]> 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 636e89ac848aadbca4ecc4fbed6e3f6e94ae4262..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
@@ -58,6 +55,7 @@
 #include <linux/init.h>
 #include <linux/can.h>
 #include <linux/kthread.h>
+#include <linux/hrtimer.h>
 
 /* Should be in include/linux/tty.h */
 #define N_SLLIN         25
@@ -68,7 +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
@@ -88,14 +86,45 @@ 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_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 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))
+#define SLLIN_SRC_SLAVE                (1 << (SLLIN_CANFR_FLAGS_OFFS + 2))
+#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 */
+};
+
 struct sllin {
        int                     magic;
 
@@ -108,14 +137,16 @@ struct sllin {
        unsigned char           rx_buff[SLLIN_BUFF_LEN]; /* LIN Rx buffer */
        unsigned char           tx_buff[SLLIN_BUFF_LEN]; /* LIN Tx buffer */
        int                     rx_expect;      /* expected number of Rx chars */
-       int                     rx_lim;         /* maximum Rx chars for ID  */
+       int                     rx_lim;         /* maximum Rx chars for current frame */
        int                     rx_cnt;         /* message buffer Rx fill level  */
        int                     tx_lim;         /* actual limit of bytes to Tx */
        int                     tx_cnt;         /* number of already Tx bytes */
        char                    lin_master;     /* node is a master node */
        int                     lin_baud;       /* LIN baudrate */
        int                     lin_state;      /* state */
-       int                     id_to_send;     /* there is ID to be sent */
+       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            */
@@ -123,15 +154,23 @@ struct sllin {
 #define SLF_RXEVENT            2               /* Rx wake event             */
 #define SLF_TXEVENT            3               /* Tx wake event             */
 #define SLF_MSGEVENT           4               /* CAN message to sent       */
+#define SLF_TMOUTEVENT          5               /* Timeout on received data  */
 
        dev_t                   line;
        struct task_struct      *kwthread;
        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          *tx_req_skb;    /* Socket buffer with CAN frame received
+                                               from network stack*/
 
-       struct sk_buff          *rec_skb;       /* Socket buffer with received CAN frame */
+       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,
@@ -168,123 +207,41 @@ 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;
-//     int i, dlc_pos, tmp;
-//     unsigned long ultmp;
-//     char cmd = sl->rbuff[0];
-//
-//     if ((cmd != 't') && (cmd != 'T') && (cmd != 'r') && (cmd != 'R'))
-//             return;
-//
-//     if (cmd & 0x20) /* tiny chars 'r' 't' => standard frame format */
-//             dlc_pos = 4; /* dlc position tiiid */
-//     else
-//             dlc_pos = 9; /* dlc position Tiiiiiiiid */
-//
-//     if (!((sl->rbuff[dlc_pos] >= '0') && (sl->rbuff[dlc_pos] < '9')))
-//             return;
-//
-//     cf.can_dlc = sl->rbuff[dlc_pos] - '0'; /* get can_dlc from ASCII val */
-//
-//     sl->rbuff[dlc_pos] = 0; /* terminate can_id string */
-//
-//     if (strict_strtoul(sl->rbuff+1, 16, &ultmp))
-//             return;
-//
-//     cf.can_id = ultmp;
-//
-//     if (!(cmd & 0x20)) /* NO tiny chars => extended frame format */
-//             cf.can_id |= CAN_EFF_FLAG;
-//
-//     if ((cmd | 0x20) == 'r') /* RTR frame */
-//             cf.can_id |= CAN_RTR_FLAG;
-//
-//     *(u64 *) (&cf.data) = 0; /* clear payload */
-//
-//     for (i = 0, dlc_pos++; i < cf.can_dlc; i++) {
-//
-//             tmp = asc2nibble(sl->rbuff[dlc_pos++]);
-//             if (tmp > 0x0F)
-//                     return;
-//             cf.data[i] = (tmp << 4);
-//             tmp = asc2nibble(sl->rbuff[dlc_pos++]);
-//             if (tmp > 0x0F)
-//                     return;
-//             cf.data[i] |= tmp;
-//     }
-//
-//
-//     skb = dev_alloc_skb(sizeof(struct can_frame));
-//     if (!skb)
-//             return;
-//
-//     skb->dev = sl->dev;
-//     skb->protocol = htons(ETH_P_CAN);
-//     skb->pkt_type = PACKET_BROADCAST;
-//     skb->ip_summed = CHECKSUM_UNNECESSARY;
-//     memcpy(skb_put(skb, sizeof(struct can_frame)),
-//            &cf, sizeof(struct can_frame));
-//     netif_rx(skb);
-//
-//     sl->dev->stats.rx_packets++;
-//     sl->dev->stats.rx_bytes += cf.can_dlc;
-}
+       struct sk_buff *skb;
+       struct can_frame cf;
+
+       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)
+               return;
 
