mlxsw: spectrum: qdiscs: Support stats for PRIO qdisc

Support basic stats for PRIO qdisc, which includes tx packets and bytes
count, drops count and backlog size. The rest of the stats are irrelevant
for this qdisc offload.
Since backlog is not only incremental but reflecting momentary value, in
case of a qdisc that stops being offloaded but is not destroyed, backlog
value needs to be updated about the un-offloading.
For that reason an unoffload function is being added to the ops struct.

Signed-off-by: Nogah Frankel <nogahf@mellanox.com>
Reviewed-by: Yuval Mintz <yuvalm@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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

@@ -66,6 +66,11 @@ struct mlxsw_sp_qdisc_ops {
 			  void *xstats_ptr);
 	void (*clean_stats)(struct mlxsw_sp_port *mlxsw_sp_port,
 			    struct mlxsw_sp_qdisc *mlxsw_sp_qdisc);
+	/* unoffload - to be used for a qdisc that stops being offloaded without
+	 * being destroyed.
+	 */
+	void (*unoffload)(struct mlxsw_sp_port *mlxsw_sp_port,
+			  struct mlxsw_sp_qdisc *mlxsw_sp_qdisc, void *params);
 };
 
 struct mlxsw_sp_qdisc {
@@ -79,6 +84,7 @@ struct mlxsw_sp_qdisc {
 		u64 tx_packets;
 		u64 drops;
 		u64 overlimits;
+		u64 backlog;
 	} stats_base;
 
 	struct mlxsw_sp_qdisc_ops *ops;
@@ -144,6 +150,9 @@ mlxsw_sp_qdisc_replace(struct mlxsw_sp_port *mlxsw_sp_port, u32 handle,
 
 err_bad_param:
 err_config:
+	if (mlxsw_sp_qdisc->handle == handle && ops->unoffload)
+		ops->unoffload(mlxsw_sp_port, mlxsw_sp_qdisc, params);
+
 	mlxsw_sp_qdisc_destroy(mlxsw_sp_port, mlxsw_sp_qdisc);
 	return err;
 }
@@ -451,11 +460,88 @@ mlxsw_sp_qdisc_prio_replace(struct mlxsw_sp_port *mlxsw_sp_port,
 	return 0;
 }
 
+void
+mlxsw_sp_qdisc_prio_unoffload(struct mlxsw_sp_port *mlxsw_sp_port,
+			      struct mlxsw_sp_qdisc *mlxsw_sp_qdisc,
+			      void *params)
+{
+	struct tc_prio_qopt_offload_params *p = params;
+	u64 backlog;
+
+	backlog = mlxsw_sp_cells_bytes(mlxsw_sp_port->mlxsw_sp,
+				       mlxsw_sp_qdisc->stats_base.backlog);
+	p->qstats->backlog -= backlog;
+}
+
+static int
+mlxsw_sp_qdisc_get_prio_stats(struct mlxsw_sp_port *mlxsw_sp_port,
+			      struct mlxsw_sp_qdisc *mlxsw_sp_qdisc,
+			      struct tc_qopt_offload_stats *stats_ptr)
+{
+	u64 tx_bytes, tx_packets, drops = 0, backlog = 0;
+	struct mlxsw_sp_qdisc_stats *stats_base;
+	struct mlxsw_sp_port_xstats *xstats;
+	struct rtnl_link_stats64 *stats;
+	int i;
+
+	xstats = &mlxsw_sp_port->periodic_hw_stats.xstats;
+	stats = &mlxsw_sp_port->periodic_hw_stats.stats;
+	stats_base = &mlxsw_sp_qdisc->stats_base;
+
+	tx_bytes = stats->tx_bytes - stats_base->tx_bytes;
+	tx_packets = stats->tx_packets - stats_base->tx_packets;
+
+	for (i = 0; i < IEEE_8021QAZ_MAX_TCS; i++) {
+		drops += xstats->tail_drop[i];
+		backlog += xstats->backlog[i];
+	}
+	drops = drops - stats_base->drops;
+
+	_bstats_update(stats_ptr->bstats, tx_bytes, tx_packets);
+	stats_ptr->qstats->drops += drops;
+	stats_ptr->qstats->backlog +=
+				mlxsw_sp_cells_bytes(mlxsw_sp_port->mlxsw_sp,
+						     backlog) -
+				mlxsw_sp_cells_bytes(mlxsw_sp_port->mlxsw_sp,
+						     stats_base->backlog);
+	stats_base->backlog = backlog;
+	stats_base->drops += drops;
+	stats_base->tx_bytes += tx_bytes;
+	stats_base->tx_packets += tx_packets;
+	return 0;
+}
+
+static void
+mlxsw_sp_setup_tc_qdisc_prio_clean_stats(struct mlxsw_sp_port *mlxsw_sp_port,
+					 struct mlxsw_sp_qdisc *mlxsw_sp_qdisc)
+{
+	struct mlxsw_sp_qdisc_stats *stats_base;
+	struct mlxsw_sp_port_xstats *xstats;
+	struct rtnl_link_stats64 *stats;
+	int i;
+
+	xstats = &mlxsw_sp_port->periodic_hw_stats.xstats;
+	stats = &mlxsw_sp_port->periodic_hw_stats.stats;
+	stats_base = &mlxsw_sp_qdisc->stats_base;
+
+	stats_base->tx_packets = stats->tx_packets;
+	stats_base->tx_bytes = stats->tx_bytes;
+
+	stats_base->drops = 0;
+	for (i = 0; i < IEEE_8021QAZ_MAX_TCS; i++)
+		stats_base->drops += xstats->tail_drop[i];
+
+	mlxsw_sp_qdisc->stats_base.backlog = 0;
+}
+
 static struct mlxsw_sp_qdisc_ops mlxsw_sp_qdisc_ops_prio = {
 	.type = MLXSW_SP_QDISC_PRIO,
 	.check_params = mlxsw_sp_qdisc_prio_check_params,
 	.replace = mlxsw_sp_qdisc_prio_replace,
+	.unoffload = mlxsw_sp_qdisc_prio_unoffload,
 	.destroy = mlxsw_sp_qdisc_prio_destroy,
+	.get_stats = mlxsw_sp_qdisc_get_prio_stats,
+	.clean_stats = mlxsw_sp_setup_tc_qdisc_prio_clean_stats,
 };
 
 int mlxsw_sp_setup_tc_prio(struct mlxsw_sp_port *mlxsw_sp_port,
@@ -480,6 +566,9 @@ int mlxsw_sp_setup_tc_prio(struct mlxsw_sp_port *mlxsw_sp_port,
 	switch (p->command) {
 	case TC_PRIO_DESTROY:
 		return mlxsw_sp_qdisc_destroy(mlxsw_sp_port, mlxsw_sp_qdisc);
+	case TC_PRIO_STATS:
+		return mlxsw_sp_qdisc_get_stats(mlxsw_sp_port, mlxsw_sp_qdisc,
+						&p->stats);
 	default:
 		return -EOPNOTSUPP;
 	}