As suggested by commit [1], now the driver uses the functions and the
data structures provided by the CAN network device driver interface.
There is no way to set bitrate for SLCAN based devices via ip tool, so
you'll have to do this by slcand/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 (-1) before
it is called.
[1] 39549eef3587f ("can: CAN Network device driver and Netlink interface")
Signed-off-by: Dario Binacchi <[email protected]>
---
drivers/net/can/slcan.c | 112 ++++++++++++++++++++--------------------
1 file changed, 57 insertions(+), 55 deletions(-)
diff --git a/drivers/net/can/slcan.c b/drivers/net/can/slcan.c
index 964b02f321ab..956b47bd40a7 100644
--- a/drivers/net/can/slcan.c
+++ b/drivers/net/can/slcan.c
@@ -56,7 +56,6 @@
#include <linux/can.h>
#include <linux/can/dev.h>
#include <linux/can/skb.h>
-#include <linux/can/can-ml.h>
MODULE_ALIAS_LDISC(N_SLCAN);
MODULE_DESCRIPTION("serial line CAN interface");
@@ -79,6 +78,7 @@ MODULE_PARM_DESC(maxdev, "Maximum number of slcan interfaces");
#define SLC_EFF_ID_LEN 8
struct slcan {
+ struct can_priv can;
int magic;
/* Various fields. */
@@ -100,6 +100,7 @@ struct slcan {
};
static struct net_device **slcan_devs;
+static DEFINE_SPINLOCK(slcan_lock);
/************************************************************************
* SLCAN ENCAPSULATION FORMAT *
@@ -369,7 +370,7 @@ static netdev_tx_t slc_xmit(struct sk_buff *skb, struct net_device *dev)
spin_unlock(&sl->lock);
out:
- kfree_skb(skb);
+ can_put_echo_skb(skb, dev, 0, 0);
return NETDEV_TX_OK;
}
@@ -389,6 +390,8 @@ static int slc_close(struct net_device *dev)
clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
}
netif_stop_queue(dev);
+ close_candev(dev);
+ sl->can.state = CAN_STATE_STOPPED;
sl->rcount = 0;
sl->xleft = 0;
spin_unlock_bh(&sl->lock);
@@ -400,21 +403,36 @@ static int slc_close(struct net_device *dev)
static int slc_open(struct net_device *dev)
{
struct slcan *sl = netdev_priv(dev);
+ int err;
if (sl->tty == NULL)
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 0, causing open_candev() to fail.
+ * So let's set to a fake value.
+ */
+ sl->can.bittiming.bitrate = -1;
+ err = open_candev(dev);
+ if (err) {
+ netdev_err(dev, "failed to open can device\n");
+ return err;
+ }
+
+ sl->can.state = CAN_STATE_ERROR_ACTIVE;
sl->flags &= BIT(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)
+static void slc_dealloc(struct slcan *sl)
{
- int i = dev->base_addr;
+ int i = sl->dev->base_addr;
- slcan_devs[i] = NULL;
+ free_candev(sl->dev);
+ if (slcan_devs)
+ slcan_devs[i] = NULL;
}
static int slcan_change_mtu(struct net_device *dev, int new_mtu)
@@ -429,24 +447,6 @@ static const struct net_device_ops slc_netdev_ops = {
.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.
