From patchwork Wed Jan 13 21:14:04 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Marc Kleine-Budde X-Patchwork-Id: 12018385 X-Patchwork-Delegate: kuba@kernel.org Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2B130C433E6 for ; Thu, 14 Jan 2021 02:16:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DB19F23343 for ; Thu, 14 Jan 2021 02:16:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728883AbhANCQg (ORCPT ); Wed, 13 Jan 2021 21:16:36 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40646 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729045AbhAMVQZ (ORCPT ); Wed, 13 Jan 2021 16:16:25 -0500 Received: from metis.ext.pengutronix.de (metis.ext.pengutronix.de [IPv6:2001:67c:670:201:290:27ff:fe1d:cc33]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 82C6CC061382 for ; Wed, 13 Jan 2021 13:14:34 -0800 (PST) Received: from gallifrey.ext.pengutronix.de ([2001:67c:670:201:5054:ff:fe8d:eefb] helo=bjornoya.blackshift.org) by metis.ext.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1kznTN-0001vC-3X for netdev@vger.kernel.org; Wed, 13 Jan 2021 22:14:33 +0100 Received: from dspam.blackshift.org (localhost [127.0.0.1]) by bjornoya.blackshift.org (Postfix) with SMTP id E74045C3075 for ; Wed, 13 Jan 2021 21:14:24 +0000 (UTC) Received: from hardanger.blackshift.org (unknown [172.20.34.65]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-384) server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by bjornoya.blackshift.org (Postfix) with ESMTPS id 47C5E5C300F; Wed, 13 Jan 2021 21:14:13 +0000 (UTC) Received: from blackshift.org (localhost [::1]) by hardanger.blackshift.org (OpenSMTPD) with ESMTP id 3292b448; Wed, 13 Jan 2021 21:14:11 +0000 (UTC) From: Marc Kleine-Budde To: netdev@vger.kernel.org Cc: davem@davemloft.net, kuba@kernel.org, linux-can@vger.kernel.org, kernel@pengutronix.de, Vincent Mailhol , Arunachalam Santhanam , Marc Kleine-Budde Subject: [net-next 11/17] can: length: can_skb_get_frame_len(): introduce function to get data length of frame in data link layer Date: Wed, 13 Jan 2021 22:14:04 +0100 Message-Id: <20210113211410.917108-12-mkl@pengutronix.de> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20210113211410.917108-1-mkl@pengutronix.de> References: <20210113211410.917108-1-mkl@pengutronix.de> MIME-Version: 1.0 X-SA-Exim-Connect-IP: 2001:67c:670:201:5054:ff:fe8d:eefb X-SA-Exim-Mail-From: mkl@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: netdev@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org From: Vincent Mailhol This patch adds the function can_skb_get_frame_len() which returns the length of a CAN frame on the data link layer, including Start-of-frame, Identifier, various other bits, the actual data, the CRC, the End-of-frame, the Inter frame spacing. Co-developed-by: Arunachalam Santhanam Signed-off-by: Arunachalam Santhanam Co-developed-by: Vincent Mailhol Signed-off-by: Vincent Mailhol Acked-by: Vincent Mailhol Reviewed-by: Vincent Mailhol Co-developed-by: Marc Kleine-Budde Link: https://lore.kernel.org/r/20210111141930.693847-11-mkl@pengutronix.de Signed-off-by: Marc Kleine-Budde --- drivers/net/can/dev/length.c | 50 +++++++++++++++ include/linux/can/length.h | 120 +++++++++++++++++++++++++++++++++++ 2 files changed, 170 insertions(+) diff --git a/drivers/net/can/dev/length.c b/drivers/net/can/dev/length.c index d695a3bee1ed..20cd153a45a5 100644 --- a/drivers/net/can/dev/length.c +++ b/drivers/net/can/dev/length.c @@ -38,3 +38,53 @@ u8 can_fd_len2dlc(u8 len) return len2dlc[len]; } EXPORT_SYMBOL_GPL(can_fd_len2dlc); + +/** + * can_skb_get_frame_len() - Calculate the CAN Frame length in bytes + * of a given skb. + * @skb: socket buffer of a CAN message. + * + * Do a rough calculation: bit stuffing is ignored and length in bits + * is rounded up to a length in bytes. + * + * Rationale: this function is to be used for the BQL functions + * (netdev_sent_queue() and netdev_completed_queue()) which expect a + * value in bytes. Just using skb->len is insufficient because it will + * return the constant value of CAN(FD)_MTU. Doing the bit stuffing + * calculation would be too expensive in term of computing resources + * for no noticeable gain. + * + * Remarks: The payload of CAN FD frames with BRS flag are sent at a + * different bitrate. Currently, the can-utils canbusload tool does + * not support CAN-FD yet and so we could not run any benchmark to + * measure the impact. There might be possible improvement here. + * + * Return: length in