devlink: Support for pipeline debug (dpipe)

devlink: Support for pipeline debug (dpipe)

The pipeline debug is used to export the pipeline abstractions for the
main objects - tables, headers and entries. The only support for set is
for changing the counter parameter on specific table.

The basic structures:

Header - can represent a real protocol header information or internal
         metadata. Generic protocol headers like IPv4 can be shared
         between drivers. Each driver can add local headers.

Field - part of a header. Can represent protocol field or specific ASIC
        metadata field. Hardware special metadata fields can be mapped
        to different resources, for example switch ASIC ports can have
        internal number which from the systems point of view is mapped
        to netdeivce ifindex.

Match - represent specific match rule. Can describe match on specific
        field or header. The header index should be specified as well
        in order to support several header instances of the same type
        (tunneling).

Action - represents specific action rule. Actions can describe operations
         on specific field values for example like set, increment, etc.
         And header operation like add and delete.

Value - represents value which can be associated with specific match or
        action.

Table - represents a hardware block which can be described with match/
        action behavior. The match/action can be done on the packets
        data or on the internal metadata that it gathered along the
        packets traversal throw the pipeline which is vendor specific
        and should be exported in order to provide understanding of
        ASICs behavior.

Entry - represents single record in a specific table. The entry is
        identified by specific combination of values for match/action.

Prior to accessing the tables/entries the drivers provide the header/
field data base which is used by driver to user-space. The data base
is split between the shared headers and unique headers.

Signed-off-by: Arkadi Sharshevsky <arkadis@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>