******************************************/
@@ -509,11 +509,8 @@ static void slc_sync(void)
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];
@@ -526,16 +523,14 @@ static struct slcan *slc_alloc(void)
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);
+ dev = alloc_candev(sizeof(*sl), 1);
if (!dev)
return NULL;
+ snprintf(dev->name, sizeof(dev->name), "slcan%d", i);
+ dev->netdev_ops = &slc_netdev_ops;
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;
@@ -568,11 +563,7 @@ static int slcan_open(struct tty_struct *tty)
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();
+ spin_lock(&slcan_lock);
/* Collect hanged up channels. */
slc_sync();
@@ -600,13 +591,15 @@ static int slcan_open(struct tty_struct *tty)
set_bit(SLF_INUSE, &sl->flags);
- err = register_netdevice(sl->dev);
- if (err)
+ err = register_candev(sl->dev);
+ if (err) {
+ pr_err("slcan: can't register candev\n");
goto err_free_chan;
+ }
}
/* Done. We have linked the TTY line to a channel. */
- rtnl_unlock();
+ spin_unlock(&slcan_lock);
tty->receive_room = 65536; /* We don't flow control */
/* TTY layer expects 0 on success */
@@ -616,14 +609,10 @@ static int slcan_open(struct tty_struct *tty)
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;
+ slc_dealloc(sl);
err_exit:
- rtnl_unlock();
+ spin_unlock(&slcan_lock);
/* Count references from TTY module */
return err;
@@ -653,9 +642,11 @@ static void slcan_close(struct tty_struct *tty)
synchronize_rcu();
flush_work(&sl->tx_work);
- /* Flush network side */
- unregister_netdev(sl->dev);
- /* This will complete via sl_free_netdev */
+ slc_close(sl->dev);
+ unregister_candev(sl->dev);
+ spin_lock(&slcan_lock);
+ slc_dealloc(sl);
+ spin_unlock(&slcan_lock);
}
static void slcan_hangup(struct tty_struct *tty)
@@ -763,18 +754,29 @@ static void __exit slcan_exit(void)
dev = slcan_devs[i];
if (!dev)
continue;
- slcan_devs[i] = NULL;
- sl = netdev_priv(dev);
- if (sl->tty) {
- netdev_err(dev, "tty discipline still running\n");
- }
+ spin_lock(&slcan_lock);
+ dev = slcan_devs[i];
+ if (dev) {
+ slcan_devs[i] = NULL;
+ spin_unlock(&slcan_lock);
+ sl = netdev_priv(dev);
+ if (sl->tty) {
+ netdev_err(dev,
+ "tty discipline still running\n");
+ }
- unregister_netdev(dev);
+ slc_close(dev);
+ unregister_candev(dev);
+ } else {
+ spin_unlock(&slcan_lock);
+ }
}
+ spin_lock(&slcan_lock);
kfree(slcan_devs);
slcan_devs = NULL;
+ spin_unlock(&slcan_lock);
tty_unregister_ldisc(&slc_ldisc);
}
--
2.32.0
On 07.06.2022 11:47:43, Dario Binacchi wrote:
> As suggested by commit [1], now the driver uses the functions and the
> data structures provided by the CAN network device driver interface.
>
> There is no way to set bitrate for SLCAN based devices via ip tool, so
^^^^^^^^^^^^^^^
Currently the driver doesn't implement a way
> you'll have to do this by slcand/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 (-1) before
> it is called.
What does
| ip --details -s -s link show
show as the bit rate?
Marc
--
Pengutronix e.K. | Marc Kleine-Budde |
Embedded Linux | https://www.pengutronix.de |
Vertretung West/Dortmund | Phone: +49-231-2826-924 |
Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
Hi Marc,
On Tue, Jun 7, 2022 at 1:13 PM Marc Kleine-Budde <[email protected]> wrote:
>
> On 07.06.2022 11:47:43, Dario Binacchi wrote:
> > As suggested by commit [1], now the driver uses the functions and the
> > data structures provided by the CAN network device driver interface.
> >
> > There is no way to set bitrate for SLCAN based devices via ip tool, so
> ^^^^^^^^^^^^^^^
> Currently the driver doesn't implement a way
Ok, I'll do it.
>
> > you'll have to do this by slcand/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 (-1) before
> > it is called.
>
> What does
>
> | ip --details -s -s link show
>
> show as the bit rate?