bytes. + */ +unsigned int can_skb_get_frame_len(const struct sk_buff *skb) +{ + const struct canfd_frame *cf = (const struct canfd_frame *)skb->data; + u8 len; + + if (can_is_canfd_skb(skb)) + len = canfd_sanitize_len(cf->len); + else if (cf->can_id & CAN_RTR_FLAG) + len = 0; + else + len = cf->len; + + if (can_is_canfd_skb(skb)) { + if (cf->can_id & CAN_EFF_FLAG) + len += CANFD_FRAME_OVERHEAD_EFF; + else + len += CANFD_FRAME_OVERHEAD_SFF; + } else { + if (cf->can_id & CAN_EFF_FLAG) + len += CAN_FRAME_OVERHEAD_EFF; + else + len += CAN_FRAME_OVERHEAD_SFF; + } + + return len; +} +EXPORT_SYMBOL_GPL(can_skb_get_frame_len); diff --git a/include/linux/can/length.h b/include/linux/can/length.h index b2313b2a0b02..6995092b774e 100644 --- a/include/linux/can/length.h +++ b/include/linux/can/length.h @@ -1,10 +1,127 @@ /* SPDX-License-Identifier: GPL-2.0 */ /* Copyright (C) 2020 Oliver Hartkopp + * Copyright (C) 2020 Marc Kleine-Budde */ #ifndef _CAN_LENGTH_H #define _CAN_LENGTH_H +/* + * Size of a Classical CAN Standard Frame + * + * Name of Field Bits + * --------------------------------------------------------- + * Start-of-frame 1 + * Identifier 11 + * Remote transmission request (RTR) 1 + * Identifier extension bit (IDE) 1 + * Reserved bit (r0) 1 + * Data length code (DLC) 4 + * Data field 0...64 + * CRC 15 + * CRC delimiter 1 + * ACK slot 1 + * ACK delimiter 1 + * End-of-frame (EOF) 7 + * Inter frame spacing 3 + * + * rounded up and ignoring bitstuffing + */ +#define CAN_FRAME_OVERHEAD_SFF DIV_ROUND_UP(47, 8) + +/* + * Size of a Classical CAN Extended Frame + * + * Name of Field Bits + * --------------------------------------------------------- + * Start-of-frame 1 + * Identifier A 11 + * Substitute remote request (SRR) 1 + * Identifier extension bit (IDE) 1 + * Identifier B 18 + * Remote transmission request (RTR) 1 + * Reserved bits (r1, r0) 2 + * Data length code (DLC) 4 + * Data field 0...64 + * CRC 15 + * CRC delimiter 1 + * ACK slot 1 + * ACK delimiter 1 + * End-of-frame (EOF) 7 + * Inter frame spacing 3 + * + * rounded up and ignoring bitstuffing + */ +#define CAN_FRAME_OVERHEAD_EFF DIV_ROUND_UP(67, 8) + +/* + * Size of a CAN-FD Standard Frame + * + * Name of Field Bits + * --------------------------------------------------------- + * Start-of-frame 1 + * Identifier 11 + * Reserved bit (r1) 1 + * Identifier extension bit (IDE) 1 + * Flexible data rate format (FDF) 1 + * Reserved bit (r0) 1 + * Bit Rate Switch (BRS) 1 + * Error Status Indicator (ESI) 1 + * Data length code (DLC) 4 + * Data field 0...512 + * Stuff Bit Count (SBC) 0...16: 4 20...64:5 + * CRC 0...16: 17 20...64:21 + * CRC delimiter (CD) 1 + * ACK slot (AS) 1 + * ACK delimiter (AD) 1 + * End-of-frame (EOF) 7 + * Inter frame spacing 3 + * + * assuming CRC21, rounded up and ignoring bitstuffing + */ +#define CANFD_FRAME_OVERHEAD_SFF DIV_ROUND_UP(61, 8) + +/* + * Size of a CAN-FD Extended Frame + * + * Name of Field Bits + * --------------------------------------------------------- + * Start-of-frame 1 + * Identifier A 11 + * Substitute remote request (SRR) 1 + * Identifier extension bit (IDE) 1 + * Identifier B 18 + * Reserved bit (r1) 1 + * Flexible data rate format (FDF) 1 + * Reserved bit (r0) 1 + * Bit Rate Switch (BRS) 1 + * Error Status Indicator (ESI) 1 + * Data length code (DLC) 4 + * Data field 0...512 + * Stuff Bit Count (SBC) 0...16: 4 20...64:5 + * CRC 0...16: 17 20...64:21 + * CRC delimiter (CD) 1 + * ACK slot (AS) 1 + * ACK delimiter (AD) 1 + * End-of-frame (EOF) 7 + * Inter frame spacing 3 + * + * assuming CRC21, rounded up and ignoring bitstuffing + */ +#define CANFD_FRAME_OVERHEAD_EFF DIV_ROUND_UP(80, 8) + +/* + * Maximum size of a Classical CAN frame + * (rounded up and ignoring bitstuffing) + */ +#define CAN_FRAME_LEN_MAX (CAN_FRAME_OVERHEAD_EFF + CAN_MAX_DLEN) + +/* + * Maximum size of a CAN-FD frame + * (rounded up and ignoring bitstuffing) + */ +#define CANFD_FRAME_LEN_MAX (CANFD_FRAME_OVERHEAD_EFF + CANFD_MAX_DLEN) + /* * can_cc_dlc2len(value) - convert a given data length code (dlc) of a * Classical CAN frame into a valid data length of max. 8 bytes. @@ -45,6 +162,9 @@ u8 can_fd_dlc2len(u8 dlc); /* map the sanitized data length to an appropriate data length code */ u8 can_fd_len2dlc(u8 len); +/* calculate the CAN Frame length in bytes of a given skb */ +unsigned int can_skb_get_frame_len(const struct sk_buff *skb); + /* map the data length to an appropriate data link layer length */ static inline u8 canfd_sanitize_len(u8 len) {