Remove accept_flaky_uart module option.

[elmcan.git] / module / elmcan.c

diff --git a/module/elmcan.c b/module/elmcan.c
index 49df7c1600ca993703e97811f3f5227d8822095f..3d35821fae7d34e0b707d96d8f80146af942ba55 100644 (file)
--- a/module/elmcan.c
+++ b/module/elmcan.c
@@ -42,15 +42,6 @@ MODULE_DESCRIPTION("ELM327 based CAN interface");
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Max Staudt <max-linux@enpas.org>");
 
-/* 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
@@ -343,6 +334,12 @@ static inline void elm327_hw_failure(struct elmcan *elm)
        can_bus_off(elm->dev);
 }
 
+/* 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)
 {
@@ -352,15 +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
@@ -371,25 +369,25 @@ 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, "<RX ERROR", 9))
+               if (!_memstrcmp(elm->rxbuf, "<RX ERROR"))
                        frame.can_id |= CAN_ERR_PROT;
                break;
        case 8:
-               if (!memcmp(elm->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;
@@ -441,12 +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] &&
@@ -508,7 +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;
        }
 
@@ -558,7 +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;
        }
 
@@ -931,8 +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 ||