Commit fa759a93 authored by Vincent Mailhol's avatar Vincent Mailhol Committed by Marc Kleine-Budde
Browse files

can: dev: add can_tdc_get_relative_tdco() helper function 

struct can_tdc::tdco represents the absolute offset from TDCV. Some
controllers use instead an offset relative to the Sample Point (SP)
such that:
| SSP = TDCV + absolute TDCO
|     = TDCV + SP + relative TDCO

Consequently:
| relative TDCO = absolute TDCO - SP

The function can_tdc_get_relative_tdco() allow to retrieve this
relative TDCO value.

Link: https://lore.kernel.org/all/20210918095637.20108-7-mailhol.vincent@wanadoo.fr


CC: Stefan Mätje <Stefan.Maetje@esd.eu>
Signed-off-by: default avatarVincent Mailhol <mailhol.vincent@wanadoo.fr>
Signed-off-by: default avatarMarc Kleine-Budde <mkl@pengutronix.de>
parent e8060f08

include/linux/can/dev.h

+29 −0
Original line number Diff line number Diff line
@@ -102,6 +102,35 @@ static inline bool can_tdc_is_enabled(const struct can_priv *priv) 
	return !!(priv->ctrlmode & CAN_CTRLMODE_TDC_MASK);

}



/*

 * can_get_relative_tdco() - TDCO relative to the sample point

 *

 * struct can_tdc::tdco represents the absolute offset from TDCV. Some

 * controllers use instead an offset relative to the Sample Point (SP)

 * such that:

 *

 * SSP = TDCV + absolute TDCO

 *     = TDCV + SP + relative TDCO

 *

 * -+----------- one bit ----------+-- TX pin

 *  |<--- Sample Point --->|

 *

 *                         --+----------- one bit ----------+-- RX pin

 *  |<-------- TDCV -------->|

 *                           |<------------------------>| absolute TDCO

 *                           |<--- Sample Point --->|

 *                           |                      |<->| relative TDCO

 *  |<------------- Secondary Sample Point ------------>|

 */

static inline s32 can_get_relative_tdco(const struct can_priv *priv)

{

	const struct can_bittiming *dbt = &priv->data_bittiming;

	s32 sample_point_in_tc = (CAN_SYNC_SEG + dbt->prop_seg +

				  dbt->phase_seg1) * dbt->brp;



	return (s32)priv->tdc.tdco - sample_point_in_tc;

}



/* helper to define static CAN controller features at device creation time */

static inline void can_set_static_ctrlmode(struct net_device *dev,

					   u32 static_mode)