mlxsw: spectrum_router: Configure default routing priority

When routing ip packets, the kernel is setting the SKB's priority
based on the tos field of the packet.
Imitate this behavior in the mlxsw router, having the internal
switch priority of a routed packet determined according to its DS
field.

Signed-off-by: Yuval Mintz <yuvalm@mellanox.com>
Signed-off-by: Nogah Frankel <nogahf@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_router.c

@@ -7011,6 +7011,24 @@ static int mlxsw_sp_mp_hash_init(struct mlxsw_sp *mlxsw_sp)
 }
 #endif
 
+static int mlxsw_sp_dscp_init(struct mlxsw_sp *mlxsw_sp)
+{
+	char rdpm_pl[MLXSW_REG_RDPM_LEN];
+	unsigned int i;
+
+	MLXSW_REG_ZERO(rdpm, rdpm_pl);
+
+	/* HW is determining switch priority based on DSCP-bits, but the
+	 * kernel is still doing that based on the ToS. Since there's a
+	 * mismatch in bits we need to make sure to translate the right
+	 * value ToS would observe, skipping the 2 least-significant ECN bits.
+	 */
+	for (i = 0; i < MLXSW_REG_RDPM_DSCP_ENTRY_REC_MAX_COUNT; i++)
+		mlxsw_reg_rdpm_pack(rdpm_pl, i, rt_tos2priority(i << 2));
+
+	return mlxsw_reg_write(mlxsw_sp->core, MLXSW_REG(rdpm), rdpm_pl);
+}
+
 static int __mlxsw_sp_router_init(struct mlxsw_sp *mlxsw_sp)
 {
 	char rgcr_pl[MLXSW_REG_RGCR_LEN];
@@ -7023,6 +7041,7 @@ static int __mlxsw_sp_router_init(struct mlxsw_sp *mlxsw_sp)
 
 	mlxsw_reg_rgcr_pack(rgcr_pl, true, true);
 	mlxsw_reg_rgcr_max_router_interfaces_set(rgcr_pl, max_rifs);
+	mlxsw_reg_rgcr_usp_set(rgcr_pl, true);
 	err = mlxsw_reg_write(mlxsw_sp->core, MLXSW_REG(rgcr), rgcr_pl);
 	if (err)
 		return err;
@@ -7098,6 +7117,10 @@ int mlxsw_sp_router_init(struct mlxsw_sp *mlxsw_sp)
 	if (err)
 		goto err_mp_hash_init;
 
+	err = mlxsw_sp_dscp_init(mlxsw_sp);
+	if (err)
+		goto err_dscp_init;
+
 	mlxsw_sp->router->fib_nb.notifier_call = mlxsw_sp_router_fib_event;
 	err = register_fib_notifier(&mlxsw_sp->router->fib_nb,
 				    mlxsw_sp_router_fib_dump_flush);
@@ -7107,6 +7130,7 @@ int mlxsw_sp_router_init(struct mlxsw_sp *mlxsw_sp)
 	return 0;
 
 err_register_fib_notifier:
+err_dscp_init:
 err_mp_hash_init:
 	unregister_netevent_notifier(&mlxsw_sp->router->netevent_nb);
 err_register_netevent_notifier: