/* * slcan.c - serial line CAN interface driver (using tty line discipline) * * This file is derived from linux/drivers/net/slip.c * * slip.c Authors : Laurence Culhane * Fred N. van Kempen * slcan.c Author : Oliver Hartkopp * * 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 * Free Software Foundation; either version 2 of the License, or (at your * option) any later version. * * This program is distributed in the hope that it will be useful, but * WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * General Public License for more details. * * You should have received a copy of the GNU General Public License along * with this program; if not, write to the Free Software Foundation, Inc., * 59 Temple Place, Suite 330, Boston, MA 02111-1307. You can also get it * at http://www.gnu.org/licenses/gpl.html * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH * DAMAGE. * * Send feedback to * */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include static __initdata const char banner[] = KERN_INFO "slcan: serial line CAN interface driver\n"; MODULE_ALIAS_LDISC(N_SLCAN); MODULE_DESCRIPTION("serial line CAN interface"); MODULE_LICENSE("GPL"); MODULE_AUTHOR("Oliver Hartkopp "); #define SLCAN_MAGIC 0x53CA static int maxdev = 10; /* MAX number of SLCAN channels; This can be overridden with insmod slcan.ko maxdev=nnn */ module_param(maxdev, int, 0); MODULE_PARM_DESC(maxdev, "Maximum number of slcan interfaces"); /* maximum rx buffer len: extended CAN frame with timestamp */ #define SLC_MTU (sizeof("T1111222281122334455667788EA5F\r")+1) struct slcan { int magic; /* Various fields. */ struct tty_struct *tty; /* ptr to TTY structure */ struct net_device *dev; /* easy for intr handling */ spinlock_t lock; /* These are pointers to the malloc()ed frame buffers. */ unsigned char rbuff[SLC_MTU]; /* receiver buffer */ int rcount; /* received chars counter */ unsigned char xbuff[SLC_MTU]; /* transmitter buffer */ unsigned char *xhead; /* pointer to next XMIT byte */ int xleft; /* bytes left in XMIT queue */ unsigned long flags; /* Flag values/ mode etc */ #define SLF_INUSE 0 /* Channel in use */ #define SLF_ERROR 1 /* Parity, etc. error */ unsigned char leased; dev_t line; pid_t pid; }; static struct net_device **slcan_devs; /************************************************************************ * SLCAN ENCAPSULATION FORMAT * ************************************************************************/ /* * A CAN frame has a can_id (11 bit standard frame format OR 29 bit extended * frame format) a data length code (can_dlc) which can be from 0 to 8 * and up to data bytes as payload. * Additionally a CAN frame may become a remote transmission frame if the * RTR-bit is set. This causes another ECU to send a CAN frame with the * given can_id. * * The SLCAN ASCII representation of these different frame types is: * * * * Extended frames (29 bit) are defined by capital characters in the type. * RTR frames are defined as 'r' types - normal frames have 't' type: * t => 11 bit data frame * r => 11 bit RTR frame * T => 29 bit data frame * R => 29 bit RTR frame * * The is 3 (standard) or 8 (extended) bytes in ASCII Hex (base64). * The is a one byte ASCII number ('0' - '8') * The section has at much ASCII Hex bytes as defined by the * * Examples: * * t1230 : can_id 0x123, can_dlc 0, no data * t4563112233 : can_id 0x456, can_dlc 3, data 0x11 0x22 0x33 * T12ABCDEF2AA55 : extended can_id 0x12ABCDEF, can_dlc 2, data 0xAA 0x55 * r1230 : can_id 0x123, can_dlc 0, no data, remote transmission request * */ /************************************************************************ * STANDARD SLCAN DECAPSULATION * ************************************************************************/ static int asc2nibble(char c) { if ((c >= '0') && (c <= '9')) return c - '0'; if ((c >= 'A') && (c <= 'F')) return c - 'A' + 10; if ((c >= 'a') && (c <= 'f')) return c - 'a' + 10; return 16; /* error */ } /* Send one completely decapsulated can_frame to the network layer */ static void slc_bump(struct slcan *sl) { 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; } /* parse tty input stream */ static void slcan_unesc(struct slcan *sl, unsigned char s) { if ((s == '\r') || (s == '\a')) { /* CR or BEL ends the pdu */ if (!test_and_clear_bit(SLF_ERROR, &sl->flags) && (sl->rcount > 4)) { slc_bump(sl); } sl->rcount = 0; } else { if (!test_bit(SLF_ERROR, &sl->flags)) { if (sl->rcount < SLC_MTU) { sl->rbuff[sl->rcount++] = s; return; } else { sl->dev->stats.rx_over_errors++; set_bit(SLF_ERROR, &sl->flags); } } } } /************************************************************************ * STANDARD SLCAN ENCAPSULATION * ************************************************************************/ /* Encapsulate one can_frame and stuff into a TTY queue. */ static void slc_encaps(struct slcan *sl, struct can_frame *cf) { int actual, idx, i; char cmd; if (cf->can_id & CAN_RTR_FLAG) cmd = 'R'; /* becomes 'r' in standard frame format */ else cmd = 'T'; /* becomes 't' in standard frame format */ if (cf->can_id & CAN_EFF_FLAG) sprintf(sl->xbuff, "%c%08X%d", cmd, cf->can_id & CAN_EFF_MASK, cf->can_dlc); else sprintf(sl->xbuff, "%c%03X%d", cmd | 0x20, cf->can_id & CAN_SFF_MASK, cf->can_dlc); idx = strlen(sl->xbuff); for (i = 0; i < cf->can_dlc; i++) sprintf(&sl->xbuff[idx + 2*i], "%02X", cf->data[i]); strcat(sl->xbuff, "\r"); /* add terminating character */ /* 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; } /* * Called by the driver when there's room for more data. If we have * more packets to send, we send them here. */ static void slcan_write_wakeup(struct tty_struct *tty) { int actual; struct slcan *sl = (struct slcan *) tty->disc_data; /* First make sure we're connected. */ if (!sl || sl->magic != SLCAN_MAGIC || !netif_running(sl->dev)) return; if (sl->xleft <= 0) { /* Now serial buffer is almost free & we can start * transmission of another packet */ sl->dev->stats.tx_packets++; clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); netif_wake_queue(sl->dev); return; } actual = tty->ops->write(tty, sl->xhead, sl->xleft); sl->xleft -= actual; sl->xhead += actual; } /* Send a can_frame to a TTY queue. */ static netdev_tx_t slc_xmit(struct sk_buff *skb, struct net_device *dev) { struct slcan *sl = netdev_priv(dev); if (skb->len != sizeof(struct can_frame)) goto 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 out; } if (sl->tty == NULL) { spin_unlock(&sl->lock); goto out; } netif_stop_queue(sl->dev); slc_encaps(sl, (struct can_frame *) skb->data); /* encaps & send */ spin_unlock(&sl->lock); out: kfree_skb(skb); return NETDEV_TX_OK; } /****************************************** * Routines looking at netdevice side. ******************************************/ /* Netdevice UP -> DOWN routine */ static int slc_close(struct net_device *dev) { struct slcan *sl = netdev_priv(dev); spin_lock_bh(&sl->lock); if (sl->tty) { /* TTY discipline is running. */ clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags); } netif_stop_queue(dev); sl->rcount = 0; sl->xleft = 0; spin_unlock_bh(&sl->lock); return 0; } /* Netdevice DOWN -> UP routine */ static int slc_open(struct net_device *dev) { struct slcan *sl = netdev_priv(dev); if (sl->tty == NULL) return -ENODEV; sl->flags &= (1 << SLF_INUSE); netif_start_queue(dev); return 0; } /* Hook the destructor so we can free slcan devs at the right point in time */ static void slc_free_netdev(struct