Currently the hardware counters reset when the interface is
brought down, causing stats visible to userspace to drop to zero.
Save the accumulated stats before bringing the interface down
so they persist across routine down/up cycles.

Signed-off-by: Anshumali Gaur <agaur@marvell.com>
---
v5:
  - Split variable declaration and initialization in otx2_stop (Paolo)
  - Fix reverse christmas tree order in otx2_get_stats64() (Paolo)
  - Move stats collection just before otx2_free_hw_resources() to
    avoid race with NAPI (Paolo/Sashiko)
  - Remove duplicate otx2_rxtx_enable() call
v4:
  - Move stats accumulation after disabling tx/rx (Dragos)
  - Fetch latest HW counters before accumulating in otx2_stop()
v3:
  - Code format according to kernel coding style
  - Reword commit message
v2:
  - Fix subject prefix to target net-next
 .../marvell/octeontx2/nic/otx2_common.c       | 20 ++++++++++--------
 .../marvell/octeontx2/nic/otx2_common.h       |  1 +
 .../ethernet/marvell/octeontx2/nic/otx2_pf.c  | 21 +++++++++++++++++++
 3 files changed, 33 insertions(+), 9 deletions(-)

diff --git a/drivers/net/ethernet/marvell/octeontx2/nic/otx2_common.c b/drivers/net/ethernet/marvell/octeontx2/nic/otx2_common.c
index 971fcab1c248..fce46816446f 100644
--- a/drivers/net/ethernet/marvell/octeontx2/nic/otx2_common.c
+++ b/drivers/net/ethernet/marvell/octeontx2/nic/otx2_common.c
@@ -138,20 +138,22 @@ void otx2_get_dev_stats(struct otx2_nic *pfvf)
 void otx2_get_stats64(struct net_device *netdev,
 		      struct rtnl_link_stats64 *stats)
 {
+	struct otx2_dev_stats *dev_stats, *old_stats;
 	struct otx2_nic *pfvf = netdev_priv(netdev);
-	struct otx2_dev_stats *dev_stats;
 
 	otx2_get_dev_stats(pfvf);
 
 	dev_stats = &pfvf->hw.dev_stats;
-	stats->rx_bytes = dev_stats->rx_bytes;
-	stats->rx_packets = dev_stats->rx_frames;
-	stats->rx_dropped = dev_stats->rx_drops;
-	stats->multicast = dev_stats->rx_mcast_frames;
-
-	stats->tx_bytes = dev_stats->tx_bytes;
-	stats->tx_packets = dev_stats->tx_frames;
-	stats->tx_dropped = dev_stats->tx_drops;
+	old_stats = &pfvf->hw.old_stats;
+
+	stats->rx_bytes = old_stats->rx_bytes + dev_stats->rx_bytes;
+	stats->rx_packets = old_stats->rx_frames + dev_stats->rx_frames;
+	stats->rx_dropped = old_stats->rx_drops + dev_stats->rx_drops;
+	stats->multicast = old_stats->rx_mcast_frames + dev_stats->rx_mcast_frames;
+
+	stats->tx_bytes = old_stats->tx_bytes + dev_stats->tx_bytes;
+	stats->tx_packets = old_stats->tx_frames + dev_stats->tx_frames;
+	stats->tx_dropped = old_stats->tx_drops + dev_stats->tx_drops;
 }
 EXPORT_SYMBOL(otx2_get_stats64);
 
diff --git a/drivers/net/ethernet/marvell/octeontx2/nic/otx2_common.h b/drivers/net/ethernet/marvell/octeontx2/nic/otx2_common.h
index eecee612b7b2..ad65aa19b80d 100644
--- a/drivers/net/ethernet/marvell/octeontx2/nic/otx2_common.h
+++ b/drivers/net/ethernet/marvell/octeontx2/nic/otx2_common.h
@@ -255,6 +255,7 @@ struct otx2_hw {
 
 	/* Stats */
 	struct otx2_dev_stats	dev_stats;
+	struct otx2_dev_stats	old_stats;
 	struct otx2_drv_stats	drv_stats;
 	u64			cgx_rx_stats[CGX_RX_STATS_COUNT];
 	u64			cgx_tx_stats[CGX_TX_STATS_COUNT];
diff --git a/drivers/net/ethernet/marvell/octeontx2/nic/otx2_pf.c b/drivers/net/ethernet/marvell/octeontx2/nic/otx2_pf.c
index ee623476e5ff..3b4e32d899b7 100644
--- a/drivers/net/ethernet/marvell/octeontx2/nic/otx2_pf.c
+++ b/drivers/net/ethernet/marvell/octeontx2/nic/otx2_pf.c
@@ -2154,6 +2154,7 @@ EXPORT_SYMBOL(otx2_open);
 int otx2_stop(struct net_device *netdev)
 {
 	struct otx2_nic *pf = netdev_priv(netdev);
+	struct otx2_dev_stats *old_stats, *dev;
 	struct otx2_cq_poll *cq_poll = NULL;
 	struct otx2_qset *qset = &pf->qset;
 	int qidx, vec, wrk;
@@ -2200,6 +2201,26 @@ int otx2_stop(struct net_device *netdev)
 		cancel_delayed_work_sync(&pf->refill_wrk[wrk].pool_refill_work);
 	devm_kfree(pf->dev, pf->refill_wrk);
 
+	/* Read final HW counters and accumulate */
+	dev = &pf->hw.dev_stats;
+	old_stats = &pf->hw.old_stats;
+	otx2_get_dev_stats(pf);
+
+	/* Accumulate old stats */
+	old_stats->rx_bytes     += dev->rx_bytes;
+	old_stats->rx_drops     += dev->rx_drops;
+	old_stats->rx_bcast_frames      += dev->rx_bcast_frames;
+	old_stats->rx_mcast_frames      += dev->rx_mcast_frames;
+	old_stats->rx_ucast_frames      += dev->rx_ucast_frames;
+	old_stats->rx_frames            += dev->rx_frames;
+
+	old_stats->tx_bytes             += dev->tx_bytes;
+	old_stats->tx_drops             += dev->tx_drops;
+	old_stats->tx_bcast_frames      += dev->tx_bcast_frames;
+	old_stats->tx_mcast_frames      += dev->tx_mcast_frames;
+	old_stats->tx_ucast_frames      += dev->tx_ucast_frames;
+	old_stats->tx_frames            += dev->tx_frames;
+
 	otx2_free_hw_resources(pf);
 	otx2_free_cints(pf, pf->hw.cint_cnt);
 	otx2_disable_napi(pf);
-- 
2.25.1