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linux-sg2042/drivers/net/can/slcan.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
*
* 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>
*
* 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 <linux/module.h>
#include <linux/moduleparam.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/if_arp.h>
#include <linux/if_ether.h>
#include <linux/sched.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/workqueue.h>
#include <linux/can.h>
#include <linux/can/skb.h>
#include <linux/can/can-ml.h>
MODULE_ALIAS_LDISC(N_SLCAN);
MODULE_DESCRIPTION("serial line CAN interface");
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Oliver Hartkopp <socketcan@hartkopp.net>");
#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 <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 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,
.num = N_SLCAN,
.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(&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;
tty_unregister_ldisc(&slc_ldisc);
}
module_init(slcan_init);
module_exit(slcan_exit);
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