]> rtime.felk.cvut.cz Git - linux-lin.git/blobdiff - sllin/sllin.c
sllin: Checking of checksum on received LIN frames.
[linux-lin.git] / sllin / sllin.c
index eaf1187d98cf063faf697d1b34adcf7a474fd31f..03d6137fc35b4e3e7c26eb436903e96102e7ad9e 100644 (file)
@@ -1,11 +1,8 @@
 /*
  * sllin.c - serial line LIN interface driver (using tty line discipline)
  *
- * This file is derived from linux/drivers/net/slip.c
- *
- * slip.c Authors  : Laurence Culhane <loz@holmes.demon.co.uk>
- *                   Fred N. van Kempen <waltje@uwalt.nl.mugnet.org>
- * sllin.c Author  : Oliver Hartkopp <socketcan@hartkopp.net>
+ * This file is derived from drivers/net/can/slcan.c
+ * slcan.c Author: Oliver Hartkopp <socketcan@hartkopp.net>
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License as published by the
@@ -69,7 +66,7 @@ static __initdata const char banner[] =
 MODULE_ALIAS_LDISC(N_SLLIN);
 MODULE_DESCRIPTION("serial line LIN interface");
 MODULE_LICENSE("GPL");
-MODULE_AUTHOR("Oliver Hartkopp <socketcan@hartkopp.net>");
+MODULE_AUTHOR("");
 
 #define SLLIN_MAGIC 0x53CA
 // #define BREAK_BY_BAUD
@@ -89,21 +86,28 @@ MODULE_PARM_DESC(maxdev, "Maximum number of sllin interfaces");
 #define SLLIN_BUFF_ID   2
 #define SLLIN_BUFF_DATA         3
 
-#define SLLIN_ID_MASK  0x3f
-#define SLLIN_ID_MAX   SLLIN_ID_MASK
+#define SLLIN_ID_MASK          0x3f
+#define SLLIN_ID_MAX           SLLIN_ID_MASK
+#define SLLIN_CTRL_FRAME       CAN_EFF_FLAG
+
+#define SLLIN_SAMPLES_PER_CHAR 10
+#define SLLIN_CHARS_TO_TIMEOUT 12
 
 enum slstate {
        SLSTATE_IDLE = 0,
        SLSTATE_BREAK_SENT,
        SLSTATE_ID_SENT,
-       SLSTATE_RESPONSE_WAIT,
+       SLSTATE_RESPONSE_WAIT, /* Wait for response */
+       SLSTATE_RESPONSE_WAIT_BUS, /* Wait for response from LIN bus
+                               only (CAN frames from network stack
+                               are not processed in this moment) */
        SLSTATE_RESPONSE_SENT,
 };
 
 struct sllin_conf_entry {
        int dlc;                /* Length of data in LIN frame */
 #define SLLIN_CANFR_FLAGS_OFFS 6 /* Lower 6 bits in can_id correspond to LIN ID */
-/* Save configuration for particualr LIN ID */
+/* Save configuration for particular LIN ID */
 #define SLLIN_LIN_ID_CONF      (1 <<  SLLIN_CANFR_FLAGS_OFFS)
 /* Publisher of particular LIN response is SLLIN Master */
 #define SLLIN_SRC_MASTER       (1 << (SLLIN_CANFR_FLAGS_OFFS + 1))
@@ -111,6 +115,12 @@ struct sllin_conf_entry {
 #define SLLIN_SLAVE_LOCAL      (1 << (SLLIN_CANFR_FLAGS_OFFS + 3))
 #define SLLIN_SLAVE_REMOTE     (1 << (SLLIN_CANFR_FLAGS_OFFS + 4))
 #define SLLIN_LOC_SLAVE_CACHE  (1 << (SLLIN_CANFR_FLAGS_OFFS + 5))
+#define SLLIN_CHECKSUM_EXTENDED        (1 << (SLLIN_CANFR_FLAGS_OFFS + 6))
+
+#define SLLIN_ERR_RX_TIMEOUT    (1 << (SLLIN_CANFR_FLAGS_OFFS + 7))
+#define SLLIN_ERR_CHECKSUM      (1 << (SLLIN_CANFR_FLAGS_OFFS + 8))
+//#define SLLIN_ERR_FRAMING     (1 << (SLLIN_CANFR_FLAGS_OFFS + 9))
+
        canid_t frame_fl;       /* LIN frame flags. Passed from userspace as canid_t data type */
        u8 data[8];             /* LIN frame data payload */
 };
@@ -136,6 +146,7 @@ struct sllin {
        int                     lin_state;      /* state */
        char                    id_to_send;     /* there is ID to be sent */
        char                    data_to_send;   /* there are data to be sent */
+       char                    resp_len_known; /* Length of the response is known */
 
