net: dsa: tag_ocelot: use traffic class to map priority on injected header

For Ocelot switches, the CPU injected frames have an injection header
where it can specify the QoS class of the packet and the DSA tag, now it
uses the SKB priority to set that. If a traffic class to priority
mapping is configured on the netdevice (with mqprio for example ...), it
won't be considered for CPU injected headers. This patch make the QoS
class aligned to the priority to traffic class mapping if it exists.

Fixes: 8dce89a ("net: dsa: ocelot: add tagger for Ocelot/Felix switches")
Signed-off-by: Xiaoliang Yang <xiaoliang.yang_1@nxp.com>
Signed-off-by: Marouen Ghodhbane <marouen.ghodhbane@nxp.com>
Link: https://lore.kernel.org/r/20211223072211.33130-1-xiaoliang.yang_1@nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: Xiaoliang Yang

net/dsa/tag_ocelot.c

@@ -47,17 +47,21 @@ static void ocelot_xmit_common(struct sk_buff *skb, struct net_device *netdev,
 	void *injection;
 	__be32 *prefix;
 	u32 rew_op = 0;
+	u64 qos_class;
 
 	ocelot_xmit_get_vlan_info(skb, dp, &vlan_tci, &tag_type);
 
+	qos_class = netdev_get_num_tc(netdev) ?
+		    netdev_get_prio_tc_map(netdev, skb->priority) : skb->priority;
+
 	injection = skb_push(skb, OCELOT_TAG_LEN);
 	prefix = skb_push(skb, OCELOT_SHORT_PREFIX_LEN);
 
 	*prefix = ifh_prefix;
 	memset(injection, 0, OCELOT_TAG_LEN);
 	ocelot_ifh_set_bypass(injection, 1);
 	ocelot_ifh_set_src(injection, ds->num_ports);
-	ocelot_ifh_set_qos_class(injection, skb->priority);
+	ocelot_ifh_set_qos_class(injection, qos_class);
 	ocelot_ifh_set_vlan_tci(injection, vlan_tci);
 	ocelot_ifh_set_tag_type(injection, tag_type);