CS5535-UDCF AMD (ADVANCED MICRO DEVICES), CS5535-UDCF Datasheet - Page 56

• Manufacturer Part Number: CS5535-UDCF
• Manufacturer: AMD (ADVANCED MICRO DEVICES)

Specifications of CS5535-UDCF

• Operating Temperature (min): 0C
• Operating Temperature (max): 85C
• Operating Temperature Classification: Commercial
• Mounting: Surface Mount
• Lead Free Status / RoHS Status: Compliant

The GLIU implements the “bus”. Transactions between
GeodeLink Devices and GLIU are conducted with packets.
The GLIU accepts request packets from masters and
routes them to slaves. Similarly, slave response packets
are routed back to the master. The bus is non-blocking.
Several requests can be pending, but order is guaranteed.
Broadcasts are not allowed. All packets have one source
and one destination.
4.1.2
The Physical to Device (P2D) descriptors control the rout-
ing of the packets. The descriptors are initialized by soft-
ware at system setup. They establish the address map to
be used by the system. They associate a memory or I/O
address range with a GLIU port.
When a request packet arrives from a Request Out (RO)
port, the address and other attributes in the packet are
used to look up the destination port. If the port Request In
(RI) is available, the request is passed. If there are multiple
requests, priorities are used to establish which requestor
and destination port utilize the transfer cycle. A transfer
from an RO to an RI takes one clock edge.
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Routing
31506B
4.1.3
Earlier in this section, it was indicated that an RO can be
used to present a write data packet or a read response
packet. The use and need of a read response packet for a
read request is obvious. However, there is also an optional
write response packet. This tells the requestor that the
write has completed. This is used to hold a processor I/O
write instruction until the response is received, that is, I/O
writes are never posted. Memory writes are always posted.
The response packet is also used to generate Synchro-
nous System Management Interrupts (SSMIs). System
Management Mode (SMM) is used for hardware emulation
and other traps. An SSMI can be generated by a
GeodeLink Device or via special GLIU descriptors. When
the response arrives back at the processor, interface cir-
cuits generate an SMI to invoke the SMM software. Lastly,
all response packets contain an exception flag that can be
set to indicate an error.
AMD Geode™ CS5535 Companion Device Data Book
Response Packets
Global Concepts and Features