mlxsw: Initialize txhdr_info according to PTP operations

A next patch will construct Tx header as part of pci.c. The switch driver
(mlxsw_spectrum.ko) should encapsulate all the differences between the
different ASICs and the bus driver (mlxsw_pci.ko) should remain unaware.

As preparation, add the relevant info as part of mlxsw_txhdr_info
structure, so later bus driver will merely construct the Tx header based on
information passed from the switch driver.

Most of the packets are transmitted as control packets, but PTP packets in
Spectrum-2 and Spectrum-3 should be handled differently. The driver
transmits them as data packets, and the default VLAN tag (4095) is added if
the packet is not already tagged.

Extend PTP operations to store a boolean which indicates whether packets
should be transmitted as data packets. Set it for Spectrum-2 and
Spectrum-3 only. Extend mlxsw_txhdr_info to store fields which will be used
later to construct Tx header. Initialize such fields according to the new
boolean which is stored in PTP operations.

Note that for now, mlxsw_txhdr_info structure is initialized, but not used,
a next patch will use it.

Signed-off-by: Amit Cohen <amcohen@nvidia.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Petr Machata <petrm@nvidia.com>
Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Link: https://patch.msgid.link/efcaacd4bedef524e840a0c29f96cebf2c4bc0e0.1737044384.git.petrm@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: Amit Cohen

drivers/net/ethernet/mellanox/mlxsw/core.h

@@ -74,6 +74,8 @@ struct mlxsw_tx_info {
 
 struct mlxsw_txhdr_info {
 	struct mlxsw_tx_info tx_info;
+	bool data;
+	u16 max_fid; /* Used for PTP packets which are sent as data. */
 };
 
 struct mlxsw_rx_md_info {

drivers/net/ethernet/mellanox/mlxsw/spectrum.c

@@ -299,6 +299,33 @@ static bool mlxsw_sp_skb_requires_ts(struct sk_buff *skb)
 	return !!ptp_parse_header(skb, type);
 }
 
+static void mlxsw_sp_txhdr_info_data_init(struct mlxsw_core *mlxsw_core,
+					  struct sk_buff *skb,
+					  struct mlxsw_txhdr_info *txhdr_info)
+{
+	/* Resource validation was done as part of PTP init. */
+	u16 max_fid = MLXSW_CORE_RES_GET(mlxsw_core, FID);
+
+	txhdr_info->data = true;
+	txhdr_info->max_fid = max_fid;
+}
+
+static void
+mlxsw_sp_txhdr_preparations(struct mlxsw_sp *mlxsw_sp, struct sk_buff *skb,
+			    struct mlxsw_txhdr_info *txhdr_info)
+{
+	if (likely(!mlxsw_sp_skb_requires_ts(skb)))
+		return;
+
+	if (!mlxsw_sp->ptp_ops->tx_as_data)
+		return;
+
+	/* Special handling for PTP events that require a time stamp and cannot
+	 * be transmitted as regular control packets.
+	 */
+	mlxsw_sp_txhdr_info_data_init(mlxsw_sp->core, skb, txhdr_info);
+}
+
 static int mlxsw_sp_txhdr_handle(struct mlxsw_core *mlxsw_core,
 				 struct mlxsw_sp_port *mlxsw_sp_port,
 				 struct sk_buff *skb,
@@ -721,7 +748,7 @@ static netdev_tx_t mlxsw_sp_port_xmit(struct sk_buff *skb,
 	struct mlxsw_sp_port *mlxsw_sp_port = netdev_priv(dev);
 	struct mlxsw_sp *mlxsw_sp = mlxsw_sp_port->mlxsw_sp;
 	struct mlxsw_sp_port_pcpu_stats *pcpu_stats;
-	const struct mlxsw_txhdr_info txhdr_info = {
+	struct mlxsw_txhdr_info txhdr_info = {
 		.tx_info.local_port = mlxsw_sp_port->local_port,
 		.tx_info.is_emad = false,
 	};
@@ -738,6 +765,8 @@ static netdev_tx_t mlxsw_sp_port_xmit(struct sk_buff *skb,
 		return NETDEV_TX_OK;
 	}
 
+	mlxsw_sp_txhdr_preparations(mlxsw_sp, skb, &txhdr_info);
+
 	err = mlxsw_sp_txhdr_handle(mlxsw_sp->core, mlxsw_sp_port, skb,
 				    &txhdr_info.tx_info);
 	if (err)
@@ -2812,6 +2841,7 @@ static const struct mlxsw_sp_ptp_ops mlxsw_sp2_ptp_ops = {
 	.get_stats_strings = mlxsw_sp2_get_stats_strings,
 	.get_stats	= mlxsw_sp2_get_stats,
 	.txhdr_construct = mlxsw_sp2_ptp_txhdr_construct,
+	.tx_as_data     = true,
 };
 
 static const struct mlxsw_sp_ptp_ops mlxsw_sp4_ptp_ops = {

drivers/net/ethernet/mellanox/mlxsw/spectrum.h

@@ -247,6 +247,7 @@ struct mlxsw_sp_ptp_ops {
 			       struct mlxsw_sp_port *mlxsw_sp_port,
 			       struct sk_buff *skb,
 			       const struct mlxsw_tx_info *tx_info);
+	bool tx_as_data;
 };
 
 struct mlxsw_sp_fid_core_ops {

drivers/net/ethernet/mellanox/mlxsw/spectrum_ptp.c

@@ -1353,6 +1353,10 @@ struct mlxsw_sp_ptp_state *mlxsw_sp2_ptp_init(struct mlxsw_sp *mlxsw_sp)
 	struct mlxsw_sp2_ptp_state *ptp_state;
 	int err;
 
+	/* Max FID will be used in data path, check validity as part of init. */
+	if (!MLXSW_CORE_RES_VALID(mlxsw_sp->core, FID))
+		return ERR_PTR(-EIO);
+
 	ptp_state = kzalloc(sizeof(*ptp_state), GFP_KERNEL);
 	if (!ptp_state)
 		return ERR_PTR(-ENOMEM);