/* 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) 4 * CRC 0...16: 17 20...64:21 * CRC delimiter (CD) 1 * Fixed Stuff bits (FSB) 0...16: 6 20...64:7 * ACK slot (AS) 1 * ACK delimiter (AD) 1 * End-of-frame (EOF) 7 * Inter frame spacing 3 * * assuming CRC21, rounded up and ignoring dynamic bitstuffing */ #define CANFD_FRAME_OVERHEAD_SFF DIV_ROUND_UP(67, 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) 4 * CRC 0...16: 17 20...64:21 * CRC delimiter (CD) 1 * Fixed Stuff bits (FSB) 0...16: 6 20...64:7 * ACK slot (AS) 1 * ACK delimiter (AD) 1 * End-of-frame (EOF) 7 * Inter frame spacing 3 * * assuming CRC21, rounded up and ignoring dynamic bitstuffing */ #define CANFD_FRAME_OVERHEAD_EFF DIV_ROUND_UP(86, 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. * * To be used in the CAN netdriver receive path to ensure conformance with * ISO 11898-1 Chapter 8.4.2.3 (DLC field) */ #define can_cc_dlc2len(dlc) (min_t(u8, (dlc), CAN_MAX_DLEN)) /* helper to get the data length code (DLC) for Classical CAN raw DLC access */ static inline u8 can_get_cc_dlc(const struct can_frame *cf, const u32 ctrlmode) { /* return len8_dlc as dlc value only if all conditions apply */ if ((ctrlmode & CAN_CTRLMODE_CC_LEN8_DLC) && (cf->len == CAN_MAX_DLEN) && (cf->len8_dlc > CAN_MAX_DLEN && cf->len8_dlc <= CAN_MAX_RAW_DLC)) return cf->len8_dlc; /* return the payload length as dlc value */ return cf->len; } /* helper to set len and len8_dlc value for Classical CAN raw DLC access */ static inline void can_frame_set_cc_len(struct can_frame *cf, const u8 dlc, const u32 ctrlmode) { /* the caller already ensured that dlc is a value from 0 .. 15 */ if (ctrlmode & CAN_CTRLMODE_CC_LEN8_DLC && dlc > CAN_MAX_DLEN) cf->len8_dlc = dlc; /* limit the payload length 'len' to CAN_MAX_DLEN */ cf->len = can_cc_dlc2len(dlc); } /* get data length from raw data length code (DLC) */ 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) { return can_fd_dlc2len(can_fd_len2dlc(len)); } #endif /* !_CAN_LENGTH_H */