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// 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>
void can_sjw_set_default(struct can_bittiming *bt)
{
if (bt->sjw)
return;
/* If user space provides no sjw, use sane default of phase_seg2 / 2 */
bt->sjw = max(1U, min(bt->phase_seg1, bt->phase_seg2 / 2));
}
int can_sjw_check(const struct net_device *dev, const struct can_bittiming *bt,
const struct can_bittiming_const *btc, struct netlink_ext_ack *extack)
{
if (bt->sjw > btc->sjw_max) {
NL_SET_ERR_MSG_FMT(extack, "sjw: %u greater than max sjw: %u",
bt->sjw, btc->sjw_max);
return -EINVAL;
}
if (bt->sjw > bt->phase_seg1) {
NL_SET_ERR_MSG_FMT(extack,
"sjw: %u greater than phase-seg1: %u",
bt->sjw, bt->phase_seg1);
return -EINVAL;
}
if (bt->sjw > bt->phase_seg2) {
NL_SET_ERR_MSG_FMT(extack,
"sjw: %u greater than phase-seg2: %u",
bt->sjw, bt->phase_seg2);
return -EINVAL;
}
return 0;
}
/* 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(const struct net_device *dev, struct can_bittiming *bt,
const struct can_bittiming_const *btc,
struct netlink_ext_ack *extack)
{
const unsigned int tseg1 = bt->prop_seg + bt->phase_seg1;
const struct can_priv *priv = netdev_priv(dev);
u64 brp64;
int err;
if (tseg1 < btc->tseg1_min) {
NL_SET_ERR_MSG_FMT(extack, "prop-seg + phase-seg1: %u less than tseg1-min: %u",
tseg1, btc->tseg1_min);
return -EINVAL;
}
if (tseg1 > btc->tseg1_max) {
NL_SET_ERR_MSG_FMT(extack, "prop-seg + phase-seg1: %u greater than tseg1-max: %u",
tseg1, btc->tseg1_max);
return -EINVAL;
}
if (bt->phase_seg2 < btc->tseg2_min) {
NL_SET_ERR_MSG_FMT(extack, "phase-seg2: %u less than tseg2-min: %u",
bt->phase_seg2, btc->tseg2_min);
return -EINVAL;
}
if (bt->phase_seg2 > btc->tseg2_max) {
NL_SET_ERR_MSG_FMT(extack, "phase-seg2: %u greater than tseg2-max: %u",
bt->phase_seg2, btc->tseg2_max);
return -EINVAL;
}
can_sjw_set_default(bt);
err = can_sjw_check(dev, bt, btc, extack);
if (err)
return err;
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) {
NL_SET_ERR_MSG_FMT(extack, "resulting brp: %u less than brp-min: %u",
bt->brp, btc->brp_min);
return -EINVAL;
}
if (bt->brp > btc->brp_max) {
NL_SET_ERR_MSG_FMT(extack, "resulting brp: %u greater than brp-max: %u",
bt->brp, btc->brp_max);
return -EINVAL;
}
bt->bitrate = priv->clock.freq / (bt->brp * can_bit_time(bt));
bt->sample_point = ((CAN_SYNC_SEG + tseg1) * 1000) / can_bit_time(bt);
bt->tq = DIV_U64_ROUND_CLOSEST(mul_u32_u32(bt->brp, NSEC_PER_SEC),
priv->clock.freq);
return 0;
}
/* Checks the validity of predefined bitrate settings */
static int
can_validate_bitrate(const struct net_device *dev, const struct can_bittiming *bt,
const u32 *bitrate_const,
const unsigned int bitrate_const_cnt,
struct netlink_ext_ack *extack)
{
unsigned int i;
for (i = 0; i < bitrate_const_cnt; i++) {
if (bt->bitrate == bitrate_const[i])
return 0;
}
NL_SET_ERR_MSG_FMT(extack, "bitrate %u bps not supported",
bt->brp);
return -EINVAL;
}
int can_get_bittiming(const struct net_device *dev, struct can_bittiming *bt,
const struct can_bittiming_const *btc,
const u32 *bitrate_const,
const unsigned int bitrate_const_cnt,
struct netlink_ext_ack *extack)
{
/* 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)
return can_calc_bittiming(dev, bt, btc, extack);
if (bt->tq && !bt->bitrate && btc)
return can_fixup_bittiming(dev, bt, btc, extack);
if (!bt->tq && bt->bitrate && bitrate_const)
return can_validate_bitrate(dev, bt, bitrate_const,
bitrate_const_cnt, extack);
return -EINVAL;
}
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