Convert bus_extend_resource to a bus method

[mst_semihalf.com]

Summary

Allow parents to extend resources with additional description or data. This can be used e.g. to add trigger/polarity information to a resource describing an interrupt.

This change allows MSI-X interrupts on Alpine platform to be successfully setup (usage: D7571). If the extended data is not included PIC_SETUP_INTR() returns with an error.

[andrew]

Why is this needed? It's a little difficult to know if this is the best approach without seeing the driver that will make use of this.

[nwhitehorn]

How does this interact with D7493? That change removes this method entirely.

I'm also dubious about using this kind of method with MSI for the reasons mentioned earlier: the bus API deal with IRQ numbers, rather than struct resource *, and so bus_extend_resource() has some nasty corner cases. I have some comments on this in the driver revision (D7571).

[mst_semihalf.com]

In D7567#157144, @nwhitehorn wrote:

How does this interact with D7493? That change removes this method entirely.

I'm also dubious about using this kind of method with MSI for the reasons mentioned earlier: the bus API deal with IRQ numbers, rather than struct resource *, and so bus_extend_resource() has some nasty corner cases. I have some comments on this in the driver revision (D7571).

I was not aware of D7493 (I see it has just been committed). I will need to look into it to see how I can make INTX/MSIX work on Alpine with the new interface.

[mst_semihalf.com]

I'm abandoning this revision as bus_extend_resource has been removed in rS304459 (D7493).