On 12/22/2017 02:31 PM, Faiz Abbas wrote: > From: Franklin S Cooper Jr <[email protected]> > > Various CAN or CAN-FD IP may be able to run at a faster rate than > what the transceiver the CAN node is connected to. This can lead to > unexpected errors. However, CAN transceivers typically have fixed > limitations and provide no means to discover these limitations at > runtime. Therefore, add support for a can-transceiver node that > can be reused by other CAN peripheral drivers to determine for both > CAN and CAN-FD what the max bitrate that can be used. If the user > tries to configure CAN to pass these maximum bitrates it will throw > an error. > > Signed-off-by: Franklin S Cooper Jr <[email protected]> > [[email protected]: fix build error with !CONFIG_OF] > Signed-off-by: Sekhar Nori <[email protected]> > Signed-off-by: Faiz Abbas <[email protected]> > --- > v6 changes: > fix build error with !CONFIG_OF > > drivers/net/can/dev.c | 39 +++++++++++++++++++++++++++++++++++++++ > include/linux/can/dev.h | 8 ++++++++ > 2 files changed, 47 insertions(+) > > diff --git a/drivers/net/can/dev.c b/drivers/net/can/dev.c > index 365a8cc..007cfc0 100644 > --- a/drivers/net/can/dev.c > +++ b/drivers/net/can/dev.c > @@ -27,6 +27,7 @@ > #include <linux/can/skb.h> > #include <linux/can/netlink.h> > #include <linux/can/led.h> > +#include <linux/of.h> > #include <net/rtnetlink.h> > > #define MOD_DESC "CAN device driver interface" > @@ -814,6 +815,30 @@ int open_candev(struct net_device *dev) > } > EXPORT_SYMBOL_GPL(open_candev); > > +#ifdef CONFIG_OF > +/* > + * Common function that can be used to understand the limitation of > + * a transceiver when it provides no means to determine these limitations > + * at runtime. > + */ > +void of_can_transceiver(struct net_device *dev) > +{ > + struct device_node *dn; > + struct can_priv *priv = netdev_priv(dev); > + struct device_node *np = dev->dev.parent->of_node; > + int ret; > + > + dn = of_get_child_by_name(np, "can-transceiver"); > + if (!dn) > + return; > + > + ret = of_property_read_u32(dn, "max-bitrate", &priv->max_bitrate); > + if ((ret && ret != -EINVAL) || (!ret && !priv->max_bitrate)) > + netdev_warn(dev, "Invalid value for transceiver max bitrate. > Ignoring bitrate limit.\n"); > +} > +EXPORT_SYMBOL_GPL(of_can_transceiver); > +#endif > + > /* > * Common close function for cleanup before the device gets closed. > * > @@ -913,6 +938,13 @@ static int can_changelink(struct net_device *dev, struct > nlattr *tb[], > priv->bitrate_const_cnt); > if (err) > return err; > + > + if (priv->max_bitrate && bt.bitrate > priv->max_bitrate) { > + netdev_err(dev, "arbitration bitrate surpasses > transceiver capabilities of %d bps\n", > + priv->max_bitrate); > + return -EINVAL; > + }
What about movong this check into can_get_bittiming()? Although we loose
the "arbitration" vs "canfd data".
> +
> memcpy(&priv->bittiming, &bt, sizeof(bt));
>
> if (priv->do_set_bittiming) {
> @@ -997,6 +1029,13 @@ static int can_changelink(struct net_device *dev,
> struct nlattr *tb[],
> priv->data_bitrate_const_cnt);
> if (err)
> return err;
> +
> + if (priv->max_bitrate && dbt.bitrate > priv->max_bitrate) {
> + netdev_err(dev, "canfd data bitrate surpasses
> transceiver capabilities of %d bps\n",
> + priv->max_bitrate);
> + return -EINVAL;
> + }
> +
> memcpy(&priv->data_bittiming, &dbt, sizeof(dbt));
>
> if (priv->do_set_data_bittiming) {
> diff --git a/include/linux/can/dev.h b/include/linux/can/dev.h
> index 61f1cf2..fbb7810 100644
> --- a/include/linux/can/dev.h
> +++ b/include/linux/can/dev.h
> @@ -48,6 +48,8 @@ struct can_priv {
> unsigned int data_bitrate_const_cnt;
> struct can_clock clock;
>
> + unsigned int max_bitrate;
Please make it an u32, name it "bitrate_max" and ...
>> struct can_priv {
>> struct net_device *dev;
>> struct can_device_stats can_stats;
>>
>> struct can_bittiming bittiming, data_bittiming;
>> const struct can_bittiming_const *bittiming_const,
>> *data_bittiming_const;
>> const u16 *termination_const;
>> unsigned int termination_const_cnt;
>> u16 termination;
>> const u32 *bitrate_const;
>> unsigned int bitrate_const_cnt;
>> const u32 *data_bitrate_const;
>> unsigned int data_bitrate_const_cnt;
...move it here.
>> struct can_clock clock;
>
> +
> enum can_state state;
>
> /* CAN controller features - see include/uapi/linux/can/netlink.h */
> @@ -166,6 +168,12 @@ void can_put_echo_skb(struct sk_buff *skb, struct
> net_device *dev,
> unsigned int can_get_echo_skb(struct net_device *dev, unsigned int idx);
> void can_free_echo_skb(struct net_device *dev, unsigned int idx);
>
> +#ifdef CONFIG_OF
> +void of_can_transceiver(struct net_device *dev);
> +#else
> +static inline void of_can_transceiver(struct net_device *dev) { }
> +#endif
> +
> struct sk_buff *alloc_can_skb(struct net_device *dev, struct can_frame **cf);
> struct sk_buff *alloc_canfd_skb(struct net_device *dev,
> struct canfd_frame **cfd);
>
Marc
--
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