1 /* SPDX-License-Identifier: GPL-2.0 */ 2 /* Copyright (C) 2020 Oliver Hartkopp <socketcan@hartkopp.net> 3 * Copyright (C) 2020 Marc Kleine-Budde <kernel@pengutronix.de> 4 */ 5 6 #ifndef _CAN_LENGTH_H 7 #define _CAN_LENGTH_H 8 9 /* 10 * Size of a Classical CAN Standard Frame 11 * 12 * Name of Field Bits 13 * --------------------------------------------------------- 14 * Start-of-frame 1 15 * Identifier 11 16 * Remote transmission request (RTR) 1 17 * Identifier extension bit (IDE) 1 18 * Reserved bit (r0) 1 19 * Data length code (DLC) 4 20 * Data field 0...64 21 * CRC 15 22 * CRC delimiter 1 23 * ACK slot 1 24 * ACK delimiter 1 25 * End-of-frame (EOF) 7 26 * Inter frame spacing 3 27 * 28 * rounded up and ignoring bitstuffing 29 */ 30 #define CAN_FRAME_OVERHEAD_SFF DIV_ROUND_UP(47, 8) 31 32 /* 33 * Size of a Classical CAN Extended Frame 34 * 35 * Name of Field Bits 36 * --------------------------------------------------------- 37 * Start-of-frame 1 38 * Identifier A 11 39 * Substitute remote request (SRR) 1 40 * Identifier extension bit (IDE) 1 41 * Identifier B 18 42 * Remote transmission request (RTR) 1 43 * Reserved bits (r1, r0) 2 44 * Data length code (DLC) 4 45 * Data field 0...64 46 * CRC 15 47 * CRC delimiter 1 48 * ACK slot 1 49 * ACK delimiter 1 50 * End-of-frame (EOF) 7 51 * Inter frame spacing 3 52 * 53 * rounded up and ignoring bitstuffing 54 */ 55 #define CAN_FRAME_OVERHEAD_EFF DIV_ROUND_UP(67, 8) 56 57 /* 58 * Size of a CAN-FD Standard Frame 59 * 60 * Name of Field Bits 61 * --------------------------------------------------------- 62 * Start-of-frame 1 63 * Identifier 11 64 * Reserved bit (r1) 1 65 * Identifier extension bit (IDE) 1 66 * Flexible data rate format (FDF) 1 67 * Reserved bit (r0) 1 68 * Bit Rate Switch (BRS) 1 69 * Error Status Indicator (ESI) 1 70 * Data length code (DLC) 4 71 * Data field 0...512 72 * Stuff Bit Count (SBC) 0...16: 4 20...64:5 73 * CRC 0...16: 17 20...64:21 74 * CRC delimiter (CD) 1 75 * ACK slot (AS) 1 76 * ACK delimiter (AD) 1 77 * End-of-frame (EOF) 7 78 * Inter frame spacing 3 79 * 80 * assuming CRC21, rounded up and ignoring bitstuffing 81 */ 82 #define CANFD_FRAME_OVERHEAD_SFF DIV_ROUND_UP(61, 8) 83 84 /* 85 * Size of a CAN-FD Extended Frame 86 * 87 * Name of Field Bits 88 * --------------------------------------------------------- 89 * Start-of-frame 1 90 * Identifier A 11 91 * Substitute remote request (SRR) 1 92 * Identifier extension bit (IDE) 1 93 * Identifier B 18 94 * Reserved bit (r1) 1 95 * Flexible data rate format (FDF) 1 96 * Reserved bit (r0) 1 97 * Bit Rate Switch (BRS) 1 98 * Error Status Indicator (ESI) 1 99 * Data length code (DLC) 4 100 * Data field 0...512 101 * Stuff Bit Count (SBC) 0...16: 4 20...64:5 102 * CRC 0...16: 17 20...64:21 103 * CRC delimiter (CD) 1 104 * ACK slot (AS) 1 105 * ACK delimiter (AD) 1 106 * End-of-frame (EOF) 7 107 * Inter frame spacing 3 108 * 109 * assuming CRC21, rounded up and ignoring bitstuffing 110 */ 111 #define CANFD_FRAME_OVERHEAD_EFF DIV_ROUND_UP(80, 8) 112 113 /* 114 * Maximum size of a Classical CAN frame 115 * (rounded up and ignoring bitstuffing) 116 */ 117 #define CAN_FRAME_LEN_MAX (CAN_FRAME_OVERHEAD_EFF + CAN_MAX_DLEN) 118 119 /* 120 * Maximum size of a CAN-FD frame 121 * (rounded up and ignoring bitstuffing) 122 */ 123 #define CANFD_FRAME_LEN_MAX (CANFD_FRAME_OVERHEAD_EFF + CANFD_MAX_DLEN) 124 125 /* 126 * can_cc_dlc2len(value) - convert a given data length code (dlc) of a 127 * Classical CAN frame into a valid data length of max. 8 bytes. 128 * 129 * To be used in the CAN netdriver receive path to ensure conformance with 130 * ISO 11898-1 Chapter 8.4.2.3 (DLC field) 131 */ 132 #define can_cc_dlc2len(dlc) (min_t(u8, (dlc), CAN_MAX_DLEN)) 133 134 /* helper to get the data length code (DLC) for Classical CAN raw DLC access */ 135 static inline u8 can_get_cc_dlc(const struct can_frame *cf, const u32 ctrlmode) 136 { 137 /* return len8_dlc as dlc value only if all conditions apply */ 138 if ((ctrlmode & CAN_CTRLMODE_CC_LEN8_DLC) && 139 (cf->len == CAN_MAX_DLEN) && 140 (cf->len8_dlc > CAN_MAX_DLEN && cf->len8_dlc <= CAN_MAX_RAW_DLC)) 141 return cf->len8_dlc; 142 143 /* return the payload length as dlc value */ 144 return cf->len; 145 } 146 147 /* helper to set len and len8_dlc value for Classical CAN raw DLC access */ 148 static inline void can_frame_set_cc_len(struct can_frame *cf, const u8 dlc, 149 const u32 ctrlmode) 150 { 151 /* the caller already ensured that dlc is a value from 0 .. 15 */ 152 if (ctrlmode & CAN_CTRLMODE_CC_LEN8_DLC && dlc > CAN_MAX_DLEN) 153 cf->len8_dlc = dlc; 154 155 /* limit the payload length 'len' to CAN_MAX_DLEN */ 156 cf->len = can_cc_dlc2len(dlc); 157 } 158 159 /* get data length from raw data length code (DLC) */ 160 u8 can_fd_dlc2len(u8 dlc); 161 162 /* map the sanitized data length to an appropriate data length code */ 163 u8 can_fd_len2dlc(u8 len); 164 165 /* calculate the CAN Frame length in bytes of a given skb */ 166 unsigned int can_skb_get_frame_len(const struct sk_buff *skb); 167 168 /* map the data length to an appropriate data link layer length */ 169 static inline u8 canfd_sanitize_len(u8 len) 170 { 171 return can_fd_dlc2len(can_fd_len2dlc(len)); 172 } 173 174 #endif /* !_CAN_LENGTH_H */ 175