net: dcb: Add priority-to-DSCP map getters

On ingress, a network device such as a switch assigns to packets
priority based on various criteria. Common options include interpreting
PCP and DSCP fields according to user configuration. When a packet
egresses the switch, a reverse process may rewrite PCP and/or DSCP
values according to packet priority.

The following three functions support a) obtaining a DSCP-to-priority
map or vice versa, and b) finding default-priority entries in APP
database.

The DCB subsystem supports for APP entries a very generous M:N mapping
between priorities and protocol identifiers. Understandably,
several (say) DSCP values can map to the same priority. But this
asymmetry holds the other way around as well--one priority can map to
several DSCP values. For this reason, the following functions operate in
terms of bitmaps, with ones in positions that match some APP entry.

- dcb_ieee_getapp_dscp_prio_mask_map() to compute for a given netdevice
  a map of DSCP-to-priority-mask, which gives for each DSCP value a
  bitmap of priorities related to that DSCP value by APP, along the
  lines of dcb_ieee_getapp_mask().

- dcb_ieee_getapp_prio_dscp_mask_map() similarly to compute for a given
  netdevice a map from priorities to a bitmap of DSCPs.

- dcb_ieee_getapp_default_prio_mask() which finds all default-priority
  rules for a given port in APP database, and returns a mask of
  priorities allowed by these default-priority rules.

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

1 files changed, 13 insertions, 0 deletions

diff --git a/include/net/dcbnl.h b/include/net/dcbnl.h
index 0e5e91be2d30..e22a8a3c089b 100644
--- a/include/net/dcbnl.h
+++ b/include/net/dcbnl.h
@@ -34,6 +34,19 @@ int dcb_ieee_setapp(struct net_device *, struct dcb_app *);
 int dcb_ieee_delapp(struct net_device *, struct dcb_app *);
 u8 dcb_ieee_getapp_mask(struct net_device *, struct dcb_app *);
 
+struct dcb_ieee_app_prio_map {
+	u64 map[IEEE_8021QAZ_MAX_TCS];
+};
+void dcb_ieee_getapp_prio_dscp_mask_map(const struct net_device *dev,
+					struct dcb_ieee_app_prio_map *p_map);
+
+struct dcb_ieee_app_dscp_map {
+	u8 map[64];
+};
+void dcb_ieee_getapp_dscp_prio_mask_map(const struct net_device *dev,
+					struct dcb_ieee_app_dscp_map *p_map);
+u8 dcb_ieee_getapp_default_prio_mask(const struct net_device *dev);
+
 int dcbnl_ieee_notify(struct net_device *dev, int event, int cmd,
 		      u32 seq, u32 pid);
 int dcbnl_cee_notify(struct net_device *dev, int event, int cmd,