soc/amd/cezanne/romstage: Preload fspm.bin

FSP-M is normally memmapped and then decompressed. The SPI DMA
controller can actually read faster than mmap. So by reading the
contents into a buffer and then decompressing we reduce boot time.

It is interesting that FSP-M takes an additional 8ms to execute. I
suspect since we call it 50ms earlier it's having to wait for one of
its dependencies.

BUG=b:179699789
TEST=Boot guybrush and see 30ms reduction in boot time
| 970 - loading FSP-M                                 | 0.316     | 0.997     Δ(  0.68,    0.05%) |
| 17 - starting LZ4 decompress (ignore for x86)       | 0.026     | 13.874    Δ( 13.85,    0.96%) |
| 18 - finished LZ4 decompress (ignore for x86)       | 64.361    | 0.337     Δ(-64.02,   -4.43%) |
| 2 - before RAM initialization                       | 0.534     | 0.529     Δ( -0.01,   -0.00%) |
| 950 - calling FspMemoryInit                         | 1.455     | 1.132     Δ( -0.32,   -0.02%) |
| 951 - returning from FspMemoryInit                  | 207.695   | 216.537   Δ(  8.84,    0.61%) |

Signed-off-by: Raul E Rangel <rrangel@chromium.org>
Change-Id: I850b1576501753a355e7b23745e04802a0560387
Reviewed-on: https://review.coreboot.org/c/coreboot/+/58988
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Karthik Ramasubramanian <kramasub@google.com>

0 files changed, 0 insertions, 0 deletions