Commit 5a9d5ecd authored by Marc Kleine-Budde's avatar Marc Kleine-Budde
Browse files

can: dev: move bittiming related code into seperate file 



This patch moves the bittiming related code of the CAN device infrastructure
into a separate file.

Reviewed-by: default avatarVincent Mailhol <mailhol.vincent@wanadoo.fr>
Link: https://lore.kernel.org/r/20210111141930.693847-4-mkl@pengutronix.de


Signed-off-by: default avatarMarc Kleine-Budde <mkl@pengutronix.de>
parent 3e77f70e

MAINTAINERS

+1 −0
Original line number Diff line number Diff line
@@ -3943,6 +3943,7 @@ T: git git://git.kernel.org/pub/scm/linux/kernel/git/mkl/linux-can.git 
T:	git git://git.kernel.org/pub/scm/linux/kernel/git/mkl/linux-can-next.git

F:	Documentation/devicetree/bindings/net/can/

F:	drivers/net/can/

F:	include/linux/can/bittiming.h

F:	include/linux/can/dev.h

F:	include/linux/can/led.h

F:	include/linux/can/platform/

drivers/net/can/dev/Makefile

+1 −0
Original line number Diff line number Diff line 
# SPDX-License-Identifier: GPL-2.0



obj-$(CONFIG_CAN_DEV)		+= can-dev.o

can-dev-y			+= bittiming.o

can-dev-y			+= dev.o

can-dev-y			+= rx-offload.o

drivers/net/can/dev/bittiming.c

0 → 100644
+261 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0-only

/* Copyright (C) 2005 Marc Kleine-Budde, Pengutronix

 * Copyright (C) 2006 Andrey Volkov, Varma Electronics

 * Copyright (C) 2008-2009 Wolfgang Grandegger <wg@grandegger.com>

 */



#include <linux/can/dev.h>



#ifdef CONFIG_CAN_CALC_BITTIMING

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



/* Bit-timing calculation derived from:

 *

 * Code based on LinCAN sources and H8S2638 project

 * Copyright 2004-2006 Pavel Pisa - DCE FELK CVUT cz

 * Copyright 2005      Stanislav Marek

 * email: pisa@cmp.felk.cvut.cz

 *

 * Calculates proper bit-timing parameters for a specified bit-rate

 * and sample-point, which can then be used to set the bit-timing

 * registers of the CAN controller. You can find more information

 * in the header file linux/can/netlink.h.

 */

static int

can_update_sample_point(const struct can_bittiming_const *btc,

			unsigned int sample_point_nominal, unsigned int tseg,

			unsigned int *tseg1_ptr, unsigned int *tseg2_ptr,

			unsigned int *sample_point_error_ptr)

{

	unsigned int sample_point_error, best_sample_point_error = UINT_MAX;

	unsigned int sample_point, best_sample_point = 0;

	unsigned int tseg1, tseg2;

	int i;



	for (i = 0; i <= 1; i++) {

		tseg2 = tseg + CAN_SYNC_SEG -

			(sample_point_nominal * (tseg + CAN_SYNC_SEG)) /

			1000 - i;

		tseg2 = clamp(tseg2, btc->tseg2_min, btc->tseg2_max);

		tseg1 = tseg - tseg2;

		if (tseg1 > btc->tseg1_max) {

			tseg1 = btc->tseg1_max;

			tseg2 = tseg - tseg1;

		}



		sample_point = 1000 * (tseg + CAN_SYNC_SEG - tseg2) /

			(tseg + CAN_SYNC_SEG);

		sample_point_error = abs(sample_point_nominal - sample_point);



		if (sample_point <= sample_point_nominal &&

		    sample_point_error < best_sample_point_error) {

			best_sample_point = sample_point;

			best_sample_point_error = sample_point_error;

			*tseg1_ptr = tseg1;

			*tseg2_ptr = tseg2;

		}

	}



	if (sample_point_error_ptr)

