| /* SPDX-License-Identifier: GPL-2.0 */ |
| /* Copyright (C) 2020 Oliver Hartkopp <socketcan@hartkopp.net> |
| * Copyright (C) 2020 Marc Kleine-Budde <kernel@pengutronix.de> |
| * Copyright (C) 2020, 2023 Vincent Mailhol <mailhol.vincent@wanadoo.fr> |
| */ |
| |
| #ifndef _CAN_LENGTH_H |
| #define _CAN_LENGTH_H |
| |
| #include <linux/bits.h> |
| #include <linux/can.h> |
| #include <linux/can/netlink.h> |
| #include <linux/math.h> |
| |
| /* |
| * Size of a Classical CAN Standard Frame header in bits |
| * |
| * Name of Field Bits |
| * --------------------------------------------------------- |
| * Start Of Frame (SOF) 1 |
| * Arbitration field: |
| * base ID 11 |
| * Remote Transmission Request (RTR) 1 |
| * Control field: |
| * IDentifier Extension bit (IDE) 1 |
| * FD Format indicator (FDF) 1 |
| * Data Length Code (DLC) 4 |
| * |
| * including all fields preceding the data field, ignoring bitstuffing |
| */ |
| #define CAN_FRAME_HEADER_SFF_BITS 19 |
| |
| /* |
| * Size of a Classical CAN Extended Frame header in bits |
| * |
| * Name of Field Bits |
| * --------------------------------------------------------- |
| * Start Of Frame (SOF) 1 |
| * Arbitration field: |
| * base ID 11 |
| * Substitute Remote Request (SRR) 1 |
| * IDentifier Extension bit (IDE) 1 |
| * ID extension 18 |
| * Remote Transmission Request (RTR) 1 |
| * Control field: |
| * FD Format indicator (FDF) 1 |
| * Reserved bit (r0) 1 |
| * Data length code (DLC) 4 |
| * |
| * including all fields preceding the data field, ignoring bitstuffing |
| */ |
| #define CAN_FRAME_HEADER_EFF_BITS 39 |
| |
| /* |
| * Size of a CAN-FD Standard Frame in bits |
| * |
| * Name of Field Bits |
| * --------------------------------------------------------- |
| * Start Of Frame (SOF) 1 |
| * Arbitration field: |
| * base ID 11 |
| * Remote Request Substitution (RRS) 1 |
| * Control field: |
| * IDentifier Extension bit (IDE) 1 |
| * FD Format indicator (FDF) 1 |
| * Reserved bit (res) 1 |
| * Bit Rate Switch (BRS) 1 |
| * Error Status Indicator (ESI) 1 |
| * Data length code (DLC) 4 |
| * |
| * including all fields preceding the data field, ignoring bitstuffing |
| */ |
| #define CANFD_FRAME_HEADER_SFF_BITS 22 |
| |
| /* |
| * Size of a CAN-FD Extended Frame in bits |
| * |
| * Name of Field Bits |
| * --------------------------------------------------------- |
| * Start Of Frame (SOF) 1 |
| * Arbitration field: |
| * base ID 11 |
| * Substitute Remote Request (SRR) 1 |
| * IDentifier Extension bit (IDE) 1 |
| * ID extension 18 |
| * Remote Request Substitution (RRS) 1 |
| * Control field: |
| * FD Format indicator (FDF) 1 |
| * Reserved bit (res) 1 |
| * Bit Rate Switch (BRS) 1 |
| * Error Status Indicator (ESI) 1 |
| * Data length code (DLC) 4 |
| * |
| * including all fields preceding the data field, ignoring bitstuffing |
| */ |
| #define CANFD_FRAME_HEADER_EFF_BITS 41 |
| |
| /* |
| * Size of a CAN CRC Field in bits |
| * |
| * Name of Field Bits |
| * --------------------------------------------------------- |
| * CRC sequence (CRC15) 15 |
| * CRC Delimiter 1 |
| * |
| * ignoring bitstuffing |
| */ |
| #define CAN_FRAME_CRC_FIELD_BITS 16 |
| |
| /* |
| * Size of a CAN-FD CRC17 Field in bits (length: 0..16) |
| * |
| * Name of Field Bits |
| * --------------------------------------------------------- |
| * Stuff Count 4 |
| * CRC Sequence (CRC17) 17 |
| * CRC Delimiter 1 |
| * Fixed stuff bits 6 |
| */ |
| #define CANFD_FRAME_CRC17_FIELD_BITS 28 |
| |
| /* |
| * Size of a CAN-FD CRC21 Field in bits (length: 20..64) |
| * |
| * Name of Field Bits |
| * --------------------------------------------------------- |
| * Stuff Count 4 |
| * CRC sequence (CRC21) 21 |
| * CRC Delimiter 1 |
| * Fixed stuff bits 7 |
| */ |
| #define CANFD_FRAME_CRC21_FIELD_BITS 33 |
| |
| /* |
| * Size of a CAN(-FD) Frame footer in bits |
| * |
| * Name of Field Bits |
| * --------------------------------------------------------- |
| * ACK slot 1 |
| * ACK delimiter 1 |
| * End Of Frame (EOF) 7 |
