diff options
Diffstat (limited to 'drivers/net/can/slcan/slcan-core.c')
| -rw-r--r-- | drivers/net/can/slcan/slcan-core.c | 939 |
1 files changed, 939 insertions, 0 deletions
diff --git a/drivers/net/can/slcan/slcan-core.c b/drivers/net/can/slcan/slcan-core.c new file mode 100644 index 000000000000..fbb34139daa1 --- /dev/null +++ b/drivers/net/can/slcan/slcan-core.c @@ -0,0 +1,939 @@ +/* + * slcan.c - serial line CAN interface driver (using tty line discipline) + * + * This file is derived from linux/drivers/net/slip/slip.c and got + * inspiration from linux/drivers/net/can/can327.c for the rework made + * on the line discipline code. + * + * slip.c Authors : Laurence Culhane <loz@holmes.demon.co.uk> + * Fred N. van Kempen <waltje@uwalt.nl.mugnet.org> + * slcan.c Author : Oliver Hartkopp <socketcan@hartkopp.net> + * can327.c Author : Max Staudt <max-linux@enpas.org> + * + * 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. + * + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <linux/module.h> + +#include <linux/uaccess.h> +#include <linux/bitops.h> +#include <linux/string.h> +#include <linux/tty.h> +#include <linux/errno.h> +#include <linux/netdevice.h> +#include <linux/skbuff.h> +#include <linux/rtnetlink.h> +#include <linux/init.h> +#include <linux/kernel.h> +#include <linux/workqueue.h> +#include <linux/can.h> +#include <linux/can/dev.h> +#include <linux/can/skb.h> + +#include "slcan.h" + +MODULE_ALIAS_LDISC(N_SLCAN); +MODULE_DESCRIPTION("serial line CAN interface"); +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Oliver Hartkopp <socketcan@hartkopp.net>"); +MODULE_AUTHOR("Dario Binacchi <dario.binacchi@amarulasolutions.com>"); + +/* maximum rx buffer len: extended CAN frame with timestamp */ +#define SLCAN_MTU (sizeof("T1111222281122334455667788EA5F\r") + 1) + +#define SLCAN_CMD_LEN 1 +#define SLCAN_SFF_ID_LEN 3 +#define SLCAN_EFF_ID_LEN 8 +#define SLCAN_STATE_LEN 1 +#define SLCAN_STATE_BE_RXCNT_LEN 3 +#define SLCAN_STATE_BE_TXCNT_LEN 3 +#define SLCAN_STATE_FRAME_LEN (1 + SLCAN_CMD_LEN + \ + SLCAN_STATE_BE_RXCNT_LEN + \ + SLCAN_STATE_BE_TXCNT_LEN) +struct slcan { + struct can_priv can; + + /* 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[SLCAN_MTU]; /* receiver buffer */ + int rcount; /* received chars counter */ + unsigned char xbuff[SLCAN_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_ERROR 0 /* Parity, etc. error */ +#define SLF_XCMD 1 /* Command transmission */ + unsigned long cmd_flags; /* Command flags */ +#define CF_ERR_RST 0 /* Reset errors on open */ + wait_queue_head_t xcmd_wait; /* Wait queue for commands */ + /* transmission */ +}; + +static const u32 slcan_bitrate_const[] = { + 10000, 20000, 50000, 100000, 125000, + 250000, 500000, 800000, 1000000 +}; + +bool slcan_err_rst_on_open(struct net_device *ndev) +{ + struct slcan *sl = netdev_priv(ndev); + + return !!test_bit(CF_ERR_RST, &sl->cmd_flags); +} + +int slcan_enable_err_rst_on_open(struct net_device *ndev, bool on) +{ + struct slcan *sl = netdev_priv(ndev); + + if (netif_running(ndev)) + return -EBUSY; + + if (on) + set_bit(CF_ERR_RST, &sl->cmd_flags); + else + clear_bit(CF_ERR_RST, &sl->cmd_flags); + + return 0; +} + +/************************************************************************* + * 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 <len> 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: + * <type> <id> <dlc> <data>* + * + * 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 <id> is 3 (standard) or 8 (extended) bytes in ASCII Hex (base64). + * The <dlc> is a one byte ASCII number ('0' - '8') + * The <data> section has at much ASCII Hex bytes as defined by the <dlc> + * + * 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 slcan_bump_frame(struct slcan *sl) +{ + struct sk_buff *skb; + struct can_frame *cf; + int i, tmp; + u32 tmpid; + char *cmd = sl->rbuff; + + skb = alloc_can_skb(sl->dev, &cf); + if (unlikely(!skb)) { + sl->dev->stats.rx_dropped++; + return; + } + + 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[SLCAN_CMD_LEN + SLCAN_SFF_ID_LEN]; + sl->rbuff[SLCAN_CMD_LEN + SLCAN_SFF_ID_LEN] = 0; + /* point to payload data behind the dlc */ + cmd += SLCAN_CMD_LEN + SLCAN_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[SLCAN_CMD_LEN + SLCAN_EFF_ID_LEN]; + sl->rbuff[SLCAN_CMD_LEN + SLCAN_EFF_ID_LEN] = 0; + /* point to payload data behind the dlc */ + cmd += SLCAN_CMD_LEN + SLCAN_EFF_ID_LEN + 1; + break; + default: + goto decode_failed; + } + + if (kstrtou32(sl->rbuff + SLCAN_CMD_LEN, 16, &tmpid)) + goto decode_failed; + + cf->can_id |= tmpid; + + /* get len from sanitized ASCII value */ + if (cf->len >= '0' && cf->len < '9') + cf->len -= '0'; + else + goto decode_failed; + + /* 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) + goto decode_failed; + + cf->data[i] = (tmp << 4); + tmp = hex_to_bin(*cmd++); + if (tmp < 0) + goto decode_failed; + + cf->data[i] |= tmp; + } + } + + sl->dev->stats.rx_packets++; + if (!(cf->can_id & CAN_RTR_FLAG)) + sl->dev->stats.rx_bytes += cf->len; + + netif_rx(skb); + return; + +decode_failed: + sl->dev->stats.rx_errors++; + dev_kfree_skb(skb); +} + +/* A change state frame must contain state info and receive and transmit + * error counters. + * + * Examples: + * + * sb256256 : state bus-off: rx counter 256, tx counter 256 + * sa057033 : state active, rx counter 57, tx counter 33 + */ +static void slcan_bump_state(struct slcan *sl) +{ + struct net_device *dev = sl->dev; + struct sk_buff *skb; + struct can_frame *cf; + char *cmd = sl->rbuff; + u32 rxerr, txerr; + enum can_state state, rx_state, tx_state; + + switch (cmd[1]) { + case 'a': + state = CAN_STATE_ERROR_ACTIVE; + break; + case 'w': + state = CAN_STATE_ERROR_WARNING; + break; + case 'p': + state = CAN_STATE_ERROR_PASSIVE; + break; + case 'b': + state = CAN_STATE_BUS_OFF; + break; + default: + return; + } + + if (state == sl->can.state || sl->rcount < SLCAN_STATE_FRAME_LEN) + return; + + cmd += SLCAN_STATE_BE_RXCNT_LEN + SLCAN_CMD_LEN + 1; + cmd[SLCAN_STATE_BE_TXCNT_LEN] = 0; + if (kstrtou32(cmd, 10, &txerr)) + return; + + *cmd = 0; + cmd -= SLCAN_STATE_BE_RXCNT_LEN; + if (kstrtou32(cmd, 10, &rxerr)) + return; + + skb = alloc_can_err_skb(dev, &cf); + + tx_state = txerr >= rxerr ? state : 0; + rx_state = txerr <= rxerr ? state : 0; + can_change_state(dev, cf, tx_state, rx_state); + + if (state == CAN_STATE_BUS_OFF) { + can_bus_off(dev); + } else if (skb) { + cf->can_id |= CAN_ERR_CNT; + cf->data[6] = txerr; + cf->data[7] = rxerr; + } + + if (skb) + netif_rx(skb); +} + +/* An error frame can contain more than one type of error. + * + * Examples: + * + * e1a : len 1, errors: ACK error + * e3bcO: len 3, errors: Bit0 error, CRC error, Tx overrun error + */ +static void slcan_bump_err(struct slcan *sl) +{ + struct net_device *dev = sl->dev; + struct sk_buff *skb; + struct can_frame *cf; + char *cmd = sl->rbuff; + bool rx_errors = false, tx_errors = false, rx_over_errors = false; + int i, len; + + /* get len from sanitized ASCII value */ + len = cmd[1]; + if (len >= '0' && len < '9') + len -= '0'; + else + return; + + if ((len + SLCAN_CMD_LEN + 1) > sl->rcount) + return; + + skb = alloc_can_err_skb(dev, &cf); + + if (skb) + cf->can_id |= CAN_ERR_PROT | CAN_ERR_BUSERROR; + + cmd += SLCAN_CMD_LEN + 1; + for (i = 0; i < len; i++, cmd++) { + switch (*cmd) { + case 'a': + netdev_dbg(dev, "ACK error\n"); + tx_errors = true; + if (skb) { + cf->can_id |= CAN_ERR_ACK; + cf->data[3] = CAN_ERR_PROT_LOC_ACK; + } + + break; + case 'b': + netdev_dbg(dev, "Bit0 error\n"); + tx_errors = true; + if (skb) + cf->data[2] |= CAN_ERR_PROT_BIT0; + + break; + case 'B': + netdev_dbg(dev, "Bit1 error\n"); + tx_errors = true; + if (skb) + cf->data[2] |= CAN_ERR_PROT_BIT1; + + break; + case 'c': + netdev_dbg(dev, "CRC error\n"); + rx_errors = true; + if (skb) { + cf->data[2] |= CAN_ERR_PROT_BIT; + cf->data[3] = CAN_ERR_PROT_LOC_CRC_SEQ; + } + + break; + case 'f': + netdev_dbg(dev, "Form Error\n"); + rx_errors = true; + if (skb) + cf->data[2] |= CAN_ERR_PROT_FORM; + + break; + case 'o': + netdev_dbg(dev, "Rx overrun error\n"); + rx_over_errors = true; + rx_errors = true; + if (skb) { + cf->can_id |= CAN_ERR_CRTL; + cf->data[1] = CAN_ERR_CRTL_RX_OVERFLOW; + } + + break; + case 'O': + netdev_dbg(dev, "Tx overrun error\n"); + tx_errors = true; + if (skb) { + cf->can_id |= CAN_ERR_CRTL; + cf->data[1] = CAN_ERR_CRTL_TX_OVERFLOW; + } + + break; + case 's': + netdev_dbg(dev, "Stuff error\n"); + rx_errors = true; + if (skb) + cf->data[2] |= CAN_ERR_PROT_STUFF; + + break; + default: + if (skb) + dev_kfree_skb(skb); + + return; + } + } + + if (rx_errors) + dev->stats.rx_errors++; + + if (rx_over_errors) + dev->stats.rx_over_errors++; + + if (tx_errors) + dev->stats.tx_errors++; + + if (skb) + netif_rx(skb); +} + +static void slcan_bump(struct slcan *sl) +{ + switch (sl->rbuff[0]) { + case 'r': + fallthrough; + case 't': + fallthrough; + case 'R': + fallthrough; + case 'T': + return slcan_bump_frame(sl); + case 'e': + return slcan_bump_err(sl); + case 's': + return slcan_bump_state(sl); + default: + return; + } +} + +/* 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) + slcan_bump(sl); + + sl->rcount = 0; + } else { + if (!test_bit(SLF_ERROR, &sl->flags)) { + if (sl->rcount < SLCAN_MTU) { + sl->rbuff[sl->rcount++] = s; + return; + } + + 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 slcan_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 + SLCAN_EFF_ID_LEN; + } else { + *pos |= 0x20; /* convert R/T to lower case for SFF */ + id &= CAN_SFF_MASK; + endpos = pos + SLCAN_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) ? + SLCAN_EFF_ID_LEN : SLCAN_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]); + + sl->dev->stats.tx_bytes += cf->len; + } + + *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; +} + +/* 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 (unlikely(!netif_running(sl->dev)) && + likely(!test_bit(SLF_XCMD, &sl->flags))) { + spin_unlock_bh(&sl->lock); + return; + } + + if (sl->xleft <= 0) { + if (unlikely(test_bit(SLF_XCMD, &sl->flags))) { + clear_bit(SLF_XCMD, &sl->flags); + clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags); + spin_unlock_bh(&sl->lock); + wake_up(&sl->xcmd_wait); + return; + } + + /* 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 = (struct slcan *)tty->disc_data; + + schedule_work(&sl->tx_work); +} + +/* Send a can_frame to a TTY queue. */ +static netdev_tx_t slcan_netdev_xmit(struct sk_buff *skb, + struct net_device *dev) +{ + struct slcan *sl = netdev_priv(dev); + + if (can_dev_dropped_skb(dev, skb)) + return NETDEV_TX_OK; + + spin_lock(&sl->lock); + if (!netif_running(dev)) { + spin_unlock(&sl->lock); + netdev_warn(dev, "xmit: iface is down\n"); + goto out; + } + if (!sl->tty) { + spin_unlock(&sl->lock); + goto