177 lines
4.9 KiB
C
177 lines
4.9 KiB
C
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/* SPDX-License-Identifier: GPL-2.0 */
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/* Copyright (C) 2020 Oliver Hartkopp <socketcan@hartkopp.net>
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* Copyright (C) 2020 Marc Kleine-Budde <kernel@pengutronix.de>
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*/
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#ifndef _CAN_LENGTH_H
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#define _CAN_LENGTH_H
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/*
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* Size of a Classical CAN Standard Frame
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*
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* Name of Field Bits
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* ---------------------------------------------------------
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* Start-of-frame 1
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* Identifier 11
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* Remote transmission request (RTR) 1
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* Identifier extension bit (IDE) 1
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* Reserved bit (r0) 1
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* Data length code (DLC) 4
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* Data field 0...64
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* CRC 15
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* CRC delimiter 1
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* ACK slot 1
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* ACK delimiter 1
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* End-of-frame (EOF) 7
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* Inter frame spacing 3
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*
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* rounded up and ignoring bitstuffing
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*/
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#define CAN_FRAME_OVERHEAD_SFF DIV_ROUND_UP(47, 8)
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/*
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* Size of a Classical CAN Extended Frame
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*
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* Name of Field Bits
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* ---------------------------------------------------------
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* Start-of-frame 1
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* Identifier A 11
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* Substitute remote request (SRR) 1
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* Identifier extension bit (IDE) 1
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* Identifier B 18
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* Remote transmission request (RTR) 1
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* Reserved bits (r1, r0) 2
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* Data length code (DLC) 4
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* Data field 0...64
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* CRC 15
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* CRC delimiter 1
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* ACK slot 1
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* ACK delimiter 1
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* End-of-frame (EOF) 7
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* Inter frame spacing 3
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*
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* rounded up and ignoring bitstuffing
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*/
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#define CAN_FRAME_OVERHEAD_EFF DIV_ROUND_UP(67, 8)
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/*
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* Size of a CAN-FD Standard Frame
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*
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* Name of Field Bits
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* ---------------------------------------------------------
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* Start-of-frame 1
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* Identifier 11
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* Reserved bit (r1) 1
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* Identifier extension bit (IDE) 1
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* Flexible data rate format (FDF) 1
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* Reserved bit (r0) 1
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* Bit Rate Switch (BRS) 1
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* Error Status Indicator (ESI) 1
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* Data length code (DLC) 4
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* Data field 0...512
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* Stuff Bit Count (SBC) 4
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* CRC 0...16: 17 20...64:21
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* CRC delimiter (CD) 1
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* Fixed Stuff bits (FSB) 0...16: 6 20...64:7
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* ACK slot (AS) 1
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* ACK delimiter (AD) 1
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* End-of-frame (EOF) 7
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* Inter frame spacing 3
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*
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* assuming CRC21, rounded up and ignoring dynamic bitstuffing
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*/
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#define CANFD_FRAME_OVERHEAD_SFF DIV_ROUND_UP(67, 8)
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/*
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* Size of a CAN-FD Extended Frame
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*
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* Name of Field Bits
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* ---------------------------------------------------------
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* Start-of-frame 1
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* Identifier A 11
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* Substitute remote request (SRR) 1
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* Identifier extension bit (IDE) 1
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* Identifier B 18
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* Reserved bit (r1) 1
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* Flexible data rate format (FDF) 1
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* Reserved bit (r0) 1
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* Bit Rate Switch (BRS) 1
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* Error Status Indicator (ESI) 1
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* Data length code (DLC) 4
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* Data field 0...512
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* Stuff Bit Count (SBC) 4
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* CRC 0...16: 17 20...64:21
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* CRC delimiter (CD) 1
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* Fixed Stuff bits (FSB) 0...16: 6 20...64:7
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* ACK slot (AS) 1
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* ACK delimiter (AD) 1
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* End-of-frame (EOF) 7
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* Inter frame spacing 3
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*
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* assuming CRC21, rounded up and ignoring dynamic bitstuffing
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*/
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#define CANFD_FRAME_OVERHEAD_EFF DIV_ROUND_UP(86, 8)
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/*
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* Maximum size of a Classical CAN frame
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* (rounded up and ignoring bitstuffing)
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*/
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#define CAN_FRAME_LEN_MAX (CAN_FRAME_OVERHEAD_EFF + CAN_MAX_DLEN)
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/*
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* Maximum size of a CAN-FD frame
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* (rounded up and ignoring bitstuffing)
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*/
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#define CANFD_FRAME_LEN_MAX (CANFD_FRAME_OVERHEAD_EFF + CANFD_MAX_DLEN)
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/*
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* can_cc_dlc2len(value) - convert a given data length code (dlc) of a
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* Classical CAN frame into a valid data length of max. 8 bytes.
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*
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* To be used in the CAN netdriver receive path to ensure conformance with
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* ISO 11898-1 Chapter 8.4.2.3 (DLC field)
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*/
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#define can_cc_dlc2len(dlc) (min_t(u8, (dlc), CAN_MAX_DLEN))
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/* helper to get the data length code (DLC) for Classical CAN raw DLC access */
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static inline u8 can_get_cc_dlc(const struct can_frame *cf, const u32 ctrlmode)
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{
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/* return len8_dlc as dlc value only if all conditions apply */
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if ((ctrlmode & CAN_CTRLMODE_CC_LEN8_DLC) &&
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(cf->len == CAN_MAX_DLEN) &&
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(cf->len8_dlc > CAN_MAX_DLEN && cf->len8_dlc <= CAN_MAX_RAW_DLC))
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return cf->len8_dlc;
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/* return the payload length as dlc value */
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return cf->len;
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}
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/* helper to set len and len8_dlc value for Classical CAN raw DLC access */
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static inline void can_frame_set_cc_len(struct can_frame *cf, const u8 dlc,
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const u32 ctrlmode)
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{
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/* the caller already ensured that dlc is a value from 0 .. 15 */
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if (ctrlmode & CAN_CTRLMODE_CC_LEN8_DLC && dlc > CAN_MAX_DLEN)
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cf->len8_dlc = dlc;
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/* limit the payload length 'len' to CAN_MAX_DLEN */
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cf->len = can_cc_dlc2len(dlc);
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}
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/* get data length from raw data length code (DLC) */
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u8 can_fd_dlc2len(u8 dlc);
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/* map the sanitized data length to an appropriate data length code */
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u8 can_fd_len2dlc(u8 len);
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/* calculate the CAN Frame length in bytes of a given skb */
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unsigned int can_skb_get_frame_len(const struct sk_buff *skb);
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/* map the data length to an appropriate data link layer length */
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static inline u8 canfd_sanitize_len(u8 len)
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{
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return can_fd_dlc2len(can_fd_len2dlc(len));
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}
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#endif /* !_CAN_LENGTH_H */
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