		*sample_point_error_ptr = best_sample_point_error;



	return best_sample_point;

}



int can_calc_bittiming(struct net_device *dev, struct can_bittiming *bt,

		       const struct can_bittiming_const *btc)

{

	struct can_priv *priv = netdev_priv(dev);

	unsigned int bitrate;			/* current bitrate */

	unsigned int bitrate_error;		/* difference between current and nominal value */

	unsigned int best_bitrate_error = UINT_MAX;

	unsigned int sample_point_error;	/* difference between current and nominal value */

	unsigned int best_sample_point_error = UINT_MAX;

	unsigned int sample_point_nominal;	/* nominal sample point */

	unsigned int best_tseg = 0;		/* current best value for tseg */

	unsigned int best_brp = 0;		/* current best value for brp */

	unsigned int brp, tsegall, tseg, tseg1 = 0, tseg2 = 0;

	u64 v64;



	/* Use CiA recommended sample points */

	if (bt->sample_point) {

		sample_point_nominal = bt->sample_point;

	} else {

		if (bt->bitrate > 800000)

			sample_point_nominal = 750;

		else if (bt->bitrate > 500000)

			sample_point_nominal = 800;

		else

			sample_point_nominal = 875;

	}



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

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

	     tseg >= (btc->tseg1_min + btc->tseg2_min) * 2; tseg--) {

		tsegall = CAN_SYNC_SEG + tseg / 2;



		/* Compute all possible tseg choices (tseg=tseg1+tseg2) */

		brp = priv->clock.freq / (tsegall * bt->bitrate) + tseg % 2;



		/* choose brp step which is possible in system */

		brp = (brp / btc->brp_inc) * btc->brp_inc;

		if (brp < btc->brp_min || brp > btc->brp_max)

			continue;



		bitrate = priv->clock.freq / (brp * tsegall);

		bitrate_error = abs(bt->bitrate - bitrate);



		/* tseg brp biterror */

		if (bitrate_error > best_bitrate_error)

			continue;



		/* reset sample point error if we have a better bitrate */

		if (bitrate_error < best_bitrate_error)

			best_sample_point_error = UINT_MAX;



		can_update_sample_point(btc, sample_point_nominal, tseg / 2,

					&tseg1, &tseg2, &sample_point_error);

		if (sample_point_error > best_sample_point_error)

			continue;



		best_sample_point_error = sample_point_error;

		best_bitrate_error = bitrate_error;

		best_tseg = tseg / 2;

		best_brp = brp;



		if (bitrate_error == 0 && sample_point_error == 0)

			break;

	}



	if (best_bitrate_error) {

		/* Error in one-tenth of a percent */

		v64 = (u64)best_bitrate_error * 1000;

		do_div(v64, bt->bitrate);

		bitrate_error = (u32)v64;

		if (bitrate_error > CAN_CALC_MAX_ERROR) {

			netdev_err(dev,

				   "bitrate error %d.%d%% too high\n",

				   bitrate_error / 10, bitrate_error % 10);

			return -EDOM;

		}

		netdev_warn(dev, "bitrate error %d.%d%%\n",

			    bitrate_error / 10, bitrate_error % 10);

	}



	/* real sample point */

	bt->sample_point = can_update_sample_point(btc, sample_point_nominal,

						   best_tseg, &tseg1, &tseg2,

						   NULL);



	v64 = (u64)best_brp * 1000 * 1000 * 1000;

	do_div(v64, priv->clock.freq);

	bt->tq = (u32)v64;

	bt->prop_seg = tseg1 / 2;

	bt->phase_seg1 = tseg1 - bt->prop_seg;

	bt->phase_seg2 = tseg2;



	/* check for sjw user settings */

	if (!bt->sjw || !btc->sjw_max) {

		bt->sjw = 1;

	} else {

		/* bt->sjw is at least 1 -> sanitize upper bound to sjw_max */

		if (bt->sjw > btc->sjw_max)

			bt->sjw = btc->sjw_max;