        unsigned long           flags;          /* Flag values/ mode etc     */
 #define SLF_INUSE              0               /* Channel in use            */
@@ -150,13 +161,16 @@ struct sllin {
        wait_queue_head_t       kwt_wq;
        struct hrtimer          rx_timer;       /* RX timeout timer */
        ktime_t                 rx_timer_timeout; /* RX timeout timer value */
-       struct sk_buff          *rec_skb;       /* Socket buffer with received CAN frame */
+       struct sk_buff          *tx_req_skb;    /* Socket buffer with CAN frame received
+                                               from network stack*/
 
        struct sllin_conf_entry linfr_cache[SLLIN_ID_MAX + 1]; /* List with configurations for
                                                each of 0 to SLLIN_ID_MAX LIN IDs */
 };
 
 static struct net_device **sllin_devs;
+static int sllin_configure_frame_cache(struct sllin *sl, struct can_frame *cf);
+
 
 const unsigned char sllin_id_parity_table[] = {
         0x80,0xc0,0x40,0x00,0xc0,0x80,0x00,0x40,
@@ -193,15 +207,17 @@ static int sltty_change_speed(struct tty_struct *tty, unsigned speed)
 }
 
 
-/* Send one completely decapsulated can_frame to the network layer */
-static void sll_bump(struct sllin *sl)
+/* Send one can_frame to the network layer */
+static void sllin_send_canfr(struct sllin *sl, canid_t id, char *data, int len)
 {
        struct sk_buff *skb;
        struct can_frame cf;
 
-       cf.can_id = sl->rx_buff[SLLIN_BUFF_ID] & SLLIN_ID_MASK;
-       cf.can_dlc = sl->rx_cnt - SLLIN_BUFF_DATA;
-       memcpy(&cf.data, sl->rx_buff + SLLIN_BUFF_DATA, cf.can_dlc);
+       cf.can_id = id;
+       cf.can_dlc = len;
+       if (cf.can_dlc > 0) {
+               memcpy(&cf.data, data, cf.can_dlc);
+       }
 
        skb = dev_alloc_skb(sizeof(struct can_frame));
        if (!skb)
@@ -217,59 +233,15 @@ static void sll_bump(struct sllin *sl)
 
        sl->dev->stats.rx_packets++;
        sl->dev->stats.rx_bytes += cf.can_dlc;
-}
 
 
- /************************************************************************
-  *                    STANDARD SLLIN ENCAPSULATION                     *
-  ************************************************************************/
+}
 
