mlxsw: pci: PTP: Hook into packet transmit path

On Spectrum-1, timestamps are delivered separately from the packets, and
need to paired up. Therefore, at some point after mlxsw_sp_port_xmit()
is invoked, it is necessary to involve the chip-specific driver code to
allow it to do the necessary bookkeeping and matching.

On Spectrum-2, timestamps are delivered in CQE. For that reason,
position the point of driver involvement into mlxsw_pci_cqe_sdq_handle()
to make it hopefully easier to extend for Spectrum-2 in the future.

To tell the driver what port the packet was sent on, keep tx_info
in SKB control buffer.

Introduce a new driver core interface mlxsw_core_ptp_transmitted(), a
driver callback ptp_transmitted, and a PTP op transmitted. The callee is
responsible for taking care of releasing the SKB passed to the new
interfaces, and correspondingly have the new stub callbacks just call
dev_kfree_skb_any().

Follow-up patches will introduce the actual content into
mlxsw_sp1_ptp_transmitted() in particular.

Signed-off-by: Petr Machata <petrm@mellanox.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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

@@ -1245,6 +1245,15 @@ int mlxsw_core_skb_transmit(struct mlxsw_core *mlxsw_core, struct sk_buff *skb,
 }
 EXPORT_SYMBOL(mlxsw_core_skb_transmit);
 
+void mlxsw_core_ptp_transmitted(struct mlxsw_core *mlxsw_core,
+				struct sk_buff *skb, u8 local_port)
+{
+	if (mlxsw_core->driver->ptp_transmitted)
+		mlxsw_core->driver->ptp_transmitted(mlxsw_core, skb,
+						    local_port);
+}
+EXPORT_SYMBOL(mlxsw_core_ptp_transmitted);
+
 static bool __is_rx_listener_equal(const struct mlxsw_rx_listener *rxl_a,
 				   const struct mlxsw_rx_listener *rxl_b)
 {

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

@@ -48,6 +48,8 @@ bool mlxsw_core_skb_transmit_busy(struct mlxsw_core *mlxsw_core,
 				  const struct mlxsw_tx_info *tx_info);
 int mlxsw_core_skb_transmit(struct mlxsw_core *mlxsw_core, struct sk_buff *skb,
 			    const struct mlxsw_tx_info *tx_info);
+void mlxsw_core_ptp_transmitted(struct mlxsw_core *mlxsw_core,
+				struct sk_buff *skb, u8 local_port);
 
 struct mlxsw_rx_listener {
 	void (*func)(struct sk_buff *skb, u8 local_port, void *priv);
@@ -296,6 +298,13 @@ struct mlxsw_driver {
 			     u64 *p_linear_size);
 	int (*params_register)(struct mlxsw_core *mlxsw_core);
 	void (*params_unregister)(struct mlxsw_core *mlxsw_core);
+
+	/* Notify a driver that a timestamped packet was transmitted. Driver
+	 * is responsible for freeing the passed-in SKB.
+	 */
+	void (*ptp_transmitted)(struct mlxsw_core *mlxsw_core,
+				struct sk_buff *skb, u8 local_port);
+
 	u8 txhdr_len;
 	const struct mlxsw_config_profile *profile;
 	bool res_query_enabled;
@@ -419,6 +428,7 @@ enum mlxsw_devlink_param_id {
 };
 
 struct mlxsw_skb_cb {
+	struct mlxsw_tx_info tx_info;
 };
 
 static inline struct mlxsw_skb_cb *mlxsw_skb_cb(struct sk_buff *skb)

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

@@ -508,17 +508,28 @@ static void mlxsw_pci_cqe_sdq_handle(struct mlxsw_pci *mlxsw_pci,
 {
 	struct pci_dev *pdev = mlxsw_pci->pdev;
 	struct mlxsw_pci_queue_elem_info *elem_info;
+	struct mlxsw_tx_info tx_info;
 	char *wqe;
 	struct sk_buff *skb;
 	int i;
 
 	spin_lock(&q->lock);
 	elem_info = mlxsw_pci_queue_elem_info_consumer_get(q);
+	tx_info = mlxsw_skb_cb(elem_info->u.sdq.skb)->tx_info;
 	skb = elem_info->u.sdq.skb;
 	wqe = elem_info->elem;
 	for (i = 0; i < MLXSW_PCI_WQE_SG_ENTRIES; i++)
 		mlxsw_pci_wqe_frag_unmap(mlxsw_pci, wqe, i, DMA_TO_DEVICE);
-	dev_kfree_skb_any(skb);
+
+	if (unlikely(!tx_info.is_emad &&
+		     skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP)) {
+		mlxsw_core_ptp_transmitted(mlxsw_pci->core, skb,
+					   tx_info.local_port);
+		skb = NULL;
+	}
+
+	if (skb)
+		dev_kfree_skb_any(skb);
 	elem_info->u.sdq.skb = NULL;
 
 	if (q->consumer_counter++ != consumer_counter_limit)
@@ -1548,6 +1559,7 @@ static int mlxsw_pci_skb_transmit(void *bus_priv, struct sk_buff *skb,
 		err = -EAGAIN;
 		goto unlock;
 	}
+	mlxsw_skb_cb(skb)->tx_info = *tx_info;
 	elem_info->u.sdq.skb = skb;
 
 	wqe = elem_info->elem;
@@ -1571,6 +1583,9 @@ static int mlxsw_pci_skb_transmit(void *bus_priv, struct sk_buff *skb,
 			goto unmap_frags;
 	}
 
+	if (unlikely(skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP))
+		skb_shinfo(skb)->tx_flags |= SKBTX_IN_PROGRESS;
+
 	/* Set unused sq entries byte count to zero. */
 	for (i++; i < MLXSW_PCI_WQE_SG_ENTRIES; i++)
 		mlxsw_pci_wqe_byte_count_set(wqe, i, 0);

