RELEASED
PMC-Sierra, Inc.
PM9311/2/3/5 ETT1™ CHIP SET
Data Sheet
PMC-2000164
ISSUE 3
ENHANCED TT1™ SWITCH FABRIC
4.1.1 OOB Interface and Control/Status Registers
All of the devices have an OOB interface. This interface allows a single local CPU to control and monitor all
of the devices within a core fabric. Internally, each device provides registers that can be mapped into the
CPU’s address space. These registers are described in more detail in Section 4.4 “Crossbar Registers”.
4.2 MODES OF OPERATION
The default mode of operation is for the Crossbar to act as a 32-port switch. In this mode, each ETT1 port
has one connection to each of the Crossbars. If an 8- or 16-port switch is required, the Crossbar can be
configured so that fewer Crossbar devices are required. In these modes, the term superport represents a
system port.
In 8-port mode, the Crossbar considers four of its ports to be a single superport. For example, ports 0, 1, 2,
and 3 make up superport 0, ports 28, 29, 30, and 31 are superport 7. A single superport is connected to
only three Crossbars. For example, superport 0 has its first 4 Dataslices connected to ports 0, 1, 2, and 3
of Crossbar 0, its next 4 Dataslices connected to ports 0, 1, 2, and 3 of Crossbar 1, and its last 4 Dataslices
connected to ports 0, 1, 2, and 3 of Crossbar 2.
In 16-port mode, the Crossbar considers two of its ports to be a single superport. Ports 0 & 1 make up
superport 0, and ports 30 & 31 make up superport 15 for example. A single superport is connected to six
Crossbars. In this case, superport 0 has its first 2 Dataslices connected to ports 0 and 1 of Crossbar 0, and
its last Dataslices are connected to ports 0 and 1 of Crossbar 5.
The mode is set via the OOB bus. The Crossbar acts as if the superports make up a ‘trunk’, so that either
two or four of the inputs are routed as a single port.
4.3 OOB ACCESS
The Crossbars can be written and read via the OOB bus. In addition to the device select addresses 0x7FF
(all devices) and 0x7B (all Crossbars), each Crossbar can be addressed with an individual device select
specified by {000100, CCCC, 000, C} where CCCCC is the Crossbar number in the range 0-31 (these
correspond to device selects 0x200 to 0x2F1, not including all addresses within that range). The Registers
section of this chapter illustrates the usage of the subaddress field to specify registers within the Crossbar.
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMERS’ INTERNAL USE
227
PMC [ PMC-SIERRA, INC ]
