[M] Change in flashrom[master]: tree/: Move programmer_delay() out of programmer state machine

[Anastasia Klimchuk (Code Review)]

Attention is currently required from: Felix Singer, Nico Huber, Thomas Heijligen, Edward O'Callaghan, Angel Pons.

Anastasia Klimchuk has posted comments on this change. ( https://review.coreboot.org/c/flashrom/+/67393 )

Change subject: tree/: Move programmer_delay() out of programmer state machine
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Patch Set 9:

(3 comments)

Commit Message:

https://review.coreboot.org/c/flashrom/+/67393/comment/dfd95801_4125cad4 
PS4, Line 13:
> I modified the signature as above and updated the commit message to explain that programmer specific […]

I re-read the discussion, and it seems resolved to me.
The last question from Angel:
> If the long-term goal is to remove the global state, in which struct should these currently-global variables go?

These currently-global variables should move together with ex-global variables, which is going into a data struct that every registered master has already.
But Edward gave a lot more more detailed explanation above.

I am resolving this thread (I added two other comments, but that's a different story :) ). However, Angel, if you have more thoughts please tell us!

File flashrom.c:

https://review.coreboot.org/c/flashrom/+/67393/comment/2b409423_8fef924d 
PS9, Line 265: 	if (flash->mst->buses_supported & BUS_SPI) {
             : 		if (flash->mst->spi.delay)
             : 			flash->mst->spi.delay(flash, usecs);
             : 	} else if (flash->mst->buses_supported & BUS_PARALLEL) {
             : 		if (flash->mst->par.delay)
             : 			flash->mst->par.delay(flash, usecs);
             : 	} else
             : 		internal_delay(usecs);
This changes the logic, it seems to me?
If we need to keep the logic "internal_delay is default unless custom delay defined" then internal_delay needs to always be called unless custom delay defined.
Which would be (in my mind):

```
if (flash->mst->buses_supported & BUS_SPI)
        if (flash->mst->spi.delay)
    	return flash->mst->spi.delay(flash, usecs);

if (flash->mst->buses_supported & BUS_PARALLEL)
    if (flash->mst->par.delay)
    	return flash->mst->par.delay(flash, usecs);
    
return internal_delay(usecs);
```

"If there is nothing custom, call internal_delay"

Does this seem right to you?

File serprog.c:

https://review.coreboot.org/c/flashrom/+/67393/comment/0b36bcdb_1ab1c994 
PS9, Line 456: static void serprog_delay(const struct flashctx *flash, unsigned int usecs);
I am missing something, why the static forward declaration is needed? Can it be the `serprog_delay` itself here?