bridge: cfm: Kernel space implementation of CFM. CCM frame RX added.

This is the third commit of the implementation of the CFM protocol
according to 802.1Q section 12.14.

Functionality is extended with CCM frame reception.
The MEP instance now contains CCM based status information.
Most important is the CCM defect status indicating if correct
CCM frames are received with the expected interval.

Signed-off-by: Henrik Bjoernlund <henrik.bjoernlund@microchip.com>
Reviewed-by: Horatiu Vultur <horatiu.vultur@microchip.com>
Acked-by: Nikolay Aleksandrov <nikolay@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

bridge: cfm: Kernel space implementation of CFM. CCM frame TX added.

This is the second commit of the implementation of the CFM protocol
according to 802.1Q section 12.14.

Functionality is extended with CCM frame transmission.

Interface is extended with these functions:
br_cfm_cc_rdi_set()
br_cfm_cc_ccm_tx()
br_cfm_cc_config_set()

A MEP Continuity Check feature can be configured by
br_cfm_cc_config_set()
The Continuity Check parameters can be configured to be used when
transmitting CCM.

A MEP can be configured to start or stop transmission of CCM frames by
br_cfm_cc_ccm_tx()
The CCM will be transmitted for a selected period in seconds.
Must call this function before timeout to keep transmission alive.

A MEP transmitting CCM can be configured with inserted RDI in PDU by
br_cfm_cc_rdi_set()

Signed-off-by: Henrik Bjoernlund <henrik.bjoernlund@microchip.com>
Reviewed-by: Horatiu Vultur <horatiu.vultur@microchip.com>
Acked-by: Nikolay Aleksandrov <nikolay@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

bridge: cfm: Kernel space implementation of CFM. MEP create/delete.

This is the first commit of the implementation of the CFM protocol
according to 802.1Q section 12.14.

It contains MEP instance create, delete and configuration.

Connectivity Fault Management (CFM) comprises capabilities for
detecting, verifying, and isolating connectivity failures in
Virtual Bridged Networks. These capabilities can be used in
networks operated by multiple independent organizations, each
with restricted management access to each others equipment.

CFM functions are partitioned as follows:
- Path discovery
- Fault detection
- Fault verification and isolation
- Fault notification
- Fault recovery

Interface consists of these functions:
br_cfm_mep_create()
br_cfm_mep_delete()
br_cfm_mep_config_set()
br_cfm_cc_config_set()
br_cfm_cc_peer_mep_add()
br_cfm_cc_peer_mep_remove()

A MEP instance is created by br_cfm_mep_create()
-It is the Maintenance association End Point
described in 802.1Q section 19.2.
-It is created on a specific level (1-7) and is assuring
that no CFM frames are passing through this MEP on lower levels.
-It initiates and validates CFM frames on its level.
-It can only exist on a port that is related to a bridge.
-Attributes given cannot be changed until the instance is
deleted.

A MEP instance can be deleted by br_cfm_mep_delete().

A created MEP instance has attributes that can be
configured by br_cfm_mep_config_set().

A MEP Continuity Check feature can be configured by
br_cfm_cc_config_set()
The Continuity Check Receiver state machine can be
enabled and disabled.
According to 802.1Q section 19.2.8

A MEP can have Peer MEPs added and removed by
br_cfm_cc_peer_mep_add() and br_cfm_cc_peer_mep_remove()
The Continuity Check feature can maintain connectivity
status on each added Peer MEP.

Signed-off-by: Henrik Bjoernlund <henrik.bjoernlund@microchip.com>
Reviewed-by: Horatiu Vultur <horatiu.vultur@microchip.com>
Acked-by: Nikolay Aleksandrov <nikolay@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>