+/**
+ * sllin_rx_validate() -- Validate received frame, i,e. check checksum
+ *
+ * @sl:
+ */
+static int sllin_rx_validate(struct sllin *sl)
+{
+ unsigned long flags;
+ int actual_id;
+ int ext_chcks_fl;
+ int lin_dlc;
+ unsigned char rec_chcksm = sl->rx_buff[sl->rx_cnt - 1];
+ struct sllin_conf_entry *sce;
+
+ actual_id = sl->rx_buff[SLLIN_BUFF_ID] & LIN_ID_MASK;
+ sce = &sl->linfr_cache[actual_id];
+
+ spin_lock_irqsave(&sl->linfr_lock, flags);
+ lin_dlc = sce->dlc;
+ ext_chcks_fl = sce->frame_fl & LIN_CHECKSUM_EXTENDED;
+ spin_unlock_irqrestore(&sl->linfr_lock, flags);
+
+ if (sllin_checksum(sl->rx_buff, sl->rx_cnt - 1, ext_chcks_fl) !=
+ rec_chcksm) {
+
+ /* Type of checksum is configured for particular frame */
+ if (lin_dlc > 0) {
+ return -1;
+ } else {
+ if (sllin_checksum(sl->rx_buff, sl->rx_cnt - 1,
+ !ext_chcks_fl) != rec_chcksm) {
+ return -1;
+ }
+ }
+ }
+
+ return 0;
+}
+
+static void sllin_slave_finish_rx_msg(struct sllin *sl)
+{
+ if (sllin_rx_validate(sl) == -1) {
+ netdev_dbg(sl->dev, "sllin: RX validation failed.\n");
+ sllin_report_error(sl, LIN_ERR_CHECKSUM);
+ } else {
+ /* Send CAN non-RTR frame with data */
+ netdev_dbg(sl->dev, "sllin: sending NON-RTR CAN frame with LIN payload.");
+ sll_bump(sl); /* send packet to the network layer */
+ }
+ /* 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;
+}
+
+static void sllin_slave_receive_buf(struct tty_struct *tty,
+ const unsigned char *cp, char *fp, int count)
+{
+ struct sllin *sl = (struct sllin *) tty->disc_data;
+ int lin_id;
+ struct sllin_conf_entry *sce;
+
+
+ /* Read the characters out of the buffer */
+ while (count--) {
+ if (fp && *fp++) {
+ /*
+ * If we don't know the length of the current message
+ * and received at least the LIN ID, we received here
+ * the break of the next message.
+ * Evaluate the previous one before continuing.
+ */
+ if ((sl->rx_len_unknown == true) &&
+ (sl->rx_cnt >= SLLIN_BUFF_ID))
+ {
+ hrtimer_cancel(&sl->rx_timer);
+ sllin_slave_finish_rx_msg(sl);
+
+ set_bit(SLF_RXEVENT, &sl->flags);
+ wake_up(&sl->kwt_wq);
+ }
+
+ netdev_dbg(sl->dev, "sllin_slave_receive_buf char 0x%02x ignored "
+ "due marker 0x%02x, flags 0x%lx\n",
+ *cp, *(fp-1), sl->flags);
+
+ /* 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;
+ }
+
+ if (sl->rx_cnt < SLLIN_BUFF_LEN) {
+ netdev_dbg(sl->dev, "LIN_RX[%d]: 0x%02x\n", sl->rx_cnt, *cp);
+
+ /* We did not receive break (0x00) character */
+ if ((sl->rx_cnt == SLLIN_BUFF_BREAK) && (*cp == 0x55)) {
+ sl->rx_buff[sl->rx_cnt++] = 0x00;
+ }
+
+ if (sl->rx_cnt == SLLIN_BUFF_SYNC) {
+ /* 'Duplicated' break character -- ignore */
+ if (*cp == 0x00) {
+ cp++;
+ continue;
+ }
+
+ /* Wrong sync character */
+ if (*cp != 0x55)
+ break;
+ }
+
+ sl->rx_buff[sl->rx_cnt++] = *cp++;
+ }
+
+ /* Header received */
+ if ((sl->header_received == false) && (sl->rx_cnt >= (SLLIN_BUFF_ID + 1))) {
+ unsigned long flags;
+
+ lin_id = sl->rx_buff[SLLIN_BUFF_ID] & LIN_ID_MASK;
+ sce = &sl->linfr_cache[lin_id];
+
+ spin_lock_irqsave(&sl->linfr_lock, flags);
+
+ sl->lin_state = SLSTATE_ID_RECEIVED;
+ /* Is the length of data set in frame cache? */
+ if (sce->dlc > 0) {
+ sl->rx_expect += sce->dlc + 1; /* + checksum */
+ sl->rx_len_unknown = false;
+ wake_up(&sl->kwt_wq);
+ } else {
+ sl->rx_expect += SLLIN_DATA_MAX + 1; /* + checksum */
+ sl->rx_len_unknown = true;
+ }
+ spin_unlock_irqrestore(&sl->linfr_lock, flags);
+
+ sl->header_received = true;
+
+ hrtimer_start(&sl->rx_timer,
+ ktime_add(ktime_get(), sl->rx_timer_timeout),
+ HRTIMER_MODE_ABS);
+ sll_send_rtr(sl);
+ continue;
+ }
+
+ /* Response received */
+ if ((sl->header_received == true) &&
+ ((sl->rx_cnt >= sl->rx_expect))) {
+
+ hrtimer_cancel(&sl->rx_timer);
+ netdev_dbg(sl->dev, "Received LIN header & LIN response. "
+ "rx_cnt = %u, rx_expect = %u\n", sl->rx_cnt,
+ sl->rx_expect);
+ sllin_slave_finish_rx_msg(sl);
+
+ set_bit(SLF_RXEVENT, &sl->flags);
+ wake_up(&sl->kwt_wq);
+ }
+ }
+}
+
+static void sllin_receive_buf(struct tty_struct *tty,
+ const unsigned char *cp, char *fp, int count)
+{
+ struct sllin *sl = (struct sllin *) tty->disc_data;
+ netdev_dbg(sl->dev, "sllin_receive_buf invoked, count = %u\n", count);
+
+ if (!sl || sl->magic != SLLIN_MAGIC || !netif_running(sl->dev))
+ return;
+
+ if (sl->lin_master)
+ sllin_master_receive_buf(tty, cp, fp, count);
+ else
+ sllin_slave_receive_buf(tty, cp, fp, count);
+
+}
+
+static int sllin_send_tx_buff(struct sllin *sl)