| * |
| * including all fields following the CRC field |
| */ |
| #define CAN_FRAME_FOOTER_BITS 9 |
| |
| /* |
| * First part of the Inter Frame Space |
| * (a.k.a. IMF - intermission field) |
| */ |
| #define CAN_INTERMISSION_BITS 3 |
| |
| /** |
| * can_bitstuffing_len() - Calculate the maximum length with bitstuffing |
| * @destuffed_len: length of a destuffed bit stream |
| * |
| * The worst bit stuffing case is a sequence in which dominant and |
| * recessive bits alternate every four bits: |
| * |
| * Destuffed: 1 1111 0000 1111 0000 1111 |
| * Stuffed: 1 1111o 0000i 1111o 0000i 1111o |
| * |
| * Nomenclature |
| * |
| * - "0": dominant bit |
| * - "o": dominant stuff bit |
| * - "1": recessive bit |
| * - "i": recessive stuff bit |
| * |
| * Aside from the first bit, one stuff bit is added every four bits. |
| * |
| * Return: length of the stuffed bit stream in the worst case scenario. |
| */ |
| #define can_bitstuffing_len(destuffed_len) \ |
| (destuffed_len + (destuffed_len - 1) / 4) |
| |
| #define __can_bitstuffing_len(bitstuffing, destuffed_len) \ |
| (bitstuffing ? can_bitstuffing_len(destuffed_len) : \ |
| destuffed_len) |
| |
| #define __can_cc_frame_bits(is_eff, bitstuffing, \ |
| intermission, data_len) \ |
| ( \ |
| __can_bitstuffing_len(bitstuffing, \ |
| (is_eff ? CAN_FRAME_HEADER_EFF_BITS : \ |
| CAN_FRAME_HEADER_SFF_BITS) + \ |
| (data_len) * BITS_PER_BYTE + \ |
| CAN_FRAME_CRC_FIELD_BITS) + \ |
| CAN_FRAME_FOOTER_BITS + \ |
| (intermission ? CAN_INTERMISSION_BITS : 0) \ |
| ) |
| |
| #define __can_fd_frame_bits(is_eff, bitstuffing, \ |
| intermission, data_len) \ |
| ( \ |
| __can_bitstuffing_len(bitstuffing, \ |
| (is_eff ? CANFD_FRAME_HEADER_EFF_BITS : \ |
| CANFD_FRAME_HEADER_SFF_BITS) + \ |
| (data_len) * BITS_PER_BYTE) + \ |
| ((data_len) <= 16 ? \ |
| CANFD_FRAME_CRC17_FIELD_BITS : \ |
| CANFD_FRAME_CRC21_FIELD_BITS) + \ |
| CAN_FRAME_FOOTER_BITS + \ |
| (intermission ? CAN_INTERMISSION_BITS : 0) \ |
| ) |
| |
| /** |
| * can_frame_bits() - Calculate the number of bits on the wire in a |
| * CAN frame |
| * @is_fd: true: CAN-FD frame; false: Classical CAN frame. |
| * @is_eff: true: Extended frame; false: Standard frame. |
| * @bitstuffing: true: calculate the bitstuffing worst case; false: |
| * calculate the bitstuffing best case (no dynamic |
| * bitstuffing). CAN-FD's fixed stuff bits are always included. |
| * @intermission: if and only if true, include the inter frame space |
| * assuming no bus idle (i.e. only the intermission). Strictly |
| * speaking, the inter frame space is not part of the |
| * frame. However, it is needed when calculating the delay |
| * between the Start Of Frame of two consecutive frames. |
| * @data_len: length of the data field in bytes. Correspond to |
| * can(fd)_frame->len. Should be zero for remote frames. No |
| * sanitization is done on @data_len and it shall have no side |
| * effects. |
| * |
| * Return: the numbers of bits on the wire of a CAN frame. |
| */ |
| #define can_frame_bits(is_fd, is_eff, bitstuffing, \ |
| intermission, data_len) \ |
| ( \ |
| is_fd ? __can_fd_frame_bits(is_eff, bitstuffing, \ |
| intermission, data_len) : \ |
| __can_cc_frame_bits(is_eff, bitstuffing, \ |
| intermission, data_len) \ |
| ) |
| |
| /* |
| * Number of bytes in a CAN frame |
| * (rounded up, including intermission) |
| */ |
| #define can_frame_bytes(is_fd, is_eff, bitstuffing, data_len) \ |
| DIV_ROUND_UP(can_frame_bits(is_fd, is_eff, bitstuffing, \ |
| true, data_len), \ |
| BITS_PER_BYTE) |
| |
| /* |
| * Maximum size of a Classical CAN frame |
| * (rounded up, ignoring bitstuffing but including intermission) |
| */ |
| #define CAN_FRAME_LEN_MAX can_frame_bytes(false, true, false, CAN_MAX_DLEN) |
| |
| /* |
| * Maximum size of a CAN-FD frame |
| * (rounded up, ignoring dynamic bitstuffing but including intermission) |
| */ |
| #define CANFD_FRAME_LEN_MAX can_frame_bytes(true, true, false, 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 */ |