		/* bt->sjw must not be higher than tseg2 */

		if (tseg2 < bt->sjw)

			bt->sjw = tseg2;

	}



	bt->brp = best_brp;



	/* real bitrate */

	bt->bitrate = priv->clock.freq /

		(bt->brp * (CAN_SYNC_SEG + tseg1 + tseg2));



	return 0;

}

#endif /* CONFIG_CAN_CALC_BITTIMING */



/* Checks the validity of the specified bit-timing parameters prop_seg,

 * phase_seg1, phase_seg2 and sjw and tries to determine the bitrate

 * prescaler value brp. You can find more information in the header

 * file linux/can/netlink.h.

 */

static int can_fixup_bittiming(struct net_device *dev, struct can_bittiming *bt,

			       const struct can_bittiming_const *btc)

{

	struct can_priv *priv = netdev_priv(dev);

	int tseg1, alltseg;

	u64 brp64;



	tseg1 = bt->prop_seg + bt->phase_seg1;

	if (!bt->sjw)

		bt->sjw = 1;

	if (bt->sjw > btc->sjw_max ||

	    tseg1 < btc->tseg1_min || tseg1 > btc->tseg1_max ||

	    bt->phase_seg2 < btc->tseg2_min || bt->phase_seg2 > btc->tseg2_max)

		return -ERANGE;



	brp64 = (u64)priv->clock.freq * (u64)bt->tq;

	if (btc->brp_inc > 1)

		do_div(brp64, btc->brp_inc);

	brp64 += 500000000UL - 1;

	do_div(brp64, 1000000000UL); /* the practicable BRP */

	if (btc->brp_inc > 1)

		brp64 *= btc->brp_inc;

	bt->brp = (u32)brp64;



	if (bt->brp < btc->brp_min || bt->brp > btc->brp_max)

		return -EINVAL;



	alltseg = bt->prop_seg + bt->phase_seg1 + bt->phase_seg2 + 1;

	bt->bitrate = priv->clock.freq / (bt->brp * alltseg);

	bt->sample_point = ((tseg1 + 1) * 1000) / alltseg;



	return 0;

}



/* Checks the validity of predefined bitrate settings */

static int

can_validate_bitrate(struct net_device *dev, struct can_bittiming *bt,

		     const u32 *bitrate_const,

		     const unsigned int bitrate_const_cnt)

{

	struct can_priv *priv = netdev_priv(dev);

	unsigned int i;



	for (i = 0; i < bitrate_const_cnt; i++) {

		if (bt->bitrate == bitrate_const[i])

			break;

	}



	if (i >= priv->bitrate_const_cnt)

		return -EINVAL;



	return 0;

}



int can_get_bittiming(struct net_device *dev, struct can_bittiming *bt,

		      const struct can_bittiming_const *btc,

		      const u32 *bitrate_const,

		      const unsigned int bitrate_const_cnt)

{

	int err;



	/* Depending on the given can_bittiming parameter structure the CAN

	 * timing parameters are calculated based on the provided bitrate OR

	 * alternatively the CAN timing parameters (tq, prop_seg, etc.) are

	 * provided directly which are then checked and fixed up.

	 */

	if (!bt->tq && bt->bitrate && btc)

		err = can_calc_bittiming(dev, bt, btc);

	else if (bt->tq && !bt->bitrate && btc)

		err = can_fixup_bittiming(dev, bt, btc);

	else if (!bt->tq && bt->bitrate && bitrate_const)

		err = can_validate_bitrate(dev, bt, bitrate_const,

					   bitrate_const_cnt);

	else

		err = -EINVAL;



	return err;

}

drivers/net/can/dev/dev.c

+0 −261
Original line number Diff line number Diff line
@@ -58,267 +58,6 @@ u8 can_fd_len2dlc(u8 len) 
}

EXPORT_SYMBOL_GPL(can_fd_len2dlc);