-/* Convert particular CAN frame into LIN frame and send it to TTY queue. */
-static void sll_encaps(struct sllin *sl, struct can_frame *cf)
+static void sll_bump(struct sllin *sl)
 {
-//     int actual, idx, i;
-//     char lframe[16] = {0x00, 0x55}; /* Fake break, Sync byte */
-//     struct tty_struct *tty = sl->tty;
-//
-//     pr_debug("sllin: %s() invoked\n", __FUNCTION__);
-//
-//     /* We do care only about SFF frames */
-//     if (cf->can_id & CAN_EFF_FLAG)
-//             return;
-//
-//     /* Send only header */
-//     if (cf->can_id & CAN_RTR_FLAG) {
-//             pr_debug("sllin: %s() RTR CAN frame\n", __FUNCTION__);
-//             lframe[2] = (u8)cf->can_id; /* Get one byte LIN ID */
-//
-//             sltty_change_speed(tty, sl->lin_baud * 2 / 3);
-//             tty->ops->write(tty, &lframe[0], 1);
-//             sltty_change_speed(tty, sl->lin_baud);
-//             tty->ops->write(tty, &lframe[1], 1);
-//             tty->ops->write(tty, &lframe[2], 1);
-//     } else {
-//             pr_debug("sllin: %s() non-RTR CAN frame\n", __FUNCTION__);
-//             /*      idx = strlen(sl->xbuff);
-//
-//                     for (i = 0; i < cf->can_dlc; i++)
-//                     sprintf(&sl->xbuff[idx + 2*i], "%02X", cf->data[i]);
-//
-//              * Order of next two lines is *very* important.
-//              * When we are sending a little amount of data,
-//              * the transfer may be completed inside the ops->write()
-//              * routine, because it's running with interrupts enabled.
-//              * In this case we *never* got WRITE_WAKEUP event,
-//              * if we did not request it before write operation.
-//              *       14 Oct 1994  Dmitry Gorodchanin.
-//
-//              set_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
-//              actual = sl->tty->ops->write(sl->tty, sl->xbuff, strlen(sl->xbuff));
-//              sl->xleft = strlen(sl->xbuff) - actual;
-//              sl->xhead = sl->xbuff + actual;
-//              sl->dev->stats.tx_bytes += cf->can_dlc;
-//              */
-//     }
-//
+       sllin_send_canfr(sl, sl->rx_buff[SLLIN_BUFF_ID] & SLLIN_ID_MASK,
+               sl->rx_buff + SLLIN_BUFF_DATA,
+               sl->rx_cnt - SLLIN_BUFF_DATA - 1); /* without checksum */
 }
 
 /*
@@ -313,29 +285,37 @@ static void sllin_write_wakeup(struct tty_struct *tty)
 static netdev_tx_t sll_xmit(struct sk_buff *skb, struct net_device *dev)
 {
        struct sllin *sl = netdev_priv(dev);
+       struct can_frame *cf;
 
        if (skb->len != sizeof(struct can_frame))
                goto err_out;
 
        spin_lock(&sl->lock);
        if (!netif_running(dev))  {
-               spin_unlock(&sl->lock);
                printk(KERN_WARNING "%s: xmit: iface is down\n", dev->name);
-               goto err_out;
+               goto err_out_unlock;
        }
        if (sl->tty == NULL) {
-               spin_unlock(&sl->lock);
-               goto err_out;
+               goto err_out_unlock;
+       }
+
+       cf = (struct can_frame *) skb->data;
+       if (cf->can_id & SLLIN_CTRL_FRAME) {
+               sllin_configure_frame_cache(sl, cf);
+               goto free_out_unlock;
        }
 
        netif_stop_queue(sl->dev);
 
-       sl->rec_skb = skb;
+       sl->tx_req_skb = skb;
        set_bit(SLF_MSGEVENT, &sl->flags);
        wake_up(&sl->kwt_wq);
        spin_unlock(&sl->lock);
        return NETDEV_TX_OK;
 
