can: slcan: use CAN network device driver API
As suggested by commit [1], now the driver uses the functions and the
data structures provided by the CAN network device driver interface.
Currently the driver doesn't implement a way to set bitrate for SLCAN
based devices via ip tool, so you'll have to do this by slcand or
slcan_attach invocation through the -sX parameter:
- slcan_attach -f -s6 -o /dev/ttyACM0
- slcand -f -s8 -o /dev/ttyUSB0
where -s6 in will set adapter's bitrate to 500 Kbit/s and -s8 to
1Mbit/s.
See the table below for further CAN bitrates:
- s0 -> 10 Kbit/s
- s1 -> 20 Kbit/s
- s2 -> 50 Kbit/s
- s3 -> 100 Kbit/s
- s4 -> 125 Kbit/s
- s5 -> 250 Kbit/s
- s6 -> 500 Kbit/s
- s7 -> 800 Kbit/s
- s8 -> 1000 Kbit/s
In doing so, the struct can_priv::bittiming.bitrate of the driver is not
set and since the open_candev() checks that the bitrate has been set, it
must be a non-zero value, the bitrate is set to a fake value (-1U)
before it is called.
Using the rtnl_lock()/rtnl_unlock() functions has become a bit more
tricky as the register_candev() function indirectly calls rtnl_lock()
via register_netdev(). To avoid a deadlock it is therefore necessary to
call rtnl_unlock() before calling register_candev(). The same goes for
the unregister_candev() function.
[1] commit 39549eef3587f ("can: CAN Network device driver and Netlink interface")
Link: https://lore.kernel.org/all/20220628163137.413025-6-dario.binacchi@amarulasolutions.com
Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Tested-by: Jeroen Hofstee <jhofstee@victronenergy.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
This commit is contained in:
Dario Binacchi
committed by
Marc Kleine-Budde
Marc Kleine-Budde
parent
036bff2800
commit
c4e54b063f
@ -49,26 +49,6 @@ config CAN_VXCAN
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This driver can also be built as a module. If so, the module
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will be called vxcan.
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config CAN_SLCAN
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tristate "Serial / USB serial CAN Adaptors (slcan)"
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depends on TTY
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help
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CAN driver for several 'low cost' CAN interfaces that are attached
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via serial lines or via USB-to-serial adapters using the LAWICEL
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ASCII protocol. The driver implements the tty linediscipline N_SLCAN.
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As only the sending and receiving of CAN frames is implemented, this
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driver should work with the (serial/USB) CAN hardware from:
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www.canusb.com / www.can232.com / www.mictronics.de / www.canhack.de
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Userspace tools to attach the SLCAN line discipline (slcan_attach,
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slcand) can be found in the can-utils at the linux-can project, see
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https://github.com/linux-can/can-utils for details.
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The slcan driver supports up to 10 CAN netdevices by default which
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can be changed by the 'maxdev=xx' module option. This driver can
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also be built as a module. If so, the module will be called slcan.
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config CAN_NETLINK
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bool "CAN device drivers with Netlink support"
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default y
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@ -172,6 +152,26 @@ config CAN_KVASER_PCIEFD
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Kvaser Mini PCI Express HS v2
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Kvaser Mini PCI Express 2xHS v2
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config CAN_SLCAN
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tristate "Serial / USB serial CAN Adaptors (slcan)"
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depends on TTY
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help
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CAN driver for several 'low cost' CAN interfaces that are attached
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via serial lines or via USB-to-serial adapters using the LAWICEL
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ASCII protocol. The driver implements the tty linediscipline N_SLCAN.
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As only the sending and receiving of CAN frames is implemented, this
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driver should work with the (serial/USB) CAN hardware from:
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www.canusb.com / www.can232.com / www.mictronics.de / www.canhack.de
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Userspace tools to attach the SLCAN line discipline (slcan_attach,
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slcand) can be found in the can-utils at the linux-can project, see
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https://github.com/linux-can/can-utils for details.
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The slcan driver supports up to 10 CAN netdevices by default which
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can be changed by the 'maxdev=xx' module option. This driver can
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also be built as a module. If so, the module will be called slcan.
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config CAN_SUN4I
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tristate "Allwinner A10 CAN controller"
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depends on MACH_SUN4I || MACH_SUN7I || COMPILE_TEST
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@ -56,7 +56,6 @@
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#include <linux/can.h>
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#include <linux/can/dev.h>
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#include <linux/can/skb.h>
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#include <linux/can/can-ml.h>
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MODULE_ALIAS_LDISC(N_SLCAN);
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MODULE_DESCRIPTION("serial line CAN interface");
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@ -79,6 +78,7 @@ MODULE_PARM_DESC(maxdev, "Maximum number of slcan interfaces");
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#define SLC_EFF_ID_LEN 8
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struct slcan {
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struct can_priv can;
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int magic;
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/* Various fields. */
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@ -394,6 +394,8 @@ static int slc_close(struct net_device *dev)
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clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
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}
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netif_stop_queue(dev);
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close_candev(dev);
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sl->can.state = CAN_STATE_STOPPED;
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sl->rcount = 0;
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sl->xleft = 0;
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spin_unlock_bh(&sl->lock);
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@ -405,20 +407,34 @@ static int slc_close(struct net_device *dev)
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static int slc_open(struct net_device *dev)
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{
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struct slcan *sl = netdev_priv(dev);
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int err;
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if (sl->tty == NULL)
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return -ENODEV;
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/* The baud rate is not set with the command
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* `ip link set <iface> type can bitrate <baud>' and therefore
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* can.bittiming.bitrate is CAN_BITRATE_UNSET (0), causing
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* open_candev() to fail. So let's set to a fake value.