#ifdef CONFIG_CAN_CALC_BITTIMING

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



/* Bit-timing calculation derived from:

 *

 * Code based on LinCAN sources and H8S2638 project

 * Copyright 2004-2006 Pavel Pisa - DCE FELK CVUT cz

 * Copyright 2005      Stanislav Marek

 * email: pisa@cmp.felk.cvut.cz

 *

 * Calculates proper bit-timing parameters for a specified bit-rate

 * and sample-point, which can then be used to set the bit-timing

 * registers of the CAN controller. You can find more information

 * in the header file linux/can/netlink.h.

 */

static int

can_update_sample_point(const struct can_bittiming_const *btc,

			unsigned int sample_point_nominal, unsigned int tseg,

			unsigned int *tseg1_ptr, unsigned int *tseg2_ptr,

			unsigned int *sample_point_error_ptr)

{

	unsigned int sample_point_error, best_sample_point_error = UINT_MAX;

	unsigned int sample_point, best_sample_point = 0;

	unsigned int tseg1, tseg2;

	int i;



	for (i = 0; i <= 1; i++) {

		tseg2 = tseg + CAN_SYNC_SEG -

			(sample_point_nominal * (tseg + CAN_SYNC_SEG)) /

			1000 - i;

		tseg2 = clamp(tseg2, btc->tseg2_min, btc->tseg2_max);

		tseg1 = tseg - tseg2;

		if (tseg1 > btc->tseg1_max) {

			tseg1 = btc->tseg1_max;

			tseg2 = tseg - tseg1;

		}



		sample_point = 1000 * (tseg + CAN_SYNC_SEG - tseg2) /

			(tseg + CAN_SYNC_SEG);

		sample_point_error = abs(sample_point_nominal - sample_point);



		if (sample_point <= sample_point_nominal &&

		    sample_point_error < best_sample_point_error) {

			best_sample_point = sample_point;

			best_sample_point_error = sample_point_error;

			*tseg1_ptr = tseg1;

			*tseg2_ptr = tseg2;

		}

	}



	if (sample_point_error_ptr)

		*sample_point_error_ptr = best_sample_point_error;



	return best_sample_point;

}



static int can_calc_bittiming(struct net_device *dev, struct can_bittiming *bt,

			      const struct can_bittiming_const *btc)

{

	struct can_priv *priv = netdev_priv(dev);

	unsigned int bitrate;			/* current bitrate */

	unsigned int bitrate_error;		/* difference between current and nominal value */

	unsigned int best_bitrate_error = UINT_MAX;

	unsigned int sample_point_error;	/* difference between current and nominal value */

	unsigned int best_sample_point_error = UINT_MAX;

	unsigned int sample_point_nominal;	/* nominal sample point */

	unsigned int best_tseg = 0;		/* current best value for tseg */

	unsigned int best_brp = 0;		/* current best value for brp */

	unsigned int brp, tsegall, tseg, tseg1 = 0, tseg2 = 0;

	u64 v64;



	/* Use CiA recommended sample points */

	if (bt->sample_point) {

		sample_point_nominal = bt->sample_point;

	} else {

		if (bt->bitrate > 800000)

			sample_point_nominal = 750;

		else if (bt->bitrate > 500000)

			sample_point_nominal = 800;

		else

			sample_point_nominal = 875;

	}



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

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

	     tseg >= (btc->tseg1_min + btc->tseg2_min) * 2; tseg--) {

		tsegall = CAN_SYNC_SEG + tseg / 2;



		/* Compute all possible tseg choices (tseg=tseg1+tseg2) */

		brp = priv->clock.freq / (tsegall * bt->bitrate) + tseg % 2;



		/* choose brp step which is possible in system */

		brp = (brp / btc->brp_inc) * btc->brp_inc;

		if (brp < btc->brp_min || brp > btc->brp_max)

			continue;



		bitrate = priv->clock.freq / (brp * tsegall);

		bitrate_error = abs(bt->bitrate - bitrate);



