[PATCH v9 4/7] can: provide a separate bittiming_const parameter to bittiming functions

[Oliver Hartkopp <socketcan@hartkopp.net>]

As the bittiming calculation functions are to be used with different
bittiming_const structures for CAN and CAN FD the direct reference to
priv->bittiming_const inside these functions has to be removed.

Also simplify the return value generation in can_get_bittiming() as only
correct return values of can_[calc|fixup]_bittiming() lead to a return value
of zero. And moved the check for existing bittiming const to one place.

Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
---
 drivers/net/can/dev.c | 59 ++++++++++++++++++++++-----------------------------
 1 file changed, 25 insertions(+), 34 deletions(-)

diff --git a/drivers/net/can/dev.c b/drivers/net/can/dev.c
index 89fc798..8141290 100644
--- a/drivers/net/can/dev.c
+++ b/drivers/net/can/dev.c
@@ -99,10 +99,10 @@ static int can_update_spt(const struct can_bittiming_const *btc,
 	return 1000 * (tseg + 1 - *tseg2) / (tseg + 1);
 }
 
-static int can_calc_bittiming(struct net_device *dev, struct can_bittiming *bt)
+static int can_calc_bittiming(struct net_device *dev, struct can_bittiming *bt,
+			      const struct can_bittiming_const *btc)
 {
 	struct can_priv *priv = netdev_priv(dev);
-	const struct can_bittiming_const *btc = priv->bittiming_const;
 	long rate, best_rate = 0;
 	long best_error = 1000000000, error = 0;
 	int best_tseg = 0, best_brp = 0, brp = 0;
@@ -110,9 +110,6 @@ static int can_calc_bittiming(struct net_device *dev, struct can_bittiming *bt)
 	int spt_error = 1000, spt = 0, sampl_pt;
 	u64 v64;
 
-	if (!priv->bittiming_const)
-		return -ENOTSUPP;
-
 	/* Use CIA recommended sample points */
 	if (bt->sample_point) {
 		sampl_pt = bt->sample_point;
@@ -204,7 +201,8 @@ static int can_calc_bittiming(struct net_device *dev, struct can_bittiming *bt)
 	return 0;
 }
 #else /* !CONFIG_CAN_CALC_BITTIMING */
-static int can_calc_bittiming(struct net_device *dev, struct can_bittiming *bt)
+static int can_calc_bittiming(struct net_device *dev, struct can_bittiming *bt,
+			      const struct can_bittiming_const *btc)
 {
 	netdev_err(dev, "bit-timing calculation not available\n");
 	return -EINVAL;
@@ -217,16 +215,13 @@ static int can_calc_bittiming(struct net_device *dev, struct can_bittiming *bt)
  * prescaler value brp. You can find more information in the header
  * file linux/can/netlink.h.
  */
-static int can_fixup_bittiming(struct net_device *dev, struct can_bittiming *bt)
+static int can_fixup_bittiming(struct net_device *dev, struct can_bittiming *bt,
+			       const struct can_bittiming_const *btc)
 {
 	struct can_priv *priv = netdev_priv(dev);
-	const struct can_bittiming_const *btc = priv->bittiming_const;
 	int tseg1, alltseg;
 	u64 brp64;
 
-	if (!priv->bittiming_const)
-		return -ENOTSUPP;
-
 	tseg1 = bt->prop_seg + bt->phase_seg1;
 	if (!bt->sjw)
 		bt->sjw = 1;
@@ -254,33 +249,29 @@ static int can_fixup_bittiming(struct net_device *dev, struct can_bittiming *bt)
 	return 0;
 }
 
-static int can_get_bittiming(struct net_device *dev, struct can_bittiming *bt)
+static int can_get_bittiming(struct net_device *dev, struct can_bittiming *bt,
+			     const struct can_bittiming_const *btc)
 {
-	struct can_priv *priv = netdev_priv(dev);
 	int err;
 
 	/* Check if the CAN device has bit-timing parameters */
-	if (priv->bittiming_const) {
-
-		/* Non-expert mode? Check if the bitrate has been pre-defined */
-		if (!bt->tq) {
-			/* Determine bit-timing parameters */
-			if (bt->bitrate)
-				err = can_calc_bittiming(dev, bt);
-			else
-				return -EINVAL;
-		} else {
-			/* Check bit-timing params and calculate proper brp */
-			if (!bt->bitrate)
-				err = can_fixup_bittiming(dev, bt);
-			else
-				return -EINVAL;
-		}
-		if (err)
-			return err;
-	}
+	if (!btc)
+		return -ENOTSUPP;
 
-	return 0;
+	/*
+	 * 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)
+		err = can_calc_bittiming(dev, bt, btc);
+	else if (bt->tq && !bt->bitrate)
+		err = can_fixup_bittiming(dev, bt, btc);
+	else
+		err = -EINVAL;
+
+	return err;
 }
 
 /*
@@ -674,7 +665,7 @@ static int can_changelink(struct net_device *dev,
 		if (dev->flags & IFF_UP)
 			return -EBUSY;
 		memcpy(&bt, nla_data(data[IFLA_CAN_BITTIMING]), sizeof(bt));
-		err = can_get_bittiming(dev, &bt);
+		err = can_get_bittiming(dev, &bt, priv->bittiming_const);
 		if (err)
 			return err;
 		memcpy(&priv->bittiming, &bt, sizeof(bt));
-- 
1.9.0