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linux-zen-desktop/drivers/net/can/slcan/slcan-core.c

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/*
* 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_candev(sl->dev);
/*
* The netdev needn't be UP (so .ndo_stop() is not called). Hence make
* sure this is not running before freeing it up.
*/
flush_work(&sl->tx_work);
/* 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);
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