@@ -1,11 +1,14 @@
/*
* slcan.c - serial line CAN interface driver (using tty line discipline)
*
- * This file is derived from linux/drivers/net/slip/slip.c
+ * 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
@@ -38,7 +41,6 @@
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
-#include <linux/moduleparam.h>
#include <linux/uaccess.h>
#include <linux/bitops.h>
@@ -48,7 +50,6 @@
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <linux/rtnetlink.h>
-#include <linux/delay.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/workqueue.h>
@@ -63,15 +64,6 @@ 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)
@@ -85,7 +77,6 @@ MODULE_PARM_DESC(maxdev, "Maximum number of slcan interfaces");
SLC_STATE_BE_TXCNT_LEN)
struct slcan {
struct can_priv can;
- int magic;
/* Various fields. */
struct tty_struct *tty; /* ptr to TTY structure */
@@ -101,17 +92,14 @@ struct slcan {
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 */
-#define SLF_XCMD 2 /* Command transmission */
+#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 struct net_device **slcan_devs;
-
static const u32 slcan_bitrate_const[] = {
10000, 20000, 50000, 100000, 125000,
250000, 500000, 800000, 1000000
@@ -555,9 +543,8 @@ static void slcan_transmit(struct work_struct *work)
spin_lock_bh(&sl->lock);
/* First make sure we're connected. */
- if (!sl->tty || sl->magic != SLCAN_MAGIC ||
- (unlikely(!netif_running(sl->dev)) &&
- likely(!test_bit(SLF_XCMD, &sl->flags)))) {
+ if (unlikely(!netif_running(sl->dev)) &&
+ likely(!test_bit(SLF_XCMD, &sl->flags))) {
spin_unlock_bh(&sl->lock);
return;
}
@@ -592,13 +579,9 @@ static void slcan_transmit(struct work_struct *work)
*/
static void slcan_write_wakeup(struct tty_struct *tty)
{
- struct slcan *sl;
+ struct slcan *sl = (struct slcan *)tty->disc_data;
- rcu_read_lock();
- sl = rcu_dereference(tty->disc_data);
- if (sl)
- schedule_work(&sl->tx_work);
- rcu_read_unlock();
+ schedule_work(&sl->tx_work);
}
/* Send a can_frame to a TTY queue. */
@@ -669,25 +652,21 @@ static int slc_close(struct net_device *dev)
struct slcan *sl = netdev_priv(dev);
int err;
- spin_lock_bh(&sl->lock);
- if (sl->tty) {
- if (sl->can.bittiming.bitrate &&
- sl->can.bittiming.bitrate != CAN_BITRATE_UNKNOWN) {
- spin_unlock_bh(&sl->lock);
- err = slcan_transmit_cmd(sl, "C\r");
- spin_lock_bh(&sl->lock);
- 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);
+ 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;
- spin_unlock_bh(&sl->lock);
close_candev(dev);
sl->can.state = CAN_STATE_STOPPED;
if (sl->can.bittiming.bitrate == CAN_BITRATE_UNKNOWN)
@@ -703,9 +682,6 @@ static int slc_open(struct net_device *dev)
unsigned char cmd[SLC_MTU];
int err, s;
- if (!sl->tty)
- return -ENODEV;
-
/* 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
@@ -720,8 +696,6 @@ static int slc_open(struct net_device *dev)
return err;
}
- sl->flags &= BIT(SLF_INUSE);
-
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])
@@ -765,14 +739,6 @@ static int slc_open(struct net_device *dev)
return err;
}
-static void slc_dealloc(struct slcan *sl)
-{
- int i = sl->dev->base_addr;
-
- free_candev(sl->dev);
- slcan_devs[i] = NULL;
-}
-
static int slcan_change_mtu(struct net_device *dev, int new_mtu)
{
return -EINVAL;
@@ -802,7 +768,7 @@ static void slcan_receive_buf(struct tty_struct *tty,
{
struct slcan *sl = (struct slcan *)tty->disc_data;
- if (!sl || sl->magic != SLCAN_MAGIC || !netif_running(sl->dev))
+ if (!netif_running(sl->dev))
return;
/* Read the characters out of the buffer */
@@ -817,80 +783,15 @@ static void slcan_receive_buf(struct tty_struct *tty,
}
}
-/************************************
- * 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)
- 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;
- struct net_device *dev = NULL;
- struct slcan *sl;
-
- for (i = 0; i < maxdev; i++) {
- dev = slcan_devs[i];
- if (!dev)
- break;
- }
-
- /* Sorry, too many, all slots in use */
- if (i >= maxdev)
- return NULL;
-
- dev = alloc_candev(sizeof(*sl), 1);
- if (!dev)
- return NULL;
-
- snprintf(dev->name, sizeof(dev->name), KBUILD_MODNAME "%d", i);
- dev->netdev_ops = &slc_netdev_ops;
- dev->base_addr = i;
- slcan_set_ethtool_ops(dev);
- sl = netdev_priv(dev);
-
- /* Initialize channel control data */
- sl->magic = SLCAN_MAGIC;
- sl->dev = dev;
- sl->can.bitrate_const = slcan_bitrate_const;
- sl->can.bitrate_const_cnt = ARRAY_SIZE(slcan_bitrate_const);
- spin_lock_init(&sl->lock);
- INIT_WORK(&sl->tx_work, slcan_transmit);
- init_waitqueue_head(&sl->xcmd_wait);
- 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...