+free_out_unlock:
+err_out_unlock:
+       spin_unlock(&sl->lock);
 err_out:
        kfree_skb(skb);
        return NETDEV_TX_OK;
@@ -469,7 +449,13 @@ static void sllin_receive_buf(struct tty_struct *tty,
 /*****************************************
  *  sllin message helper routines
  *****************************************/
-int sllin_configure_frame_cache(struct sllin *sl, struct can_frame *cf)
+void sllin_report_error(struct sllin *sl, int err)
+{
+       sllin_send_canfr(sl, 0 | CAN_EFF_FLAG | 
+               (err & ~SLLIN_ID_MASK), NULL, 0);
+}
+
+static int sllin_configure_frame_cache(struct sllin *sl, struct can_frame *cf)
 {
        struct sllin_conf_entry *sce;
        if (!(cf->can_id & SLLIN_LIN_ID_CONF))
@@ -479,23 +465,52 @@ int sllin_configure_frame_cache(struct sllin *sl, struct can_frame *cf)
        printk(KERN_INFO "Setting frame cache with EFF CAN frame. "
                "LIN ID = %d\n", cf->can_id & SLLIN_ID_MASK);
 
-       sce->dlc = (cf->can_dlc > 8) ? 8 : cf->can_dlc;
+       sce->dlc = cf->can_dlc;
+       if (sce->dlc > SLLIN_DATA_MAX)
+               sce->dlc = SLLIN_DATA_MAX;
+
        sce->frame_fl = (cf->can_id & ~SLLIN_ID_MASK) & CAN_EFF_MASK;
        memcpy(sce->data, cf->data, cf->can_dlc);
 
        return 0;
 }
 
+static inline unsigned sllin_checksum(unsigned char *data, int length, int enhanced_fl)
+{
+       unsigned csum = 0;
+       int i;
+
+       if (enhanced_fl) {
+               i = SLLIN_BUFF_ID;
+       } else {
+               i = SLLIN_BUFF_DATA;
+       }
+       
+       for (; i < length; i++) {
+               csum += data[i];
+               if (csum > 255)
+                       csum -= 255;
+       }
+
+       return ~csum & 0xff;
+}
+
+#define SLLIN_STPMSG_RESPONLY          (1) /* Message will be LIN Response only */
+#define SLLIN_STPMSG_CHCKSUM_CLS       (1 << 1)
+#define SLLIN_STPMSG_CHCKSUM_ENH       (1 << 2)
+
 int sllin_setup_msg(struct sllin *sl, int mode, int id,
                unsigned char *data, int len)
 {
        if (id > SLLIN_ID_MASK)
                return -1;
 
-       sl->rx_cnt = 0;
-       sl->tx_cnt = 0;
-       sl->rx_expect = 0;
-       sl->rx_lim = SLLIN_BUFF_LEN;
+       if (!(mode & SLLIN_STPMSG_RESPONLY)) {
+               sl->rx_cnt = 0;
+               sl->tx_cnt = 0;
+               sl->rx_expect = 0;
+               sl->rx_lim = SLLIN_BUFF_LEN;
+       }
 
        sl->tx_buff[SLLIN_BUFF_BREAK] = 0;
        sl->tx_buff[SLLIN_BUFF_SYNC]  = 0x55;
@@ -503,19 +518,10 @@ int sllin_setup_msg(struct sllin *sl, int mode, int id,
        sl->tx_lim = SLLIN_BUFF_DATA;
 
        if ((data != NULL) && len) {
-               int i;
-               unsigned csum  = 0;
-
                sl->tx_lim += len;
                memcpy(sl->tx_buff + SLLIN_BUFF_DATA, data, len);
-               /* compute data parity there */
-               for (i = SLLIN_BUFF_DATA; i < sl->tx_lim; i++) {
-                       csum += sl->tx_buff[i];
-                       if (csum > 255)
-                               csum -= 255;
-               }
-
-               sl->tx_buff[sl->tx_lim++] = csum;
+               sl->tx_buff[sl->tx_lim++] = sllin_checksum(sl->tx_buff,
+                               sl->tx_lim, mode & SLLIN_STPMSG_CHCKSUM_ENH);
        }
        if (len != 0)
                sl->rx_lim = SLLIN_BUFF_DATA + len + 1;
@@ -593,10 +599,12 @@ int sllin_send_break(struct sllin *sl)
 int sllin_send_break(struct sllin *sl)
 {
        struct tty_struct *tty = sl->tty;
-       unsigned long break_baud;
-       unsigned long flags;    
        int retval;
+       unsigned long break_baud;
+       unsigned long usleep_range_min;
+       unsigned long usleep_range_max;
 