net_device *dev) { int i = dev->base_addr; free_netdev(dev); slcan_devs[i] = NULL; } static const struct net_device_ops slc_netdev_ops = { .ndo_open = slc_open, .ndo_stop = slc_close, .ndo_start_xmit = slc_xmit, }; static void slc_setup(struct net_device *dev) { dev->netdev_ops = &slc_netdev_ops; dev->destructor = slc_free_netdev; dev->hard_header_len = 0; dev->addr_len = 0; dev->tx_queue_len = 10; dev->mtu = sizeof(struct can_frame); dev->type = ARPHRD_CAN; /* New-style flags. */ dev->flags = IFF_NOARP; dev->features = NETIF_F_NO_CSUM; } /****************************************** Routines looking at TTY side. ******************************************/ /* * Handle the 'receiver data ready' interrupt. * This function is called by the 'tty_io' module in the kernel when * a block of SLCAN data has been received, which can now be decapsulated * and sent on to some IP layer for further processing. This will not * be re-entered while running but other ldisc functions may be called * in parallel */ static unsigned int slcan_receive_buf(struct tty_struct *tty, const unsigned char *cp, char *fp, int count) { struct slcan *sl = (struct slcan *) tty->disc_data; int bytes = count; if (!sl || sl->magic != SLCAN_MAGIC || !netif_running(sl->dev)) return -ENODEV; /* Read the characters out of the buffer */ while (bytes--) { if (fp && *fp++) { if (!test_and_set_bit(SLF_ERROR, &sl->flags)) sl->dev->stats.rx_errors++; cp++; continue; } slcan_unesc(sl, *cp++); } return count; } /************************************ * slcan_open helper routines. ************************************/ /* Collect hanged up channels */ static void slc_sync(void) { int i; struct net_device *dev; struct slcan *sl; for (i = 0; i < maxdev; i++) { dev = slcan_devs[i]; if (dev == NULL) break; sl = netdev_priv(dev); if (sl->tty || sl->leased) continue; if (dev->flags & IFF_UP) dev_close(dev); } } /* Find a free SLCAN channel, and link in this `tty' line. */ static struct slcan *slc_alloc(dev_t line) { int i; struct net_device *dev = NULL; struct slcan *sl; if (slcan_devs == NULL) return NULL; /* Master array missing ! */ for (i = 0; i < maxdev; i++) { dev = slcan_devs[i]; if (dev == NULL) break; } /* Sorry, too many, all slots in use */ if (i >= maxdev) return NULL; if (dev) { sl = netdev_priv(dev); if (test_bit(SLF_INUSE, &sl->flags)) { unregister_netdevice(dev); dev = NULL; slcan_devs[i] = NULL; } } if (!dev) { char name[IFNAMSIZ]; sprintf(name, "slcan%d", i); dev = alloc_netdev(sizeof(*sl), name, slc_setup); if (!dev) return NULL; dev->base_addr = i; } sl = netdev_priv(dev); /* Initialize channel control data */ sl->magic = SLCAN_MAGIC; sl->dev = dev; spin_lock_init(&sl->lock); slcan_devs[i] = dev; return sl; } /* * Open the high-level part of the SLCAN channel. * This function is called by the TTY module when the * SLCAN line discipline is called for. Because we are * sure the tty line exists, we only have to link it to * a free SLCAN channel... * * Called in process context serialized from other ldisc calls. */ static int slcan_open(struct tty_struct *tty) { struct slcan *sl; int err; if (!capable(CAP_NET_ADMIN)) return -EPERM; if (tty->ops->write == NULL) return -EOPNOTSUPP; /* RTnetlink lock is misused here to serialize concurrent opens of slcan channels. There are better ways, but it is the simplest one. */ rtnl_lock(); /* Collect hanged up channels. */ slc_sync(); sl = tty->disc_data; err = -EEXIST; /* First make sure we're not already connected. */ if (sl && sl->magic == SLCAN_MAGIC) goto err_exit; /* OK. Find a free SLCAN channel to use. */ err = -ENFILE; sl = slc_alloc(tty_devnum(tty)); if (sl == NULL) goto err_exit; sl->tty = tty; tty->disc_data = sl; sl->line = tty_devnum(tty); sl->pid = current->pid; if (!test_bit(SLF_INUSE, &sl->flags)) { /* Perform the low-level SLCAN initialization. */ sl->rcount = 0; sl->xleft = 0; set_bit(SLF_INUSE, &sl->flags); err = register_netdevice(sl->dev); if (err) goto err_free_chan; } /* Done. We have linked the TTY line to a channel. */ rtnl_unlock(); tty->receive_room = 65536; /* We don't flow control */ return sl->dev->base_addr; err_free_chan: sl->tty = NULL; tty->disc_data = NULL; clear_bit(SLF_INUSE, &sl->flags); err_exit: rtnl_unlock(); /* Count references from TTY module */ return err; } /* * Close down a SLCAN channel. * This means flushing out any pending queues, and then returning. This * call is serialized against other ldisc functions. * * We also use this method for a hangup event. */ static void slcan_close(struct tty_struct *tty) { struct slcan *sl = (struct slcan *) tty->disc_data; /* First make sure we're connected. */ if (!sl || sl->magic != SLCAN_MAGIC || sl->tty != tty) return; tty->disc_data = NULL; sl->tty = NULL; if (!sl->leased) sl->line = 0; /* Flush network side */ unregister_netdev(sl->dev); /* This will complete via sl_free_netdev */ } static int slcan_hangup(struct tty_struct *tty) { slcan_close(tty); return 0; } /* Perform I/O control on an active SLCAN channel. */ static int slcan_ioctl(struct tty_struct *tty, struct file *file, unsigned int cmd, unsigned long arg) { struct slcan *sl = (struct slcan *) tty->disc_data; unsigned int tmp; /* First make sure we're connected. */ if (!sl || sl->magic != SLCAN_MAGIC) return -EINVAL; switch (cmd) { case SIOCGIFNAME: tmp = strlen(sl->dev->name) + 1; if (copy_to_user((void __user *)arg, sl->dev->name, tmp)) return -EFAULT; return 0; case SIOCSIFHWADDR: return -EINVAL; default: return tty_mode_ioctl(tty, file, cmd, arg); } } static struct tty_ldisc_ops slc_ldisc = { .owner = THIS_MODULE, .magic = TTY_LDISC_MAGIC, .name = "slcan", .open = slcan_open, .close = slcan_close, .hangup = slcan_hangup, .ioctl = slcan_ioctl, .receive_buf = slcan_receive_buf, .write_wakeup = slcan_write_wakeup, }; static int __init slcan_init(void) { int status; if (maxdev < 4) maxdev = 4; /* Sanity */ printk(banner); printk(KERN_INFO "slcan: %d dynamic interface channels.\n", maxdev); slcan_devs = kzalloc(sizeof(struct net_device *)*maxdev, GFP_KERNEL); if (!slcan_devs) { printk(KERN_ERR "slcan: can't allocate slcan device array!\n"); return -ENOMEM; } /* Fill in our line protocol discipline, and register it */ status = tty_register_ldisc(N_SLCAN, &slc_ldisc); if (status) { printk(KERN_ERR "slcan: can't register line discipline\n"); kfree(slcan_devs); } return status; } static void __exit slcan_exit(void) { int i; struct net_device *dev; struct slcan *sl; unsigned long timeout = jiffies + HZ; int busy = 0; if (slcan_devs == NULL) return; /* First of all: check for active disciplines and hangup them. */ do { if (busy) msleep_interruptible(100); busy = 0; for (i = 0; i < maxdev; i++) { dev = slcan_devs[i]; if (!dev) continue; sl = netdev_priv(dev); spin_lock_bh(&sl->lock); if (sl->tty) { busy++; tty_hangup(sl->tty); } spin_unlock_bh(&sl->lock); } } while (busy && time_before(jiffies, timeout)); /* FIXME: hangup is async so we should wait when doing this second phase */ for (i = 0; i < maxdev; i++) { dev = slcan_devs[i]; if (!dev) continue; slcan_devs[i] = NULL; sl = netdev_priv(dev); if (sl->tty) { printk(KERN_ERR "%s: tty discipline still running\n", dev->name); /* Intentionally leak the control block. */ dev->destructor = NULL; } unregister_netdev(dev); } kfree(slcan_devs); slcan_devs = NULL; i = tty_unregister_ldisc(N_SLCAN); if (i) printk(KERN_ERR "slcan: can't unregister ldisc (err %d)\n", i); } module_init(slcan_init); module_exit(slcan_exit);