mlxsw: spectrum_span: Add SPAN probability rate support

Currently, every packet that matches a mirroring trigger (e.g., received
packets, buffer dropped packets) is mirrored. Spectrum-2 and later ASICs
support mirroring with probability, where every 1 in N matched packets
is mirrored.

Extend the API that creates the binding between the trigger and the SPAN
agent with a probability rate parameter, which is an attribute of the
trigger. Set it to '1' to maintain existing behavior.

Subsequent patches will use it to perform more sophisticated sampling,
by mirroring packets to the CPU with probability.
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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

@@ -51,6 +51,7 @@ mlxsw_sp_mall_port_mirror_add(struct mlxsw_sp_port *mlxsw_sp_port,
 	trigger = mall_entry->ingress ? MLXSW_SP_SPAN_TRIGGER_INGRESS :
 					MLXSW_SP_SPAN_TRIGGER_EGRESS;
 	parms.span_id = mall_entry->mirror.span_id;
+	parms.probability_rate = 1;
 	err = mlxsw_sp_span_agent_bind(mlxsw_sp, trigger, mlxsw_sp_port,
 				       &parms);
 	if (err)

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

@@ -1341,6 +1341,7 @@ static int mlxsw_sp_qevent_span_configure(struct mlxsw_sp *mlxsw_sp,
 		goto err_analyzed_port_get;
 
 	trigger_parms.span_id = span_id;
+	trigger_parms.probability_rate = 1;
 	err = mlxsw_sp_span_agent_bind(mlxsw_sp, qevent_binding->span_trigger, mlxsw_sp_port,
 				       &trigger_parms);
 	if (err)

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

@@ -1231,8 +1231,12 @@ __mlxsw_sp_span_trigger_port_bind(struct mlxsw_sp_span *span,
 		return -EINVAL;
 	}
 
+	if (trigger_entry->parms.probability_rate > MLXSW_REG_MPAR_RATE_MAX)
+		return -EINVAL;
+
 	mlxsw_reg_mpar_pack(mpar_pl, trigger_entry->local_port, i_e, enable,
-			    trigger_entry->parms.span_id, 1);
+			    trigger_entry->parms.span_id,
+			    trigger_entry->parms.probability_rate);
 	return mlxsw_reg_write(span->mlxsw_sp->core, MLXSW_REG(mpar), mpar_pl);
 }
 
@@ -1366,8 +1370,11 @@ mlxsw_sp2_span_trigger_global_bind(struct mlxsw_sp_span_trigger_entry *
 		return -EINVAL;
 	}
 
+	if (trigger_entry->parms.probability_rate > MLXSW_REG_MPAGR_RATE_MAX)
+		return -EINVAL;
+
 	mlxsw_reg_mpagr_pack(mpagr_pl, trigger, trigger_entry->parms.span_id,
-			     1);
+			     trigger_entry->parms.probability_rate);
 	return mlxsw_reg_write(mlxsw_sp->core, MLXSW_REG(mpagr), mpagr_pl);
 }
 
@@ -1565,7 +1572,9 @@ int mlxsw_sp_span_agent_bind(struct mlxsw_sp *mlxsw_sp,
 							 trigger,
 							 mlxsw_sp_port);
 	if (trigger_entry) {
-		if (trigger_entry->parms.span_id != parms->span_id)
+		if (trigger_entry->parms.span_id != parms->span_id ||
+		    trigger_entry->parms.probability_rate !=
+		    parms->probability_rate)
 			return -EINVAL;
 		refcount_inc(&trigger_entry->ref_count);
 		goto out;

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

@@ -48,6 +48,7 @@ enum mlxsw_sp_span_trigger {
 
 struct mlxsw_sp_span_trigger_parms {
 	int span_id;
+	u32 probability_rate;
 };
 
 struct mlxsw_sp_span_agent_parms {