+       break_baud = ((sl->lin_baud * 2) / 3);
        sl->rx_cnt = SLLIN_BUFF_BREAK;
        sl->rx_expect = SLLIN_BUFF_BREAK + 1;
        sl->lin_state = SLSTATE_BREAK_SENT;
@@ -608,10 +616,14 @@ int sllin_send_break(struct sllin *sl)
                return retval;
 
        //udelay(712);
-       usleep_range(650, 750);
+       usleep_range_min = (1000000l * SLLIN_SAMPLES_PER_CHAR) / break_baud;
+       usleep_range_max = usleep_range_min + 50;
+       usleep_range(usleep_range_min, usleep_range_max);
 
        retval = tty->ops->break_ctl(tty, 0);
-       usleep_range(50, 100);
+       usleep_range_min = (1000000l * 1 /* 1 bit */) / break_baud;
+       usleep_range_max = usleep_range_min + 30;
+       usleep_range(usleep_range_min, usleep_range_max);
        
        tty->ops->flush_buffer(tty);
 
@@ -630,12 +642,42 @@ static enum hrtimer_restart sllin_rx_timeout_handler(struct hrtimer *hrtimer)
 {
        struct sllin *sl = container_of(hrtimer, struct sllin, rx_timer);
 
+       sllin_report_error(sl, SLLIN_ERR_RX_TIMEOUT);
        set_bit(SLF_TMOUTEVENT, &sl->flags);
        wake_up(&sl->kwt_wq);
 
        return HRTIMER_NORESTART;
 }
 
+static int sllin_rx_validate(struct sllin *sl)
+{
+       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 *scf;   
+
+       actual_id = sl->rx_buff[SLLIN_BUFF_ID] & SLLIN_ID_MASK; 
+       scf = &sl->linfr_cache[actual_id];
+       lin_dlc = scf->dlc;
+       ext_chcks_fl = scf->frame_fl & SLLIN_CHECKSUM_EXTENDED;
+
+       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;
+}
 
 /*****************************************
  *  sllin_kwthread - kernel worker thread
@@ -646,10 +688,6 @@ int sllin_kwthread(void *ptr)
        struct sllin *sl = (struct sllin *)ptr;
        struct tty_struct *tty = sl->tty;
        struct sched_param schparam = { .sched_priority = 40 };
-       int res;
-       struct can_frame *cf;
-       char *lin_data;
-       int lin_dlc;
        int tx_bytes = 0; /* Used for Network statistics */
 
 
@@ -660,6 +698,12 @@ int sllin_kwthread(void *ptr)
        sltty_change_speed(tty, sl->lin_baud);
 
        while (!kthread_should_stop()) {
+               struct can_frame *cf;
+               u8 *lin_data;
+               int lin_dlc;
+               u8 lin_data_buff[SLLIN_DATA_MAX];
+
+
                if ((sl->lin_state == SLSTATE_IDLE) && sl->lin_master &&
                        sl->id_to_send) {
                        if(sllin_send_break(sl) < 0) {
@@ -671,7 +715,9 @@ int sllin_kwthread(void *ptr)
                        test_bit(SLF_RXEVENT, &sl->flags) ||
                        test_bit(SLF_TXEVENT, &sl->flags) ||
                        test_bit(SLF_TMOUTEVENT, &sl->flags) ||
-                       ((sl->lin_state == SLSTATE_IDLE) && test_bit(SLF_MSGEVENT, &sl->flags)));
+                       (((sl->lin_state == SLSTATE_IDLE) || 
+                               (sl->lin_state == SLSTATE_RESPONSE_WAIT)) 
+                               && test_bit(SLF_MSGEVENT, &sl->flags)));
 
                if (test_and_clear_bit(SLF_RXEVENT, &sl->flags)) {
                        printk(KERN_INFO "sllin_kthread RXEVENT \n");
@@ -694,54 +740,62 @@ int sllin_kwthread(void *ptr)
                        sl->lin_state = SLSTATE_IDLE;
                }
 