		/* tseg brp biterror */

		if (bitrate_error > best_bitrate_error)

			continue;



		/* reset sample point error if we have a better bitrate */

		if (bitrate_error < best_bitrate_error)

			best_sample_point_error = UINT_MAX;



		can_update_sample_point(btc, sample_point_nominal, tseg / 2,

					&tseg1, &tseg2, &sample_point_error);

		if (sample_point_error > best_sample_point_error)

			continue;



		best_sample_point_error = sample_point_error;

		best_bitrate_error = bitrate_error;

		best_tseg = tseg / 2;

		best_brp = brp;



		if (bitrate_error == 0 && sample_point_error == 0)

			break;

	}



	if (best_bitrate_error) {

		/* Error in one-tenth of a percent */

		v64 = (u64)best_bitrate_error * 1000;

		do_div(v64, bt->bitrate);

		bitrate_error = (u32)v64;

		if (bitrate_error > CAN_CALC_MAX_ERROR) {

			netdev_err(dev,

				   "bitrate error %d.%d%% too high\n",

				   bitrate_error / 10, bitrate_error % 10);

			return -EDOM;

		}

		netdev_warn(dev, "bitrate error %d.%d%%\n",

			    bitrate_error / 10, bitrate_error % 10);

	}



	/* real sample point */

	bt->sample_point = can_update_sample_point(btc, sample_point_nominal,

						   best_tseg, &tseg1, &tseg2,

						   NULL);



	v64 = (u64)best_brp * 1000 * 1000 * 1000;

	do_div(v64, priv->clock.freq);

	bt->tq = (u32)v64;

	bt->prop_seg = tseg1 / 2;

	bt->phase_seg1 = tseg1 - bt->prop_seg;

	bt->phase_seg2 = tseg2;



	/* check for sjw user settings */

	if (!bt->sjw || !btc->sjw_max) {

		bt->sjw = 1;

	} else {

		/* bt->sjw is at least 1 -> sanitize upper bound to sjw_max */

		if (bt->sjw > btc->sjw_max)

			bt->sjw = btc->sjw_max;

		/* bt->sjw must not be higher than tseg2 */

		if (tseg2 < bt->sjw)

			bt->sjw = tseg2;

	}



	bt->brp = best_brp;



	/* real bitrate */

	bt->bitrate = priv->clock.freq /

		(bt->brp * (CAN_SYNC_SEG + tseg1 + tseg2));



	return 0;

}

#else /* !CONFIG_CAN_CALC_BITTIMING */

static int can_calc_bittiming(struct net_device *dev, struct can_bittiming *bt,

			      const struct can_bittiming_const *btc)

{

	netdev_err(dev, "bit-timing calculation not available\n");

	return -EINVAL;

}

#endif /* CONFIG_CAN_CALC_BITTIMING */



/* Checks the validity of the specified bit-timing parameters prop_seg,

 * phase_seg1, phase_seg2 and sjw and tries to determine the bitrate

 * prescaler value brp. You can find more information in the header

 * file linux/can/netlink.h.

 */

static int can_fixup_bittiming(struct net_device *dev, struct can_bittiming *bt,

			       const struct can_bittiming_const *btc)

{

	struct can_priv *priv = netdev_priv(dev);

	int tseg1, alltseg;

	u64 brp64;



	tseg1 = bt->prop_seg + bt->phase_seg1;

	if (!bt->sjw)

		bt->sjw = 1;

	if (bt->sjw > btc->sjw_max ||

	    tseg1 < btc->tseg1_min || tseg1 > btc->tseg1_max ||

	    bt->phase_seg2 < btc->tseg2_min || bt->phase_seg2 > btc->tseg2_max)

		return -ERANGE;



	brp64 = (u64)priv->clock.freq * (u64)bt->tq;

	if (btc->brp_inc > 1)