- /************************************************************************
-  *                    STANDARD SLLIN ENCAPSULATION                     *
-  ************************************************************************/
+       skb->dev = sl->dev;
+       skb->protocol = htons(ETH_P_CAN);
+       skb->pkt_type = PACKET_BROADCAST;
+       skb->ip_summed = CHECKSUM_UNNECESSARY;
+       memcpy(skb_put(skb, sizeof(struct can_frame)),
+              &cf, sizeof(struct can_frame));
+       netif_rx(skb);
 
-/* Convert particular CAN frame into LIN frame and send it to TTY queue. */
-static void sll_encaps(struct sllin *sl, struct can_frame *cf)
+       sl->dev->stats.rx_packets++;
+       sl->dev->stats.rx_bytes += cf.can_dlc;
+
+
+}
+
+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 */
 }
 
 /*
@@ -328,29 +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;
@@ -484,16 +449,68 @@ static void sllin_receive_buf(struct tty_struct *tty,
 /*****************************************
  *  sllin message helper routines
  *****************************************/
+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))
+               return -1;
+
+       sce = &sl->linfr_cache[cf->can_id & SLLIN_ID_MASK];
+       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;
+       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 > 0x3f)
+       if (id > SLLIN_ID_MASK)
                return -1;
 
-       sl->rx_cnt = 0;
-       sl->tx_cnt = 0;
-       sl->rx_expect = 0;
+       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;
@@ -501,22 +518,13 @@ 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 += len + 1;
+               sl->rx_lim = SLLIN_BUFF_DATA + len + 1;
 
        return 0;
 }
@@ -591,10 +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;
@@ -606,10 +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);
 
@@ -623,6 +637,48 @@ int sllin_send_break(struct sllin *sl)
 }
 #endif /* BREAK_BY_BAUD */
 
+
+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
  *****************************************/
@@ -632,8 +688,8 @@ 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;
+       int tx_bytes = 0; /* Used for Network statistics */
+
 
        printk(KERN_INFO "sllin: sllin_kwthread started.\n");
        sched_setscheduler(current, SCHED_FIFO, &schparam);
@@ -642,6 +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) {
@@ -652,7 +714,10 @@ int sllin_kwthread(void *ptr)
                wait_event_killable(sl->kwt_wq, kthread_should_stop() ||
                        test_bit(SLF_RXEVENT, &sl->flags) ||
                        test_bit(SLF_TXEVENT, &sl->flags) ||
-                       ((sl->lin_state == SLSTATE_IDLE) && test_bit(SLF_MSGEVENT, &sl->flags)));
+                       test_bit(SLF_TMOUTEVENT, &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");
@@ -662,37 +727,75 @@ int sllin_kwthread(void *ptr)
                        printk(KERN_INFO "sllin_kthread TXEVENT \n");
                }
 
-               if ((sl->lin_state == SLSTATE_IDLE) && test_bit(SLF_MSGEVENT, &sl->flags)) {
-                       cf = (struct can_frame *)sl->rec_skb->data;
-
-                       /* We do care only about SFF frames */
-                       if (cf->can_id & CAN_EFF_FLAG)
-                               goto release_skb;
+               if (test_and_clear_bit(SLF_TMOUTEVENT, &sl->flags)) {
+                       printk(KERN_INFO "sllin_kthread TMOUTEVENT \n");
+                       sl->rx_cnt = 0;
+                       sl->rx_expect = 0;
+                       sl->rx_lim = sl->lin_master ? 0 : SLLIN_BUFF_LEN;
+                       sl->tx_cnt = 0;
+                       sl->tx_lim = 0;
+                       sl->id_to_send = false;
+                       sl->data_to_send = false;
+                       
+                       sl->lin_state = SLSTATE_IDLE;
+               }
 
