#define ELM327_READY_CHAR '>'
/* Bits in elm->cmds_todo */
-enum ELM327_TX_DO_BITS {
+enum elm327_to_to_do_bits {
ELM327_TX_DO_CAN_DATA = 0,
ELM327_TX_DO_CANID_11BIT,
ELM327_TX_DO_CANID_29BIT_LOW,
/* Per-channel lock */
spinlock_t lock;
- /* Stop the channel on hardware failure.
+ /* Stop the channel on UART side hardware failure, e.g. stray
+ * characters or neverending lines. This may be caused by bad
+ * UART wiring, a bad ELM327, a bad UART bridge...
* Once this is true, nothing will be sent to the TTY.
*/
- bool hw_failure;
+ bool uart_side_failure;
/* TTY TX helpers */
struct work_struct tx_work; /* Flushes TTY TX buffer */
unsigned long cmds_todo;
};
-static inline void elm327_hw_failure(struct elmcan *elm);
+static inline void elm327_uart_side_failure(struct elmcan *elm);
static void elm327_send(struct elmcan *elm, const void *buf, size_t len)
{
lockdep_assert_held(elm->lock);
- if (elm->hw_failure)
+ if (elm->uart_side_failure)
return;
memcpy(elm->txbuf, buf, len);
netdev_err(elm->dev,
"Failed to write to tty %s.\n",
elm->tty->name);
- elm327_hw_failure(elm);
+ elm327_uart_side_failure(elm);
return;
}
elm327_kick_into_cmd_mode(elm);
}
-/* ELM327 initialisation sequence. */
+/* ELM327 initialisation sequence.
+ * The line length is limited by the buffer in elm327_handle_prompt().
+ */
static char *elm327_init_script[] = {
"AT WS\r", /* v1.0: Warm Start */
"AT PP FF OFF\r", /* v1.0: All Programmable Parameters Off */
}
/* Called when we're out of ideas and just want it all to end. */
-static inline void elm327_hw_failure(struct elmcan *elm)
+static inline void elm327_uart_side_failure(struct elmcan *elm)
{
struct can_frame *frame;
struct sk_buff *skb;
lockdep_assert_held(elm->lock);
- elm->hw_failure = true;
+ elm->uart_side_failure = true;
elm->can.can_stats.bus_off++;
netif_stop_queue(elm->dev);
elm327_feed_frame_to_netdev(elm, skb);
}
-/* Compare a buffer to a fixed string */
-static inline int _memstrcmp(const u8 *mem, const char *str)
-{
- return memcmp(mem, str, strlen(str));
-}
-
/* Compare buffer to string length, then compare buffer to fixed string.
* This ensures two things:
* - It flags cases where the fixed string is only the start of the
* buffer, rather than exactly all of it.
* - It avoids byte comparisons in case the length doesn't match.
+ *
+ * strncmp() cannot be used here because it accepts the following wrong case:
+ * strncmp("CAN ER", "CAN ERROR", 6);
+ * This must fail, hence this helper function.
*/
-static inline int _len_memstrcmp(const u8 *mem, size_t mem_len, const char *str)
+static inline int check_len_then_cmp(const u8 *mem, size_t mem_len, const char *str)
{
size_t str_len = strlen(str);
- return (mem_len != str_len) || memcmp(mem, str, str_len);
+ return (mem_len == str_len) && !memcmp(mem, str, str_len);
}
static void elm327_parse_error(struct elmcan *elm, size_t len)
return;
/* Filter possible error messages based on length of RX'd line */
- if (!_len_memstrcmp(elm->rxbuf, len, "UNABLE TO CONNECT")) {
+ if (check_len_then_cmp(elm->rxbuf, len, "UNABLE TO CONNECT")) {
netdev_err(elm->dev,
"ELM327 reported UNABLE TO CONNECT. Please check your setup.\n");
- } else if (!_len_memstrcmp(elm->rxbuf, len, "BUFFER FULL")) {
+ } else if (check_len_then_cmp(elm->rxbuf, len, "BUFFER FULL")) {
/* This will only happen if the last data line was complete.
* Otherwise, elm327_parse_frame() will heuristically
* emit this kind of error frame instead.
