Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752129AbdHCAyM (ORCPT ); Wed, 2 Aug 2017 20:54:12 -0400 Received: from fllnx209.ext.ti.com ([198.47.19.16]:53849 "EHLO fllnx209.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752005AbdHCAyK (ORCPT ); Wed, 2 Aug 2017 20:54:10 -0400 From: Franklin S Cooper Jr To: , , , , , , , , , , , CC: Franklin S Cooper Jr Subject: [PATCH v3 1/4] can: dev: Add support for limiting configured bitrate Date: Wed, 2 Aug 2017 19:51:47 -0500 Message-ID: <20170803005150.9286-2-fcooper@ti.com> X-Mailer: git-send-email 2.9.4.dirty In-Reply-To: <20170803005150.9286-1-fcooper@ti.com> References: <20170803005150.9286-1-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: 3928 Lines: 123 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 fixed-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 --- drivers/net/can/dev.c | 50 +++++++++++++++++++++++++++++++++++++++++++++++++ include/linux/can/dev.h | 5 +++++ 2 files changed, 55 insertions(+) diff --git a/drivers/net/can/dev.c b/drivers/net/can/dev.c index 365a8cc..db56914 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 +815,39 @@ 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_fixed(struct net_device *dev) +{ + struct device_node *dn; + struct can_priv *priv = netdev_priv(dev); + struct device_node *np; + unsigned int max_bitrate; + int ret; + + np = dev->dev.parent->of_node; + + dn = of_get_child_by_name(np, "fixed-transceiver"); + if (!dn) + return; + + max_bitrate = 0; + ret = of_property_read_u32(dn, "max-bitrate", &max_bitrate); + + if (max_bitrate > 0) { + priv->max_bitrate = max_bitrate; + priv->is_bitrate_limited = true; + } else if (ret != -EINVAL) { + netdev_warn(dev, "Invalid value for transceiver max bitrate\n"); + } +} +EXPORT_SYMBOL(of_can_transceiver_fixed); +#endif + /* * Common close function for cleanup before the device gets closed. * @@ -913,6 +947,14 @@ static int can_changelink(struct net_device *dev, struct nlattr *tb[], priv->bitrate_const_cnt); if (err) return err; + + if (priv->is_bitrate_limited && + 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 +1039,14 @@ static int can_changelink(struct net_device *dev, struct nlattr *tb[], priv->data_bitrate_const_cnt); if (err) return err; + + if (priv->is_bitrate_limited && + 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..a6e62df 100644 --- a/include/linux/can/dev.h +++ b/include/linux/can/dev.h @@ -47,6 +47,9 @@ struct can_priv { unsigned int data_bitrate_const_cnt; struct can_clock clock; + unsigned int max_bitrate; + bool is_bitrate_limited; + enum can_state state; /* CAN controller features - see include/uapi/linux/can/netlink.h */ @@ -165,6 +168,8 @@ 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_fixed(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