/* * slcan.c - serial line CAN interface driver (using tty line discipline) * * This file is derived from linux/drivers/net/slip/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, see 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. * */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include 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) #define SLC_CMD_LEN 1 #define SLC_SFF_ID_LEN 3 #define SLC_EFF_ID_LEN 8 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; struct work_struct tx_work; /* Flushes transmit buffer */ /* 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 */ }; 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 (len) 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, len 0, no data * t4563112233 : can_id 0x456, len 3, data 0x11 0x22 0x33 * T12ABCDEF2AA55 : extended can_id 0x12ABCDEF, len 2, data 0xAA 0x55 * r1230 : can_id 0x123, len 0, no data, remote transmission request * */ /************************************************************************ * STANDARD SLCAN DECAPSULATION * ************************************************************************/ /* 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, tmp; u32 tmpid; char *cmd = sl->rbuff; memset(&cf, 0, sizeof(cf)); switch (*cmd) { case 'r': cf.can_id = CAN_RTR_FLAG; fallthrough; case 't': /* store dlc ASCII value and terminate SFF CAN ID string */ cf.len = sl->rbuff[SLC_CMD_LEN + SLC_SFF_ID_LEN]; sl->rbuff[SLC_CMD_LEN + SLC_SFF_ID_LEN] = 0; /* point to payload data behind the dlc */ cmd += SLC_CMD_LEN + SLC_SFF_ID_LEN + 1; break; case 'R': cf.can_id = CAN_RTR_FLAG; fallthrough; case 'T': cf.can_id |= CAN_EFF_FLAG; /* store dlc ASCII value and terminate EFF CAN ID string */ cf.len = sl->rbuff[SLC_CMD_LEN + SLC_EFF_ID_LEN]; sl->rbuff[SLC_CMD_LEN + SLC_EFF_ID_LEN] = 0; /* point to payload data behind the dlc */ cmd += SLC_CMD_LEN + SLC_EFF_ID_LEN + 1; break; default: return; } if (kstrtou32(sl->rbuff + SLC_CMD_LEN, 16, &tmpid)) return; cf.can_id |= tmpid; /* get len from sanitized ASCII value */ if (cf.len >= '0' && cf.len < '9') cf.len -= '0'; else return; /* RTR frames may have a dlc > 0 but they never have any data bytes */ if (!(cf.can_id & CAN_RTR_FLAG)) { for (i = 0; i < cf.len; i++) { tmp = hex_to_bin(*cmd++); if (tmp < 0) return; cf.data[i] = (tmp << 4); tmp = hex_to_bin(*cmd++); if (tmp < 0) return; cf.data[i] |= tmp; } } skb = dev_alloc_skb(sizeof(struct can_frame) + sizeof(struct can_skb_priv)); if (!skb) return; skb->dev = sl->dev; skb->protocol = htons(ETH_P_CAN); skb->pkt_type = PACKET_BROADCAST; skb->ip_summed = CHECKSUM_UNNECESSARY; can_skb_reserve(skb); can_skb_prv(skb)->ifindex = sl->dev->ifindex; can_skb_prv(skb)->skbcnt = 0; skb_put_data(skb, &cf, sizeof(struct can_frame)); sl->dev->stats.rx_packets++; sl->dev->stats.rx_bytes += cf.len; netif_rx_ni(skb); } /* 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, i; unsigned char *pos; unsigned char *endpos; canid_t id = cf->can_id; pos = sl->xbuff; if (cf->can_id & CAN_RTR_FLAG) *pos = 'R'; /* becomes 'r' in standard frame format (SFF) */ else *pos = 'T'; /* becomes 't' in standard frame format (SSF) */ /* determine number of chars for the CAN-identifier */ if (cf->can_id & CAN_EFF_FLAG) { id &= CAN_EFF_MASK; endpos = pos + SLC_EFF_ID_LEN; } else { *pos |= 0x20; /* convert R/T to lower case for SFF */ id &= CAN_SFF_MASK; endpos = pos + SLC_SFF_ID_LEN; } /* build 3 (SFF) or 8 (EFF) digit CAN identifier */ pos++; while (endpos >= pos) { *endpos-- = hex_asc_upper[id & 0xf]; id >>= 4; } pos += (cf->can_id & CAN_EFF_FLAG) ? SLC_EFF_ID_LEN : SLC_SFF_ID_LEN; *pos++ = cf->len + '0'; /* RTR frames may have a dlc > 0 but they never have any data bytes */ if (!