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Diffstat (limited to '')
| -rw-r--r-- | include/linux/can/length.h | 174 |
1 files changed, 174 insertions, 0 deletions
diff --git a/include/linux/can/length.h b/include/linux/can/length.h new file mode 100644 index 000000000000..6995092b774e --- /dev/null +++ b/include/linux/can/length.h @@ -0,0 +1,174 @@ +/* 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 */ |