, int len) return 0; } +/* Assumes elm->lock taken. */ static void elm327_parse_line(struct elmcan *elm, int len) { /* Skip empty lines */ @@ -584,7 +554,7 @@ static void elm327_parse_line(struct elmcan *elm, int len) if (elm->drop_next_line) { elm->drop_next_line = 0; return; - } else if (elm->rxbuf[0] == 'A' && elm->rxbuf[1] == 'T') { + } else if (!_memstrcmp(elm->rxbuf, "AT")) { return; } @@ -604,6 +574,7 @@ static void elm327_parse_line(struct elmcan *elm, int len) } } +/* Assumes elm->lock taken. */ static void elm327_handle_prompt(struct elmcan *elm) { struct can_frame *frame = &elm->can_frame; @@ -688,12 +659,14 @@ static bool elm327_is_ready_char(char c) return (c & 0x3f) == ELM327_READY_CHAR; } +/* Assumes elm->lock taken. */ static void elm327_drop_bytes(struct elmcan *elm, int i) { memmove(&elm->rxbuf[0], &elm->rxbuf[i], ELM327_SIZE_RXBUF - i); elm->rxfill -= i; } +/* Assumes elm->lock taken. */ static void elm327_parse_rxbuf(struct elmcan *elm) { int len; @@ -780,12 +753,6 @@ static void elm327_parse_rxbuf(struct elmcan *elm) } } - /*********************************************************************** - * netdev * - * * - * (takes elm->lock) * - ***********************************************************************/ - /* Dummy needed to use can_rx_offload */ static struct sk_buff *elmcan_mailbox_read(struct can_rx_offload *offload, unsigned int n, u32 *timestamp, @@ -925,12 +892,6 @@ static const struct net_device_ops elmcan_netdev_ops = { .ndo_change_mtu = can_change_mtu, }; - /*********************************************************************** - * Line discipline * - * * - * (takes elm->lock) * - ***********************************************************************/ - /* Get a reference to our struct, taking into account locks/refcounts. * This is to ensure ordering in case we are shutting down, and to ensure * there is a refcount at all (otherwise tty->disc_data may be freed and @@ -966,8 +927,7 @@ static void put_elm(struct elmcan *elm) static bool elmcan_is_valid_rx_char(char c) { - return (accept_flaky_uart || - isdigit(c) || + return (isdigit(c) || isupper(c) || c == ELM327_MAGIC_CHAR || c == ELM327_READY_CHAR || @@ -1129,8 +1089,6 @@ static const u32 elmcan_bitrate_const[64] = { /* Dummy needed to use bitrate_const */ static int elmcan_do_set_bittiming(struct net_device *netdev) { - (void)netdev; - return 0; } @@ -1171,7 +1129,7 @@ static int elmcan_ldisc_open(struct tty_struct *tty) elm->can.do_set_bittiming = elmcan_do_set_bittiming; elm->can.ctrlmode_supported = CAN_CTRLMODE_LISTENONLY; - /* Configure netlink interface */ + /* Configure netdev interface */ elm->dev = dev; dev->netdev_ops = &elmcan_netdev_ops; @@ -1304,9 +1262,6 @@ 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"); - #if LINUX_VERSION_CODE < KERNEL_VERSION(5,14,0) status = tty_register_ldisc(N_ELMCAN, &elmcan_ldisc); #else