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path: root/drivers/net/can/dev/bittiming.c
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Diffstat (limited to 'drivers/net/can/dev/bittiming.c')
-rw-r--r--drivers/net/can/dev/bittiming.c216
1 files changed, 216 insertions, 0 deletions
diff --git a/drivers/net/can/dev/bittiming.c b/drivers/net/can/dev/bittiming.c
new file mode 100644
index 000000000000..8f82418230ce
--- /dev/null
+++ b/drivers/net/can/dev/bittiming.c
@@ -0,0 +1,216 @@
+// 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;
+}
generated by cgit (git 2.34.1) at 2025-12-24 23:29:17 +0000