+ * 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;
@@ -900,72 +801,49 @@ static int slcan_open(struct tty_struct *tty)
if (!tty->ops->write)
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();
+ dev = alloc_candev(sizeof(*sl), 1);
+ if (!dev)
+ return -ENFILE;
- /* Collect hanged up channels. */
- slc_sync();
+ sl = netdev_priv(dev);
- sl = tty->disc_data;
+ /* 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);
- err = -EEXIST;
- /* First make sure we're not already connected. */
- if (sl && sl->magic == SLCAN_MAGIC)
- goto err_exit;
+ /* Configure CAN metadata */
+ sl->can.bitrate_const = slcan_bitrate_const;
+ sl->can.bitrate_const_cnt = ARRAY_SIZE(slcan_bitrate_const);
- /* OK. Find a free SLCAN channel to use. */
- err = -ENFILE;
- sl = slc_alloc();
- if (!sl)
- goto err_exit;
+ /* Configure netdev interface */
+ sl->dev = dev;
+ dev->netdev_ops = &slc_netdev_ops;
+ slcan_set_ethtool_ops(dev);
+ /* Mark ldisc channel as alive */
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);
-
- rtnl_unlock();
- err = register_candev(sl->dev);
- if (err) {
- pr_err("can't register candev\n");
- goto err_free_chan;
- }
- } else {
- rtnl_unlock();
+ err = register_candev(dev);
+ if (err) {
+ free_candev(dev);
+ pr_err("can't register candev\n");
+ return err;
}
- tty->receive_room = 65536; /* We don't flow control */
-
+ netdev_info(dev, "slcan on %s.\n", tty->name);
/* TTY layer expects 0 on success */
return 0;
-
-err_free_chan:
- rtnl_lock();
- sl->tty = NULL;
- tty->disc_data = NULL;
- clear_bit(SLF_INUSE, &sl->flags);
- slc_dealloc(sl);
- rtnl_unlock();
- 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.
+ * Once this is called, no other ldisc function of ours is entered.
*
* We also use this method for a hangup event.
*/
@@ -973,28 +851,20 @@ 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;
+ /* 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);
- rcu_assign_pointer(tty->disc_data, NULL);
+ tty->disc_data = NULL;
sl->tty = NULL;
spin_unlock_bh(&sl->lock);
- synchronize_rcu();
- flush_work(&sl->tx_work);
-
- slc_close(sl->dev);
- unregister_candev(sl->dev);
- rtnl_lock();
- slc_dealloc(sl);
- rtnl_unlock();
-}
-
-static void slcan_hangup(struct tty_struct *tty)
-{
- slcan_close(tty);
+ netdev_info(sl->dev, "slcan off %s.\n", tty->name);
+ free_candev(sl->dev);
}
/* Perform I/O control on an active SLCAN channel. */
@@ -1004,10 +874,6 @@ static int slcan_ioctl(struct tty_struct *tty, unsigned int cmd,
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;
@@ -1029,7 +895,6 @@ static struct tty_ldisc_ops slc_ldisc = {
.name = KBUILD_MODNAME,
.open = slcan_open,
.close = slcan_close,
- .hangup = slcan_hangup,
.ioctl = slcan_ioctl,
.receive_buf = slcan_receive_buf,
.write_wakeup = slcan_write_wakeup,
@@ -1039,78 +904,21 @@ static int __init slcan_init(void)
{
int status;
- if (maxdev < 4)
- maxdev = 4; /* Sanity */
-
pr_info("serial line CAN interface driver\n");
- pr_info("%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) {
+ if (status)
pr_err("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)
- 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
+ /* This will only be called when all channels have been closed by
+ * userspace - tty_ldisc.c takes care of the module's refcount.
*/
-
- for (i = 0; i < maxdev; i++) {
- dev = slcan_devs[i];
- if (!dev)
- continue;
-
- sl = netdev_priv(dev);
- if (sl->tty)
- netdev_err(dev, "tty discipline still running\n");
-
- slc_close(dev);
- unregister_candev(dev);
- slc_dealloc(sl);
- }
-
- kfree(slcan_devs);
- slcan_devs = NULL;
-
tty_unregister_ldisc(&slc_ldisc);
}