-               if ((sl->lin_state == SLSTATE_IDLE) && test_bit(SLF_MSGEVENT, &sl->flags)) {
-                       cf = (struct can_frame *)sl->rec_skb->data;
-
-                       /* EFF CAN frame -> "Configuration" frame */
-                       if (cf->can_id & CAN_EFF_FLAG) {
-                               sllin_configure_frame_cache(sl, cf);
-                               goto free_skb;
-                       } /* SFF RTR CAN frame -> LIN header */ 
-                       else if (cf->can_id & CAN_RTR_FLAG) {
-                               printk(KERN_INFO "%s: RTR SFF CAN frame, ID = %x\n",
-                                       __FUNCTION__, cf->can_id & SLLIN_ID_MASK);
-
-                               /* Is there Slave response in linfr_cache to be sent? */
-                               if ((sl->linfr_cache[cf->can_id & SLLIN_ID_MASK].frame_fl & 
-                                       SLLIN_LOC_SLAVE_CACHE) 
-                                       && (sl->linfr_cache[cf->can_id & SLLIN_ID_MASK].dlc > 0)) {
-                                       
-                                       printk(KERN_INFO "Sending LIN response from linfr_cache\n");
-                                       lin_data = &sl->linfr_cache[cf->can_id & SLLIN_ID_MASK].data;
-                                       lin_dlc = sl->linfr_cache[cf->can_id & SLLIN_ID_MASK].dlc;
-                               } else {
-                                       lin_data = NULL;
-                                       lin_dlc = 0;
+               switch (sl->lin_state) {
+                       case SLSTATE_IDLE:
+                               if (!test_bit(SLF_MSGEVENT, &sl->flags))
+                                       break;
+
+                               cf = (struct can_frame *)sl->tx_req_skb->data;
+
+                               /* SFF RTR CAN frame -> LIN header */ 
+                               if (cf->can_id & CAN_RTR_FLAG) {
+                                       spin_lock(&sl->lock);
+                                       printk(KERN_INFO "%s: RTR SFF CAN frame, ID = %x\n",
+                                               __FUNCTION__, cf->can_id & SLLIN_ID_MASK);
+
+                                       /* Is there Slave response in linfr_cache to be sent? */
+                                       if ((sl->linfr_cache[cf->can_id & SLLIN_ID_MASK].frame_fl & 
+                                               SLLIN_LOC_SLAVE_CACHE) 
+                                               && (sl->linfr_cache[cf->can_id & SLLIN_ID_MASK].dlc > 0)) {
+                                               
+                                               printk(KERN_INFO "Sending LIN response from linfr_cache\n");
+                                               lin_data = sl->linfr_cache[cf->can_id & SLLIN_ID_MASK].data;
+                                               lin_dlc = sl->linfr_cache[cf->can_id & SLLIN_ID_MASK].dlc;
+                                               if (lin_dlc > SLLIN_DATA_MAX)
+                                                       lin_dlc = SLLIN_DATA_MAX;
+                                               memcpy(lin_data_buff, lin_data, lin_dlc);
+                                               lin_data = lin_data_buff;
+                                       } else {
+                                               lin_data = NULL;
+                                               lin_dlc = sl->linfr_cache[cf->can_id & SLLIN_ID_MASK].dlc;
+                                       }
+                                       spin_unlock(&sl->lock);
+                               } else { /* SFF NON-RTR CAN frame -> LIN header + LIN response */
+                                       printk(KERN_INFO "%s: NON-RTR SFF CAN frame, ID = %x\n",
+                                               __FUNCTION__, (int)cf->can_id & SLLIN_ID_MASK);
+
+                                       lin_data = cf->data;
+                                       lin_dlc = cf->can_dlc;
+                                       if (lin_dlc > SLLIN_DATA_MAX)
+                                               lin_dlc = SLLIN_DATA_MAX;
+                                       tx_bytes = lin_dlc;
                                }
-                       } else { /* SFF NON-RTR CAN frame -> LIN header + LIN response */
-                               printk(KERN_INFO "%s: NON-RTR SFF CAN frame, ID = %x\n",
-                                       __FUNCTION__, (int)cf->can_id & SLLIN_ID_MASK);
 