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*/
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sl->can.bittiming.bitrate = CAN_BITRATE_UNKNOWN;
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err = open_candev(dev);
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if (err) {
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netdev_err(dev, "failed to open can device\n");
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return err;
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}
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sl->can.state = CAN_STATE_ERROR_ACTIVE;
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sl->flags &= BIT(SLF_INUSE);
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netif_start_queue(dev);
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return 0;
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}
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/* Hook the destructor so we can free slcan devs at the right point in time */
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static void slc_free_netdev(struct net_device *dev)
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static void slc_dealloc(struct slcan *sl)
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{
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int i = dev->base_addr;
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int i = sl->dev->base_addr;
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free_candev(sl->dev);
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slcan_devs[i] = NULL;
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}
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@ -434,24 +450,6 @@ static const struct net_device_ops slc_netdev_ops = {
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.ndo_change_mtu = slcan_change_mtu,
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};
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static void slc_setup(struct net_device *dev)
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{
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dev->netdev_ops = &slc_netdev_ops;
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dev->needs_free_netdev = true;
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dev->priv_destructor = slc_free_netdev;
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dev->hard_header_len = 0;
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dev->addr_len = 0;
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dev->tx_queue_len = 10;
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dev->mtu = CAN_MTU;
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dev->type = ARPHRD_CAN;
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/* New-style flags. */
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dev->flags = IFF_NOARP;
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dev->features = NETIF_F_HW_CSUM;
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}
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/******************************************
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Routines looking at TTY side.
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******************************************/
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@ -514,11 +512,8 @@ static void slc_sync(void)
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static struct slcan *slc_alloc(void)
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{
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int i;
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char name[IFNAMSIZ];
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struct net_device *dev = NULL;
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struct can_ml_priv *can_ml;
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struct slcan *sl;
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int size;
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for (i = 0; i < maxdev; i++) {
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dev = slcan_devs[i];
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@ -531,16 +526,14 @@ static struct slcan *slc_alloc(void)
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if (i >= maxdev)
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return NULL;
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sprintf(name, "slcan%d", i);
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size = ALIGN(sizeof(*sl), NETDEV_ALIGN) + sizeof(struct can_ml_priv);
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dev = alloc_netdev(size, name, NET_NAME_UNKNOWN, slc_setup);
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dev = alloc_candev(sizeof(*sl), 1);
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if (!dev)
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return NULL;
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snprintf(dev->name, sizeof(dev->name), "slcan%d", i);
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dev->netdev_ops = &slc_netdev_ops;
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dev->base_addr = i;
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sl = netdev_priv(dev);
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can_ml = (void *)sl + ALIGN(sizeof(*sl), NETDEV_ALIGN);
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can_set_ml_priv(dev, can_ml);
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/* Initialize channel control data */
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sl->magic = SLCAN_MAGIC;
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@ -605,26 +598,28 @@ static int slcan_open(struct tty_struct *tty)
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set_bit(SLF_INUSE, &sl->flags);
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err = register_netdevice(sl->dev);
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if (err)
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rtnl_unlock();
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err = register_candev(sl->dev);
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if (err) {
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pr_err("slcan: can't register candev\n");
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goto err_free_chan;
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}
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} else {
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rtnl_unlock();
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}
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/* Done. We have linked the TTY line to a channel. */
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rtnl_unlock();
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tty->receive_room = 65536; /* We don't flow control */
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/* TTY layer expects 0 on success */
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return 0;
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err_free_chan:
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rtnl_lock();
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sl->tty = NULL;
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tty->disc_data = NULL;
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clear_bit(SLF_INUSE, &sl->flags);
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slc_free_netdev(sl->dev);
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/* do not call free_netdev before rtnl_unlock */
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slc_dealloc(sl);
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rtnl_unlock();
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free_netdev(sl->dev);
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return err;
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err_exit:
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@ -658,9 +653,11 @@ static void slcan_close(struct tty_struct *tty)
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synchronize_rcu();
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flush_work(&sl->tx_work);
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/* Flush network side */
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unregister_netdev(sl->dev);
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/* This will complete via sl_free_netdev */
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slc_close(sl->dev);
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unregister_candev(sl->dev);
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rtnl_lock();
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slc_dealloc(sl);
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rtnl_unlock();
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}
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static void slcan_hangup(struct tty_struct *tty)
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@ -768,14 +765,15 @@ static void __exit slcan_exit(void)
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dev = slcan_devs[i];
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if (!dev)
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continue;
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slcan_devs[i] = NULL;
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sl = netdev_priv(dev);
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if (sl->tty) {
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netdev_err(dev, "tty discipline still running\n");
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}
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unregister_netdev(dev);
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slc_close(dev);
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unregister_candev(dev);
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slc_dealloc(sl);
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}
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kfree(slcan_devs);
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