/* SPDX-License-Identifier: GPL-2.0-only */ /* Copyright (c) 2020 Pengutronix, Marc Kleine-Budde * Copyright (c) 2021 Vincent Mailhol */ #ifndef _CAN_BITTIMING_H #define _CAN_BITTIMING_H #include #include #define CAN_SYNC_SEG 1 /* Kilobits and Megabits per second */ #define CAN_KBPS 1000UL #define CAN_MBPS 1000000UL /* Megahertz */ #define CAN_MHZ 1000000UL /* * struct can_tdc - CAN FD Transmission Delay Compensation parameters * * At high bit rates, the propagation delay from the TX pin to the RX * pin of the transceiver causes measurement errors: the sample point * on the RX pin might occur on the previous bit. * * To solve this issue, ISO 11898-1 introduces in section 11.3.3 * "Transmitter delay compensation" a SSP (Secondary Sample Point) * equal to the distance, in time quanta, from the start of the bit * time on the TX pin to the actual measurement on the RX pin. * * This structure contains the parameters to calculate that SSP. * * @tdcv: Transmitter Delay Compensation Value. Distance, in time * quanta, from when the bit is sent on the TX pin to when it is * received on the RX pin of the transmitter. Possible options: * * O: automatic mode. The controller dynamically measure @tdcv * for each transmitted CAN FD frame. * * Other values: manual mode. Use the fixed provided value. * * @tdco: Transmitter Delay Compensation Offset. Offset value, in time * quanta, defining the distance between the start of the bit * reception on the RX pin of the transceiver and the SSP * position such as SSP = @tdcv + @tdco. * * If @tdco is zero, then TDC is disabled and both @tdcv and * @tdcf should be ignored. * * @tdcf: Transmitter Delay Compensation Filter window. Defines the * minimum value for the SSP position in time quanta. If SSP is * less than @tdcf, then no delay compensations occur and the * normal sampling point is used instead. The feature is enabled * if and only if @tdcv is set to zero (automatic mode) and @tdcf * is configured to a value greater than @tdco. */ struct can_tdc { u32 tdcv; u32 tdco; u32 tdcf; }; /* * struct can_tdc_const - CAN hardware-dependent constant for * Transmission Delay Compensation * * @tdcv_max: Transmitter Delay Compensation Value maximum value. * Should be set to zero if the controller does not support * manual mode for tdcv. * @tdco_max: Transmitter Delay Compensation Offset maximum value. * Should not be zero. If the controller does not support TDC, * then the pointer to this structure should be NULL. * @tdcf_max: Transmitter Delay Compensation Filter window maximum * value. Should be set to zero if the controller does not * support this feature. */ struct can_tdc_const { u32 tdcv_max; u32 tdco_max; u32 tdcf_max; }; #ifdef CONFIG_CAN_CALC_BITTIMING int can_calc_bittiming(struct net_device *dev, struct can_bittiming *bt, const struct can_bittiming_const *btc); void can_calc_tdco(struct net_device *dev); #else /* !CONFIG_CAN_CALC_BITTIMING */ static inline int can_calc_bittiming(struct net_device *dev, struct can_bittiming *bt, const struct can_bittiming_const *btc) { netdev_err(dev, "bit-timing calculation not available\n"); return -EINVAL; } static inline void can_calc_tdco(struct net_device *dev) { } #endif /* CONFIG_CAN_CALC_BITTIMING */ int can_get_bittiming(struct net_device *dev, struct can_bittiming *bt, const struct can_bittiming_const *btc, const u32 *bitrate_const, const unsigned int bitrate_const_cnt); /* * can_bit_time() - Duration of one bit * * Please refer to ISO 11898-1:2015, section 11.3.1.1 "Bit time" for * additional information. * * Return: the number of time quanta in one bit. */ static inline unsigned int can_bit_time(const struct can_bittiming *bt) { return CAN_SYNC_SEG + bt->prop_seg + bt->phase_seg1 + bt->phase_seg2; } #endif /* !_CAN_BITTIMING_H */