X-Git-Url: https://git.enpas.org/?a=blobdiff_plain;f=module%2Felmcan.c;h=abdf8b561eef2dbd9bb23a2661fca2292d8d3fc0;hb=744e0f3efe073d2551ffa551f674bd5be44e4296;hp=b3dc70c93f5dce79bb8536a4a7b5fae845ca4523;hpb=e8b36f064bc8c312a7714f200d41dd03038fc4a9;p=elmcan.git diff --git a/module/elmcan.c b/module/elmcan.c index b3dc70c..abdf8b5 100644 --- a/module/elmcan.c +++ b/module/elmcan.c @@ -1,16 +1,15 @@ +// SPDX-License-Identifier: GPL-2.0 /* * 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.c Author : Max Staudt * slcan.c Author : Oliver Hartkopp * slip.c Authors : Laurence Culhane * Fred N. van Kempen * - * SPDX-License-Identifier: GPL-2.0 - * */ #define pr_fmt(fmt) "[elmcan] " fmt @@ -22,6 +21,7 @@ #include #include +#include #include #include #include @@ -45,6 +45,16 @@ 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 @@ -66,6 +76,7 @@ enum ELM_TODO { ELM_TODO_CANID_11BIT, ELM_TODO_CANID_29BIT_LOW, ELM_TODO_CANID_29BIT_HIGH, + ELM_TODO_CAN_CONFIG_PART2, ELM_TODO_CAN_CONFIG, ELM_TODO_RESPONSES, ELM_TODO_SILENT_MONITOR, @@ -81,8 +92,6 @@ struct elmcan { struct tty_struct *tty; struct net_device *dev; - char ifname[IFNAMSIZ]; - /* Per-channel lock */ spinlock_t lock; @@ -95,6 +104,11 @@ struct elmcan { */ atomic_t refcount; + /* Stop the channel on hardware failure. + * Once this is true, nothing will be sent to the TTY. + */ + bool hw_failure; + /* TTY TX helpers */ struct work_struct tx_work; /* Flushes TTY TX buffer */ unsigned char txbuf[32]; @@ -116,7 +130,8 @@ struct elmcan { int drop_next_line; /* The CAN frame and config the ELM327 is sending/using, - * or will send/use after finishing all cmds_todo */ + * or will send/use after finishing all cmds_todo + */ struct can_frame can_frame; unsigned short can_config; unsigned long can_bitrate; @@ -151,6 +166,9 @@ static void elm327_send(struct elmcan *elm, const void *buf, size_t len) { int actual; + if (elm->hw_failure) + return; + memcpy(elm->txbuf, buf, len); /* Order of next two lines is *very* important. @@ -164,8 +182,11 @@ static void elm327_send(struct elmcan *elm, const void *buf, size_t len) set_bit(TTY_DO_WRITE_WAKEUP, &elm->tty->flags); actual = elm->tty->ops->write(elm->tty, elm->txbuf, len); if (actual < 0) { - netdev_err(elm->dev, "Failed to write to tty %s.\n", elm->tty->name); + netdev_err(elm->dev, + "Failed to write to tty %s.\n", + elm->tty->name); elm327_hw_failure(elm); + return; } elm->txleft = len - actual; @@ -184,7 +205,6 @@ static void elm327_kick_into_cmd_mode(struct elmcan *elm) elm327_send(elm, ELM327_MAGIC_STRING, 1); elm->state = ELM_GETMAGICCHAR; - elm->rxfill = 0; } } @@ -200,8 +220,11 @@ static void elm327_send_frame(struct elmcan *elm, struct can_frame *frame) /* Schedule any necessary changes in ELM327's CAN configuration */ 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) + 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; @@ -293,14 +316,14 @@ static void elm327_init(struct elmcan *elm) * (assumes elm->lock taken) * ************************************************************************/ -static void elm327_feed_frame_to_netdev(struct elmcan *elm, const struct can_frame *frame) +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)) { + if (!netif_running(elm->dev)) return; - } skb = alloc_can_skb(elm->dev, &cf); @@ -327,16 +350,20 @@ static void elm327_feed_frame_to_netdev(struct elmcan *elm, const struct can_fra /* Called when we're out of ideas and just want it all to end. */ static inline void elm327_hw_failure(struct elmcan *elm) { - struct can_frame frame = {0}; + struct can_frame frame; - frame.can_id = CAN_ERR_FLAG | CAN_ERR_RESTARTED; + memset(&frame, 0, sizeof(frame)); + frame.can_id = CAN_ERR_FLAG; frame.can_dlc = CAN_ERR_DLC; + frame.data[5] = 'R'; + frame.data[6] = 'I'; + frame.data[7] = 'P'; elm327_feed_frame_to_netdev(elm, &frame); - pr_err("ELM327 misbehaved. Re-initializing.