Change in coreboot[master]: soc/intel/alderlake: Refactor MultiPhaseSiInit API calling method

[Subrata Banik (Code Review)]

Attention is currently required from: Furquan Shaikh, Tim Wawrzynczak, Paul Menzel, Angel Pons, Patrick Rudolph, EricR Lai.
Subrata Banik has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/56382 )

Change subject: soc/intel/alderlake: Refactor MultiPhaseSiInit API calling method
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Patch Set 9:

(1 comment)

File src/drivers/intel/fsp2_0/silicon_init.c:

https://review.coreboot.org/c/coreboot/+/56382/comment/7bc6cf53_ccd4723c 
PS8, Line 80: #endif
> Right, so TGL has an UPD to enable multi-phase Si init, but it's not in the FSPS_ARCH_UPD... Then, if I understand correctly, on TGL the `EnableMultiPhaseSiliconInit` UPD would need to be set from SoC-specific code depending on whether multi-phase Si init is to be enabled.
>
> Hmmm, how about the following:
> Make `enable_multi_phase_init()` non-static, add a declaration in some header and change the definition in this file like so:
>
> #if CONFIG(FSPS_HAS_ARCH_UPD)
>  void enable_multi_phase_init(FSPS_UPD *supd)
>  {
>    FSPS_ARCH_UPD *s_arch_cfg = &supd->FspsArchUpd;
>    s_arch_cfg->EnableMultiPhaseSiliconInit = 1;
>  }
>  #endif

are you suggesting to have some __weak implementation where in FSP driver code, we have #1 as you have mentioned with little change (as below) and TGL SoC only have override (as per #2 code snippet that you have shared) to set the SoC UPD (not the arch UPD)?

src/drivers/intel/fsp2_0/silicon_init.c:

void __weak enable_multi_phase_init(FSPS_UPD *supd)
{
#if CONFIG(FSPS_HAS_ARCH_UPD)
    FSPS_ARCH_UPD *s_arch_cfg = &supd->FspsArchUpd;
    s_arch_cfg->EnableMultiPhaseSiliconInit = 1;
#endif
}

In that way, we might don't need to guard the function declaration under #if/#endif guard? Please share your thoughts?

https://github.com/coreboot/coreboot/blob/master/src/soc/intel/tigerlake/fsp... (move this code into an override function ?)
In TGL code, define this function:
void enable_multi_phase_init(FSPS_UPD *supd)
{
    FSP_S_CONFIG *params = &supd->FspsConfig;
    params->EnableMultiPhaseSiliconInit = 1;
}