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1/* SPDX-License-Identifier: GPL-2.0-only */2/* Copyright (c) 2020 Pengutronix, Marc Kleine-Budde <kernel@pengutronix.de>3 * Copyright (c) 2021 Vincent Mailhol <mailhol.vincent@wanadoo.fr>4 */5 6#ifndef _CAN_BITTIMING_H7#define _CAN_BITTIMING_H8 9#include <linux/netdevice.h>10#include <linux/can/netlink.h>11 12#define CAN_SYNC_SEG 113 14#define CAN_BITRATE_UNSET 015#define CAN_BITRATE_UNKNOWN (-1U)16 17#define CAN_CTRLMODE_TDC_MASK \18 (CAN_CTRLMODE_TDC_AUTO | CAN_CTRLMODE_TDC_MANUAL)19 20/*21 * struct can_tdc - CAN FD Transmission Delay Compensation parameters22 *23 * At high bit rates, the propagation delay from the TX pin to the RX24 * pin of the transceiver causes measurement errors: the sample point25 * on the RX pin might occur on the previous bit.26 *27 * To solve this issue, ISO 11898-1 introduces in section 11.3.328 * "Transmitter delay compensation" a SSP (Secondary Sample Point)29 * equal to the distance from the start of the bit time on the TX pin30 * to the actual measurement on the RX pin.31 *32 * This structure contains the parameters to calculate that SSP.33 *34 * -+----------- one bit ----------+-- TX pin35 * |<--- Sample Point --->|36 *37 * --+----------- one bit ----------+-- RX pin38 * |<-------- TDCV -------->|39 * |<------- TDCO ------->|40 * |<----------- Secondary Sample Point ---------->|41 *42 * To increase precision, contrary to the other bittiming parameters43 * which are measured in time quanta, the TDC parameters are measured44 * in clock periods (also referred as "minimum time quantum" in ISO45 * 11898-1).46 *47 * @tdcv: Transmitter Delay Compensation Value. The time needed for48 * the signal to propagate, i.e. the distance, in clock periods,49 * from the start of the bit on the TX pin to when it is received50 * on the RX pin. @tdcv depends on the controller modes:51 *52 * CAN_CTRLMODE_TDC_AUTO is set: The transceiver dynamically53 * measures @tdcv for each transmitted CAN FD frame and the54 * value provided here should be ignored.55 *56 * CAN_CTRLMODE_TDC_MANUAL is set: use the fixed provided @tdcv57 * value.58 *59 * N.B. CAN_CTRLMODE_TDC_AUTO and CAN_CTRLMODE_TDC_MANUAL are60 * mutually exclusive. Only one can be set at a time. If both61 * CAN_TDC_CTRLMODE_AUTO and CAN_TDC_CTRLMODE_MANUAL are unset,62 * TDC is disabled and all the values of this structure should be63 * ignored.64 *65 * @tdco: Transmitter Delay Compensation Offset. Offset value, in66 * clock periods, defining the distance between the start of the67 * bit reception on the RX pin of the transceiver and the SSP68 * position such that SSP = @tdcv + @tdco.69 *70 * @tdcf: Transmitter Delay Compensation Filter window. Defines the71 * minimum value for the SSP position in clock periods. If the72 * SSP position is less than @tdcf, then no delay compensations73 * occur and the normal sampling point is used instead. The74 * feature is enabled if and only if @tdcv is set to zero75 * (automatic mode) and @tdcf is configured to a value greater76 * than @tdco.77 */78struct can_tdc {79 u32 tdcv;80 u32 tdco;81 u32 tdcf;82};83 84/*85 * struct can_tdc_const - CAN hardware-dependent constant for86 * Transmission Delay Compensation87 *88 * @tdcv_min: Transmitter Delay Compensation Value minimum value. If89 * the controller does not support manual mode for tdcv90 * (c.f. flag CAN_CTRLMODE_TDC_MANUAL) then this value is91 * ignored.92 * @tdcv_max: Transmitter Delay Compensation Value maximum value. If93 * the controller does not support manual mode for tdcv94 * (c.f. flag CAN_CTRLMODE_TDC_MANUAL) then this value is95 * ignored.96 *97 * @tdco_min: Transmitter Delay Compensation Offset minimum value.98 * @tdco_max: Transmitter Delay Compensation Offset maximum value.99 * Should not be zero. If the controller does not support TDC,100 * then the pointer to this structure should be NULL.101 *102 * @tdcf_min: Transmitter Delay Compensation Filter window minimum103 * value. If @tdcf_max is zero, this value is ignored.104 * @tdcf_max: Transmitter Delay Compensation Filter window maximum105 * value. Should be set to zero if the controller does not106 * support this feature.107 */108struct can_tdc_const {109 u32 tdcv_min;110 u32 tdcv_max;111 u32 tdco_min;112 u32 tdco_max;113 u32 tdcf_min;114 u32 tdcf_max;115};116 117#ifdef CONFIG_CAN_CALC_BITTIMING118int can_calc_bittiming(const struct net_device *dev, struct can_bittiming *bt,119 const struct can_bittiming_const *btc, struct netlink_ext_ack *extack);120 121void can_calc_tdco(struct can_tdc *tdc, const struct can_tdc_const *tdc_const,122 const struct can_bittiming *dbt,123 u32 *ctrlmode, u32 ctrlmode_supported);124#else /* !CONFIG_CAN_CALC_BITTIMING */125static inline int126can_calc_bittiming(const struct net_device *dev, struct can_bittiming *bt,127 const struct can_bittiming_const *btc, struct netlink_ext_ack *extack)128{129 netdev_err(dev, "bit-timing calculation not available\n");130 return -EINVAL;131}132 133static inline void134can_calc_tdco(struct can_tdc *tdc, const struct can_tdc_const *tdc_const,135 const struct can_bittiming *dbt,136 u32 *ctrlmode, u32 ctrlmode_supported)137{138}139#endif /* CONFIG_CAN_CALC_BITTIMING */140 141void can_sjw_set_default(struct can_bittiming *bt);142 143int can_sjw_check(const struct net_device *dev, const struct can_bittiming *bt,144 const struct can_bittiming_const *btc, struct netlink_ext_ack *extack);145 146int can_get_bittiming(const struct net_device *dev, struct can_bittiming *bt,147 const struct can_bittiming_const *btc,148 const u32 *bitrate_const,149 const unsigned int bitrate_const_cnt,150 struct netlink_ext_ack *extack);151 152/*153 * can_bit_time() - Duration of one bit154 *155 * Please refer to ISO 11898-1:2015, section 11.3.1.1 "Bit time" for156 * additional information.157 *158 * Return: the number of time quanta in one bit.159 */160static inline unsigned int can_bit_time(const struct can_bittiming *bt)161{162 return CAN_SYNC_SEG + bt->prop_seg + bt->phase_seg1 + bt->phase_seg2;163}164 165#endif /* !_CAN_BITTIMING_H */166