# ip --details -s -s link show dev can0
can0: <NOARP,UP,LOWER_UP> mtu 16 qdisc pfifo_fast state UP mode
DEFAULT group default qlen 10
link/can promiscuity 0 minmtu 0 maxmtu 0
can state ERROR-ACTIVE restart-ms 0
bitrate 500000 sample-point 0.875
tq 41 prop-seg 20 phase-seg1 21 phase-seg2 6 sjw 1
slcan: tseg1 2..256 tseg2 1..128 sjw 1..128 brp 1..256 brp-inc 1
clock 24000000
re-started bus-errors arbit-lost error-warn error-pass bus-off
0 0 0 0 0 0
numtxqueues 1 numrxqueues 1 gso_max_size 65536 gso_max_segs 65535
RX: bytes packets errors dropped overrun mcast
292 75 0 0 0 0
RX errors: length crc frame fifo missed
0 0 0 0 0
TX: bytes packets errors dropped carrier collsns
0 0 0 0 0 0
TX errors: aborted fifo window heartbeat transns
0 0 0 0 1
And after applying your suggestions about using the CAN framework
support for setting the fixed bit rates (you'll
find it in V2), this is the output instead:
# ip --details -s -s link show dev can0
5: can0: <NOARP,UP,LOWER_UP> mtu 16 qdisc pfifo_fast state UP mode
DEFAULT group default qlen 10
link/can promiscuity 0 minmtu 0 maxmtu 0
can state ERROR-ACTIVE restart-ms 0
bitrate 500000
[ 10000, 20000, 50000, 100000, 125000, 250000,
500000, 800000, 1000000 ]
clock 0
re-started bus-errors arbit-lost error-warn error-pass bus-off
0 0 0 0 0 0
numtxqueues 1 numrxqueues 1 gso_max_size 65536 gso_max_segs 65535
RX: bytes packets errors dropped overrun mcast
37307 4789 0 0 0 0
RX errors: length crc frame fifo missed
0 0 0 0 0
TX: bytes packets errors dropped carrier collsns
7276 988 0 0 0 0
TX errors: aborted fifo window heartbeat transns
0 0 0 0 1
Thanks and regards,
Dario
>
> Marc
>
> --
> Pengutronix e.K. | Marc Kleine-Budde |
> Embedded Linux | https://www.pengutronix.de |
> Vertretung West/Dortmund | Phone: +49-231-2826-924 |
> Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
--
Dario Binacchi
Embedded Linux Developer
[email protected]
__________________________________
Amarula Solutions SRL
Via Le Canevare 30, 31100 Treviso, Veneto, IT
T. +39 042 243 5310
[email protected]
http://www.amarulasolutions.com
On 08.06.2022 18:42:09, Dario Binacchi wrote:
> > > 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 (-1) before
> > > it is called.
> >
> > What does
> >
> > | ip --details -s -s link show
> >
> > show as the bit rate?
>
> # ip --details -s -s link show dev can0
This is the bitrate configured with "ip"?
> can0: <NOARP,UP,LOWER_UP> mtu 16 qdisc pfifo_fast state UP mode
> DEFAULT group default qlen 10
> link/can promiscuity 0 minmtu 0 maxmtu 0
> can state ERROR-ACTIVE restart-ms 0
> bitrate 500000 sample-point 0.875
> tq 41 prop-seg 20 phase-seg1 21 phase-seg2 6 sjw 1
> slcan: tseg1 2..256 tseg2 1..128 sjw 1..128 brp 1..256 brp-inc 1
> clock 24000000
> re-started bus-errors arbit-lost error-warn error-pass bus-off
> 0 0 0 0 0 0
> numtxqueues 1 numrxqueues 1 gso_max_size 65536 gso_max_segs 65535
> RX: bytes packets errors dropped overrun mcast
> 292 75 0 0 0 0
> RX errors: length crc frame fifo missed
> 0 0 0 0 0
> TX: bytes packets errors dropped carrier collsns
> 0 0 0 0 0 0
> TX errors: aborted fifo window heartbeat transns
> 0 0 0 0 1
>
> And after applying your suggestions about using the CAN framework
> support for setting the fixed bit rates (you'll
> find it in V2), this is the output instead:
This looks good.
> # ip --details -s -s link show dev can0
> 5: can0: <NOARP,UP,LOWER_UP> mtu 16 qdisc pfifo_fast state UP mode
> DEFAULT group default qlen 10
> link/can promiscuity 0 minmtu 0 maxmtu 0
> can state ERROR-ACTIVE restart-ms 0
> bitrate 500000
> [ 10000, 20000, 50000, 100000, 125000, 250000,
> 500000, 800000, 1000000 ]
> clock 0
> re-started bus-errors arbit-lost error-warn error-pass bus-off
> 0 0 0 0 0 0
> numtxqueues 1 numrxqueues 1 gso_max_size 65536 gso_max_segs 65535
> RX: bytes packets errors dropped overrun mcast
> 37307 4789 0 0 0 0
> RX errors: length crc frame fifo missed
> 0 0 0 0 0
> TX: bytes packets errors dropped carrier collsns
> 7276 988 0 0 0 0
> TX errors: aborted fifo window heartbeat transns
> 0 0 0 0 1
Can you configure the bitrate with slcand and show the output of "ip
--details -s -s link show dev can0". I fear it will show 4294967295 as
the bitrate, which I don't like.
