SMART PMCspan, Manual

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40 PMCspan PMC Carrier Module Installation and Use (6806800A59C)
Programming Model
Type 1 to Type 1 Forwarding
4.3.3 Type 1 to Type 1 Forwarding
If the PCI6150 detects a Type 1 configuration transaction intended for a PCI bus
downstream from the secondary bus (such as another PCI bus on a PMC module) the
PCI6150 will forward the transaction unchanged to the secondary bus. This transaction
eventually gets translated to a Type 0 transaction or a Special Cycle by a downstream
PCI-to-PCI bridge.
4.3.4 Special Cycles
Special cycle transactions generated on the primary PCI bus are ignored by the PCI6150.
However, Special Cycle commands can be sent to the PMC module using a Type 1
Configuration transaction. The PCI6150 will generate a Special Cycle on the secondary
bus when it detects a Type 1 transaction on the primary bus with the following conditions:
 The lower two primary address bits AD(1:0) are 01 (binary)
 The device number in AD(15:11) is 1_1111 (binary)
 The function number in AD(10:8) is 111 (binary)
 The register number in AD(7:2) is 00_0000 (binary)
 The bus number in AD(23:16) is $01 (the value in the Secondary Bus Number
Register)
 The bus command on C/BE# is a configuration write command
The PCI6150 translates the Type 1 Configuration command to a Special Cycle and
forwards the address and data unchanged. The transaction is forwarded as a delayed
transaction but the target response is not forwarded back because Special Cycles result in
a master abort. If more than one data transfer is requested during a Special Cycle, the
PCI6150 responds with a target disconnect during the first data phase.