// 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>
 * Copyright (c) 2025 Vincent Mailhol <mailhol@kernel.org>
 */

#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;
}

int can_validate_pwm_bittiming(const struct net_device *dev,
                               const struct can_pwm *pwm,
                               struct netlink_ext_ack *extack)
{
        const struct can_priv *priv = netdev_priv(dev);
        u32 xl_bit_time_tqmin = can_bit_time_tqmin(&priv->xl.data_bittiming);
        u32 nom_bit_time_tqmin = can_bit_time_tqmin(&priv->bittiming);
        u32 pwms_ns = can_tqmin_to_ns(pwm->pwms, priv->clock.freq);
        u32 pwml_ns = can_tqmin_to_ns(pwm->pwml, priv->clock.freq);

        if (pwms_ns + pwml_ns > CAN_PWM_NS_MAX) {
                NL_SET_ERR_MSG_FMT(extack,
                                   "The PWM symbol duration: %u ns may not exceed %u ns",
                                   pwms_ns + pwml_ns, CAN_PWM_NS_MAX);
                return -EINVAL;
        }

        if (pwms_ns < CAN_PWM_DECODE_NS) {
                NL_SET_ERR_MSG_FMT(extack,
                                   "PWMS: %u ns shall be at least %u ns",
                                   pwms_ns, CAN_PWM_DECODE_NS);
                return -EINVAL;
        }

        if (pwm->pwms >= pwm->pwml) {
                NL_SET_ERR_MSG_FMT(extack,
                                   "PWMS: %u tqmin shall be smaller than PWML: %u tqmin",
                                   pwm->pwms, pwm->pwml);
                return -EINVAL;
        }

        if (pwml_ns - pwms_ns < 2 * CAN_PWM_DECODE_NS) {
                NL_SET_ERR_MSG_FMT(extack,
                                   "At least %u ns shall separate PWMS: %u ns from PMWL: %u ns",
                                   2 * CAN_PWM_DECODE_NS, pwms_ns, pwml_ns);
                return -EINVAL;
        }

        if (xl_bit_time_tqmin % (pwm->pwms + pwm->pwml) != 0) {
                NL_SET_ERR_MSG_FMT(extack,
                                   "PWM duration: %u tqmin does not divide XL's bit time: %u tqmin",
                                   pwm->pwms + pwm->pwml, xl_bit_time_tqmin);
                return -EINVAL;
        }

        if (pwm->pwmo >= pwm->pwms + pwm->pwml) {
                NL_SET_ERR_MSG_FMT(extack,
                                   "PWMO: %u tqmin can not be greater than PWMS + PWML: %u tqmin",
                                   pwm->pwmo, pwm->pwms + pwm->pwml);
                return -EINVAL;
        }

        if (nom_bit_time_tqmin % (pwm->pwms + pwm->pwml) != pwm->pwmo) {
                NL_SET_ERR_MSG_FMT(extack,
                                   "Can not assemble nominal bit time: %u tqmin out of PWMS + PMWL and PWMO",
                                   nom_bit_time_tqmin);
                return -EINVAL;
        }

        return 0;
}