*/
frame->can_id |= CAN_ERR_CRTL;
frame->data[1] = CAN_ERR_CRTL_RX_OVERFLOW;
- } else if (!_len_memstrcmp(elm->rxbuf, len, "BUS ERROR")) {
+ } else if (check_len_then_cmp(elm->rxbuf, len, "BUS ERROR")) {
frame->can_id |= CAN_ERR_BUSERROR;
- } else if (!_len_memstrcmp(elm->rxbuf, len, "CAN ERROR")) {
+ } else if (check_len_then_cmp(elm->rxbuf, len, "CAN ERROR")) {
frame->can_id |= CAN_ERR_PROT;
- } else if (!_len_memstrcmp(elm->rxbuf, len, "<RX ERROR")) {
+ } else if (check_len_then_cmp(elm->rxbuf, len, "<RX ERROR")) {
frame->can_id |= CAN_ERR_PROT;
- } else if (!_len_memstrcmp(elm->rxbuf, len, "BUS BUSY")) {
+ } else if (check_len_then_cmp(elm->rxbuf, len, "BUS BUSY")) {
frame->can_id |= CAN_ERR_PROT;
frame->data[2] = CAN_ERR_PROT_OVERLOAD;
- } else if (!_len_memstrcmp(elm->rxbuf, len, "FB ERROR")) {
+ } else if (check_len_then_cmp(elm->rxbuf, len, "FB ERROR")) {
frame->can_id |= CAN_ERR_PROT;
frame->data[2] = CAN_ERR_PROT_TX;
- } else if (len == 5 && !_memstrcmp(elm->rxbuf, "ERR")) {
+ } else if (len == 5 && !memcmp(elm->rxbuf, "ERR", 3)) {
/* ERR is followed by two digits, hence line length 5 */
netdev_err(elm->dev, "ELM327 reported an ERR%c%c. Please power it off and on again.\n",
elm->rxbuf[3], elm->rxbuf[4]);
/* Check for RTR frame */
if (elm->rxfill >= hexlen + 3 &&
- !_memstrcmp(&elm->rxbuf[hexlen], "RTR")) {
+ !memcmp(&elm->rxbuf[hexlen], "RTR", 3)) {
frame->can_id |= CAN_RTR_FLAG;
}
if (elm->drop_next_line) {
elm->drop_next_line = 0;
return;
- } else if (!_memstrcmp(elm->rxbuf, "AT")) {
+ } else if (!memcmp(elm->rxbuf, "AT", 2)) {
return;
}
static void elm327_handle_prompt(struct elmcan *elm)
{
struct can_frame *frame = &elm->can_frame_to_send;
- char local_txbuf[20];
+ /* Size this buffer for the largest ELM327 line we may generate,
+ * which is currently an 8 byte CAN frame's payload hexdump.
+ * Items in elm327_init_script must fit here, too!
+ */
+ char local_txbuf[sizeof("0102030405060708\r")];
lockdep_assert_held(elm->lock);
/* Reconfigure ELM327 step by step as indicated by elm->cmds_todo */
if (test_bit(ELM327_TX_DO_INIT, &elm->cmds_todo)) {
- strcpy(local_txbuf, *elm->next_init_cmd);
+ snprintf(local_txbuf, sizeof(local_txbuf),
+ "%s",
+ *elm->next_init_cmd);
elm->next_init_cmd++;
if (!(*elm->next_init_cmd)) {
}
} else if (test_and_clear_bit(ELM327_TX_DO_SILENT_MONITOR, &elm->cmds_todo)) {
- sprintf(local_txbuf, "ATCSM%i\r",
+ snprintf(local_txbuf, sizeof(local_txbuf),
+ "ATCSM%i\r",
!(!(elm->can.ctrlmode & CAN_CTRLMODE_LISTENONLY)));
} else if (test_and_clear_bit(ELM327_TX_DO_RESPONSES, &elm->cmds_todo)) {
- sprintf(local_txbuf, "ATR%i\r",
+ snprintf(local_txbuf, sizeof(local_txbuf),
+ "ATR%i\r",
!(elm->can.ctrlmode & CAN_CTRLMODE_LISTENONLY));
} else if (test_and_clear_bit(ELM327_TX_DO_CAN_CONFIG, &elm->cmds_todo)) {
- sprintf(local_txbuf, "ATPC\r");
+ snprintf(local_txbuf, sizeof(local_txbuf),
+ "ATPC\r");
set_bit(ELM327_TX_DO_CAN_CONFIG_PART2, &elm->cmds_todo);
} else if (test_and_clear_bit(ELM327_TX_DO_CAN_CONFIG_PART2, &elm->cmds_todo)) {
- sprintf(local_txbuf, "ATPB%04X\r",
+ snprintf(local_txbuf, sizeof(local_txbuf),
+ "ATPB%04X\r",
elm->can_config);
} else if (test_and_clear_bit(ELM327_TX_DO_CANID_29BIT_HIGH, &elm->cmds_todo)) {
- sprintf(local_txbuf, "ATCP%02X\r",
+ snprintf(local_txbuf, sizeof(local_txbuf),
+ "ATCP%02X\r",
(frame->can_id & CAN_EFF_MASK) >> 24);
} else if (test_and_clear_bit(ELM327_TX_DO_CANID_29BIT_LOW, &elm->cmds_todo)) {
- sprintf(local_txbuf, "ATSH%06X\r",
+ snprintf(local_txbuf, sizeof(local_txbuf),
+ "ATSH%06X\r",
frame->can_id & CAN_EFF_MASK & ((1 << 24) - 1));
} else if (test_and_clear_bit(ELM327_TX_DO_CANID_11BIT, &elm->cmds_todo)) {
- sprintf(local_txbuf, "ATSH%03X\r",
+ snprintf(local_txbuf, sizeof(local_txbuf),
+ "ATSH%03X\r",
frame->can_id & CAN_SFF_MASK);
} else if (test_and_clear_bit(ELM327_TX_DO_CAN_DATA, &elm->cmds_todo)) {
/* Send an RTR frame. Their DLC is fixed.