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

@@ -157,6 +157,12 @@ struct mlxsw_sp_ptp_ops {
 	 */
 	void (*receive)(struct mlxsw_sp *mlxsw_sp, struct sk_buff *skb,
 			u8 local_port);
+
+	/* Notify a driver that a timestamped packet was transmitted. Driver
+	 * is responsible for freeing the passed-in SKB.
+	 */
+	void (*transmitted)(struct mlxsw_sp *mlxsw_sp, struct sk_buff *skb,
+			    u8 local_port);
 };
 
 static int mlxsw_sp_component_query(struct mlxfw_dev *mlxfw_dev,
@@ -4424,12 +4430,14 @@ static const struct mlxsw_sp_ptp_ops mlxsw_sp1_ptp_ops = {
 	.clock_init	= mlxsw_sp1_ptp_clock_init,
 	.clock_fini	= mlxsw_sp1_ptp_clock_fini,
 	.receive	= mlxsw_sp1_ptp_receive,
+	.transmitted	= mlxsw_sp1_ptp_transmitted,
 };
 
 static const struct mlxsw_sp_ptp_ops mlxsw_sp2_ptp_ops = {
 	.clock_init	= mlxsw_sp2_ptp_clock_init,
 	.clock_fini	= mlxsw_sp2_ptp_clock_fini,
 	.receive	= mlxsw_sp2_ptp_receive,
+	.transmitted	= mlxsw_sp2_ptp_transmitted,
 };
 
 static int mlxsw_sp_netdevice_event(struct notifier_block *unused,
@@ -4995,6 +5003,15 @@ static void mlxsw_sp2_params_unregister(struct mlxsw_core *mlxsw_core)
 	mlxsw_sp_params_unregister(mlxsw_core);
 }
 
+static void mlxsw_sp_ptp_transmitted(struct mlxsw_core *mlxsw_core,
+				     struct sk_buff *skb, u8 local_port)
+{
+	struct mlxsw_sp *mlxsw_sp = mlxsw_core_driver_priv(mlxsw_core);
+
+	skb_pull(skb, MLXSW_TXHDR_LEN);
+	mlxsw_sp->ptp_ops->transmitted(mlxsw_sp, skb, local_port);
+}
+
 static struct mlxsw_driver mlxsw_sp1_driver = {
 	.kind				= mlxsw_sp1_driver_name,
 	.priv_size			= sizeof(struct mlxsw_sp),
@@ -5019,6 +5036,7 @@ static struct mlxsw_driver mlxsw_sp1_driver = {
 	.kvd_sizes_get			= mlxsw_sp_kvd_sizes_get,
 	.params_register		= mlxsw_sp_params_register,
 	.params_unregister		= mlxsw_sp_params_unregister,
+	.ptp_transmitted		= mlxsw_sp_ptp_transmitted,
 	.txhdr_len			= MLXSW_TXHDR_LEN,
 	.profile			= &mlxsw_sp1_config_profile,
 	.res_query_enabled		= true,
@@ -5047,6 +5065,7 @@ static struct mlxsw_driver mlxsw_sp2_driver = {
 	.resources_register		= mlxsw_sp2_resources_register,
 	.params_register		= mlxsw_sp2_params_register,
 	.params_unregister		= mlxsw_sp2_params_unregister,
+	.ptp_transmitted		= mlxsw_sp_ptp_transmitted,
 	.txhdr_len			= MLXSW_TXHDR_LEN,
 	.profile			= &mlxsw_sp2_config_profile,
 	.res_query_enabled		= true,

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

@@ -270,3 +270,9 @@ void mlxsw_sp1_ptp_receive(struct mlxsw_sp *mlxsw_sp, struct sk_buff *skb,
 {
 	mlxsw_sp_rx_listener_no_mark_func(skb, local_port, mlxsw_sp);
 }
+
+void mlxsw_sp1_ptp_transmitted(struct mlxsw_sp *mlxsw_sp,
+			       struct sk_buff *skb, u8 local_port)
+{
+	dev_kfree_skb_any(skb);
+}

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

@@ -20,6 +20,9 @@ void mlxsw_sp1_ptp_clock_fini(struct mlxsw_sp_ptp_clock *clock);
 void mlxsw_sp1_ptp_receive(struct mlxsw_sp *mlxsw_sp, struct sk_buff *skb,
 			   u8 local_port);
 
+void mlxsw_sp1_ptp_transmitted(struct mlxsw_sp *mlxsw_sp,
+			       struct sk_buff *skb, u8 local_port);
+
 #else
 
 static inline struct mlxsw_sp_ptp_clock *
@@ -38,6 +41,12 @@ static inline void mlxsw_sp1_ptp_receive(struct mlxsw_sp *mlxsw_sp,
 	mlxsw_sp_rx_listener_no_mark_func(skb, local_port, mlxsw_sp);
 }
 
+static inline void mlxsw_sp1_ptp_transmitted(struct mlxsw_sp *mlxsw_sp,
+					     struct sk_buff *skb, u8 local_port)
+{
+	dev_kfree_skb_any(skb);
+}
+
 #endif
 
 static inline struct mlxsw_sp_ptp_clock *
@@ -56,4 +65,10 @@ static inline void mlxsw_sp2_ptp_receive(struct mlxsw_sp *mlxsw_sp,
 	mlxsw_sp_rx_listener_no_mark_func(skb, local_port, mlxsw_sp);
 }
 
+static inline void mlxsw_sp2_ptp_transmitted(struct mlxsw_sp *mlxsw_sp,
+					     struct sk_buff *skb, u8 local_port)
+{
+	dev_kfree_skb_any(skb);
+}
+
 #endif