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/* SPDX-License-Identifier: GPL-2.0 */
/* Copyright (C) 2020 Oliver Hartkopp <socketcan@hartkopp.net>
* Copyright (C) 2020 Marc Kleine-Budde <kernel@pengutronix.de>
*/
#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) 0...16: 4 20...64:5
* CRC 0...16: 17 20...64:21
* CRC delimiter (CD) 1
* ACK slot (AS) 1
* ACK delimiter (AD) 1
* End-of-frame (EOF) 7
* Inter frame spacing 3
*
* assuming CRC21, rounded up and ignoring bitstuffing
*/
#define CANFD_FRAME_OVERHEAD_SFF DIV_ROUND_UP(61, 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) 0...16: 4 20...64:5
* CRC 0...16: 17 20...64:21
* CRC delimiter (CD) 1
* ACK slot (AS) 1
* ACK delimiter (AD) 1
* End-of-frame (EOF) 7
* Inter frame spacing 3
*
* assuming CRC21, rounded up and ignoring bitstuffing
*/
#define CANFD_FRAME_OVERHEAD_EFF DIV_ROUND_UP(80, 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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