/* SPDX-License-Identifier: GPL-2.0 */
/* Copyright (C) 2020 Oliver Hartkopp <socketcan@hartkopp.net>
 */

#ifndef _CAN_LENGTH_H
#define _CAN_LENGTH_H

/*
 * 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);

#endif /* !_CAN_LENGTH_H */