On 26.09.19 18:45, Aaron Durbin via coreboot wrote:
> Here's some of the requirements/issues we should resolve that come to mind:
>
> 1. Easy way to directly retrieve a device's chip config object w/o
> traversing the device hierarchy. Which leads to...
> 2. Symbol alias for accessing struct device directly (no bdf lookup)

What we already have:

Static pointers to `struct device` for devices with a globally valid
address (PCI devices on bus 0 and PNP devices), e.g.:

    DEVTREE_CONST struct device *DEVTREE_CONST __pci_0_02_0 = &_dev6;
    DEVTREE_CONST struct device *DEVTREE_CONST __pnp_002e_00 = &_dev56;

What I suggested somewhere on Gerrit:

At the chip driver level, add a header file that maps these to more
distinct names, e.g.

    #define igd_dev __pci_0_02_0;

But that was last week. Since then I've written yet another override
tree and realized something. We write a lot lines like

    device pci 02.0 on  end # Integrated Graphics Device

What's wrong with that? (if you know me it's obvious) there is a
comment! IIRC, Kyösti suggested it already, we could let sconfig
read a chip specific mapping for device names. That would also
allow us to write the above as

    device igd on end

Mapping could look like this:

    device pci 00.0 alias mch
    device pci 02.0 alias igd

and we could directly generate pointers with these names:

    DEVTREE_CONST struct device *DEVTREE_CONST igd_dev = &_dev6;

Limitations: Actually, chip drivers can't provide global names. What
should sconfig generate if a second instance of a chip pops up? So
the generated pointers must somehow be limited to chips that can only
occur once, e.g. PCH, single socket CPU.

What do you think?

Nico