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- /* SPDX-License-Identifier: GPL-2.0 */
- /* Copyright (C) 2020 Oliver Hartkopp <[email protected]>
- * Copyright (C) 2020 Marc Kleine-Budde <[email protected]>
- */
- #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 */
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