(cf->can_id & CAN_RTR_FLAG)) { for (i = 0; i < cf->len; i++) pos = hex_byte_pack_upper(pos, cf->data[i]); } *pos++ = '\r'; /* 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, pos - sl->xbuff); sl->xleft = (pos - sl->xbuff) - actual; sl->xhead = sl->xbuff + actual; sl->dev->stats.tx_bytes += cf->len; } /* Write out any remaining transmit buffer. Scheduled when tty is writable */ static void slcan_transmit(struct work_struct *work) { struct slcan *sl = container_of(work, struct slcan, tx_work); int actual; spin_lock_bh(&sl->lock); /* First make sure we're connected. */ if (!sl->tty || sl->magic != SLCAN_MAGIC || !netif_running(sl->dev)) { spin_unlock_bh(&sl->lock); 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, &sl->tty->flags); spin_unlock_bh(&sl->lock); netif_wake_queue(sl->dev); return; } actual = sl->tty->ops->write(sl->tty, sl->xhead, sl->xleft); sl->xleft -= actual; sl->xhead += actual; spin_unlock_bh(&sl->lock); } /* * Called by the driver when there's room for more data. * Schedule the transmit. */ static void slcan_write_wakeup(struct tty_struct *tty) { struct slcan *sl; rcu_read_lock(); sl = rcu_dereference(tty->disc_data); if (sl) schedule_work(&sl->tx_work); rcu_read_unlock(); } /* 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 != CAN_MTU) 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; slcan_devs[i] = NULL; } static int slcan_change_mtu(struct net_device *dev, int new_mtu) { return -EINVAL; } static const struct net_device_ops slc_netdev_ops = { .ndo_open = slc_open, .ndo_stop = slc_close, .ndo_start_xmit = slc_xmit, .ndo_change_mtu = slcan_change_mtu, }; static void slc_setup(struct net_device *dev) { dev->netdev_ops = &slc_netdev_ops; dev->needs_free_netdev = true; dev->priv_destructor = slc_free_netdev; dev->hard_header_len = 0; dev->addr_len = 0; dev->tx_queue_len = 10; dev->mtu = CAN_MTU; dev->type = ARPHRD_CAN; /* New-style flags. */ dev->flags = IFF_NOARP; dev->features = NETIF_F_HW_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 void slcan_receive_buf(struct tty_struct *tty, const unsigned char *cp, const char *fp, int count) { struct slcan *sl = (struct slcan *) tty->disc_data; if (!sl || sl->magic != SLCAN_MAGIC || !netif_running(sl->dev)) return; /* Read the characters out of the buffer */ while (count--) { if (fp && *fp++) { if (!test_and_set_bit(SLF_ERROR, &sl->flags)) sl->dev->stats.rx_errors++; cp++; continue; } slcan_unesc(sl, *cp++); } } /************************************ * 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) 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(void) { int i; char name[IFNAMSIZ]; struct net_device *dev = NULL; struct can_ml_priv *can_ml; struct slcan *sl; int size; 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; sprintf(name, "slcan%d", i); size = ALIGN(sizeof(*sl), NETDEV_ALIGN) + sizeof(struct can_ml_priv); dev = alloc_netdev(size, name, NET_NAME_UNKNOWN, slc_setup); if (!dev) return NULL; dev->base_addr = i; sl = netdev_priv(dev); can_ml = (void *)sl + ALIGN(sizeof(*sl), NETDEV_ALIGN); can_set_ml_priv(dev, can_ml); /* Initialize channel control data */ sl->magic = SLCAN_MAGIC; sl->dev = dev; spin_lock_init(&sl->lock); INIT_WORK(&sl->tx_work, slcan_transmit); 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(); if (sl == NULL) goto err_exit; sl->tty = tty; tty->disc_data = sl; 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 */ /* TTY layer expects 0 on success */ return 0; err_free_chan: sl->tty = NULL; tty->disc_data = NULL; clear_bit(SLF_INUSE, &sl->flags); slc_free_netdev(sl->dev); /* do not call free_netdev before rtnl_unlock */ rtnl_unlock(); free_netdev(sl->dev); return err; 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; spin_lock_bh(&sl->lock); rcu_assign_pointer(tty->disc_data, NULL); sl->tty = NULL; spin_unlock_bh(&sl->lock); synchronize_rcu(); flush_work(&sl->tx_work); /* 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, .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 */ pr_info("slcan: serial line CAN interface driver\n"); pr_info("slcan: %d dynamic interface channels.\n", maxdev); slcan_devs = kcalloc(maxdev, sizeof(struct net_device *), GFP_KERNEL); if (!slcan_devs) 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); } 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);