can: bittiming: move bittiming calculation functions to calc_bittiming.c
The canonical way to select or deselect an object during compilation is to use this pattern in the relevant Makefile: bar-$(CONFIG_FOO) := foo.o bittiming.c instead uses some #ifdef CONFIG_CAN_CALC_BITTIMG. Create a new file named calc_bittiming.c with all the functions which are conditionally compiled with CONFIG_CAN_CALC_BITTIMG and modify the Makefile according to above pattern. Link: https://lore.kernel.org/all/20220610143009.323579-4-mailhol.vincent@wanadoo.fr Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr> Acked-by: Max Staudt <max@enpas.org> Tested-by: Oliver Hartkopp <socketcan@hartkopp.net> Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
This commit is contained in:
Vincent Mailhol
Marc Kleine-Budde
parent
6a5286442f
commit
0c7e115138
@ -96,6 +96,10 @@ config CAN_CALC_BITTIMING
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source clock frequencies. Disabling saves some space, but then the
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bit-timing parameters must be specified directly using the Netlink
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arguments "tq", "prop_seg", "phase_seg1", "phase_seg2" and "sjw".
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The additional features selected by this option will be added to the
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can-dev module.
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If unsure, say Y.
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config CAN_AT91
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@ -4,6 +4,7 @@ obj-$(CONFIG_CAN_DEV) += can-dev.o
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can-dev-y += skb.o
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can-dev-$(CONFIG_CAN_CALC_BITTIMING) += calc_bittiming.o
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can-dev-$(CONFIG_CAN_NETLINK) += bittiming.o
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can-dev-$(CONFIG_CAN_NETLINK) += dev.o
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can-dev-$(CONFIG_CAN_NETLINK) += length.o
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@ -4,205 +4,8 @@
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* Copyright (C) 2008-2009 Wolfgang Grandegger <wg@grandegger.com>
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*/
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#include <linux/units.h>
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#include <linux/can/dev.h>
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#ifdef CONFIG_CAN_CALC_BITTIMING
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#define CAN_CALC_MAX_ERROR 50 /* in one-tenth of a percent */
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/* Bit-timing calculation derived from:
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*
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* Code based on LinCAN sources and H8S2638 project
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* Copyright 2004-2006 Pavel Pisa - DCE FELK CVUT cz
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* Copyright 2005 Stanislav Marek
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* email: pisa@cmp.felk.cvut.cz
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*
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* Calculates proper bit-timing parameters for a specified bit-rate
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* and sample-point, which can then be used to set the bit-timing
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* registers of the CAN controller. You can find more information
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* in the header file linux/can/netlink.h.
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*/
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static int
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can_update_sample_point(const struct can_bittiming_const *btc,
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const unsigned int sample_point_nominal, const unsigned int tseg,
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unsigned int *tseg1_ptr, unsigned int *tseg2_ptr,
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unsigned int *sample_point_error_ptr)
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{
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unsigned int sample_point_error, best_sample_point_error = UINT_MAX;
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unsigned int sample_point, best_sample_point = 0;
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unsigned int tseg1, tseg2;
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int i;
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for (i = 0; i <= 1; i++) {
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tseg2 = tseg + CAN_SYNC_SEG -
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(sample_point_nominal * (tseg + CAN_SYNC_SEG)) /
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1000 - i;
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tseg2 = clamp(tseg2, btc->tseg2_min, btc->tseg2_max);
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tseg1 = tseg - tseg2;
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if (tseg1 > btc->tseg1_max) {
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tseg1 = btc->tseg1_max;
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tseg2 = tseg - tseg1;
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}
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sample_point = 1000 * (tseg + CAN_SYNC_SEG - tseg2) /
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(tseg + CAN_SYNC_SEG);
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sample_point_error = abs(sample_point_nominal - sample_point);
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if (sample_point <= sample_point_nominal &&
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sample_point_error < best_sample_point_error) {
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best_sample_point = sample_point;
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best_sample_point_error = sample_point_error;
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*tseg1_ptr = tseg1;
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*tseg2_ptr = tseg2;
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}
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}
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if (sample_point_error_ptr)
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*sample_point_error_ptr = best_sample_point_error;
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return best_sample_point;
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}
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int can_calc_bittiming(const 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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struct can_priv *priv = netdev_priv(dev);
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unsigned int bitrate; /* current bitrate */
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unsigned int bitrate_error; /* difference between current and nominal value */
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unsigned int best_bitrate_error = UINT_MAX;
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unsigned int sample_point_error; /* difference between current and nominal value */
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unsigned int best_sample_point_error = UINT_MAX;
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unsigned int sample_point_nominal; /* nominal sample point */
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unsigned int best_tseg = 0; /* current best value for tseg */
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unsigned int best_brp = 0; /* current best value for brp */
