can-calc-bit-timing: introduce CAN_CALC_SYNC_SEG

Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

diff --git a/can-calc-bit-timing.c b/can-calc-bit-timing.c
index 46e2c16cbd515bf3f51deee9351aa364d302d2e8..50b0d18ecdf22b623b53c80bbd1ba56ceea29fc6 100644 (file)
--- a/can-calc-bit-timing.c
+++ b/can-calc-bit-timing.c
@@ -530,6 +530,7 @@ static long common_bitrates[] = {
 };
 
 #define CAN_CALC_MAX_ERROR 50 /* in one-tenth of a percent */
+#define CAN_CALC_SYNC_SEG 1
 
 /*
  * Bit-timing calculation derived from:
@@ -547,7 +548,8 @@ static long common_bitrates[] = {
 static int can_update_spt(const struct can_bittiming_const *btc,
                          int sampl_pt, int tseg, int *tseg1, int *tseg2)
 {
-       *tseg2 = tseg + 1 - (sampl_pt * (tseg + 1)) / 1000;
+       *tseg2 = tseg + CAN_CALC_SYNC_SEG -
+               (sampl_pt * (tseg + CAN_CALC_SYNC_SEG)) / 1000;
        if (*tseg2 < btc->tseg2_min)
                *tseg2 = btc->tseg2_min;
        if (*tseg2 > btc->tseg2_max)
@@ -557,7 +559,7 @@ static int can_update_spt(const struct can_bittiming_const *btc,
                *tseg1 = btc->tseg1_max;
                *tseg2 = tseg - *tseg1;
        }
-       return 1000 * (tseg + 1 - *tseg2) / (tseg + 1);
+       return 1000 * (tseg + CAN_CALC_SYNC_SEG - *tseg2) / (tseg + CAN_CALC_SYNC_SEG);
 }
 
 static int can_calc_bittiming(struct net_device *dev, struct can_bittiming *bt,
@@ -586,7 +588,8 @@ static int can_calc_bittiming(struct net_device *dev, struct can_bittiming *bt,
        /* tseg even = round down, odd = round up */
        for (tseg = (btc->tseg1_max + btc->tseg2_max) * 2 + 1;
             tseg >= (btc->tseg1_min + btc->tseg2_min) * 2; tseg--) {
-               tsegall = 1 + tseg / 2;
+               tsegall = CAN_CALC_SYNC_SEG + tseg / 2;
+
                /* Compute all possible tseg choices (tseg=tseg1+tseg2) */
                brp = priv->clock.freq / (tsegall * bt->bitrate) + tseg % 2;
                /* chose brp step which is possible in system */
@@ -655,7 +658,7 @@ static int can_calc_bittiming(struct net_device *dev, struct can_bittiming *bt,
 
        bt->brp = best_brp;
        /* real bit-rate */
-       bt->bitrate = priv->clock.freq / (bt->brp * (tseg1 + tseg2 + 1));
+       bt->bitrate = priv->clock.freq / (bt->brp * (CAN_CALC_SYNC_SEG + tseg1 + tseg2));
 
        return 0;
 }