out; + } + + netif_stop_queue(sl->dev); + slcan_encaps(sl, (struct can_frame *)skb->data); /* encaps & send */ + spin_unlock(&sl->lock); + + skb_tx_timestamp(skb); + +out: + kfree_skb(skb); + return NETDEV_TX_OK; +} + +/****************************************** + * Routines looking at netdevice side. + ******************************************/ + +static int slcan_transmit_cmd(struct slcan *sl, const unsigned char *cmd) +{ + int ret, actual, n; + + spin_lock(&sl->lock); + if (!sl->tty) { + spin_unlock(&sl->lock); + return -ENODEV; + } + + n = scnprintf(sl->xbuff, sizeof(sl->xbuff), "%s", cmd); + set_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags); + actual = sl->tty->ops->write(sl->tty, sl->xbuff, n); + sl->xleft = n - actual; + sl->xhead = sl->xbuff + actual; + set_bit(SLF_XCMD, &sl->flags); + spin_unlock(&sl->lock); + ret = wait_event_interruptible_timeout(sl->xcmd_wait, + !test_bit(SLF_XCMD, &sl->flags), + HZ); + clear_bit(SLF_XCMD, &sl->flags); + if (ret == -ERESTARTSYS) + return ret; + + if (ret == 0) + return -ETIMEDOUT; + + return 0; +} + +/* Netdevice UP -> DOWN routine */ +static int slcan_netdev_close(struct net_device *dev) +{ + struct slcan *sl = netdev_priv(dev); + int err; + + if (sl->can.bittiming.bitrate && + sl->can.bittiming.bitrate != CAN_BITRATE_UNKNOWN) { + err = slcan_transmit_cmd(sl, "C\r"); + if (err) + netdev_warn(dev, + "failed to send close command 'C\\r'\n"); + } + + /* TTY discipline is running. */ + clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags); + flush_work(&sl->tx_work); + + netif_stop_queue(dev); + sl->rcount = 0; + sl->xleft = 0; + close_candev(dev); + sl->can.state = CAN_STATE_STOPPED; + if (sl->can.bittiming.bitrate == CAN_BITRATE_UNKNOWN) + sl->can.bittiming.bitrate = CAN_BITRATE_UNSET; + + return 0; +} + +/* Netdevice DOWN -> UP routine */ +static int slcan_netdev_open(struct net_device *dev) +{ + struct slcan *sl = netdev_priv(dev); + unsigned char cmd[SLCAN_MTU]; + int err, s; + + /* The baud rate is not set with the command + * `ip link set <iface> type can bitrate <baud>' and therefore + * can.bittiming.bitrate is CAN_BITRATE_UNSET (0), causing + * open_candev() to fail. So let's set to a fake value. + */ + if (sl->can.bittiming.bitrate == CAN_BITRATE_UNSET) + sl->can.bittiming.bitrate = CAN_BITRATE_UNKNOWN; + + err = open_candev(dev); + if (err) { + netdev_err(dev, "failed to open can device\n"); + return err; + } + + if (sl->can.bittiming.bitrate != CAN_BITRATE_UNKNOWN) { + for (s = 0; s < ARRAY_SIZE(slcan_bitrate_const); s++) { + if (sl->can.bittiming.bitrate == slcan_bitrate_const[s]) + break; + } + + /* The CAN framework has already validate the bitrate value, + * so we can avoid to check if `s' has been properly set. + */ + snprintf(cmd, sizeof(cmd), "C\rS%d\r", s); + err = slcan_transmit_cmd(sl, cmd); + if (err) { + netdev_err(dev, + "failed to send bitrate command 'C\\rS%d\\r'\n", + s); + goto cmd_transmit_failed; + } + + if (test_bit(CF_ERR_RST, &sl->cmd_flags)) { + err = slcan_transmit_cmd(sl, "F\r"); + if (err) { + netdev_err(dev, + "failed to send error command 'F\\r'\n"); + goto cmd_transmit_failed; + } + } + + if (sl->can.ctrlmode & CAN_CTRLMODE_LISTENONLY) { + err = slcan_transmit_cmd(sl, "L\r"); + if (err) { + netdev_err(dev, + "failed to send listen-only command 'L\\r'\n"); + goto cmd_transmit_failed; + } + } else { + err = slcan_transmit_cmd(sl, "O\r"); + if (err) { + netdev_err(dev, + "failed to send open command 'O\\r'\n"); + goto cmd_transmit_failed; + } + } + } + + sl->can.state = CAN_STATE_ERROR_ACTIVE; + netif_start_queue(dev); + return 0; + +cmd_transmit_failed: + close_candev(dev); + return err; +} + +static const struct net_device_ops slcan_netdev_ops = { + .ndo_open = slcan_netdev_open, + .ndo_stop = slcan_netdev_close, + .ndo_start_xmit = slcan_netdev_xmit, + .ndo_change_mtu = can_change_mtu, +}; + +/****************************************** + * 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 (!