\n"); + netdev_err(elm->dev, "ELM327 misbehaved. Blocking further communication.\n"); - elm->can.can_stats.restarts++; - elm327_init(elm); + elm->hw_failure = true; + can_bus_off(elm->dev); } @@ -347,59 +374,69 @@ static inline void elm327_hw_failure(struct elmcan *elm) * (assumes elm->lock taken) * ************************************************************************/ +static bool elm327_is_ready_char(char c) +{ + /* Bits 0xc0 are sometimes set (randomly), hence the mask. + * Probably bad hardware. + */ + return (c & 0x3f) == ELM327_READY_CHAR; +} + + static void elm327_parse_error(struct elmcan *elm, int len) { - struct can_frame frame = {0}; + struct can_frame frame; + memset(&frame, 0, sizeof(frame)); 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, "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; + switch (len) { + case 17: + if (!memcmp(elm->rxbuf, "UNABLE TO CONNECT", 17)) { + netdev_err(elm->dev, + "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)) + frame.can_id |= CAN_ERR_PROT; + if (!memcmp(elm->rxbuf, "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)) { + netdev_err(elm->dev, "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); @@ -408,11 +445,13 @@ static void elm327_parse_error(struct elmcan *elm, int len) static int elm327_parse_frame(struct elmcan *elm, int len) { - struct can_frame frame = {0}; + struct can_frame frame; int hexlen; int datastart; int i; + memset(&frame, 0, sizeof(frame)); + /* 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. @@ -425,6 +464,23 @@ 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. + */ + if (accept_flaky_uart + && hexlen < len + && !isdigit(elm->rxbuf[hexlen]) + && !isupper(elm->rxbuf[hexlen]) + && '<' != elm->rxbuf[hexlen] + && ' ' != elm->rxbuf[hexlen]) { + /* The line is likely garbled anyway, so bail. + * The main code will restart listening. + */ + elm327_kick_into_cmd_mode(elm); + return 3; + } + /* 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. @@ -483,7 +539,8 @@ static int elm327_parse_frame(struct elmcan *elm, int len) } /* Is the line long enough to hold the advertised payload? */ - if (!(frame.can_id & CAN_RTR_FLAG) && (hexlen < frame.can_dlc * 3 + datastart)) { + if (!(frame.can_id & CAN_RTR_FLAG) + && (hexlen < frame.can_dlc * 3 + datastart)) { /* Incomplete frame. */ /* Probably the ELM327's RS232 TX buffer was full. @@ -505,7 +562,7 @@ static int elm327_parse_frame(struct elmcan *elm, int len) /* 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); + | (hex_to_bin(elm->rxbuf[datastart+3*i+1]) << 0); } /* Feed the frame to the network layer. */ @@ -518,9 +575,8 @@ static int elm327_parse_frame(struct elmcan *elm, int len) static void elm327_parse_line(struct elmcan *elm, int len) { /* Skip empty lines */ - if (!len) { + if (!len) return; - } /* Skip echo lines */ if (elm->drop_next_line) { @@ -531,77 +587,104 @@ static void elm327_parse_line(struct elmcan *elm, int len) } /* Regular parsing */ - switch(elm->state) { - case ELM_RECEIVING: - if (elm327_parse_frame(elm, len)) { - /* Parse an error line. */ - elm327_parse_error(elm, len); + 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; + /* Start afresh. */ + elm327_kick_into_cmd_mode(elm); + } + 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); - netdev_info(elm->dev, "Initialization finished.\n"); - } + struct can_frame *frame = &elm->can_frame; + char local_txbuf[20]; + + if (!elm->cmds_todo) { + /* Enter CAN monitor mode */ + elm327_send(elm, "ATMA\r", 5); + elm->state = ELM_RECEIVING; + + return; + } + + /* Reconfigure ELM327 step by step as indicated by elm->cmds_todo */ + 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); + netdev_info(elm->dev, "Initialization finished.