mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-09-30 06:10:56 +00:00
can: length: can_skb_get_frame_len(): introduce function to get data length of frame in data link layer
This patch adds the function can_skb_get_frame_len() which returns the length of a CAN frame on the data link layer, including Start-of-frame, Identifier, various other bits, the actual data, the CRC, the End-of-frame, the Inter frame spacing. Co-developed-by: Arunachalam Santhanam <arunachalam.santhanam@in.bosch.com> Signed-off-by: Arunachalam Santhanam <arunachalam.santhanam@in.bosch.com> Co-developed-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr> Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr> Acked-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr> Reviewed-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr> Co-developed-by: Marc Kleine-Budde <mkl@pengutronix.de> Link: https://lore.kernel.org/r/20210111141930.693847-11-mkl@pengutronix.de Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
This commit is contained in:
Vincent Mailhol
Marc Kleine-Budde
parent
99b7beb043
commit
85d99c3e2a
2 changed files with 170 additions and 0 deletions
|
|
@ -38,3 +38,53 @@ u8 can_fd_len2dlc(u8 len)
|
|||
return len2dlc[len];
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(can_fd_len2dlc);
|
||||
|
||||
/**
|
||||
* can_skb_get_frame_len() - Calculate the CAN Frame length in bytes
|
||||
* of a given skb.
|
||||
* @skb: socket buffer of a CAN message.
|
||||
*
|
||||
* Do a rough calculation: bit stuffing is ignored and length in bits
|
||||
* is rounded up to a length in bytes.
|
||||
*
|
||||
* Rationale: this function is to be used for the BQL functions
|
||||
* (netdev_sent_queue() and netdev_completed_queue()) which expect a
|
||||
* value in bytes. Just using skb->len is insufficient because it will
|
||||
* return the constant value of CAN(FD)_MTU. Doing the bit stuffing
|
||||
* calculation would be too expensive in term of computing resources
|
||||
* for no noticeable gain.
|
||||
*
|
||||
* Remarks: The payload of CAN FD frames with BRS flag are sent at a
|
||||
* different bitrate. Currently, the can-utils canbusload tool does
|
||||
* not support CAN-FD yet and so we could not run any benchmark to
|
||||
* measure the impact. There might be possible improvement here.
|
||||
*
|
||||
* Return: length in bytes.
|
||||
*/
|
||||
unsigned int can_skb_get_frame_len(const struct sk_buff *skb)
|
||||
{
|
||||
const struct canfd_frame *cf = (const struct canfd_frame *)skb->data;
|
||||
u8 len;
|
||||
|
||||
if (can_is_canfd_skb(skb))
|
||||
len = canfd_sanitize_len(cf->len);
|
||||
else if (cf->can_id & CAN_RTR_FLAG)
|
||||
len = 0;
|
||||
else
|
||||
len = cf->len;
|
||||
|
||||
if (can_is_canfd_skb(skb)) {
|
||||
if (cf->can_id & CAN_EFF_FLAG)
|
||||
len += CANFD_FRAME_OVERHEAD_EFF;
|
||||
else
|
||||
len += CANFD_FRAME_OVERHEAD_SFF;
|
||||
} else {
|
||||
if (cf->can_id & CAN_EFF_FLAG)
|
||||
len += CAN_FRAME_OVERHEAD_EFF;
|
||||
else
|
||||
len += CAN_FRAME_OVERHEAD_SFF;
|
||||
}
|
||||
|
||||
return len;
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(can_skb_get_frame_len);
|
||||
|
|
|
|||
|
|
@ -1,10 +1,127 @@
|
|||
/* 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.
|
||||
|
|
@ -45,6 +162,9 @@ 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)
|
||||
{
|
||||
|
|
|
|||
Loading…
Reference in a new issue