[linux-block.git] / include / linux / can / length.h

/* 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 */
Commit	Line	Data
bdd2e413 MKB	1	/* SPDX-License-Identifier: GPL-2.0 */
bdd2e413 MKB	2	/* Copyright (C) 2020 Oliver Hartkopp <socketcan@hartkopp.net>
85d99c3e	3	* Copyright (C) 2020 Marc Kleine-Budde <kernel@pengutronix.de>
bdd2e413 MKB	4	*/
	5
	6	#ifndef _CAN_LENGTH_H
	7	#define _CAN_LENGTH_H
	8
85d99c3e VM	9	/*
	10	* Size of a Classical CAN Standard Frame
	11	*
	12	* Name of Field Bits
	13	* ---------------------------------------------------------
	14	* Start-of-frame 1
	15	* Identifier 11
	16	* Remote transmission request (RTR) 1
	17	* Identifier extension bit (IDE) 1
	18	* Reserved bit (r0) 1
	19	* Data length code (DLC) 4
	20	* Data field 0...64
	21	* CRC 15
	22	* CRC delimiter 1
	23	* ACK slot 1
	24	* ACK delimiter 1
	25	* End-of-frame (EOF) 7
	26	* Inter frame spacing 3
	27	*
	28	* rounded up and ignoring bitstuffing
	29	*/
	30	#define CAN_FRAME_OVERHEAD_SFF DIV_ROUND_UP(47, 8)
	31
	32	/*
	33	* Size of a Classical CAN Extended Frame
	34	*
	35	* Name of Field Bits
	36	* ---------------------------------------------------------
	37	* Start-of-frame 1
	38	* Identifier A 11
	39	* Substitute remote request (SRR) 1
	40	* Identifier extension bit (IDE) 1
	41	* Identifier B 18
	42	* Remote transmission request (RTR) 1
	43	* Reserved bits (r1, r0) 2
	44	* Data length code (DLC) 4
	45	* Data field 0...64
	46	* CRC 15
	47	* CRC delimiter 1
	48	* ACK slot 1
	49	* ACK delimiter 1
	50	* End-of-frame (EOF) 7
	51	* Inter frame spacing 3
	52	*
	53	* rounded up and ignoring bitstuffing
	54	*/
	55	#define CAN_FRAME_OVERHEAD_EFF DIV_ROUND_UP(67, 8)
	56
	57	/*
	58	* Size of a CAN-FD Standard Frame
	59	*
	60	* Name of Field Bits
	61	* ---------------------------------------------------------
	62	* Start-of-frame 1
	63	* Identifier 11
	64	* Reserved bit (r1) 1
	65	* Identifier extension bit (IDE) 1
	66	* Flexible data rate format (FDF) 1
	67	* Reserved bit (r0) 1
	68	* Bit Rate Switch (BRS) 1
	69	* Error Status Indicator (ESI) 1
	70	* Data length code (DLC) 4
	71	* Data field 0...512
	72	* Stuff Bit Count (SBC) 0...16: 4 20...64:5
73	* CRC 0...16: 17 20...64:21
74	* CRC delimiter (CD) 1
75	* ACK slot (AS) 1
76	* ACK delimiter (AD) 1
77	* End-of-frame (EOF) 7
78	* Inter frame spacing 3
79	*
80	* assuming CRC21, rounded up and ignoring bitstuffing
81	*/
82	#define CANFD_FRAME_OVERHEAD_SFF DIV_ROUND_UP(61, 8)
83
84	/*
85	* Size of a CAN-FD Extended Frame
86	*
87	* Name of Field Bits
88	* ---------------------------------------------------------
89	* Start-of-frame 1
90	* Identifier A 11
91	* Substitute remote request (SRR) 1
92	* Identifier extension bit (IDE) 1
93	* Identifier B 18
94	* Reserved bit (r1) 1
95	* Flexible data rate format (FDF) 1
