Change in coreboot[master]: Documentation/RFC: Generalize PCI support in coreboot

[Nico Huber (Code Review)]

Attention is currently required from: Shelley Chen,  Felix Singer, Furquan Shaikh, Martin Roth, Tim Wawrzynczak, Paul Menzel, Julius Werner, Angel Pons, Kyösti Mälkki, Yu-Ping Wu, Jianjun Wang.
Nico Huber has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/57861 )

Change subject: Documentation/RFC: Generalize PCI support in coreboot
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Patch Set 12:

(1 comment)

File Documentation/RFC/pci_config_access.md:

https://review.coreboot.org/c/coreboot/+/57861/comment/31a2dc25_9aa347e2 
PS12, Line 125: ### Specifying MMIO support for PCI devices that don't support ECAM
              : 
              : We’ll need to be able to distinguish between a platform using the ECAM access
              : method and any other MMIO access mechanism.  For devices that support ECAM, they
              : would have to select the `ECAM_MMONCF_SUPPORT` config.  For devices that don't
              : support ECAM and would still need MMIO support, they would need to explictly
              : select the `NO_ECAM_MMCONF_SUPPORT` config and include the `pci_mmio_cfg.h'
              : header file in their platform-specific source.
> Hi Shelley, […]

The "example" linked below around get_pci_mmio_cfgbase() looks
broken. I wouldn't worry about it too much right now.

If you want to implement method 1. only, that seems fine. All
you need in coreboot is pci_map_bus(). libpayload should get a
similar mechanism eventually.

NB. If you can, it would be helpful to provide links to public
documentation of the hardware involved.