1 files changed, 87 insertions, 0 deletions
diff --git a/drivers/net/can/dev/bittiming.c b/drivers/net/can/dev/bittiming.c
new file mode 100644
index 000000000..7ae80763c
--- /dev/null
+++ b/drivers/net/can/dev/bittiming.c
@@ -0,0 +1,87 @@
+// 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>
+
+/* 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)
+{
+	const struct can_priv *priv = netdev_priv(dev);
+	unsigned int tseg1, alltseg;
+	u64 brp64;
+
+	tseg1 = bt->prop_seg + bt->phase_seg1;
+	if (!bt->sjw)
+		bt->sjw = 1;
+	if (bt->sjw > btc->sjw_max ||
+	    tseg1 < btc->tseg1_min || tseg1 > btc->tseg1_max ||
+	    bt->phase_seg2 < btc->tseg2_min || bt->phase_seg2 > btc->tseg2_max)
+		return -ERANGE;
+
+	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 || bt->brp > btc->brp_max)
+		return -EINVAL;
+
+	alltseg = bt->prop_seg + bt->phase_seg1 + bt->phase_seg2 + 1;
+	bt->bitrate = priv->clock.freq / (bt->brp * alltseg);
+	bt->sample_point = ((tseg1 + 1) * 1000) / alltseg;
+
+	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)
+{
+	unsigned int i;
+
+	for (i = 0; i < bitrate_const_cnt; i++) {
+		if (bt->bitrate == bitrate_const[i])
+			return 0;
+	}
+
+	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)
+{
+	int err;
+
+	/* 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)
+		err = can_calc_bittiming(dev, bt, btc);
+	else if (bt->tq && !bt->bitrate && btc)
+		err = can_fixup_bittiming(dev, bt, btc);
+	else if (!bt->tq && bt->bitrate && bitrate_const)
+		err = can_validate_bitrate(dev, bt, bitrate_const,
+					   bitrate_const_cnt);
+	else
+		err = -EINVAL;
+
+	return err;
+}