307 lines
8.9 KiB
C
307 lines
8.9 KiB
C
/* 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 */
|