Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752529AbdHRUWs (ORCPT ); Fri, 18 Aug 2017 16:22:48 -0400 Received: from fllnx210.ext.ti.com ([198.47.19.17]:28926 "EHLO fllnx210.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751867AbdHRUWo (ORCPT ); Fri, 18 Aug 2017 16:22:44 -0400 From: Franklin S Cooper Jr To: , , , , , , , , , , , CC: Franklin S Cooper Jr Subject: [PATCH v5 1/4] can: dev: Add support for limiting configured bitrate Date: Fri, 18 Aug 2017 15:21:34 -0500 Message-ID: <20170818202137.29816-2-fcooper@ti.com> X-Mailer: git-send-email 2.9.4.dirty In-Reply-To: <20170818202137.29816-1-fcooper@ti.com> References: <20170818202137.29816-1-fcooper@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: 3847 Lines: 115 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 --- Version 5 changes: Set values for some variables at the very top. Remove usage of is_bitrate_limited drivers/net/can/dev.c | 39 +++++++++++++++++++++++++++++++++++++++ include/linux/can/dev.h | 4 ++++ 2 files changed, 43 insertions(+) diff --git a/drivers/net/can/dev.c b/drivers/net/can/dev.c index 365a8cc..d0e5b46 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(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 141b05a..0063c51 100644 --- a/include/linux/can/dev.h +++ b/include/linux/can/dev.h @@ -47,6 +47,8 @@ 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 */ @@ -165,6 +167,8 @@ 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); +void of_can_transceiver(struct net_device *dev); + 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); -- 2.9.4.dirty