96 lines
2.7 KiB
C
96 lines
2.7 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
|
|
/* Copyright (C) 2012, 2020 Oliver Hartkopp <socketcan@hartkopp.net>
|
|
*/
|
|
|
|
#include <linux/can/dev.h>
|
|
|
|
/* CAN DLC to real data length conversion helpers */
|
|
|
|
static const u8 dlc2len[] = {
|
|
0, 1, 2, 3, 4, 5, 6, 7,
|
|
8, 12, 16, 20, 24, 32, 48, 64
|
|
};
|
|
|
|
/* get data length from raw data length code (DLC) */
|
|
u8 can_fd_dlc2len(u8 dlc)
|
|
{
|
|
return dlc2len[dlc & 0x0F];
|
|
}
|
|
EXPORT_SYMBOL_GPL(can_fd_dlc2len);
|
|
|
|
static const u8 len2dlc[] = {
|
|
0, 1, 2, 3, 4, 5, 6, 7, 8, /* 0 - 8 */
|
|
9, 9, 9, 9, /* 9 - 12 */
|
|
10, 10, 10, 10, /* 13 - 16 */
|
|
11, 11, 11, 11, /* 17 - 20 */
|
|
12, 12, 12, 12, /* 21 - 24 */
|
|
13, 13, 13, 13, 13, 13, 13, 13, /* 25 - 32 */
|
|
14, 14, 14, 14, 14, 14, 14, 14, /* 33 - 40 */
|
|
14, 14, 14, 14, 14, 14, 14, 14, /* 41 - 48 */
|
|
15, 15, 15, 15, 15, 15, 15, 15, /* 49 - 56 */
|
|
15, 15, 15, 15, 15, 15, 15, 15 /* 57 - 64 */
|
|
};
|
|
|
|
/* map the sanitized data length to an appropriate data length code */
|
|
u8 can_fd_len2dlc(u8 len)
|
|
{
|
|
/* check for length mapping table size at build time */
|
|
BUILD_BUG_ON(ARRAY_SIZE(len2dlc) != CANFD_MAX_DLEN + 1);
|
|
|
|
if (unlikely(len > CANFD_MAX_DLEN))
|
|
return CANFD_MAX_DLC;
|
|
|
|
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);
|