2. Interface Operation
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Tsi308 User Manual
80D4000_MA001_02
Tundra Semiconductor Corporation
www.tundra.com
2.3.1.1
PCI-X Response Data Buffer
The PCI response data buffer contains read data returned from outbound reads to the PCI
interface. This data buffer can hold a total of 64 bytes for one HyperTransport read requests.
Once the response is issued, the buffer is retired. Non-posted write requests still occupy space in
the response data buffer, even though they have no read data.
2.3.1.2
End of Interrupt
When an interrupt is configured as level sensitive, upstream interrupt logic must respond to an
interrupt request packet with an end of interrupt (EOI) packet. Until the EOI packet is received
by the Tsi308, no new interrupt request packets will be generated by that interrupt pin.
2.4
Inbound Transactions
Inbound transactions are requests from the PCI-X bus or internal interrupt controller across
HyperTransport to the host bridge. From there, they are routed to destinations behind the host
bridge or reflected peer-to-peer back onto the HyperTransport chain. If the request is
non-posted, the transaction also includes the response from the host bridge back to the original
requesting unit.
The Tsi308 operates as a PCI-X target for requests from external PCI-X devices. All accepted
requests are forwarded to the HyperTransport link interface leading to the host. Reads go
through the delayed request buffers and are handled on the PCI-X bus as delayed requests when
in standard PCI mode or as split requests when in PCI-X mode. All writes, except IO writes are
posted into the posted request queue and allowed to immediately complete on the PCI-X bus.
2.4.1
PCI-X Address Map
Accesses on PCI-X bus are checked against the following ranges to determine whether the
Tsi308 is the target of the access and should assert Px_DEVSEL_N to accept the request. The
Tsi308 makes this determination with medium DEVSEL# timing. When PCI-X A bus is
configured as 64-bit target at power up, the Tsi308 asserts P0_ACK64_N in response to
P0_REQ64_N for requests it accepts.
•
Memory Mapped Cycles. The Tsi308 implements a 64-bit space for memory mapped
accesses and decodes DAC accesses for addresses above 4 GB. While operating in Tsi301
compatible mode address bits above 39 are ignored and result in the 40-bit space aliasing
through PCI’s 64-bit memory mapped space.
Содержание TSI308
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