\n"); + } + + /* 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); + + return; - /* 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. + } else if (test_and_clear_bit(ELM_TODO_SILENT_MONITOR, &elm->cmds_todo)) { + sprintf(local_txbuf, "ATCSM%i\r", + !(!(elm->can.ctrlmode & CAN_CTRLMODE_LISTENONLY))); + + } else if (test_and_clear_bit(ELM_TODO_RESPONSES, &elm->cmds_todo)) { + sprintf(local_txbuf, "ATR%i\r", + !(elm->can.ctrlmode & CAN_CTRLMODE_LISTENONLY)); + + } else if (test_and_clear_bit(ELM_TODO_CAN_CONFIG, &elm->cmds_todo)) { + sprintf(local_txbuf, "ATPC\r"); + set_bit(ELM_TODO_CAN_CONFIG_PART2, &elm->cmds_todo); + + } else if (test_and_clear_bit(ELM_TODO_CAN_CONFIG_PART2, &elm->cmds_todo)) { + sprintf(local_txbuf, "ATPB%04X\r", + elm->can_config); + + } else if (test_and_clear_bit(ELM_TODO_CANID_29BIT_HIGH, &elm->cmds_todo)) { + sprintf(local_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)) { + sprintf(local_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)) { + sprintf(local_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) { + /* Send an RTR frame. Their DLC is fixed. + * Some chips don't send them at all. */ - 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"); + sprintf(local_txbuf, "ATRTR\r"); + } else { + /* Send a regular CAN data frame */ + int i; + + for (i = 0; i < frame->can_dlc; i++) { + sprintf(&local_txbuf[2*i], "%02X", + frame->data[i]); } - elm->drop_next_line = 1; - elm->state = ELM_RECEIVING; + sprintf(&local_txbuf[2*i], "\r"); } - elm327_send(elm, txbuf, strlen(txbuf)); - } else { - /* Enter CAN monitor mode */ - elm327_send(elm, "ATMA\r", 5); + elm->drop_next_line = 1; elm->state = ELM_RECEIVING; } + + elm327_send(elm, local_txbuf, strlen(local_txbuf)); } @@ -632,7 +715,7 @@ static void elm327_parse_rxbuf(struct elmcan *elm) elm->state = ELM_GETPROMPT; i++; break; - } else if (elm->rxbuf[i] == ELM327_READY_CHAR) { + } else if (elm327_is_ready_char(elm->rxbuf[i])) { elm327_send(elm, ELM327_MAGIC_STRING, 1); i++; break; @@ -646,9 +729,8 @@ static void elm327_parse_rxbuf(struct elmcan *elm) case ELM_GETPROMPT: /* Wait for '>' */ - if (elm->rxbuf[elm->rxfill - 1] == ELM327_READY_CHAR) { + if (elm327_is_ready_char(elm->rxbuf[elm->rxfill - 1])) elm327_handle_prompt(elm); - } elm->rxfill = 0; return; @@ -665,11 +747,12 @@ static void elm327_parse_rxbuf(struct elmcan *elm) /* 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"); + netdev_err(elm->dev, + "RX buffer overflow. Faulty ELM327 or UART?\n"); elm327_hw_failure(elm); + return; } else if (len == elm->rxfill) { - if (elm->state == ELM_RECEIVING - && elm->rxbuf[elm->rxfill - 1] == ELM327_READY_CHAR) { + if (elm327_is_ready_char(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. @@ -678,12 +761,12 @@ static void elm327_parse_rxbuf(struct elmcan *elm) elm327_handle_prompt(elm); return; - } else { - /* We haven't received a full line yet. - * Wait for more data. - */ - return; } + + /* No found - we haven't received a full line yet. + * Wait for more data. + */ + return; } /* We have a full line to parse. */ @@ -693,9 +776,8 @@ static void elm327_parse_rxbuf(struct elmcan *elm) elm327_drop_bytes(elm, len+1); /* More data to parse? */ - if (elm->rxfill) { + if (elm->rxfill) elm327_parse_rxbuf(elm); - } } } @@ -709,18 +791,6 @@ static void elm327_parse_rxbuf(struct elmcan *elm) * (takes elm->lock) * ************************************************************************/ -static int elmcan_netdev_init(struct net_device *dev) -{ - struct elmcan *elm = netdev_priv(dev); - - /* Copy the interface name here, so the SIOCGIFNAME case in - * elmcan_ldisc_ioctl() doesn't race against unregister_candev(). - */ - memcpy(elm->ifname, dev->name, IFNAMSIZ); - - return 0; -} - /* Netdevice DOWN -> UP routine */ static int elmcan_netdev_open(struct net_device *dev) { @@ -728,6 +798,12 @@ static int elmcan_netdev_open(struct net_device *dev) int err; spin_lock_bh(&elm->lock); + if (elm->hw_failure) { + netdev_err(elm->dev, "Refusing to open interface after a hardware fault has been detected.