1 files changed, 102 insertions, 65 deletions

diff --git a/drivers/net/can/dev.c b/drivers/net/can/dev.c
index ad535a854..8d6208c0b 100644
--- a/drivers/net/can/dev.c
+++ b/drivers/net/can/dev.c
@@ -21,6 +21,7 @@
 #include <linux/slab.h>
 #include <linux/netdevice.h>
 #include <linux/if_arp.h>
+#include <linux/workqueue.h>
 #include <linux/can.h>
 #include <linux/can/dev.h>
 #include <linux/can/skb.h>
@@ -69,6 +70,7 @@ EXPORT_SYMBOL_GPL(can_len2dlc);
 
 #ifdef CONFIG_CAN_CALC_BITTIMING
 #define CAN_CALC_MAX_ERROR 50 /* in one-tenth of a percent */
+#define CAN_CALC_SYNC_SEG 1
 
 /*
  * Bit-timing calculation derived from:
@@ -83,98 +85,126 @@ EXPORT_SYMBOL_GPL(can_len2dlc);
  * registers of the CAN controller. You can find more information
  * in the header file linux/can/netlink.h.
  */
-static int can_update_spt(const struct can_bittiming_const *btc,
-			  int sampl_pt, int tseg, int *tseg1, int *tseg2)
+static int can_update_sample_point(const struct can_bittiming_const *btc,
+			  unsigned int sample_point_nominal, unsigned int tseg,
+			  unsigned int *tseg1_ptr, unsigned int *tseg2_ptr,
+			  unsigned int *sample_point_error_ptr)
 {
-	*tseg2 = tseg + 1 - (sampl_pt * (tseg + 1)) / 1000;
-	if (*tseg2 < btc->tseg2_min)
-		*tseg2 = btc->tseg2_min;
-	if (*tseg2 > btc->tseg2_max)
-		*tseg2 = btc->tseg2_max;
-	*tseg1 = tseg - *tseg2;
-	if (*tseg1 > btc->tseg1_max) {
-		*tseg1 = btc->tseg1_max;
-		*tseg2 = tseg - *tseg1;
+	unsigned int sample_point_error, best_sample_point_error = UINT_MAX;
+	unsigned int sample_point, best_sample_point = 0;
+	unsigned int tseg1, tseg2;
+	int i;
+
+	for (i = 0; i <= 1; i++) {
+		tseg2 = tseg + CAN_CALC_SYNC_SEG - (sample_point_nominal * (tseg + CAN_CALC_SYNC_SEG)) / 1000 - i;
+		tseg2 = clamp(tseg2, btc->tseg2_min, btc->tseg2_max);
+		tseg1 = tseg - tseg2;
+		if (tseg1 > btc->tseg1_max) {
+			tseg1 = btc->tseg1_max;
+			tseg2 = tseg - tseg1;
+		}
+
+		sample_point = 1000 * (tseg + CAN_CALC_SYNC_SEG - tseg2) / (tseg + CAN_CALC_SYNC_SEG);
+		sample_point_error = abs(sample_point_nominal - sample_point);
+
+		if ((sample_point <= sample_point_nominal) && (sample_point_error < best_sample_point_error)) {
+			best_sample_point = sample_point;
+			best_sample_point_error = sample_point_error;
+			*tseg1_ptr = tseg1;
+			*tseg2_ptr = tseg2;
+		}
 	}
-	return 1000 * (tseg + 1 - *tseg2) / (tseg + 1);
+
+	if (sample_point_error_ptr)
+		*sample_point_error_ptr = best_sample_point_error;
+
+	return best_sample_point;
 }
 
 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);
-	long best_error = 1000000000, error = 0;
-	int best_tseg = 0, best_brp = 0, brp = 0;
-	int tsegall, tseg = 0, tseg1 = 0, tseg2 = 0;
-	int spt_error = 1000, spt = 0, sampl_pt;
-	long rate;
+	unsigned int bitrate;			/* current bitrate */
+	unsigned int bitrate_error;		/* difference between current and nominal value */
+	unsigned int best_bitrate_error = UINT_MAX;
+	unsigned int sample_point_error;	/* difference between current and nominal value */
+	unsigned int best_sample_point_error = UINT_MAX;
+	unsigned int sample_point_nominal;	/* nominal sample point */
+	unsigned int best_tseg = 0;		/* current best value for tseg */
+	unsigned int best_brp = 0;		/* current best value for brp */
+	unsigned int brp, tsegall, tseg, tseg1 = 0, tseg2 = 0;
 	u64 v64;
 
