[v4,3/7] can: bittiming: move bittiming calculation functions to calc_bittiming.c

Message ID	20220603102848.17907-4-mailhol.vincent@wanadoo.fr (mailing list archive)
State	Superseded
Delegated to:	Netdev Maintainers
Headers	show Return-Path: <netdev-owner@kernel.org> Sender: Vincent Mailhol <vincent.mailhol@gmail.com> From: Vincent Mailhol <mailhol.vincent@wanadoo.fr> To: Marc Kleine-Budde <mkl@pengutronix.de> Cc: linux-can@vger.kernel.org, linux-kernel@vger.kernel.org, Max Staudt <max@enpas.org>, Oliver Hartkopp <socketcan@hartkopp.net>, netdev@vger.kernel.org, Vincent Mailhol <mailhol.vincent@wanadoo.fr> Subject: [PATCH v4 3/7] can: bittiming: move bittiming calculation functions to calc_bittiming.c Date: Fri, 3 Jun 2022 19:28:44 +0900 Message-Id: <20220603102848.17907-4-mailhol.vincent@wanadoo.fr> In-Reply-To: <20220603102848.17907-1-mailhol.vincent@wanadoo.fr> References: <20220513142355.250389-1-mailhol.vincent@wanadoo.fr> <20220603102848.17907-1-mailhol.vincent@wanadoo.fr> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk
Series	can: refactoring of can-dev module and of Kbuild \| expand [v4,0/7] can: refactoring of can-dev module and of Kbuild [v4,1/7] can: Kbuild: rename config symbol CAN_DEV into CAN_NETLINK [v4,2/7] can: Kconfig: turn menu "CAN Device Drivers" into a menuconfig using CAN_DEV [v4,3/7] can: bittiming: move bittiming calculation functions to calc_bittiming.c [v4,4/7] can: Kconfig: add CONFIG_CAN_RX_OFFLOAD [v4,5/7] net: Kconfig: move the CAN device menu to the "Device Drivers" section [v4,6/7] can: skb: move can_dropped_invalid_skb() and can_skb_headroom_valid() to skb.c [v4,7/7] can: skb: drop tx skb if in listen only mode

Context	Check	Description
netdev/tree_selection	success	Series ignored based on subject, async

diff --git a/drivers/net/can/Kconfig b/drivers/net/can/Kconfig index b1e47f6c5586..8f3b97aea638 100644 --- a/drivers/net/can/Kconfig +++ b/drivers/net/can/Kconfig @@ -96,6 +96,10 @@ config CAN_CALC_BITTIMING source clock frequencies. Disabling saves some space, but then the bit-timing parameters must be specified directly using the Netlink arguments "tq", "prop_seg", "phase_seg1", "phase_seg2" and "sjw". + + The additional features selected by this option will be added to the + can-dev module. + If unsure, say Y. config CAN_AT91 diff --git a/drivers/net/can/dev/Makefile b/drivers/net/can/dev/Makefile index 919f87e36eed..b8a55b1d90cd 100644 --- a/drivers/net/can/dev/Makefile +++ b/drivers/net/can/dev/Makefile @@ -9,3 +9,5 @@ can-dev-$(CONFIG_CAN_NETLINK) += dev.o can-dev-$(CONFIG_CAN_NETLINK) += length.o can-dev-$(CONFIG_CAN_NETLINK) += netlink.o can-dev-$(CONFIG_CAN_NETLINK) += rx-offload.o + +can-dev-$(CONFIG_CAN_CALC_BITTIMING) += calc_bittiming.o diff --git a/drivers/net/can/dev/bittiming.c b/drivers/net/can/dev/bittiming.c index c1e76f0a5064..7ae80763c960 100644 --- a/drivers/net/can/dev/bittiming.c +++ b/drivers/net/can/dev/bittiming.c @@ -4,205 +4,8 @@ * Copyright (C) 2008-2009 Wolfgang Grandegger <wg@grandegger.com> */ -#include <linux/units.h> #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, - const unsigned int sample_point_nominal, const 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(const 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 > 800 * KILO /* BPS */) - sample_point_nominal = 750; - else if (bt->bitrate > 500 * KILO /* BPS */) - 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; -} - -void can_calc_tdco(struct can_tdc *tdc, const struct can_tdc_const *tdc_const, - const struct can_bittiming *dbt, - u32 *ctrlmode, u32 ctrlmode_supported) - -{ - 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; - } -} -#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 diff --git a/drivers/net/can/dev/calc_bittiming.c b/drivers/net/can/dev/calc_bittiming.c new file mode 100644 index 000000000000..d3caa040614d --- /dev/null +++ b/drivers/net/can/dev/calc_bittiming.c @@ -0,0 +1,202 @@ +// 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/units.h> +#include <linux/can/dev.h> + +#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, + const unsigned int sample_point_nominal, const 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(const 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 > 800 * KILO /* BPS */) + sample_point_nominal = 750; + else if (bt->bitrate > 500 * KILO /* BPS */) + 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; +} + +void can_calc_tdco(struct can_tdc *tdc, const struct can_tdc_const *tdc_const, + const struct can_bittiming *dbt, + u32 *ctrlmode, u32 ctrlmode_supported) + +{ + 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; + } +}

[v4,3/7] can: bittiming: move bittiming calculation functions to calc_bittiming.c

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