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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.c153
1 files changed, 153 insertions, 0 deletions
diff --git a/drivers/net/can/dev/bittiming.c b/drivers/net/can/dev/bittiming.c
new file mode 100644
index 0000000000..0b93900b1d
--- /dev/null
+++ b/drivers/net/can/dev/bittiming.c
@@ -0,0 +1,153 @@
+// 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;
+}