 	/* Use CiA recommended sample points */
 	if (bt->sample_point) {
-		sampl_pt = bt->sample_point;
+		sample_point_nominal = bt->sample_point;
 	} else {
 		if (bt->bitrate > 800000)
-			sampl_pt = 750;
+			sample_point_nominal = 750;
 		else if (bt->bitrate > 500000)
-			sampl_pt = 800;
+			sample_point_nominal = 800;
 		else
-			sampl_pt = 875;
+			sample_point_nominal = 875;
 	}
 
 	/* 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 */
+
+		/* choose brp step which is possible in system */
 		brp = (brp / btc->brp_inc) * btc->brp_inc;
 		if ((brp < btc->brp_min) || (brp > btc->brp_max))
 			continue;
-		rate = priv->clock.freq / (brp * tsegall);
-		error = bt->bitrate - rate;
+
+		bitrate = priv->clock.freq / (brp * tsegall);
+		bitrate_error = abs(bt->bitrate - bitrate);
+
 		/* tseg brp biterror */
-		if (error < 0)
-			error = -error;
-		if (error > best_error)
+		if (bitrate_error > best_bitrate_error)
 			continue;
-		best_error = error;
-		if (error == 0) {
-			spt = can_update_spt(btc, sampl_pt, tseg / 2,
-					     &tseg1, &tseg2);
-			error = sampl_pt - spt;
-			if (error < 0)
-				error = -error;
-			if (error > spt_error)
-				continue;
-			spt_error = error;
-		}
+
+		/* reset sample point error if we have a better bitrate */
+		if (bitrate_error < best_bitrate_error)
+			best_sample_point_error = UINT_MAX;
+
+		can_update_sample_point(btc, sample_point_nominal, tseg / 2, &tseg1, &tseg2, &sample_point_error);
+		if (sample_point_error > best_sample_point_error)
+			continue;
+
+		best_sample_point_error = sample_point_error;
+		best_bitrate_error = bitrate_error;
 		best_tseg = tseg / 2;
 		best_brp = brp;
-		if (error == 0)
+
+		if (bitrate_error == 0 && sample_point_error == 0)
 			break;
 	}
 
-	if (best_error) {
+	if (best_bitrate_error) {
 		/* Error in one-tenth of a percent */
-		error = (best_error * 1000) / bt->bitrate;
-		if (error > CAN_CALC_MAX_ERROR) {
+		v64 = (u64)best_bitrate_error * 1000;
+		do_div(v64, bt->bitrate);
+		bitrate_error = (u32)v64;
+		if (bitrate_error > CAN_CALC_MAX_ERROR) {
 			netdev_err(dev,
-				   "bitrate error %ld.%ld%% too high\n",
-				   error / 10, error % 10);
+				   "bitrate error %d.%d%% too high\n",
+				   bitrate_error / 10, bitrate_error % 10);
 			return -EDOM;
-		} else {
-			netdev_warn(dev, "bitrate error %ld.%ld%%\n",
-				    error / 10, error % 10);
 		}
+		netdev_warn(dev, "bitrate error %d.%d%%\n",
+			    bitrate_error / 10, bitrate_error % 10);
 	}
 
 	/* real sample point */
-	bt->sample_point = can_update_spt(btc, sampl_pt, best_tseg,
-					  &tseg1, &tseg2);
+	bt->sample_point = can_update_sample_point(btc, sample_point_nominal, best_tseg,
+					  &tseg1, &tseg2, NULL);
 
-	v64 = (u64)best_brp * 1000000000UL;
+	v64 = (u64)best_brp * 1000 * 1000 * 1000;
 	do_div(v64, priv->clock.freq);
 	bt->tq = (u32)v64;
 	bt->prop_seg = tseg1 / 2;
@@ -182,9 +212,9 @@ static int can_calc_bittiming(struct net_device *dev, struct can_bittiming *bt,
 	bt->phase_seg2 = tseg2;
 
