From: Marc Kleine-Budde <mkl@pengutronix.de>
To: Faiz Abbas <faiz_abbas@ti.com>,
wg@grandegger.com, robh+dt@kernel.org, mark.rutland@arm.com
Cc: linux-can@vger.kernel.org, netdev@vger.kernel.org,
devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
nsekhar@ti.com, fcooper@ti.com, robh@kernel.org,
Wenyou.Yang@microchip.com, sergei.shtylyov@cogentembedded.com
Subject: Re: [PATCH v6 1/6] can: dev: Add support for limiting configured bitrate
Date: Tue, 2 Jan 2018 14:00:50 +0100 [thread overview]
Message-ID: <b3cb6058-f61f-b643-a26f-c8330d9a3ffa@pengutronix.de> (raw)
In-Reply-To: <1513949488-13026-2-git-send-email-faiz_abbas@ti.com>
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On 12/22/2017 02:31 PM, Faiz Abbas wrote:
> From: Franklin S Cooper Jr <fcooper@ti.com>
>
> 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 <fcooper@ti.com>
> [nsekhar@ti.com: fix build error with !CONFIG_OF]
> Signed-off-by: Sekhar Nori <nsekhar@ti.com>
> Signed-off-by: Faiz Abbas <faiz_abbas@ti.com>
> ---
> 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
--
Pengutronix e.K. | Marc Kleine-Budde |
Industrial Linux Solutions | Phone: +49-231-2826-924 |
Vertretung West/Dortmund | Fax: +49-5121-206917-5555 |
Amtsgericht Hildesheim, HRA 2686 | http://www.pengutronix.de |
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next prev parent reply other threads:[~2018-01-02 13:10 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-22 13:31 [PATCH v6 0/6] Add M_CAN Support for Dra76 platform Faiz Abbas
2017-12-22 13:31 ` [PATCH v6 1/6] can: dev: Add support for limiting configured bitrate Faiz Abbas
2018-01-02 13:00 ` Marc Kleine-Budde [this message]
2018-01-03 12:19 ` Faiz Abbas
2018-01-02 16:15 ` Marc Kleine-Budde
2018-01-03 12:21 ` Faiz Abbas
2017-12-22 13:31 ` [PATCH v6 2/6] can: m_can: Add call to of_can_transceiver Faiz Abbas
2017-12-22 13:31 ` [PATCH v6 3/6] can: m_can: Add PM Runtime Faiz Abbas
2018-01-02 16:07 ` Marc Kleine-Budde
2018-01-03 12:39 ` Faiz Abbas
2018-01-03 14:25 ` Marc Kleine-Budde
2018-01-03 15:06 ` Faiz Abbas
2018-01-03 15:17 ` Marc Kleine-Budde
2018-01-04 15:17 ` Faiz Abbas
2018-01-04 15:18 ` Marc Kleine-Budde
2018-01-05 1:23 ` Yang, Wenyou
2017-12-22 13:31 ` [PATCH v6 4/6] can: m_can: Support higher speed CAN-FD bitrates Faiz Abbas
2018-01-02 13:35 ` Marc Kleine-Budde
2018-01-03 12:55 ` Faiz Abbas
2017-12-22 13:31 ` [PATCH v6 5/6] dt-bindings: can: m_can: Document new can transceiver binding Faiz Abbas
2017-12-22 13:31 ` [PATCH v6 6/6] dt-bindings: can: can-transceiver: Document new binding Faiz Abbas
2017-12-29 3:38 ` [PATCH v6 0/6] Add M_CAN Support for Dra76 platform Yang, Wenyou
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