From 2290aefa2e90a43af8555ad6431d49de43259aa3 Mon Sep 17 00:00:00 2001 From: Franklin S Cooper Jr Date: Wed, 10 Jan 2018 16:25:18 +0530 Subject: [PATCH] can: dev: Add support for limiting configured bitrate 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. Also add support for reading bitrate_max via the netlink interface. Reviewed-by: Suman Anna Signed-off-by: Franklin S Cooper Jr [nsekhar@ti.com: fix build error with !CONFIG_OF] Signed-off-by: Sekhar Nori Signed-off-by: Faiz Abbas Signed-off-by: Marc Kleine-Budde --- drivers/net/can/dev.c | 45 +++++++++++++++++++++++++++++++- include/linux/can/dev.h | 7 +++++ include/uapi/linux/can/netlink.h | 1 + 3 files changed, 52 insertions(+), 1 deletion(-) diff --git a/drivers/net/can/dev.c b/drivers/net/can/dev.c index 365a8cc62405..cc94604b23e0 100644 --- a/drivers/net/can/dev.c +++ b/drivers/net/can/dev.c @@ -27,6 +27,7 @@ #include #include #include +#include #include #define MOD_DESC "CAN device driver interface" @@ -814,6 +815,29 @@ 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->bitrate_max); + if ((ret && ret != -EINVAL) || (!ret && !priv->bitrate_max)) + 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 +937,13 @@ static int can_changelink(struct net_device *dev, struct nlattr *tb[], priv->bitrate_const_cnt); if (err) return err; + + if (priv->bitrate_max && bt.bitrate > priv->bitrate_max) { + netdev_err(dev, "arbitration bitrate surpasses transceiver capabilities of %d bps\n", + priv->bitrate_max); + return -EINVAL; + } + memcpy(&priv->bittiming, &bt, sizeof(bt)); if (priv->do_set_bittiming) { @@ -997,6 +1028,13 @@ static int can_changelink(struct net_device *dev, struct nlattr *tb[], priv->data_bitrate_const_cnt); if (err) return err; + + if (priv->bitrate_max && dbt.bitrate > priv->bitrate_max) { + netdev_err(dev, "canfd data bitrate surpasses transceiver capabilities of %d bps\n", + priv->bitrate_max); + return -EINVAL; + } + memcpy(&priv->data_bittiming, &dbt, sizeof(dbt)); if (priv->do_set_data_bittiming) { @@ -1064,6 +1102,7 @@ static size_t can_get_size(const struct net_device *dev) if (priv->data_bitrate_const) /* IFLA_CAN_DATA_BITRATE_CONST */ size += nla_total_size(sizeof(*priv->data_bitrate_const) * priv->data_bitrate_const_cnt); + size += sizeof(priv->bitrate_max); /* IFLA_CAN_BITRATE_MAX */ return size; } @@ -1121,7 +1160,11 @@ static int can_fill_info(struct sk_buff *skb, const struct net_device *dev) nla_put(skb, IFLA_CAN_DATA_BITRATE_CONST, sizeof(*priv->data_bitrate_const) * priv->data_bitrate_const_cnt, - priv->data_bitrate_const)) + priv->data_bitrate_const)) || + + (nla_put(skb, IFLA_CAN_BITRATE_MAX, + sizeof(priv->bitrate_max), + &priv->bitrate_max)) ) return -EMSGSIZE; diff --git a/include/linux/can/dev.h b/include/linux/can/dev.h index 61f1cf2d9f44..055aaf5ed9af 100644 --- a/include/linux/can/dev.h +++ b/include/linux/can/dev.h @@ -46,6 +46,7 @@ struct can_priv { unsigned int bitrate_const_cnt; const u32 *data_bitrate_const; unsigned int data_bitrate_const_cnt; + u32 bitrate_max; struct can_clock clock; enum can_state state; @@ -166,6 +167,12 @@ 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); diff --git a/include/uapi/linux/can/netlink.h b/include/uapi/linux/can/netlink.h index 96710e76d5ce..9f56fad4785b 100644 --- a/include/uapi/linux/can/netlink.h +++ b/include/uapi/linux/can/netlink.h @@ -132,6 +132,7 @@ enum { IFLA_CAN_TERMINATION_CONST, IFLA_CAN_BITRATE_CONST, IFLA_CAN_DATA_BITRATE_CONST, + IFLA_CAN_BITRATE_MAX, __IFLA_CAN_MAX };