88 lines
2.6 KiB
C
88 lines
2.6 KiB
C
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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/can/dev.h>
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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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* file linux/can/netlink.h.
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*/
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static int can_fixup_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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const struct can_priv *priv = netdev_priv(dev);
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unsigned int tseg1, alltseg;
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u64 brp64;
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tseg1 = bt->prop_seg + bt->phase_seg1;
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if (!bt->sjw)
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bt->sjw = 1;
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if (bt->sjw > btc->sjw_max ||
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tseg1 < btc->tseg1_min || tseg1 > btc->tseg1_max ||
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bt->phase_seg2 < btc->tseg2_min || bt->phase_seg2 > btc->tseg2_max)
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return -ERANGE;
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brp64 = (u64)priv->clock.freq * (u64)bt->tq;
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if (btc->brp_inc > 1)
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do_div(brp64, btc->brp_inc);
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brp64 += 500000000UL - 1;
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do_div(brp64, 1000000000UL); /* the practicable BRP */
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if (btc->brp_inc > 1)
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brp64 *= btc->brp_inc;
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bt->brp = (u32)brp64;
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if (bt->brp < btc->brp_min || bt->brp > btc->brp_max)
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return -EINVAL;
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alltseg = bt->prop_seg + bt->phase_seg1 + bt->phase_seg2 + 1;
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bt->bitrate = priv->clock.freq / (bt->brp * alltseg);
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bt->sample_point = ((tseg1 + 1) * 1000) / alltseg;
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return 0;
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}
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/* Checks the validity of predefined bitrate settings */
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static int
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can_validate_bitrate(const struct net_device *dev, const struct can_bittiming *bt,
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const u32 *bitrate_const,
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const unsigned int bitrate_const_cnt)
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{
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unsigned int i;
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for (i = 0; i < bitrate_const_cnt; i++) {
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if (bt->bitrate == bitrate_const[i])
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return 0;
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}
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return -EINVAL;
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}
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int can_get_bittiming(const struct net_device *dev, struct can_bittiming *bt,
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const struct can_bittiming_const *btc,
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const u32 *bitrate_const,
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const unsigned int bitrate_const_cnt)
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{
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int err;
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/* Depending on the given can_bittiming parameter structure the CAN
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* timing parameters are calculated based on the provided bitrate OR
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* alternatively the CAN timing parameters (tq, prop_seg, etc.) are
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* provided directly which are then checked and fixed up.
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*/
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if (!bt->tq && bt->bitrate && btc)
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err = can_calc_bittiming(dev, bt, btc);
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else if (bt->tq && !bt->bitrate && btc)
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err = can_fixup_bittiming(dev, bt, btc);
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else if (!bt->tq && bt->bitrate && bitrate_const)
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err = can_validate_bitrate(dev, bt, bitrate_const,
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bitrate_const_cnt);
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else
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err = -EINVAL;
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return err;
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}
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