Chapter 4: Accessing the 4538 on the PCI Side

Local to PCI Interrupt (INTA)

The PowerQUICC II can generate an interrupt toward the PCI Host by setting a doorbell bit. Conventionally, doorbell bit 0 has been dedicated to this task, and has been associated with PCI interrupt pin –INTA in the PowerSpan Interrupt Map registers.

Example 4-3is an example of C code routines to reset the PCI-to-Local interrupt and to read the status of this interrupt from the local side.

Example 4-3. Routines Related to Local-to-PCI Interrupt

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^

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^

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Local Space Access From PCI Memory Space

The PowerSpan provides four memory windows from the PCI memory space to the Local memory space. In the 4538 design, the default setting in the PowerSpan serial EEPROM enables two windows. The first one is set with a size of 2 MB and is intended for “operational” exchanges. The second one is set with a size of 512 KB and is intended to be used for “dumps”.

During a PCI host access to local space, the high-order address bits of the local bus must be generated by the PowerSpan (as defined in the PowerSpan P1_TI0_ADDR register), the low-order address bits of the local bus come from the PCI address. This mode is called “Address Translation” in the PowerSpan manual.

NOTE

When accessing through a PowerSpan PCI-to-local window, this window must have been enabled in the I2C serial EEPROM, in order to allow the PCI host to detect it at system power-on or after hot insertion of the board, and map it in the PCI space. The corresponding PowerSpan register “PCI Target Image Control Register” must also have been initialized with the “Image Enable” bit set (IMG_EN=1) and the address translation mechanism enabled (TA_EN=1).

4538 Hardware Reference Manual

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