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// 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);
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