PCI Bus Mapping for MPC8548 with multiple PCI interfaces

[Ralf Trübenbach]

Hello,
 
I'm currently developing a bootloader for a MPC8548 based board. This board has got three PCI interfaces (PCI1, PCI2 and PCIe). At the PCIe interface the MPC8548 appears as PCI-Bridge (at bus 0 device 0), at the PCI1/2 interfaces the MPC8548 appears as normal devices (bus 0 device 0).

And now I'm a little bit unshure about how Linux expects the PCI bus mapping. I see two ways:


A)
--------
MPC8548:   PCI1         PCI2         PCIe
             |           |             |
             |           |             3
             |           |           bridge
             0           2             4
--------     |           |             |
extern:   -------      ------        ------
          |  |  |      |    |        |    |
         dev | dev     dev dev...   dev  dev ...
             0
           bridge
             1
             |
          ---------
          |   |   |
         dev dev dev...

Since I have to create Type 0 Config Read/Writes to access the first bus of an interface, my PciConfigRead/Write functions would have to convert the bus no. from 0->0 2->0 3->0 (for the example). And PCIe bridge's primary bus no. has to be set to 0.



or B)
--------
MPC8548:   PCI1         PCI2         PCIe
             |           |             |
             |           |             0
             |           |           bridge
             0           0             1
--------     |           |             |
extern:   -------      ------        ------
          |  |  |      |    |        |    |
         dev | dev     dev dev...   dev  dev ...
             0
           bridge
             1
             |
          ---------
          |   |   |
         dev dev dev...

Every bus is mapped independently. And PciConfigRead/Write functions convert the bus no. so that upper layers (and user) see a bus mapping similar to A).

Maybe someone knows how U-Boot or Linux would map the interfaces?

Thank you for your Help.

Ralf


Best Regards/Mit freundlichen Gruessen
 

Ralf Trübenbach, Software Design
MEN Mikro Elektronik GmbH
Neuwieder Straße 5-7
90411 Nuremberg, Germany
Phone +49-911-99 33 5-0
Fax +49-911-99 33 5-910
E-Mail Ralf.Truebenbach at men.de <mailto:Ralf.Truebenbach at men.de> 
www.men.de <http://www.men.de/> 

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