Addressing
The extended address bits used to access the configuration region above 256 B are all 0s when the access mechanism compatible with the
•Type 0 accesses to the 41210:
The bridge configuration spaces are accessed from PCI Express* by a Type 0 configuration transaction. Type 0 transactions from PCI Express* (not peer PCI or SMBus) to the bridge segments return a configuration retry response on PCI Express* when the “Configuration Cycle Retry” bit is set in the BINIT register (“Offset FCh:
The 41210 captures the bus and device numbers from Type 0 configuration writes, to its internal functions, from PCI Express*. The 41210 does not capture the bus/device number from Type 0 configuration writes to its internal functions, from either the PCI segment or SMBus. The captured bus/device number from Type 0 PCI Express* configuration writes are used by the 41210 in forming the Requester ID/Completer ID on PCI Express* and
•Type 1 accesses to the 41210:
Type 1 accesses from PCI Express* are intended for the PCI bus only and not for the internal configuration spaces. Type 1 configuration transactions to PCI that do not complete within
40 ∝s from the time they are received on PCI Express* receive a configuration retry response on PCI Express* when the retry response is enabled by means of the “Bridge Configuration Retry Enable” bit in the PCI Express* Device Control Register (“Offset 4Ch: EXP_DCTL— PCI Express* Device Control Register” on page 93). The 41210 continues to retry the transaction on PCI even when a retry response has been signaled on PCI Express*, and when completed, the transaction is discarded.
•Type 1 to Type 0 translation:
The 41210 performs a Type 1 to Type 0 translation when the Type 1 transaction is generated on PCI Express* and is intended for a device attached directly to its secondary bus. The bridge must convert the configuration command to a Type 0 format so that the secondary bus device can respond to it. The resulting Type 0 address is driven on the PCI bus, as shown in Figure 2. Device numbers are decoded to assert a single bit (IDSEL) in address bits[31:16]. A device number of 0 converts to PCI AD[16] being a 1; a device number of 2 converts to PCI AD[17] being a 1; and so on. When the device number is greater than 16, all bits (bits[31:16]) are 0. See Table 20, “Secondary PCI Device Addressing” on page 42.
Note: When the
Intel® 41210 Serial to Parallel PCI Bridge Developer’s Manual | 43 |