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++); + } +} + +/* 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. + * + * Called in process context serialized from other ldisc calls. + */ +static int slcan_open(struct tty_struct *tty) +{ + struct net_device *dev; + struct slcan *sl; + int err; + + if (!capable(CAP_NET_ADMIN)) + return -EPERM; + + if (!tty->ops->write) + return -EOPNOTSUPP; + + dev = alloc_candev(sizeof(*sl), 1); + if (!dev) + return -ENFILE; + + sl = netdev_priv(dev); + + /* Configure TTY interface */ + tty->receive_room = 65536; /* We don't flow control */ + sl->rcount = 0; + sl->xleft = 0; + spin_lock_init(&sl->lock); + INIT_WORK(&sl->tx_work, slcan_transmit); + init_waitqueue_head(&sl->xcmd_wait); + + /* Configure CAN metadata */ + sl->can.bitrate_const = slcan_bitrate_const; + sl->can.bitrate_const_cnt = ARRAY_SIZE(slcan_bitrate_const); + sl->can.ctrlmode_supported = CAN_CTRLMODE_LISTENONLY; + + /* Configure netdev interface */ + sl->dev = dev; + dev->netdev_ops = &slcan_netdev_ops; + dev->ethtool_ops = &slcan_ethtool_ops; + + /* Mark ldisc channel as alive */ + sl->tty = tty; + tty->disc_data = sl; + + err = register_candev(dev); + if (err) { + free_candev(dev); + pr_err("can't register candev\n"); + return err; + } + + netdev_info(dev, "slcan on %s.\n", tty->name); + /* TTY layer expects 0 on success */ + return 0; +} + +/* Close down a SLCAN channel. + * This means flushing out any pending queues, and then returning. This + * call is serialized against other ldisc functions. + * Once this is called, no other ldisc function of ours is entered. + * + * 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; + + /* unregister_netdev() calls .ndo_stop() so we don't have to. + * Our .ndo_stop() also flushes the TTY write wakeup handler, + * so we can safely set sl->tty = NULL after this. + */ + unregister_candev(sl->dev); + + /* Mark channel as dead */ + spin_lock_bh(&sl->lock); + tty->disc_data = NULL; + sl->tty = NULL; + spin_unlock_bh(&sl->lock); + + netdev_info(sl->dev, "slcan off %s.\n", tty->name); + free_candev(sl->dev); +} + +/* Perform I/O control on an active SLCAN channel. */ +static int slcan_ioctl(struct tty_struct *tty, unsigned int cmd, + unsigned long arg) +{ + struct slcan *sl = (struct slcan *)tty->disc_data; + unsigned int tmp; + + 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, cmd, arg); + } +} + +static struct tty_ldisc_ops slcan_ldisc = { + .owner = THIS_MODULE, + .num = N_SLCAN, + .name = KBUILD_MODNAME, + .open = slcan_open, + .close = slcan_close, + .ioctl = slcan_ioctl, + .receive_buf = slcan_receive_buf, + .write_wakeup = slcan_write_wakeup, +}; + +static int __init slcan_init(void) +{ + int status; + + pr_info("serial line CAN interface driver\n"); + + /* Fill in our line protocol discipline, and register it */ + status = tty_register_ldisc(&slcan_ldisc); + if (status) + pr_err("can't register line discipline\n"); + + return status; +} + +static void __exit slcan_exit(void) +{ + /* This will only be called when all channels have been closed by + * userspace - tty_ldisc.c takes care of the module's refcount. + */ + tty_unregister_ldisc(&slcan_ldisc); +} + +module_init(slcan_init); +module_exit(slcan_exit); |