bnxt_en: add support for tcp-data-split ethtool command

NICs that uses bnxt_en driver supports tcp-data-split feature by the
name of HDS(header-data-split).
But there is no implementation for the HDS to enable by ethtool.
Only getting the current HDS status is implemented and The HDS is just
automatically enabled only when either LRO, HW-GRO, or JUMBO is enabled.
The hds_threshold follows rx-copybreak value. and it was unchangeable.

This implements `ethtool -G <interface name> tcp-data-split <value>`
command option.
The value can be <on> and <auto>.
The value is <auto> and one of LRO/GRO/JUMBO is enabled, HDS is
automatically enabled and all LRO/GRO/JUMBO are disabled, HDS is
automatically disabled.

HDS feature relies on the aggregation ring.
So, if HDS is enabled, the bnxt_en driver initializes the aggregation ring.
This is the reason why BNXT_FLAG_AGG_RINGS contains HDS condition.

Acked-by: Jakub Kicinski <kuba@kernel.org>
Tested-by: Stanislav Fomichev <sdf@fomichev.me>
Tested-by: Andy Gospodarek <gospo@broadcom.com>
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Reviewed-by: Michael Chan <michael.chan@broadcom.com>
Link: https://patch.msgid.link/20250114142852.3364986-8-ap420073@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

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

@@ -4630,7 +4630,7 @@ void bnxt_set_ring_params(struct bnxt *bp)
 	bp->rx_agg_ring_size = 0;
 	bp->rx_agg_nr_pages = 0;
 
-	if (bp->flags & BNXT_FLAG_TPA)
+	if (bp->flags & BNXT_FLAG_TPA || bp->flags & BNXT_FLAG_HDS)
 		agg_factor = min_t(u32, 4, 65536 / BNXT_RX_PAGE_SIZE);
 
 	bp->flags &= ~BNXT_FLAG_JUMBO;

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

@@ -2244,8 +2244,6 @@ struct bnxt {
 	#define BNXT_FLAG_TPA		(BNXT_FLAG_LRO | BNXT_FLAG_GRO)
 	#define BNXT_FLAG_JUMBO		0x10
 	#define BNXT_FLAG_STRIP_VLAN	0x20
-	#define BNXT_FLAG_AGG_RINGS	(BNXT_FLAG_JUMBO | BNXT_FLAG_GRO | \
-					 BNXT_FLAG_LRO)
 	#define BNXT_FLAG_RFS		0x100
 	#define BNXT_FLAG_SHARED_RINGS	0x200
 	#define BNXT_FLAG_PORT_STATS	0x400
@@ -2266,6 +2264,9 @@ struct bnxt {
 	#define BNXT_FLAG_ROCE_MIRROR_CAP	0x4000000
 	#define BNXT_FLAG_TX_COAL_CMPL	0x8000000
 	#define BNXT_FLAG_PORT_STATS_EXT	0x10000000
+	#define BNXT_FLAG_HDS		0x20000000
+	#define BNXT_FLAG_AGG_RINGS	(BNXT_FLAG_JUMBO | BNXT_FLAG_GRO | \
+					 BNXT_FLAG_LRO | BNXT_FLAG_HDS)
 
 	#define BNXT_FLAG_ALL_CONFIG_FEATS (BNXT_FLAG_TPA |		\
 					    BNXT_FLAG_RFS |		\

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

@@ -840,16 +840,35 @@ static int bnxt_set_ringparam(struct net_device *dev,
 			      struct kernel_ethtool_ringparam *kernel_ering,
 			      struct netlink_ext_ack *extack)
 {
+	u8 tcp_data_split = kernel_ering->tcp_data_split;
 	struct bnxt *bp = netdev_priv(dev);
+	u8 hds_config_mod;
 
 	if ((ering->rx_pending > BNXT_MAX_RX_DESC_CNT) ||
 	    (ering->tx_pending > BNXT_MAX_TX_DESC_CNT) ||
 	    (ering->tx_pending < BNXT_MIN_TX_DESC_CNT))
 		return -EINVAL;
 
+	hds_config_mod = tcp_data_split != dev->ethtool->hds_config;
+	if (tcp_data_split == ETHTOOL_TCP_DATA_SPLIT_DISABLED && hds_config_mod)
+		return -EINVAL;
+
+	if (tcp_data_split == ETHTOOL_TCP_DATA_SPLIT_ENABLED &&
+	    hds_config_mod && BNXT_RX_PAGE_MODE(bp)) {
+		NL_SET_ERR_MSG_MOD(extack, "tcp-data-split is disallowed when XDP is attached");
+		return -EINVAL;
+	}
+
 	if (netif_running(dev))
 		bnxt_close_nic(bp, false, false);
 
+	if (hds_config_mod) {
+		if (tcp_data_split == ETHTOOL_TCP_DATA_SPLIT_ENABLED)
+			bp->flags |= BNXT_FLAG_HDS;
+		else if (tcp_data_split == ETHTOOL_TCP_DATA_SPLIT_UNKNOWN)
+			bp->flags &= ~BNXT_FLAG_HDS;
+	}
+
 	bp->rx_ring_size = ering->rx_pending;
 	bp->tx_ring_size = ering->tx_pending;
 	bnxt_set_ring_params(bp);
@@ -5371,6 +5390,7 @@ const struct ethtool_ops bnxt_ethtool_ops = {
 				     ETHTOOL_COALESCE_STATS_BLOCK_USECS |
 				     ETHTOOL_COALESCE_USE_ADAPTIVE_RX |
 				     ETHTOOL_COALESCE_USE_CQE,
+	.supported_ring_params	= ETHTOOL_RING_USE_TCP_DATA_SPLIT,
 	.get_link_ksettings	= bnxt_get_link_ksettings,
 	.set_link_ksettings	= bnxt_set_link_ksettings,
 	.get_fec_stats		= bnxt_get_fec_stats,

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

@@ -395,6 +395,10 @@ static int bnxt_xdp_set(struct bnxt *bp, struct bpf_prog *prog)
 			    bp->dev->mtu, BNXT_MAX_PAGE_MODE_MTU);
 		return -EOPNOTSUPP;
 	}
+	if (prog && bp->flags & BNXT_FLAG_HDS) {
+		netdev_warn(dev, "XDP is disallowed when HDS is enabled.\n");
+		return -EOPNOTSUPP;
+	}
 	if (!(bp->flags & BNXT_FLAG_SHARED_RINGS)) {
 		netdev_warn(dev, "ethtool rx/tx channels must be combined to support XDP.\n");
 		return -EOPNOTSUPP;