		do_div(brp64, btc->brp_inc);

	brp64 += 500000000UL - 1;

	do_div(brp64, 1000000000UL); /* the practicable BRP */

	if (btc->brp_inc > 1)

		brp64 *= btc->brp_inc;

	bt->brp = (u32)brp64;



	if (bt->brp < btc->brp_min || bt->brp > btc->brp_max)

		return -EINVAL;



	alltseg = bt->prop_seg + bt->phase_seg1 + bt->phase_seg2 + 1;

	bt->bitrate = priv->clock.freq / (bt->brp * alltseg);

	bt->sample_point = ((tseg1 + 1) * 1000) / alltseg;



	return 0;

}



/* Checks the validity of predefined bitrate settings */

static int

can_validate_bitrate(struct net_device *dev, struct can_bittiming *bt,

		     const u32 *bitrate_const,

		     const unsigned int bitrate_const_cnt)

{

	struct can_priv *priv = netdev_priv(dev);

	unsigned int i;



	for (i = 0; i < bitrate_const_cnt; i++) {

		if (bt->bitrate == bitrate_const[i])

			break;

	}



	if (i >= priv->bitrate_const_cnt)

		return -EINVAL;



	return 0;

}



static int can_get_bittiming(struct net_device *dev, struct can_bittiming *bt,

			     const struct can_bittiming_const *btc,

			     const u32 *bitrate_const,

			     const unsigned int bitrate_const_cnt)

{

	int err;



	/* Depending on the given can_bittiming parameter structure the CAN

	 * timing parameters are calculated based on the provided bitrate OR

	 * alternatively the CAN timing parameters (tq, prop_seg, etc.) are

	 * provided directly which are then checked and fixed up.

	 */

	if (!bt->tq && bt->bitrate && btc)

		err = can_calc_bittiming(dev, bt, btc);

	else if (bt->tq && !bt->bitrate && btc)

		err = can_fixup_bittiming(dev, bt, btc);

	else if (!bt->tq && bt->bitrate && bitrate_const)

		err = can_validate_bitrate(dev, bt, bitrate_const,

					   bitrate_const_cnt);

	else

		err = -EINVAL;



	return err;

}



static void can_update_state_error_stats(struct net_device *dev,

					 enum can_state new_state)

{

include/linux/can/bittiming.h

0 → 100644
+44 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0-only */

/* Copyright (c) 2020 Pengutronix, Marc Kleine-Budde <kernel@pengutronix.de>

 */



#ifndef _CAN_BITTIMING_H

#define _CAN_BITTIMING_H



#include <linux/netdevice.h>

#include <linux/can/netlink.h>



#define CAN_SYNC_SEG 1



#ifdef CONFIG_CAN_CALC_BITTIMING

int can_calc_bittiming(struct net_device *dev, struct can_bittiming *bt,

		       const struct can_bittiming_const *btc);

#else /* !CONFIG_CAN_CALC_BITTIMING */

static inline int

can_calc_bittiming(struct net_device *dev, struct can_bittiming *bt,

		   const struct can_bittiming_const *btc)

{

	netdev_err(dev, "bit-timing calculation not available\n");

	return -EINVAL;

}

#endif /* CONFIG_CAN_CALC_BITTIMING */



int can_get_bittiming(struct net_device *dev, struct can_bittiming *bt,

		      const struct can_bittiming_const *btc,

		      const u32 *bitrate_const,

		      const unsigned int bitrate_const_cnt);



/*

 * can_bit_time() - Duration of one bit

 *

 * Please refer to ISO 11898-1:2015, section 11.3.1.1 "Bit time" for

 * additional information.

 *

 * Return: the number of time quanta in one bit.

 */

static inline unsigned int can_bit_time(const struct can_bittiming *bt)

{

	return CAN_SYNC_SEG + bt->prop_seg + bt->phase_seg1 + bt->phase_seg2;

}



#endif /* !_CAN_BITTIMING_H */