* Some chips don't send them at all.
*/
- sprintf(local_txbuf, "ATRTR\r");
+ snprintf(local_txbuf, sizeof(local_txbuf),
+ "ATRTR\r");
} else {
/* Send a regular CAN data frame */
int i;
for (i = 0; i < frame->len; i++) {
- sprintf(&local_txbuf[2 * i], "%02X",
+ snprintf(&local_txbuf[2 * i], sizeof(local_txbuf),
+ "%02X",
frame->data[i]);
}
- sprintf(&local_txbuf[2 * i], "\r");
+ snprintf(&local_txbuf[2 * i], sizeof(local_txbuf),
+ "\r");
}
elm->drop_next_line = 1;
*/
netdev_err(elm->dev,
"RX buffer overflow. Faulty ELM327 or UART?\n");
- elm327_hw_failure(elm);
+ elm327_uart_side_failure(elm);
break;
} else if (len == elm->rxfill) {
if (elm327_is_ready_char(elm->rxbuf[elm->rxfill - 1])) {
int err;
spin_lock_bh(&elm->lock);
- if (elm->hw_failure) {
+ if (elm->uart_side_failure) {
netdev_err(elm->dev, "Refusing to open interface after a hardware fault has been detected.\n");
spin_unlock_bh(&elm->lock);
return -EIO;
/* We shouldn't get here after a hardware fault:
* can_bus_off() calls netif_carrier_off()
*/
- WARN_ON_ONCE(elm->hw_failure);
+ WARN_ON_ONCE(elm->uart_side_failure);
if (!elm->tty ||
- elm->hw_failure ||
+ elm->uart_side_failure ||
elm->can.ctrlmode & CAN_CTRLMODE_LISTENONLY) {
spin_unlock(&elm->lock);
goto out;
spin_lock_bh(&elm->lock);
- if (elm->hw_failure)
+ if (elm->uart_side_failure)
goto out;
while (count-- && elm->rxfill < ELM327_SIZE_RXBUF) {
if (fp && *fp++) {
netdev_err(elm->dev, "Error in received character stream. Check your wiring.");
- elm327_hw_failure(elm);
+ elm327_uart_side_failure(elm);
goto out;
}
netdev_err(elm->dev,
"Received illegal character %02x.\n",
*cp);
- elm327_hw_failure(elm);
+ elm327_uart_side_failure(elm);
goto out;
}
if (count >= 0) {
netdev_err(elm->dev, "Receive buffer overflowed. Bad chip or wiring?");
- elm327_hw_failure(elm);
+ elm327_uart_side_failure(elm);
goto out;
}
struct elmcan *elm = container_of(work, struct elmcan, tx_work);
ssize_t written;
- if (elm->hw_failure)
+ if (elm->uart_side_failure)
return;
spin_lock_bh(&elm->lock);
netdev_err(elm->dev,
"Failed to write to tty %s.\n",
elm->tty->name);
- elm327_hw_failure(elm);
+ elm327_uart_side_failure(elm);
spin_unlock_bh(&elm->lock);
return;
} else {
free_candev(elm->dev);
}
-#if LINUX_VERSION_CODE < KERNEL_VERSION(5,16,0)
-static int elmcan_ldisc_hangup(struct tty_struct *tty)
-#else
-static void elmcan_ldisc_hangup(struct tty_struct *tty)
-#endif
-{
- elmcan_ldisc_close(tty);
-#if LINUX_VERSION_CODE < KERNEL_VERSION(5,16,0)
- return 0;
-#endif
-}
-
static int elmcan_ldisc_ioctl(struct tty_struct *tty,
#if LINUX_VERSION_CODE < KERNEL_VERSION(5,17,0)
struct file *file,
.write_wakeup = elmcan_ldisc_tx_wakeup,
.open = elmcan_ldisc_open,
.close = elmcan_ldisc_close,
- .hangup = elmcan_ldisc_hangup,
.ioctl = elmcan_ldisc_ioctl,
};
projects / elmcan.git / blobdiff