From patchwork Fri Nov 20 13:32:55 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Marc Kleine-Budde X-Patchwork-Id: 11920279 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,URIBL_BLOCKED,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 4A645C63798 for ; Fri, 20 Nov 2020 13:33:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F196322272 for ; Fri, 20 Nov 2020 13:33:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728123AbgKTNd1 (ORCPT ); Fri, 20 Nov 2020 08:33:27 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51670 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726553AbgKTNdY (ORCPT ); Fri, 20 Nov 2020 08:33:24 -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 CC0DFC0613CF for ; Fri, 20 Nov 2020 05:33:23 -0800 (PST) Received: from gallifrey.ext.pengutronix.de ([2001:67c:670:201:5054:ff:fe8d:eefb] helo=blackshift.org) by metis.ext.pengutronix.de with esmtp (Exim 4.92) (envelope-from ) id 1kg6XR-0006Fn-Ux; Fri, 20 Nov 2020 14:33:22 +0100 From: Marc Kleine-Budde To: netdev@vger.kernel.org Cc: davem@davemloft.net, kuba@kernel.org, linux-can@vger.kernel.org, kernel@pengutronix.de, Oliver Hartkopp , Vincent Mailhol , Marc Kleine-Budde Subject: [net-next 02/25] can: add optional DLC element to Classical CAN frame structure Date: Fri, 20 Nov 2020 14:32:55 +0100 Message-Id: <20201120133318.3428231-3-mkl@pengutronix.de> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201120133318.3428231-1-mkl@pengutronix.de> References: <20201120133318.3428231-1-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: Oliver Hartkopp ISO 11898-1 Chapter 8.4.2.3 defines a 4 bit data length code (DLC) table which maps the DLC to the payload length of the CAN frame in bytes: DLC -> payload length 0 .. 8 -> 0 .. 8 9 .. 15 -> 8 Although the DLC values 8 .. 15 in Classical CAN always result in a payload length of 8 bytes these DLC values are transparently transmitted on the CAN bus. As the struct can_frame only provides a 'len' element (formerly 'can_dlc') which contains the plain payload length ( 0 .. 8 ) of the CAN frame, the raw DLC is not visible to the application programmer, e.g. for testing use-cases. To access the raw DLC values 9 .. 15 the len8_dlc element is introduced, which is only valid when the payload length 'len' is 8 and the DLC is greater than 8. The len8_dlc element is filled by the CAN interface driver and used for CAN frame creation by the CAN driver when the CAN_CTRLMODE_CC_LEN8_DLC flag is supported by the driver and enabled via netlink configuration interface. Reported-by: Vincent Mailhol Signed-off-by: Oliver Hartkopp Link: https://lore.kernel.org/r/20201110101852.1973-2-socketcan@hartkopp.net Signed-off-by: Marc Kleine-Budde --- include/uapi/linux/can.h | 38 ++++++++++++++++++++------------ include/uapi/linux/can/netlink.h | 1 + 2 files changed, 25 insertions(+), 14 deletions(-) diff --git a/include/uapi/linux/can.h b/include/uapi/linux/can.h index 6a6d2c7655ff..f75238ac6dce 100644 --- a/include/uapi/linux/can.h +++ b/include/uapi/linux/can.h @@ -84,6 +84,7 @@ typedef __u32 can_err_mask_t; /* CAN payload length and DLC definitions according to ISO 11898-1 */ #define CAN_MAX_DLC 8 +#define CAN_MAX_RAW_DLC 15 #define CAN_MAX_DLEN 8 /* CAN FD payload length and DLC definitions according to ISO 11898-7 */ @@ -91,23 +92,32 @@ typedef __u32 can_err_mask_t; #define CANFD_MAX_DLEN 64 /** - * struct can_frame - basic CAN frame structure - * @can_id: CAN ID of the frame and CAN_*_FLAG flags, see canid_t definition - * @can_dlc: frame payload length in byte (0 .. 8) aka data length code - * N.B. the DLC field from ISO 11898-1 Chapter 8.4.2.3 has a 1:1 - * mapping of the 'data length code' to the real payload length - * @__pad: padding - * @__res0: reserved / padding - * @__res1: reserved / padding - * @data: CAN frame payload (up to 8 byte) + * struct can_frame - Classical CAN frame structure (aka CAN 2.0B) + * @can_id: CAN ID of the frame and CAN_*_FLAG flags, see canid_t definition + * @len: CAN frame payload length in byte (0 .. 8) + * @can_dlc: deprecated name for CAN frame payload length in byte (0 .. 8) + * @__pad: padding + * @__res0: reserved / padding + * @len8_dlc: optional DLC value (9 .. 15) at 8 byte payload length + * len8_dlc contains values from 9 .. 15 when the payload length is + * 8 bytes but the DLC value (see ISO 11898-1) is greater then 8. + * CAN_CTRLMODE_CC_LEN8_DLC flag has to be enabled in CAN driver. + * @data: CAN frame payload (up to 8 byte) */ struct can_frame { canid_t can_id; /* 32 bit CAN_ID + EFF/RTR/ERR flags */ - __u8 can_dlc; /* frame payload length in byte (0 .. CAN_MAX_DLEN) */ - __u8 __pad; /* padding */ - __u8 __res0; /* reserved / padding */ - __u8 __res1; /* reserved / padding */ - __u8 data[CAN_MAX_DLEN] __attribute__((aligned(8))); + union { + /* CAN frame payload length in byte (0 .. CAN_MAX_DLEN) + * was previously named can_dlc so we need to carry that + * name for legacy support + */ + __u8 len; + __u8 can_dlc; /* deprecated */ + }; + __u8 __pad; /* padding */ + __u8 __res0; /* reserved / padding */ + __u8 len8_dlc; /* optional DLC for 8 byte payload length (9 .. 15) */ + __u8 data[CAN_MAX_DLEN] __attribute__((aligned(8))); }; /* diff --git a/include/uapi/linux/can/netlink.h b/include/uapi/linux/can/netlink.h index 6f598b73839e..f730d443b918 100644 --- a/include/uapi/linux/can/netlink.h +++ b/include/uapi/linux/can/netlink.h @@ -100,6 +100,7 @@ struct can_ctrlmode { #define CAN_CTRLMODE_FD 0x20 /* CAN FD mode */ #define CAN_CTRLMODE_PRESUME_ACK 0x40 /* Ignore missing CAN ACKs */ #define CAN_CTRLMODE_FD_NON_ISO 0x80 /* CAN FD in non-ISO mode */ +#define CAN_CTRLMODE_CC_LEN8_DLC 0x100 /* Classic CAN DLC option */ /* * CAN device statistics