bnxt_en: Allow statistics DMA to be configurable using ethtool -C.

The allowable range is 0.25 seconds to 1 second interval.  Default is
1 second.
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/bnxt/bnxt.c

@@ -3952,7 +3952,7 @@ static int bnxt_hwrm_stat_ctx_alloc(struct bnxt *bp)
 
 	bnxt_hwrm_cmd_hdr_init(bp, &req, HWRM_STAT_CTX_ALLOC, -1, -1);
 
-	req.update_period_ms = cpu_to_le32(1000);
+	req.update_period_ms = cpu_to_le32(bp->stats_coal_ticks / 1000);
 
 	mutex_lock(&bp->hwrm_cmd_lock);
 	for (i = 0; i < bp->cp_nr_rings; i++) {
@@ -5994,6 +5994,8 @@ static int bnxt_init_board(struct pci_dev *pdev, struct net_device *dev)
 	bp->tx_coal_ticks_irq = 2;
 	bp->tx_coal_bufs_irq = 2;
 
+	bp->stats_coal_ticks = BNXT_DEF_STATS_COAL_TICKS;
+
 	init_timer(&bp->timer);
 	bp->timer.data = (unsigned long)bp;
 	bp->timer.function = bnxt_timer;

drivers/net/ethernet/broadcom/bnxt/bnxt.h

@@ -1067,6 +1067,11 @@ struct bnxt {
 
 #define BNXT_USEC_TO_COAL_TIMER(x)	((x) * 25 / 2)
 
+	u32			stats_coal_ticks;
+#define BNXT_DEF_STATS_COAL_TICKS	 1000000
+#define BNXT_MIN_STATS_COAL_TICKS	  250000
+#define BNXT_MAX_STATS_COAL_TICKS	 1000000
+
 	struct work_struct	sp_task;
 	unsigned long		sp_event;
 #define BNXT_RX_MASK_SP_EVENT		0

drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c

@@ -56,6 +56,8 @@ static int bnxt_get_coalesce(struct net_device *dev,
 	coal->tx_coalesce_usecs_irq = bp->tx_coal_ticks_irq;
 	coal->tx_max_coalesced_frames_irq = bp->tx_coal_bufs_irq;
 
+	coal->stats_block_coalesce_usecs = bp->stats_coal_ticks;
+
 	return 0;
 }
 
@@ -63,6 +65,7 @@ static int bnxt_set_coalesce(struct net_device *dev,
 			     struct ethtool_coalesce *coal)
 {
 	struct bnxt *bp = netdev_priv(dev);
+	bool update_stats = false;
 	int rc = 0;
 
 	bp->rx_coal_ticks = coal->rx_coalesce_usecs;
@@ -76,8 +79,26 @@ static int bnxt_set_coalesce(struct net_device *dev,
 	bp->tx_coal_ticks_irq = coal->tx_coalesce_usecs_irq;
 	bp->tx_coal_bufs_irq = coal->tx_max_coalesced_frames_irq;
 
-	if (netif_running(dev))
-		rc = bnxt_hwrm_set_coal(bp);
+	if (bp->stats_coal_ticks != coal->stats_block_coalesce_usecs) {
+		u32 stats_ticks = coal->stats_block_coalesce_usecs;
+
+		stats_ticks = clamp_t(u32, stats_ticks,
+				      BNXT_MIN_STATS_COAL_TICKS,
+				      BNXT_MAX_STATS_COAL_TICKS);
+		stats_ticks = rounddown(stats_ticks, BNXT_MIN_STATS_COAL_TICKS);
+		bp->stats_coal_ticks = stats_ticks;
+		update_stats = true;
+	}
+
+	if (netif_running(dev)) {
+		if (update_stats) {
+			rc = bnxt_close_nic(bp, true, false);
+			if (!rc)
+				rc = bnxt_open_nic(bp, true, false);
+		} else {
+			rc = bnxt_hwrm_set_coal(bp);
+		}
+	}
 
 	return rc;
 }