154 lines · c
1// SPDX-License-Identifier: GPL-2.0-only2/* Copyright (C) 2005 Marc Kleine-Budde, Pengutronix3 * Copyright (C) 2006 Andrey Volkov, Varma Electronics4 * Copyright (C) 2008-2009 Wolfgang Grandegger <wg@grandegger.com>5 */6 7#include <linux/can/dev.h>8 9void can_sjw_set_default(struct can_bittiming *bt)10{11 if (bt->sjw)12 return;13 14 /* If user space provides no sjw, use sane default of phase_seg2 / 2 */15 bt->sjw = max(1U, min(bt->phase_seg1, bt->phase_seg2 / 2));16}17 18int can_sjw_check(const struct net_device *dev, const struct can_bittiming *bt,19 const struct can_bittiming_const *btc, struct netlink_ext_ack *extack)20{21 if (bt->sjw > btc->sjw_max) {22 NL_SET_ERR_MSG_FMT(extack, "sjw: %u greater than max sjw: %u",23 bt->sjw, btc->sjw_max);24 return -EINVAL;25 }26 27 if (bt->sjw > bt->phase_seg1) {28 NL_SET_ERR_MSG_FMT(extack,29 "sjw: %u greater than phase-seg1: %u",30 bt->sjw, bt->phase_seg1);31 return -EINVAL;32 }33 34 if (bt->sjw > bt->phase_seg2) {35 NL_SET_ERR_MSG_FMT(extack,36 "sjw: %u greater than phase-seg2: %u",37 bt->sjw, bt->phase_seg2);38 return -EINVAL;39 }40 41 return 0;42}43 44/* Checks the validity of the specified bit-timing parameters prop_seg,45 * phase_seg1, phase_seg2 and sjw and tries to determine the bitrate46 * prescaler value brp. You can find more information in the header47 * file linux/can/netlink.h.48 */49static int can_fixup_bittiming(const struct net_device *dev, struct can_bittiming *bt,50 const struct can_bittiming_const *btc,51 struct netlink_ext_ack *extack)52{53 const unsigned int tseg1 = bt->prop_seg + bt->phase_seg1;54 const struct can_priv *priv = netdev_priv(dev);55 u64 brp64;56 int err;57 58 if (tseg1 < btc->tseg1_min) {59 NL_SET_ERR_MSG_FMT(extack, "prop-seg + phase-seg1: %u less than tseg1-min: %u",60 tseg1, btc->tseg1_min);61 return -EINVAL;62 }63 if (tseg1 > btc->tseg1_max) {64 NL_SET_ERR_MSG_FMT(extack, "prop-seg + phase-seg1: %u greater than tseg1-max: %u",65 tseg1, btc->tseg1_max);66 return -EINVAL;67 }68 if (bt->phase_seg2 < btc->tseg2_min) {69 NL_SET_ERR_MSG_FMT(extack, "phase-seg2: %u less than tseg2-min: %u",70 bt->phase_seg2, btc->tseg2_min);71 return -EINVAL;72 }73 if (bt->phase_seg2 > btc->tseg2_max) {74 NL_SET_ERR_MSG_FMT(extack, "phase-seg2: %u greater than tseg2-max: %u",75 bt->phase_seg2, btc->tseg2_max);76 return -EINVAL;77 }78 79 can_sjw_set_default(bt);80 81 err = can_sjw_check(dev, bt, btc, extack);82 if (err)83 return err;84 85 brp64 = (u64)priv->clock.freq * (u64)bt->tq;86 if (btc->brp_inc > 1)87 do_div(brp64, btc->brp_inc);88 brp64 += 500000000UL - 1;89 do_div(brp64, 1000000000UL); /* the practicable BRP */90 if (btc->brp_inc > 1)91 brp64 *= btc->brp_inc;92 bt->brp = (u32)brp64;93 94 if (bt->brp < btc->brp_min) {95 NL_SET_ERR_MSG_FMT(extack, "resulting brp: %u less than brp-min: %u",96 bt->brp, btc->brp_min);97 return -EINVAL;98 }99 if (bt->brp > btc->brp_max) {100 NL_SET_ERR_MSG_FMT(extack, "resulting brp: %u greater than brp-max: %u",101 bt->brp, btc->brp_max);102 return -EINVAL;103 }104 105 bt->bitrate = priv->clock.freq / (bt->brp * can_bit_time(bt));106 bt->sample_point = ((CAN_SYNC_SEG + tseg1) * 1000) / can_bit_time(bt);107 bt->tq = DIV_U64_ROUND_CLOSEST(mul_u32_u32(bt->brp, NSEC_PER_SEC),108 priv->clock.freq);109 110 return 0;111}112 113/* Checks the validity of predefined bitrate settings */114static int115can_validate_bitrate(const struct net_device *dev, const struct can_bittiming *bt,116 const u32 *bitrate_const,117 const unsigned int bitrate_const_cnt,118 struct netlink_ext_ack *extack)119{120 unsigned int i;121 122 for (i = 0; i < bitrate_const_cnt; i++) {123 if (bt->bitrate == bitrate_const[i])124 return 0;125 }126 127 NL_SET_ERR_MSG_FMT(extack, "bitrate %u bps not supported",128 bt->brp);129 130 return -EINVAL;131}132 133int can_get_bittiming(const struct net_device *dev, struct can_bittiming *bt,134 const struct can_bittiming_const *btc,135 const u32 *bitrate_const,136 const unsigned int bitrate_const_cnt,137 struct netlink_ext_ack *extack)138{139 /* Depending on the given can_bittiming parameter structure the CAN140 * timing parameters are calculated based on the provided bitrate OR141 * alternatively the CAN timing parameters (tq, prop_seg, etc.) are142 * provided directly which are then checked and fixed up.143 */144 if (!bt->tq && bt->bitrate && btc)145 return can_calc_bittiming(dev, bt, btc, extack);146 if (bt->tq && !bt->bitrate && btc)147 return can_fixup_bittiming(dev, bt, btc, extack);148 if (!bt->tq && bt->bitrate && bitrate_const)149 return can_validate_bitrate(dev, bt, bitrate_const,150 bitrate_const_cnt, extack);151 152 return -EINVAL;153}154