Functional Description
The record signal is a single clock pulse indicating that a transmit packet egress has been detected at the
associated port MII interface. The handle value is incremented with each time sync event packet and rolls
over to zero after 7. There are 8 possible handle values so there can be a maximum of eight time sync
event packets “in flight” from the TS_TX_DEC to the TS_TX_MII block at any given time. The handle
value increments only on time sync event packets. The TS_TX_MII logic is in the transmit wireside clock
domain.
14.3.2.3 Device Level Ring (DLR) Support
Device Level Ring (DLR) support is enabled by setting the dlr_en bit in the CPSW_Control register. When
enabled, incoming received DLR packets are detected and sent to queue 3 (highest priority) of the egress
port(s). If the host port is the egress port for a DLR packet then the packet is sent on the CPDMA Rx
channel selected by the p0_dlr_cpdma_ch field in the P0_Control register. The supervisor node MAC
address feature is supported with the dlr_unicast bit in the unicast address table entry.
When set, the dlr_unicast bit causes a packet with the matching destination address to be flooded to the
vlan_member_list minus the receive port and minus the host port (the port_number field in the unicast
address table entry is a don’t care). Matching dlr_unicast packets are flooded regardless of whether the
packet is a DLR packet or not. The en_p0_uni_flood bit in the ALE_Control register has no effect on DLR
unicast packets. Packets are determined to be DLR packets, as shown:
1. DLR is enabled (dlr_en is set in the switch CPSW_Control register).
2. One of the following sequences is true:
•
The first packet ltype matches vlan_ltype1 and pX_vlan_ltype1_en is set and the second packet
ltype matches dlr_ltype.
•
The first packet ltype matches vlan_ltype2 and pX_vlan_ltype2_en is set and the second packet
ltype matches dlr_ltype.
•
The first packet ltype matches vlan_ltype1 and pX_vlan_ltype1_en is set and the second packet
ltype matches vlan_ltype2 and pX_vlan_ltype2_en is set and the third packet ltype matches
dlr_ltype.
14.3.2.4 CPDMA RX and TX Interfaces
The CPDMA submodule is a CPPI 3.0 compliant packet DMA transfer controller. The CPPI 3.0 interface is
port 0.
After reset, initialization, and configuration the host may initiate transmit operations. Transmit operations
are initiated by host writes to the appropriate transmit channel head descriptor pointer contained in the
STATERAM block. The transmit DMA controller then fetches the first packet in the packet chain from
memory in accordance with CPPI 3.0 protocol. The DMA controller writes the packet into the external
transmit FIFO in 64-byte bursts (maximum).
Receive operations are initiated by host writes to the appropriate receive channel head descriptor pointer
after host initialization and configuration. The receive DMA controller writes the receive packet data to
external memory in accordance with CPPI 3.0 protocol. See the CPPI Buffer Descriptors section for
detailed description of Buffer Descriptors
1186
Ethernet Subsystem
SPRUH73H – October 2011 – Revised April 2013
Copyright © 2011–2013, Texas Instruments Incorporated