sllin: Enhanced reception of LIN frames in Slave mode.

diff --git a/sllin/sllin.c b/sllin/sllin.c
index 0e49aa59250f267ae830ae6a794cdaf1e73b7cef..c914a4a5ea755eeb9b2ee886f71684e911b19bc8 100644 (file)
--- a/sllin/sllin.c
+++ b/sllin/sllin.c
@@ -148,6 +148,8 @@ struct sllin {
        char                    resp_len_known; /* Length of the response is known */
        char                    header_received;/* In Slave mode, set when header was already
                                                   received */
+       char                    rx_len_unknown; /* We are not sure how much data will be sent to us --
+                                                  we just guess the length */
 
        unsigned long           flags;          /* Flag values/ mode etc     */
 #define SLF_INUSE              0               /* Channel in use            */
@@ -429,6 +431,12 @@ static void sll_setup(struct net_device *dev)
 /******************************************
   Routines looking at TTY side.
  ******************************************/
+#define SLL_RESPONSE_RECEIVED          ((sl->header_received == true) && \
+                                        ((sl->rx_cnt >= sl->rx_expect) || \
+                                        ((sl->rx_len_unknown == true) && (count == 0))))
+
+#define SLL_HEADER_RECEIVED            ((sl->header_received == false) && \
+                                        (sl->rx_cnt >= (SLLIN_BUFF_ID + 1)))
 
 static void sllin_receive_buf(struct tty_struct *tty,
                              const unsigned char *cp, char *fp, int count)
@@ -453,67 +461,68 @@ static void sllin_receive_buf(struct tty_struct *tty,
                        } else { /* Received Break */
                                sl->rx_cnt = 0;
                                sl->rx_expect = SLLIN_BUFF_ID + 1;
+                               sl->rx_len_unknown = false; /* We do know exact length of the header */
                                sl->header_received = false;
-                               return;
                        }
                }
 
-               if (sl->rx_cnt < SLLIN_BUFF_LEN) {
 #ifndef BREAK_BY_BAUD
-                       /* We didn't receive Break character -- fake it! */
-                       if ((sl->rx_cnt == SLLIN_BUFF_BREAK) && (*cp == 0x55)) {
-                               pr_debug("sllin: LIN_RX[%d]: 0x00\n", sl->rx_cnt);
-                               sl->rx_buff[sl->rx_cnt++] = 0x00;
-                       }
+               /* We didn't receive Break character -- fake it! */
+               if ((sl->rx_cnt == SLLIN_BUFF_BREAK) && (*cp == 0x55)) {
+                       pr_debug("sllin: LIN_RX[%d]: 0x00\n", sl->rx_cnt);
+                       sl->rx_buff[sl->rx_cnt++] = 0x00;
+               }
 #endif
+               if (sl->rx_cnt < SLLIN_BUFF_LEN) {
                        pr_debug("sllin: LIN_RX[%d]: 0x%02x\n", sl->rx_cnt, *cp);
                        sl->rx_buff[sl->rx_cnt++] = *cp++;
                }
-       }
 
-       if (sl->lin_master == true) {
-               if (sl->rx_cnt >= sl->rx_expect) { /* Probably whole frame was received */
-                       set_bit(SLF_RXEVENT, &sl->flags);
-                       wake_up(&sl->kwt_wq);
-                       pr_debug("sllin: sllin_receive_buf count %d, wakeup\n", sl->rx_cnt);
-               } else {
-                       pr_debug("sllin: sllin_receive_buf count %d, waiting\n", sl->rx_cnt);
-               }
-       } else { /* LIN slave */
-               int lin_id;
-               struct sllin_conf_entry *sce;
-
-               pr_debug("sllin: rx_cnt = %u; header_received = %u\n",
-                       sl->rx_cnt, sl->header_received);
-
-               /* Whole header was received */
-               if ((sl->rx_cnt >= (SLLIN_BUFF_ID + 1)) &&
-                       (sl->header_received == false))
-               {
-                       lin_id = sl->rx_buff[SLLIN_BUFF_ID] & LIN_ID_MASK;
-                       sce = &sl->linfr_cache[lin_id];
-
-                       /* Is the length of data set in frame cache? */
-                       if (sce->frame_fl & LIN_LOC_SLAVE_CACHE)
-                               sl->rx_expect += sce->dlc;
-                       else
-                               sl->rx_expect += 2; /* 1 data byte + checksum */
-
-                       sl->header_received = true;
-                       sll_send_rtr(sl);
-               }
+               if (sl->lin_master == true) {
+                       if (SLL_RESPONSE_RECEIVED) {
+                               set_bit(SLF_RXEVENT, &sl->flags);
+                               wake_up(&sl->kwt_wq);
+                               pr_debug("sllin: sllin_receive_buf count %d, wakeup\n", sl->rx_cnt);
+                       } else {
+                               pr_debug("sllin: sllin_receive_buf count %d, waiting\n", sl->rx_cnt);
+                       }
+               } else { /* LIN slave */
+                       int lin_id;
+                       struct sllin_conf_entry *sce;
+
+                       pr_debug("sllin: rx_cnt = %u; header_received = %u\n",
+                                       sl->rx_cnt, sl->header_received);
 
-               /* Probably whole frame was received */
-               if ((sl->rx_cnt >= sl->rx_expect) && (sl->rx_cnt > SLLIN_BUFF_DATA)) {
-                       sll_bump(sl);
-                       pr_debug("sllin: Received LIN header & LIN response. "
-                               "rx_cnt = %u, rx_expect = %u\n", sl->rx_cnt,
-                               sl->rx_expect);
-
-                       /* Prepare for reception of new header */
-                       sl->rx_cnt = 0;
-                       sl->rx_expect = SLLIN_BUFF_ID + 1;
-                       sl->header_received = false;
+                       if (SLL_HEADER_RECEIVED) {
+                               lin_id = sl->rx_buff[SLLIN_BUFF_ID] & LIN_ID_MASK;
+                               sce = &sl->linfr_cache[lin_id];
+
+                               /* Is the length of data set in frame cache? */
+                               if (sce->frame_fl & LIN_LOC_SLAVE_CACHE) {
+                                       sl->rx_expect += sce->dlc;
+                                       sl->rx_len_unknown = false;
+                               } else {
+                                       sl->rx_expect += SLLIN_DATA_MAX + 1; /* + checksum */
+                                       sl->rx_len_unknown = true;
+                               }
+
+                               sl->header_received = true;
+                               sll_send_rtr(sl);
+                               continue;
+                       }
+
+                       if (SLL_RESPONSE_RECEIVED) {
+                               sll_bump(sl);
+                               pr_debug("sllin: Received LIN header & LIN response. "
+                                               "rx_cnt = %u, rx_expect = %u\n", sl->rx_cnt,
+                                               sl->rx_expect);
+
+                               /* Prepare for reception of new header */
+                               sl->rx_cnt = 0;
+                               sl->rx_expect = SLLIN_BUFF_ID + 1;
+                               sl->rx_len_unknown = false; /* We do know exact length of the header */
+                               sl->header_received = false;
+                       }
                }
        }
 }