96	* Reserved bit (r0) 1
97	* Bit Rate Switch (BRS) 1
98	* Error Status Indicator (ESI) 1
99	* Data length code (DLC) 4
100	* Data field 0...512
101	* Stuff Bit Count (SBC) 0...16: 4 20...64:5
102	* CRC 0...16: 17 20...64:21
103	* CRC delimiter (CD) 1
104	* ACK slot (AS) 1
105	* ACK delimiter (AD) 1
106	* End-of-frame (EOF) 7
107	* Inter frame spacing 3
108	*
109	* assuming CRC21, rounded up and ignoring bitstuffing
110	*/
111	#define CANFD_FRAME_OVERHEAD_EFF DIV_ROUND_UP(80, 8)
112
113	/*
114	* Maximum size of a Classical CAN frame
115	* (rounded up and ignoring bitstuffing)
116	*/
117	#define CAN_FRAME_LEN_MAX (CAN_FRAME_OVERHEAD_EFF + CAN_MAX_DLEN)
118
119	/*
120	* Maximum size of a CAN-FD frame
121	* (rounded up and ignoring bitstuffing)
122	*/
123	#define CANFD_FRAME_LEN_MAX (CANFD_FRAME_OVERHEAD_EFF + CANFD_MAX_DLEN)
124
bdd2e413 MKB	125	/*
	126	* can_cc_dlc2len(value) - convert a given data length code (dlc) of a
	127	* Classical CAN frame into a valid data length of max. 8 bytes.
	128	*
	129	* To be used in the CAN netdriver receive path to ensure conformance with
	130	* ISO 11898-1 Chapter 8.4.2.3 (DLC field)
	131	*/
	132	#define can_cc_dlc2len(dlc) (min_t(u8, (dlc), CAN_MAX_DLEN))
	133
	134	/* helper to get the data length code (DLC) for Classical CAN raw DLC access */
	135	static inline u8 can_get_cc_dlc(const struct can_frame *cf, const u32 ctrlmode)
	136	{
	137	/* return len8_dlc as dlc value only if all conditions apply */
	138	if ((ctrlmode & CAN_CTRLMODE_CC_LEN8_DLC) &&
	139	(cf->len == CAN_MAX_DLEN) &&
	140	(cf->len8_dlc > CAN_MAX_DLEN && cf->len8_dlc <= CAN_MAX_RAW_DLC))
	141	return cf->len8_dlc;
	142
	143	/* return the payload length as dlc value */
	144	return cf->len;
	145	}
	146
	147	/* helper to set len and len8_dlc value for Classical CAN raw DLC access */
	148	static inline void can_frame_set_cc_len(struct can_frame *cf, const u8 dlc,
	149	const u32 ctrlmode)
	150	{
	151	/* the caller already ensured that dlc is a value from 0 .. 15 */
	152	if (ctrlmode & CAN_CTRLMODE_CC_LEN8_DLC && dlc > CAN_MAX_DLEN)
	153	cf->len8_dlc = dlc;
	154
	155	/* limit the payload length 'len' to CAN_MAX_DLEN */
	156	cf->len = can_cc_dlc2len(dlc);
	157	}
	158
	159	/* get data length from raw data length code (DLC) */
	160	u8 can_fd_dlc2len(u8 dlc);
	161
	162	/* map the sanitized data length to an appropriate data length code */
	163	u8 can_fd_len2dlc(u8 len);
	164
85d99c3e VM	165	/* calculate the CAN Frame length in bytes of a given skb */
	166	unsigned int can_skb_get_frame_len(const struct sk_buff *skb);
	167
99b7beb0 MKB	168	/* map the data length to an appropriate data link layer length */
	169	static inline u8 canfd_sanitize_len(u8 len)
	170	{
	171	return can_fd_dlc2len(can_fd_len2dlc(len));
	172	}
	173
bdd2e413	174	#endif /* !_CAN_LENGTH_H */