-                       if (cf->can_id & CAN_RTR_FLAG) {
-                               printk(KERN_INFO "%s: RTR CAN frame, ID = %x\n",
-                                       __FUNCTION__, cf->can_id & CAN_SFF_MASK);
-                               if (sllin_setup_msg(sl, 0, 
-                                       cf->can_id & CAN_SFF_MASK, NULL, 0) != -1) {
-                                       sl->id_to_send = true;
+               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 {
-                               printk(KERN_INFO "%s: NON-RTR CAN frame, ID = %x\n",
-                                       __FUNCTION__, (int)cf->can_id & CAN_SFF_MASK);
 
-                               if (sllin_setup_msg(sl, 0, cf->can_id & CAN_SFF_MASK, 
-                                       cf->data, cf->can_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_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;
                                }
-                       }
 
-               release_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)
@@ -706,6 +809,93 @@ int sllin_kwthread(void *ptr)
                                break;
 
                        case SLSTATE_ID_SENT:
+                               sl->id_to_send = false;
+                               if (sl->data_to_send) {
+                                       sllin_send_tx_buff(sl);
+                                       sl->lin_state = SLSTATE_RESPONSE_SENT;
+                                       sl->rx_expect = sl->tx_lim;
+                                       goto slstate_response_sent;
+                               } else {
+                                       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, 
+                                               ktime_add(ktime_get(), sl->rx_timer_timeout),
+                                               HRTIMER_MODE_ABS);
+                                       goto slstate_response_wait;
+                               }
+                               break;
+
+                       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);
+
+                               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)
+                                       continue;
+                               
+                               sll_bump(sl); //send packet to the network layer
+                               printk(KERN_INFO "sllin: response sent ID %d len %d\n",
+                                       sl->rx_buff[SLLIN_BUFF_ID], sl->rx_cnt - SLLIN_BUFF_DATA - 1);
+
                                sl->id_to_send = false;
                                sl->lin_state = SLSTATE_IDLE;
                                break;
@@ -713,13 +903,12 @@ int sllin_kwthread(void *ptr)
 
 
 
-               /* sll_bump(sl); send packet to the network layer */
 
                /* sl->dev->stats.tx_packets++; send frames statistic */
                /* netif_wake_queue(sl->dev); allow next Tx packet arrival */
        }
 
-
+       hrtimer_cancel(&sl->rx_timer);
        printk(KERN_INFO "sllin: sllin_kwthread stopped.\n");
 
        return 0;
@@ -791,7 +980,6 @@ static struct sllin *sll_alloc(dev_t line)
        }
 
        sl = netdev_priv(dev);
-
        /* Initialize channel control data */
        sl->magic = SLLIN_MAGIC;
        sl->dev = dev;
@@ -851,17 +1039,27 @@ static int sllin_open(struct tty_struct *tty)
 
        if (!test_bit(SLF_INUSE, &sl->flags)) {
                /* Perform the low-level SLLIN initialization. */
-               sl->rx_cnt    = 0;
+               sl->lin_master = true;
+
+               sl->rx_cnt = 0;
                sl->rx_expect = 0;
-               sl->rx_lim    = 0;
-               sl->tx_cnt    = 0;
-               sl->tx_lim    = 0;
+               sl->rx_lim = sl->lin_master ? 0 : SLLIN_BUFF_LEN;
+               sl->tx_cnt = 0;
+               sl->tx_lim = 0;
+               sl->id_to_send = false;
+               sl->data_to_send = false;
 
                sl->lin_baud  = 19200;
 
-               sl->lin_master = 1;
                sl->lin_state = SLSTATE_IDLE;
 
+               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(
+                       (1000000000l / sl->lin_baud) * 
+                       SLLIN_SAMPLES_PER_CHAR * SLLIN_CHARS_TO_TIMEOUT); 
                set_bit(SLF_INUSE, &sl->flags);
 
                init_waitqueue_head(&sl->kwt_wq);
@@ -990,6 +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;
 }