A hack would be to replace the -1 by 0 in the CAN netlink code.
Marc
--
Pengutronix e.K. | Marc Kleine-Budde |
Embedded Linux | https://www.pengutronix.de |
Vertretung West/Dortmund | Phone: +49-231-2826-924 |
Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
On Thu, Jun 9, 2022 at 9:07 AM Marc Kleine-Budde <[email protected]> wrote:
>
> On 08.06.2022 18:42:09, Dario Binacchi wrote:
> > > > 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 (-1) before
> > > > it is called.
> > >
> > > What does
> > >
> > > | ip --details -s -s link show
> > >
> > > show as the bit rate?
> >
> > # ip --details -s -s link show dev can0
>
> This is the bitrate configured with "ip"?
>
> > can0: <NOARP,UP,LOWER_UP> mtu 16 qdisc pfifo_fast state UP mode
> > DEFAULT group default qlen 10
> > link/can promiscuity 0 minmtu 0 maxmtu 0
> > can state ERROR-ACTIVE restart-ms 0
> > bitrate 500000 sample-point 0.875
> > tq 41 prop-seg 20 phase-seg1 21 phase-seg2 6 sjw 1
> > slcan: tseg1 2..256 tseg2 1..128 sjw 1..128 brp 1..256 brp-inc 1
> > clock 24000000
> > re-started bus-errors arbit-lost error-warn error-pass bus-off
> > 0 0 0 0 0 0
> > numtxqueues 1 numrxqueues 1 gso_max_size 65536 gso_max_segs 65535
> > RX: bytes packets errors dropped overrun mcast
> > 292 75 0 0 0 0
> > RX errors: length crc frame fifo missed
> > 0 0 0 0 0
> > TX: bytes packets errors dropped carrier collsns
> > 0 0 0 0 0 0
> > TX errors: aborted fifo window heartbeat transns
> > 0 0 0 0 1
> >
> > And after applying your suggestions about using the CAN framework
> > support for setting the fixed bit rates (you'll
> > find it in V2), this is the output instead:
>
> This looks good.
>
> > # ip --details -s -s link show dev can0
> > 5: can0: <NOARP,UP,LOWER_UP> mtu 16 qdisc pfifo_fast state UP mode
> > DEFAULT group default qlen 10
> > link/can promiscuity 0 minmtu 0 maxmtu 0
> > can state ERROR-ACTIVE restart-ms 0
> > bitrate 500000
> > [ 10000, 20000, 50000, 100000, 125000, 250000,
> > 500000, 800000, 1000000 ]
> > clock 0
> > re-started bus-errors arbit-lost error-warn error-pass bus-off
> > 0 0 0 0 0 0
> > numtxqueues 1 numrxqueues 1 gso_max_size 65536 gso_max_segs 65535
> > RX: bytes packets errors dropped overrun mcast
> > 37307 4789 0 0 0 0
> > RX errors: length crc frame fifo missed
> > 0 0 0 0 0
> > TX: bytes packets errors dropped carrier collsns
> > 7276 988 0 0 0 0
> > TX errors: aborted fifo window heartbeat transns
> > 0 0 0 0 1
>
> Can you configure the bitrate with slcand and show the output of "ip
> --details -s -s link show dev can0". I fear it will show 4294967295 as
> the bitrate, which I don't like.
>
Yes, you are right.
> A hack would be to replace the -1 by 0 in the CAN netlink code.
You will find it in V3.
Thanks and regards,
Dario
>
> Marc
>
> --
> Pengutronix e.K. | Marc Kleine-Budde |
> Embedded Linux | https://www.pengutronix.de |
> Vertretung West/Dortmund | Phone: +49-231-2826-924 |
> Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
--
Dario Binacchi
Embedded Linux Developer
[email protected]
__________________________________
Amarula Solutions SRL
Via Le Canevare 30, 31100 Treviso, Veneto, IT
T. +39 042 243 5310
[email protected]
http://www.amarulasolutions.com