-                               lin_data = cf->data;
-                               lin_dlc = tx_bytes = cf->can_dlc;
-                       }
-
-                       if (sllin_setup_msg(sl, 0, cf->can_id & SLLIN_ID_MASK,
-                               lin_data, lin_dlc) != -1) {
+                               if (sllin_setup_msg(sl, 0, cf->can_id & SLLIN_ID_MASK,
+                                       lin_data, lin_dlc) != -1) {
 
-                               sl->id_to_send = true;
-                               sl->data_to_send = (lin_dlc > 0) ? true : false;
-                               sl->dev->stats.tx_packets++;
-                               sl->dev->stats.tx_bytes += tx_bytes;
-                       }
+                                       sl->id_to_send = true;
+                                       sl->data_to_send = (lin_data != NULL) ? true : false;
+                                       sl->resp_len_known = (lin_dlc > 0) ? true : false;
+                                       sl->dev->stats.tx_packets++;
+                                       sl->dev->stats.tx_bytes += tx_bytes;
+                               }
 
-               free_skb:
-                       clear_bit(SLF_MSGEVENT, &sl->flags);
-                       kfree_skb(sl->rec_skb);
-                       netif_wake_queue(sl->dev);
-               }
+                               clear_bit(SLF_MSGEVENT, &sl->flags);
+                               kfree_skb(sl->tx_req_skb);
+                               netif_wake_queue(sl->dev);
+                               break;
 
-               switch (sl->lin_state) {
                        case SLSTATE_BREAK_SENT:
 #ifdef BREAK_BY_BAUD
                                if (sl->rx_cnt <= SLLIN_BUFF_BREAK)
@@ -762,7 +816,11 @@ int sllin_kwthread(void *ptr)
                                        sl->rx_expect = sl->tx_lim;
                                        goto slstate_response_sent;
                                } else {
-                                       sl->rx_expect = SLLIN_BUFF_DATA + 2;
+                                       if (sl->resp_len_known) {
+                                               sl->rx_expect = sl->rx_lim;
+                                       } else {
+                                               sl->rx_expect = SLLIN_BUFF_DATA + 2;
+                                       }
                                        sl->lin_state = SLSTATE_RESPONSE_WAIT;
                                        /* If we don't receive anything, timer will "unblock" us */
                                        hrtimer_start(&sl->rx_timer, 
@@ -774,21 +832,61 @@ int sllin_kwthread(void *ptr)
 