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unsigned int brp, tsegall, tseg, tseg1 = 0, tseg2 = 0;
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u64 v64;
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/* Use CiA recommended sample points */
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if (bt->sample_point) {
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sample_point_nominal = bt->sample_point;
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} else {
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if (bt->bitrate > 800 * KILO /* BPS */)
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sample_point_nominal = 750;
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else if (bt->bitrate > 500 * KILO /* BPS */)
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sample_point_nominal = 800;
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else
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sample_point_nominal = 875;
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}
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/* tseg even = round down, odd = round up */
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for (tseg = (btc->tseg1_max + btc->tseg2_max) * 2 + 1;
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tseg >= (btc->tseg1_min + btc->tseg2_min) * 2; tseg--) {
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tsegall = CAN_SYNC_SEG + tseg / 2;
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/* Compute all possible tseg choices (tseg=tseg1+tseg2) */
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brp = priv->clock.freq / (tsegall * bt->bitrate) + tseg % 2;
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/* choose brp step which is possible in system */
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brp = (brp / btc->brp_inc) * btc->brp_inc;
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if (brp < btc->brp_min || brp > btc->brp_max)
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continue;
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bitrate = priv->clock.freq / (brp * tsegall);
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bitrate_error = abs(bt->bitrate - bitrate);
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/* tseg brp biterror */
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if (bitrate_error > best_bitrate_error)
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continue;
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/* reset sample point error if we have a better bitrate */
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if (bitrate_error < best_bitrate_error)
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best_sample_point_error = UINT_MAX;
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can_update_sample_point(btc, sample_point_nominal, tseg / 2,
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&tseg1, &tseg2, &sample_point_error);
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if (sample_point_error >= best_sample_point_error)
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continue;
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best_sample_point_error = sample_point_error;
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best_bitrate_error = bitrate_error;
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best_tseg = tseg / 2;
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best_brp = brp;
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if (bitrate_error == 0 && sample_point_error == 0)
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break;
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}
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if (best_bitrate_error) {
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/* Error in one-tenth of a percent */
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v64 = (u64)best_bitrate_error * 1000;
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do_div(v64, bt->bitrate);
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bitrate_error = (u32)v64;
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if (bitrate_error > CAN_CALC_MAX_ERROR) {
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netdev_err(dev,
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"bitrate error %d.%d%% too high\n",
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bitrate_error / 10, bitrate_error % 10);
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return -EDOM;
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}
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netdev_warn(dev, "bitrate error %d.%d%%\n",
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bitrate_error / 10, bitrate_error % 10);
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}
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/* real sample point */
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bt->sample_point = can_update_sample_point(btc, sample_point_nominal,
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best_tseg, &tseg1, &tseg2,
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NULL);
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v64 = (u64)best_brp * 1000 * 1000 * 1000;
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do_div(v64, priv->clock.freq);
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bt->tq = (u32)v64;
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bt->prop_seg = tseg1 / 2;
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bt->phase_seg1 = tseg1 - bt->prop_seg;
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bt->phase_seg2 = tseg2;
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/* check for sjw user settings */
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if (!bt->sjw || !btc->sjw_max) {
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bt->sjw = 1;
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} else {
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/* bt->sjw is at least 1 -> sanitize upper bound to sjw_max */
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if (bt->sjw > btc->sjw_max)
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bt->sjw = btc->sjw_max;
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/* bt->sjw must not be higher than tseg2 */
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if (tseg2 < bt->sjw)
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bt->sjw = tseg2;
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}
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bt->brp = best_brp;
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/* real bitrate */
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bt->bitrate = priv->clock.freq /
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(bt->brp * (CAN_SYNC_SEG + tseg1 + tseg2));
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return 0;
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}
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void can_calc_tdco(struct can_tdc *tdc, const struct can_tdc_const *tdc_const,
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const struct can_bittiming *dbt,
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u32 *ctrlmode, u32 ctrlmode_supported)
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{
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if (!tdc_const || !(ctrlmode_supported & CAN_CTRLMODE_TDC_AUTO))
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return;
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*ctrlmode &= ~CAN_CTRLMODE_TDC_MASK;
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/* As specified in ISO 11898-1 section 11.3.3 "Transmitter
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* delay compensation" (TDC) is only applicable if data BRP is
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* one or two.
