[M] Change in coreboot[main]: device: Add support for multiple PCI segment groups

[Felix Held (Code Review)]

Attention is currently required from: Cliff Huang, Fred Reitberger, Jason Glenesk, Lance Zhao, Matt DeVillier, Nico Huber, Patrick Rudolph, Tim Wawrzynczak.

Felix Held has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/79877?usp=email )

Change subject: device: Add support for multiple PCI segment groups
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Patch Set 2:

(3 comments)

File src/acpi/acpi.c:

https://review.coreboot.org/c/coreboot/+/79877/comment/f8bb765a_d87f1576 :
PS1, Line 153: 	for (int i = 0; i < CONFIG_ECAM_SEGMENT_COUNT; i++) {
another option that i'm planning to look into is to loop over the domains here and get the secondary, max_subordinate, and segment (if that info isn't already included in one of the other two) from those structs. having more than one mcfg entry for one segment group is ok if the bus numbers don't overlap

File src/device/Kconfig:

https://review.coreboot.org/c/coreboot/+/79877/comment/71e0a161_c1415d2c :
PS1, Line 559: config ECAM_SEGMENT_COUNT
> My impression was that ECAM_MMCONF_BUS_NUMBER == 256 would be the better choice for the subordinate  […]

i added a define for the maximum number of buses per segment

File src/include/device/device.h:

https://review.coreboot.org/c/coreboot/+/79877/comment/b5b72ca3_24717387 :
PS1, Line 89: 	uint8_t		segment;		/* PCI segment */
> I'd be happy to test those to not have duplicate effort. […]

i think i used a macro to get the bus and segment number from the secondary/max_subordinate. has been a while i looked into that, so i'll need to look again into my local branch