                        case SLSTATE_RESPONSE_WAIT:
                        slstate_response_wait:
+                               if (test_bit(SLF_MSGEVENT, &sl->flags)) {
+                                       unsigned char *lin_buff;
+                                       cf = (struct can_frame *)sl->tx_req_skb->data;
+
+                                       lin_buff = (sl->lin_master) ? sl->tx_buff : sl->rx_buff;
+                                       if (cf->can_id == (lin_buff[SLLIN_BUFF_ID] & SLLIN_ID_MASK)) {
+                                               if (sllin_setup_msg(sl, SLLIN_STPMSG_RESPONLY, 
+                                                       cf->can_id & SLLIN_ID_MASK,
+                                                       cf->data, cf->can_dlc) != -1) {
+
+                                                       sl->rx_expect = sl->tx_lim;
+                                                       sl->data_to_send = true;
+                                                       sl->dev->stats.tx_packets++;
+                                                       sl->dev->stats.tx_bytes += tx_bytes;
+
+                                                       if (!sl->lin_master) {
+                                                               sl->tx_cnt = SLLIN_BUFF_DATA;
+                                                       }
+                                                       
+                                                       sllin_send_tx_buff(sl);
+                                                       clear_bit(SLF_MSGEVENT, &sl->flags);
+                                                       kfree_skb(sl->tx_req_skb);
+                                                       netif_wake_queue(sl->dev);
+
+                                                       sl->lin_state = SLSTATE_RESPONSE_SENT;
+                                                       goto slstate_response_sent;
+                                               }
+                                       } else {
+                                               sl->lin_state = SLSTATE_RESPONSE_WAIT_BUS;
+                                       }
+                               }
+
+                       case SLSTATE_RESPONSE_WAIT_BUS:
                                if (sl->rx_cnt < sl->rx_expect)
                                        continue;
                        
                                hrtimer_cancel(&sl->rx_timer);
                                printk(KERN_INFO "sllin: response received ID %d len %d\n",
                                        sl->rx_buff[SLLIN_BUFF_ID], sl->rx_cnt - SLLIN_BUFF_DATA - 1);
-                               // FIXME: check checksum in sl->rx_buff
 
-                               // send CAN non-RTR frame with data
-                               printk(KERN_INFO "sllin: sending NON-RTR CAN frame with LIN payload.");
-                               sll_bump(sl); //send packet to the network layer
+                               if (sllin_rx_validate(sl) == -1) {
+                                       printk("sllin: RX validation failed.\n");
+                                       sllin_report_error(sl, SLLIN_ERR_CHECKSUM);
+                                       //FIXME tx_stat.err++
+                               } else {
+                                       // send CAN non-RTR frame with data
+                                       printk(KERN_INFO "sllin: sending NON-RTR CAN"
+                                               "frame with LIN payload.");
+                                       sll_bump(sl); //send packet to the network layer
+                               }
+
                                sl->id_to_send = false;
                                sl->lin_state = SLSTATE_IDLE;
                                break;
-
+                       
                        case SLSTATE_RESPONSE_SENT:
                        slstate_response_sent:
                                if (sl->rx_cnt < sl->tx_lim)
@@ -955,14 +1053,12 @@ static int sllin_open(struct tty_struct *tty)
 
                sl->lin_state = SLSTATE_IDLE;
 
-#define SAMPLES_PER_CHAR       10
-#define CHARS_TO_TIMEOUT       12
                hrtimer_init(&sl->rx_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
                sl->rx_timer.function = sllin_rx_timeout_handler;
                /* timeval_to_ktime(msg_head->ival1); */
                sl->rx_timer_timeout = ns_to_ktime(
-                       (1000000000 / sl->lin_baud) * 
-                       SAMPLES_PER_CHAR * CHARS_TO_TIMEOUT); 
+                       (1000000000l / sl->lin_baud) * 
+                       SLLIN_SAMPLES_PER_CHAR * SLLIN_CHARS_TO_TIMEOUT); 
  
                set_bit(SLF_INUSE, &sl->flags);
 
@@ -1092,6 +1188,13 @@ static int __init sllin_init(void)
                printk(KERN_ERR "sllin: can't register line discipline\n");
                kfree(sllin_devs);
        }
+
+#ifdef BREAK_BY_BAUD
+       printk(KERN_INFO "sllin: Break is generated by baud-rate change.");
+#else
+       printk(KERN_INFO "sllin: Break is generated manually with tiny sleep.");
+#endif
+
        return status;
 }