From: Faiz Abbas <faiz_abbas@ti.com>
To: Marc Kleine-Budde <mkl@pengutronix.de>, <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: Wed, 3 Jan 2018 17:49:33 +0530 [thread overview]
Message-ID: <b023ccf0-ec9b-30b9-f868-aaf7286df247@ti.com> (raw)
In-Reply-To: <b3cb6058-f61f-b643-a26f-c8330d9a3ffa@pengutronix.de>
Hi Marc,
On Tuesday 02 January 2018 06:30 PM, Marc Kleine-Budde wrote:
> 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".
I would prefer to keep the distinction.
>
>> +
>> 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 ...
Sure.
>
>>> 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.
Ok.
Thanks,
Faiz
next prev parent reply other threads:[~2018-01-03 12:19 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
2018-01-03 12:19 ` Faiz Abbas [this message]
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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