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*/
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if (dbt->brp == 1 || dbt->brp == 2) {
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/* Sample point in clock periods */
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u32 sample_point_in_tc = (CAN_SYNC_SEG + dbt->prop_seg +
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dbt->phase_seg1) * dbt->brp;
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if (sample_point_in_tc < tdc_const->tdco_min)
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return;
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tdc->tdco = min(sample_point_in_tc, tdc_const->tdco_max);
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*ctrlmode |= CAN_CTRLMODE_TDC_AUTO;
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}
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}
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#endif /* CONFIG_CAN_CALC_BITTIMING */
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/* Checks the validity of the specified bit-timing parameters prop_seg,
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* phase_seg1, phase_seg2 and sjw and tries to determine the bitrate
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* prescaler value brp. You can find more information in the header
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202
drivers/net/can/dev/calc_bittiming.c
Normal file
202
drivers/net/can/dev/calc_bittiming.c
Normal file
@ -0,0 +1,202 @@
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// SPDX-License-Identifier: GPL-2.0-only
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/* Copyright (C) 2005 Marc Kleine-Budde, Pengutronix
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* Copyright (C) 2006 Andrey Volkov, Varma Electronics
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* Copyright (C) 2008-2009 Wolfgang Grandegger <wg@grandegger.com>
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*/
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#include <linux/units.h>
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#include <linux/can/dev.h>
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#define CAN_CALC_MAX_ERROR 50 /* in one-tenth of a percent */
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/* Bit-timing calculation derived from:
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*
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* Code based on LinCAN sources and H8S2638 project
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* Copyright 2004-2006 Pavel Pisa - DCE FELK CVUT cz
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* Copyright 2005 Stanislav Marek
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* email: pisa@cmp.felk.cvut.cz
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*
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* Calculates proper bit-timing parameters for a specified bit-rate
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* and sample-point, which can then be used to set the bit-timing
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* registers of the CAN controller. You can find more information
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* in the header file linux/can/netlink.h.
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*/
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static int
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can_update_sample_point(const struct can_bittiming_const *btc,
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const unsigned int sample_point_nominal, const unsigned int tseg,
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unsigned int *tseg1_ptr, unsigned int *tseg2_ptr,
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unsigned int *sample_point_error_ptr)
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{
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unsigned int sample_point_error, best_sample_point_error = UINT_MAX;
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unsigned int sample_point, best_sample_point = 0;
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unsigned int tseg1, tseg2;
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int i;
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for (i = 0; i <= 1; i++) {
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tseg2 = tseg + CAN_SYNC_SEG -
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(sample_point_nominal * (tseg + CAN_SYNC_SEG)) /
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1000 - i;
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tseg2 = clamp(tseg2, btc->tseg2_min, btc->tseg2_max);
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tseg1 = tseg - tseg2;
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if (tseg1 > btc->tseg1_max) {
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tseg1 = btc->tseg1_max;
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tseg2 = tseg - tseg1;
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}
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sample_point = 1000 * (tseg + CAN_SYNC_SEG - tseg2) /
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(tseg + CAN_SYNC_SEG);
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sample_point_error = abs(sample_point_nominal - sample_point);
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if (sample_point <= sample_point_nominal &&
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sample_point_error < best_sample_point_error) {
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best_sample_point = sample_point;
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best_sample_point_error = sample_point_error;
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*tseg1_ptr = tseg1;
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*tseg2_ptr = tseg2;
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}
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}
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if (sample_point_error_ptr)
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*sample_point_error_ptr = best_sample_point_error;
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return best_sample_point;
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}
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int can_calc_bittiming(const 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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struct can_priv *priv = netdev_priv(dev);
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unsigned int bitrate; /* current bitrate */
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unsigned int bitrate_error; /* difference between current and nominal value */
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unsigned int best_bitrate_error = UINT_MAX;
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unsigned int sample_point_error; /* difference between current and nominal value */
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unsigned int best_sample_point_error = UINT_MAX;
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unsigned int sample_point_nominal; /* nominal sample point */
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unsigned int best_tseg = 0; /* current best value for tseg */
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unsigned int best_brp = 0; /* current best value for brp */
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unsigned int brp, tsegall, tseg, tseg1 = 0, tseg2 = 0;
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u64 v64;
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/* Use CiA recommended sample points */
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if (bt->sample_point) {