\n"); + spin_unlock_bh(&elm->lock); + return -EIO; + } + if (elm->tty == NULL) { spin_unlock_bh(&elm->lock); return -ENODEV; @@ -784,7 +860,8 @@ static int elmcan_netdev_close(struct net_device *dev) } /* Send a can_frame to a TTY queue. */ -static netdev_tx_t elmcan_netdev_start_xmit(struct sk_buff *skb, struct net_device *dev) +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; @@ -801,6 +878,12 @@ static netdev_tx_t elmcan_netdev_start_xmit(struct sk_buff *skb, struct net_devi * See Documentation/networking/netdevices.txt */ spin_lock(&elm->lock); + + /* We shouldn't get here after a hardware fault: + * can_bus_off() calls netif_carrier_off() + */ + BUG_ON(elm->hw_failure); + if (elm->tty == NULL || elm->can.ctrlmode & CAN_CTRLMODE_LISTENONLY) { spin_unlock(&elm->lock); @@ -828,7 +911,6 @@ static int elmcan_netdev_change_mtu(struct net_device *dev, int new_mtu) } static const struct net_device_ops elmcan_netdev_ops = { - .ndo_init = elmcan_netdev_init, .ndo_open = elmcan_netdev_open, .ndo_stop = elmcan_netdev_close, .ndo_start_xmit = elmcan_netdev_start_xmit, @@ -850,7 +932,7 @@ static const struct net_device_ops elmcan_netdev_ops = { * This is to ensure ordering in case we are shutting down, and to ensure * there is a refcount at all (because tty->disc_data may be NULL). */ -static struct elmcan* get_elm(struct tty_struct *tty) +static struct elmcan *get_elm(struct tty_struct *tty) { struct elmcan *elm; bool got_ref; @@ -869,9 +951,8 @@ static struct elmcan* get_elm(struct tty_struct *tty) got_ref = atomic_inc_not_zero(&elm->refcount); spin_unlock_bh(&elmcan_discdata_lock); - if (!got_ref) { + if (!got_ref) return NULL; - } return elm; } @@ -899,28 +980,71 @@ static void elmcan_ldisc_rx(struct tty_struct *tty, if (!elm) return; + spin_lock_bh(&elm->lock); + if (elm->hw_failure) { + spin_unlock_bh(&elm->lock); + + put_elm(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."); + netdev_err(elm->dev, "Error in received character stream. Check your wiring."); - spin_lock_bh(&elm->lock); elm327_hw_failure(elm); spin_unlock_bh(&elm->lock); put_elm(elm); return; } + + /* Ignore NUL characters, which the PIC microcontroller may + * inadvertently insert due to a known hardware bug. + * See ELM327 documentation, which refers to a Microchip PIC + * bug description. + */ if (*cp != 0) { + /* Check for stray characters on the UART line. + * No idea what causes this. + */ + if (!accept_flaky_uart + && !isdigit(*cp) + && !isupper(*cp) + && ELM327_MAGIC_CHAR != *cp + && ELM327_READY_CHAR != *cp + && '<' != *cp + && 'a' != *cp + && 'b' != *cp + && 'v' != *cp + && '.' != *cp + && '?' != *cp + && '\r' != *cp + && ' ' != *cp) { + /* We've received an invalid character, so bail. + * There's something wrong with the ELM327, or + * with the UART line. + */ + netdev_err(elm->dev, + "Received illegal character %02x.