 	/* check for sjw user settings */
-	if (!bt->sjw || !btc->sjw_max)
+	if (!bt->sjw || !btc->sjw_max) {
 		bt->sjw = 1;
-	else {
+	} else {
 		/* bt->sjw is at least 1 -> sanitize upper bound to sjw_max */
 		if (bt->sjw > btc->sjw_max)
 			bt->sjw = btc->sjw_max;
@@ -194,8 +224,9 @@ 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));
+
+	/* real bitrate */
+	bt->bitrate = priv->clock.freq / (bt->brp * (CAN_CALC_SYNC_SEG + tseg1 + tseg2));
 
 	return 0;
 }
@@ -471,9 +502,8 @@ EXPORT_SYMBOL_GPL(can_free_echo_skb);
 /*
  * CAN device restart for bus-off recovery
  */
-static void can_restart(unsigned long data)
+static void can_restart(struct net_device *dev)
 {
-	struct net_device *dev = (struct net_device *)data;
 	struct can_priv *priv = netdev_priv(dev);
 	struct net_device_stats *stats = &dev->stats;
 	struct sk_buff *skb;
@@ -513,6 +543,14 @@ restart:
 		netdev_err(dev, "Error %d during restart", err);
 }
 
+static void can_restart_work(struct work_struct *work)
+{
+	struct delayed_work *dwork = to_delayed_work(work);
+	struct can_priv *priv = container_of(dwork, struct can_priv, restart_work);
+
+	can_restart(priv->dev);
+}
+
 int can_restart_now(struct net_device *dev)
 {
 	struct can_priv *priv = netdev_priv(dev);
@@ -526,8 +564,8 @@ int can_restart_now(struct net_device *dev)
 	if (priv->state != CAN_STATE_BUS_OFF)
 		return -EBUSY;
 
-	/* Runs as soon as possible in the timer context */
-	mod_timer(&priv->restart_timer, jiffies);
+	cancel_delayed_work_sync(&priv->restart_work);
+	can_restart(dev);
 
 	return 0;
 }
@@ -548,8 +586,8 @@ void can_bus_off(struct net_device *dev)
 	netif_carrier_off(dev);
 
 	if (priv->restart_ms)
-		mod_timer(&priv->restart_timer,
-			  jiffies + (priv->restart_ms * HZ) / 1000);
+		schedule_delayed_work(&priv->restart_work,
+				      msecs_to_jiffies(priv->restart_ms));
 }
 EXPORT_SYMBOL_GPL(can_bus_off);
 
@@ -658,6 +696,7 @@ struct net_device *alloc_candev(int sizeof_priv, unsigned int echo_skb_max)
 		return NULL;
 
 	priv = netdev_priv(dev);
+	priv->dev = dev;
 
 	if (echo_skb_max) {
 		priv->echo_skb_max = echo_skb_max;
@@ -667,7 +706,7 @@ struct net_device *alloc_candev(int sizeof_priv, unsigned int echo_skb_max)
 
 	priv->state = CAN_STATE_STOPPED;
 
-	init_timer(&priv->restart_timer);
+	INIT_DELAYED_WORK(&priv->restart_work, can_restart_work);
 
 	return dev;
 }
@@ -748,8 +787,6 @@ int open_candev(struct net_device *dev)
 	if (!netif_carrier_ok(dev))
 		netif_carrier_on(dev);
 
-	setup_timer(&priv->restart_timer, can_restart, (unsigned long)dev);
-
 	return 0;
 }
 EXPORT_SYMBOL_GPL(open_candev);
@@ -764,7 +801,7 @@ void close_candev(struct net_device *dev)
 {
 	struct can_priv *priv = netdev_priv(dev);
 
-	del_timer_sync(&priv->restart_timer);
+	cancel_delayed_work_sync(&priv->restart_work);
 	can_flush_echo_skb(dev);
 }
 EXPORT_SYMBOL_GPL(close_candev);