@@ -1,5 +1,6 @@
/* SPDX-License-Identifier: GPL-2.0-only */
/* Copyright (c) 2020 Pengutronix, Marc Kleine-Budde <kernel@pengutronix.de>
+ * Copyright (c) 2021 Vincent Mailhol <mailhol.vincent@wanadoo.fr>
*/
#ifndef _CAN_BITTIMING_H
@@ -10,6 +11,70 @@
#define CAN_SYNC_SEG 1
+/*
+ * 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);
@@ -42,6 +42,9 @@ struct can_priv {
struct can_bittiming bittiming, data_bittiming;
const struct can_bittiming_const *bittiming_const,
*data_bittiming_const;
+ struct can_tdc tdc;
+ const struct can_tdc_const *tdc_const;
+
const u16 *termination_const;
unsigned int termination_const_cnt;
u16 termination;