Commit a6ddf91a authored by Vincent Mailhol's avatar Vincent Mailhol Committed by Marc Kleine-Budde
Browse files

can: calc_bittiming: add can_calc_sample_point_nrz() 



CAN XL optimal sample point for PWM encoding (when TMS is on) differs
from the NRZ optimal one. There is thus a need to calculate a
different sample point depending whether TMS is on or off.

This is a preparation change: move the sample point calculation from
can_calc_bittiming() into the new can_calc_sample_point_nrz()
function.

In an upcoming change, a function will be added to calculate the
sample point for PWM encoding.

Signed-off-by: default avatarVincent Mailhol <mailhol@kernel.org>
Signed-off-by: default avatarOliver Hartkopp <socketcan@hartkopp.net>
Link: https://patch.msgid.link/20251126-canxl-v8-13-e7e3eb74f889@pengutronix.de


Signed-off-by: default avatarMarc Kleine-Budde <mkl@pengutronix.de>
parent 1d147cb7

drivers/net/can/dev/calc_bittiming.c

+15 −10
Original line number Diff line number Diff line
@@ -10,6 +10,18 @@ 


#define CAN_CALC_MAX_ERROR 50 /* in one-tenth of a percent */



/* CiA recommended sample points for Non Return to Zero encoding. */

static int can_calc_sample_point_nrz(const struct can_bittiming *bt)

{

	if (bt->bitrate > 800 * KILO /* BPS */)

		return 750;



	if (bt->bitrate > 500 * KILO /* BPS */)

		return 800;



	return 875;

}



/* Bit-timing calculation derived from:

 *

 * Code based on LinCAN sources and H8S2638 project
@@ -79,17 +91,10 @@ int can_calc_bittiming(const struct net_device *dev, struct can_bittiming *bt, 
	u64 v64;

	int err;



	/* Use CiA recommended sample points */

	if (bt->sample_point) {

	if (bt->sample_point)

		sample_point_reference = bt->sample_point;

	} else {

		if (bt->bitrate > 800 * KILO /* BPS */)

			sample_point_reference = 750;

		else if (bt->bitrate > 500 * KILO /* BPS */)

			sample_point_reference = 800;

	else

			sample_point_reference = 875;

	}

		sample_point_reference = can_calc_sample_point_nrz(bt);



	/* tseg even = round down, odd = round up */

	for (tseg = (btc->tseg1_max + btc->tseg2_max) * 2 + 1;