Change in coreboot[master]: soc/amd/common/block/lpc/spi_dma: Implement SPI DMA functionality

[Julius Werner (Code Review)]

Attention is currently required from: Jason Glenesk, Raul Rangel, Furquan Shaikh, Marshall Dawson, Eric Peers, Karthik Ramasubramanian, Felix Held.
Julius Werner has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/56228 )

Change subject: soc/amd/common/block/lpc/spi_dma: Implement SPI DMA functionality
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Patch Set 7: Code-Review+1

(1 comment)

File src/soc/amd/common/block/lpc/Kconfig:

https://review.coreboot.org/c/coreboot/+/56228/comment/f193b3fe_03cfa4d4 
PS6, Line 15: The SPI DMA controller
            : 	  is only functional on Cezanne, Renoir or later SoCs.
> Done

I think checking a handful of specific AMD SoCs in AMD common code should be fine. If this was generic code in src/lib I'd agree it might be better to avoid.

The alternative here would be to do

config SOC_AMD_COMMON_BLOCK_LPC_SPI_DMA
   bool
   default y
   select X86_CUSTOM_BOOTMEDIA
   help
     ...

and then in src/soc/amd/picasso/Kconfig and friends do

config SOC_AMD_COMMON_BLOCK_LPC_SPI_DMA
   bool
   default n

...which also works. But it's a bit more complicated to follow, so for such a simple and localized case (where we don't expect the exception list to grow much larger than those two SoCs), I think this is fine.