Change in coreboot[master]: soc/amd/cezanne: Start loading APOB asynchronously while FSP-M executes

[Raul Rangel (Code Review)]

Attention is currently required from: Jason Glenesk, Marshall Dawson, Felix Held.
Hello build bot (Jenkins), Jason Glenesk, Marshall Dawson, Felix Held,

I'd like you to reexamine a change. Please visit

https://review.coreboot.org/c/coreboot/+/55859

to look at the new patch set (#3).

Change subject: soc/amd/cezanne: Start loading APOB asynchronously while FSP-M executes
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soc/amd/cezanne: Start loading APOB asynchronously while FSP-M executes

In the S3 resume case we will block in `soc_fill_apob_cache`
until the whole buffer has been read since the PSP has not placed
the APOB contents into RAM.

In the non-S3 case, the PSP has placed the APOB contents into RAM,
so `soc_fill_apob_cache` uses that for FSP-M. By reading the SPI
contents while FSP-M is executing, the data will be ready by the time
`soc_update_apob_cache` executes.

We currently get lucky that the APOB is only 64 KiB since the SPI DMA
controller can perform this transaction in one shot. In order to support
larger payloads, or multiple transactions while FSP-M executes, we will
need FSP-M to call `poll_futures` periodically.

BUG=b:179699789
TEST=Boot guybrush and verify APOB read timestamp has dropped from 10ms
to a few uS.

FMAP: area RW_MRC_CACHE found @ 0 (65536 bytes)
spi_dma_readat_async: dest: 0x020935c0, offset: 0x0, size: 65536
spi_dma_async_poll: current_transaction: 0x020a3620
start_spi_dma_transaction: dest: 0x020935c0, offset: 0x0, remaining: 65536

<FSP-M executes>

wait_for_promise: waiting for promise
spi_dma_async_poll: current_transaction: 0x020a3620
continue_spi_dma_transaction: dest: 0x020935c0, offset: 0x0, remaining: 65536
spi_dma_async_poll: transaction complete
spi_dma_async_poll: current_transaction: 0x00000000
wait_for_promise: took 12 us
APOB valid copy is already in flash

Signed-off-by: Raul E Rangel 
Change-Id: I4b5c1ef4cad571d1cbca33b1aff017a3cedc1be8
---
M src/soc/amd/cezanne/fsp_m_params.c
1 file changed, 14 insertions(+), 0 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/59/55859/3