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