Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933191AbdGSXiw (ORCPT ); Wed, 19 Jul 2017 19:38:52 -0400 Received: from fllnx209.ext.ti.com ([198.47.19.16]:37551 "EHLO fllnx209.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932215AbdGSXis (ORCPT ); Wed, 19 Jul 2017 19:38:48 -0400 From: Franklin S Cooper Jr To: , , , , , , , , , CC: Franklin S Cooper Jr Subject: [PATCH 1/4] can: dev: Add support for limiting configured bitrate Date: Wed, 19 Jul 2017 18:36:51 -0500 Message-ID: <20170719233654.25908-2-fcooper@ti.com> X-Mailer: git-send-email 2.10.0 In-Reply-To: <20170719233654.25908-1-fcooper@ti.com> References: <20170719233654.25908-1-fcooper@ti.com> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3733 Lines: 114 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 | 48 ++++++++++++++++++++++++++++++++++++++++++++++++ include/linux/can/dev.h | 5 +++++ 2 files changed, 53 insertions(+) diff --git a/drivers/net/can/dev.c b/drivers/net/can/dev.c index 365a8cc..fbab87d 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" @@ -806,6 +807,21 @@ int open_candev(struct net_device *dev) return -EINVAL; } + if (priv->max_trans_arbitration_speed > 0 && + priv->bittiming.bitrate > priv->max_trans_arbitration_speed) { + netdev_err(dev, "arbitration bitrate surpasses transceiver capabilities of %d bps\n", + priv->max_trans_arbitration_speed); + return -EINVAL; + } + + if (priv->max_trans_data_speed >= 0 && + (priv->ctrlmode & CAN_CTRLMODE_FD) && + (priv->data_bittiming.bitrate > priv->max_trans_data_speed)) { + netdev_err(dev, "canfd data bitrate surpasses transceiver capabilities of %d bps\n", + priv->max_trans_data_speed); + return -EINVAL; + } + /* Switch carrier on if device was stopped while in bus-off state */ if (!netif_carrier_ok(dev)) netif_carrier_on(dev); @@ -814,6 +830,38 @@ int open_candev(struct net_device *dev) } EXPORT_SYMBOL_GPL(open_candev); +#ifdef CONFIG_OF +void of_transceiver_is_fixed(struct net_device *dev) +{ + struct device_node *dn; + struct can_priv *priv = netdev_priv(dev); + u32 max_frequency; + struct device_node *np; + + np = dev->dev.parent->of_node; + + /* New binding */ + dn = of_get_child_by_name(np, "fixed-transceiver"); + if (!dn) + return; + + of_property_read_u32(dn, "max-arbitration-speed", &max_frequency); + + if (max_frequency > 0) + priv->max_trans_arbitration_speed = max_frequency; + else + priv->max_trans_arbitration_speed = -1; + + of_property_read_u32(dn, "max-data-speed", &max_frequency); + + if (max_frequency >= 0) + priv->max_trans_data_speed = max_frequency; + else + priv->max_trans_data_speed = -1; +} +EXPORT_SYMBOL(of_transceiver_is_fixed); +#endif + /* * Common close function for cleanup before the device gets closed. * diff --git a/include/linux/can/dev.h b/include/linux/can/dev.h index 141b05a..aec72b5 100644 --- a/include/linux/can/dev.h +++ b/include/linux/can/dev.h @@ -69,6 +69,9 @@ struct can_priv { unsigned int echo_skb_max; struct sk_buff **echo_skb; + unsigned int max_trans_arbitration_speed; + unsigned int max_trans_data_speed; + #ifdef CONFIG_CAN_LEDS struct led_trigger *tx_led_trig; char tx_led_trig_name[CAN_LED_NAME_SZ]; @@ -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_transceiver_is_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); -- 2.10.0