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sample_point_nominal = bt->sample_point;
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} else {
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if (bt->bitrate > 800 * KILO /* BPS */)
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sample_point_nominal = 750;
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else if (bt->bitrate > 500 * KILO /* BPS */)
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sample_point_nominal = 800;
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else
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sample_point_nominal = 875;
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}
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/* tseg even = round down, odd = round up */
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for (tseg = (btc->tseg1_max + btc->tseg2_max) * 2 + 1;
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tseg >= (btc->tseg1_min + btc->tseg2_min) * 2; tseg--) {
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tsegall = CAN_SYNC_SEG + tseg / 2;
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/* Compute all possible tseg choices (tseg=tseg1+tseg2) */
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brp = priv->clock.freq / (tsegall * bt->bitrate) + tseg % 2;
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/* choose brp step which is possible in system */
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brp = (brp / btc->brp_inc) * btc->brp_inc;
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if (brp < btc->brp_min || brp > btc->brp_max)
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continue;
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bitrate = priv->clock.freq / (brp * tsegall);
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bitrate_error = abs(bt->bitrate - bitrate);
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/* tseg brp biterror */
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if (bitrate_error > best_bitrate_error)
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continue;
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/* reset sample point error if we have a better bitrate */
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if (bitrate_error < best_bitrate_error)
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best_sample_point_error = UINT_MAX;
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can_update_sample_point(btc, sample_point_nominal, tseg / 2,
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&tseg1, &tseg2, &sample_point_error);
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if (sample_point_error >= best_sample_point_error)
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continue;
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best_sample_point_error = sample_point_error;
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best_bitrate_error = bitrate_error;
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best_tseg = tseg / 2;
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best_brp = brp;
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if (bitrate_error == 0 && sample_point_error == 0)
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break;
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}
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if (best_bitrate_error) {
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/* Error in one-tenth of a percent */
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v64 = (u64)best_bitrate_error * 1000;
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do_div(v64, bt->bitrate);
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bitrate_error = (u32)v64;
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if (bitrate_error > CAN_CALC_MAX_ERROR) {
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netdev_err(dev,
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"bitrate error %d.%d%% too high\n",
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bitrate_error / 10, bitrate_error % 10);
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return -EDOM;
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}
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netdev_warn(dev, "bitrate error %d.%d%%\n",
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bitrate_error / 10, bitrate_error % 10);
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}
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/* real sample point */
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bt->sample_point = can_update_sample_point(btc, sample_point_nominal,
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best_tseg, &tseg1, &tseg2,
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NULL);
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v64 = (u64)best_brp * 1000 * 1000 * 1000;
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do_div(v64, priv->clock.freq);
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bt->tq = (u32)v64;
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bt->prop_seg = tseg1 / 2;
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bt->phase_seg1 = tseg1 - bt->prop_seg;
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bt->phase_seg2 = tseg2;
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/* check for sjw user settings */
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if (!bt->sjw || !btc->sjw_max) {
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bt->sjw = 1;
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} else {
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/* bt->sjw is at least 1 -> sanitize upper bound to sjw_max */
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if (bt->sjw > btc->sjw_max)
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bt->sjw = btc->sjw_max;
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/* bt->sjw must not be higher than tseg2 */
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if (tseg2 < bt->sjw)
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bt->sjw = tseg2;
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}
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bt->brp = best_brp;
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/* real bitrate */
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bt->bitrate = priv->clock.freq /
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(bt->brp * (CAN_SYNC_SEG + tseg1 + tseg2));
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return 0;
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}
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void can_calc_tdco(struct can_tdc *tdc, const struct can_tdc_const *tdc_const,
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const struct can_bittiming *dbt,
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u32 *ctrlmode, u32 ctrlmode_supported)
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{
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if (!tdc_const || !(ctrlmode_supported & CAN_CTRLMODE_TDC_AUTO))
|
||||
return;
|
||||
|
||||
*ctrlmode &= ~CAN_CTRLMODE_TDC_MASK;
|
||||
|
||||
/* As specified in ISO 11898-1 section 11.3.3 "Transmitter
|
||||
* delay compensation" (TDC) is only applicable if data BRP is
|
||||
* one or two.
|
||||
*/
|
||||
if (dbt->brp == 1 || dbt->brp == 2) {
|
||||
/* Sample point in clock periods */
|
||||
u32 sample_point_in_tc = (CAN_SYNC_SEG + dbt->prop_seg +
|
||||
dbt->phase_seg1) * dbt->brp;
|
||||
|
||||
if (sample_point_in_tc < tdc_const->tdco_min)
|
||||
return;
|
||||
tdc->tdco = min(sample_point_in_tc, tdc_const->tdco_max);
|
||||
*ctrlmode |= CAN_CTRLMODE_TDC_AUTO;
|
||||
}
|
||||
}
|
||||
Loading…
x
Reference in New Issue
Block a user