[M] Change in coreboot[main]: soc/intel/cmn/sa: Add APIs into System Agent (SA) common code

[Arthur Heymans (Code Review)]

Attention is currently required from: Arthur Heymans, Kapil Porwal, Nick Vaccaro, Subrata Banik, sridhar siricilla.

Arthur Heymans has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/80362?usp=email )

Change subject: soc/intel/cmn/sa: Add APIs into System Agent (SA) common code
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Patch Set 6: Code-Review+1

(6 comments)

Patchset:

PS6: 
Looks good. I have a few suggestions.

File src/soc/intel/common/block/systemagent/systemagent.c:

https://review.coreboot.org/c/coreboot/+/80362/comment/47cfb8d4_e251c4cc :
PS6, Line 327: const struct device *dev
You know which device the sa. Why not use that directly use _pci_0_00_0? Then you have compiletime checks vs runtime null check + your sure to use the right device.

Some for all the ones below.

https://review.coreboot.org/c/coreboot/+/80362/comment/4b546c18_8db06c03 :
PS6, Line 340: BIOS_DEBUG
Probably should be BIOS_ERR if CONFIG_ECAM_MMCONF_SUPPORT (that's always the case on modern HW)?

https://review.coreboot.org/c/coreboot/+/80362/comment/41ecc884_5b541956 :
PS6, Line 346: 4 * ((uint64_t)GiB);
'4ull * GiB' looks better IMO.

https://review.coreboot.org/c/coreboot/+/80362/comment/3ddd741e_36ef56a0 :
PS6, Line 367: BIOS_DEBUG
BIOS_ERR

https://review.coreboot.org/c/coreboot/+/80362/comment/26513c81_0503c092 :
PS6, Line 432: sa_get_dpr_size
txt_get_chipset_dpr() in systemagent_early.c does the same.