Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755486AbdLVNbM (ORCPT ); Fri, 22 Dec 2017 08:31:12 -0500 Received: from lelnx194.ext.ti.com ([198.47.27.80]:49152 "EHLO lelnx194.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751770AbdLVNbJ (ORCPT ); Fri, 22 Dec 2017 08:31:09 -0500 From: Faiz Abbas To: , , , CC: , , , , , , , , , Subject: [PATCH v6 1/6] can: dev: Add support for limiting configured bitrate Date: Fri, 22 Dec 2017 19:01:23 +0530 Message-ID: <1513949488-13026-2-git-send-email-faiz_abbas@ti.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1513949488-13026-1-git-send-email-faiz_abbas@ti.com> References: <1513949488-13026-1-git-send-email-faiz_abbas@ti.com> MIME-Version: 1.0 Content-Type: text/plain X-EXCLAIMER-MD-CONFIG: e1e8a2fd-e40a-4ac6-ac9b-f7e9cc9ee180 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4078 Lines: 123 From: Franklin S Cooper Jr 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 [nsekhar@ti.com: fix build error with !CONFIG_OF] Signed-off-by: Sekhar Nori Signed-off-by: Faiz Abbas --- 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 #include #include +#include #include #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; + } + 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; + 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); -- 2.7.4