\n", + *cp); + elm327_hw_failure(elm); + spin_unlock_bh(&elm->lock); + + put_elm(elm); + return; + } + elm->rxbuf[elm->rxfill++] = *cp; } + cp++; } if (count >= 0) { - pr_err("Receive buffer overflowed. Bad chip or wiring?"); + netdev_err(elm->dev, "Receive buffer overflowed. Bad chip or wiring?"); - spin_lock_bh(&elm->lock); elm327_hw_failure(elm); spin_unlock_bh(&elm->lock); @@ -928,7 +1052,6 @@ static void elmcan_ldisc_rx(struct tty_struct *tty, return; } - spin_lock_bh(&elm->lock); elm327_parse_rxbuf(elm); spin_unlock_bh(&elm->lock); @@ -948,7 +1071,11 @@ static void elmcan_ldisc_tx_worker(struct work_struct *work) ssize_t actual; spin_lock_bh(&elm->lock); - /* First make sure we're connected. */ + if (elm->hw_failure) { + spin_unlock_bh(&elm->lock); + return; + } + if (!elm->tty || !netif_running(elm->dev)) { spin_unlock_bh(&elm->lock); return; @@ -966,8 +1093,12 @@ static void elmcan_ldisc_tx_worker(struct work_struct *work) actual = elm->tty->ops->write(elm->tty, elm->txhead, elm->txleft); if (actual < 0) { - netdev_err(elm->dev, "Failed to write to tty %s.\n", elm->tty->name); + netdev_err(elm->dev, + "Failed to write to tty %s.\n", + elm->tty->name); elm327_hw_failure(elm); + spin_unlock_bh(&elm->lock); + return; } elm->txleft -= actual; @@ -994,19 +1125,30 @@ static void elmcan_ldisc_tx_wakeup(struct tty_struct *tty) -/* 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, +/* ELM327 can only handle bitrates that are integer divisors of 500 kHz, + * or 7/8 of that. Divisors are 1 to 64. + * Currently we don't implement support for 7/8 rates. + */ +static const u32 elmcan_bitrate_const[64] = { + 7812, 7936, 8064, 8196, 8333, 8474, 8620, 8771, + 8928, 9090, 9259, 9433, 9615, 9803, 10000, 10204, + 10416, 10638, 10869, 11111, 11363, 11627, 11904, 12195, + 12500, 12820, 13157, 13513, 13888, 14285, 14705, 15151, + 15625, 16129, 16666, 17241, 17857, 18518, 19230, 20000, + 20833, 21739, 22727, 23809, 25000, 26315, 27777, 29411, + 31250, 33333, 35714, 38461, 41666, 45454, 50000, 55555, + 62500, 71428, 83333, 100000, 125000, 166666, 250000, 500000 }; +/* Dummy function to claim we're changing the bitrate. + * We actually do this when opening the net device. + */ +static int elmcan_do_set_bittiming(struct net_device *netdev) +{ + return 0; +} + + /* * Open the high-level part of the elmcan channel. * This function is called by the TTY module when the @@ -1042,8 +1184,9 @@ static int elmcan_ldisc_open(struct tty_struct *tty) /* Configure CAN metadata */ elm->can.state = CAN_STATE_STOPPED; - elm->can.clock.freq = 1000000; - elm->can.bittiming_const = &elmcan_bittiming_const; + elm->can.bitrate_const = elmcan_bitrate_const; + elm->can.bitrate_const_cnt = ARRAY_SIZE(elmcan_bitrate_const); + elm->can.do_set_bittiming = elmcan_do_set_bittiming; elm->can.ctrlmode_supported = CAN_CTRLMODE_LISTENONLY; /* Configure netlink interface */ @@ -1097,8 +1240,8 @@ static void elmcan_ldisc_close(struct tty_struct *tty) put_elm(elm); /* Spin until refcount reaches 0 */ - while(atomic_read(&elm->refcount) > 0) - msleep(1); + while (atomic_read(&elm->refcount) > 0) + msleep_interruptible(10); /* At this point, all ldisc calls to us will be no-ops. * Since the refcount is 0, they are bailing immediately. @@ -1132,14 +1275,13 @@ static int elmcan_ldisc_ioctl(struct tty_struct *tty, struct file *file, struct elmcan *elm = get_elm(tty); unsigned int tmp; - /* First make sure we're connected. */ if (!elm) return -EINVAL; switch (cmd) { case SIOCGIFNAME: - tmp = strlen(elm->ifname) + 1; - if (copy_to_user((void __user *)arg, elm->ifname, tmp)) { + tmp = strlen(elm->dev->name) + 1; + if (copy_to_user((void __user *)arg, elm->dev->name, tmp)) { put_elm(elm); return -EFAULT; } @@ -1186,9 +1328,9 @@ static int __init elmcan_init(void) /* Fill in our line protocol discipline, and register it */ status = tty_register_ldisc(N_ELMCAN, &elmcan_ldisc); - if (status) { + if (status) pr_err("can't register line discipline\n"); - } + return status; } @@ -1200,9 +1342,9 @@ static void __exit elmcan_exit(void) int status; status = tty_unregister_ldisc(N_ELMCAN); - if (status) { - pr_err("Can't unregister line discipline (error: %d)\n", status); - } + if (status) + pr_err("Can't unregister line discipline (error: %d)\n", + status); } module_init(elmcan_init);