[coreboot] Add coreboot storage driver

[Andrey Petrov]

Hi,

On 02/13/2017 12:31 PM, ron minnich wrote:
>     Another idea just popped up: Performing "background" tasks in udelay()
>     / mdelay() implementations ;)
>
>
> that is adurbin's threading model. I really like it.
>
> A lot of times, concurrency will get you just as far as ||ism without
> the nastiness.

But how do you guarantee code will get a slice of execution time when it 
needs it? For example for eMMC link training you need to issue certain 
commands with certain time interval. Lets say every 10ms. How do you 
make sure that happens? You can keep track of time and see when next 
piece of work needs to be scheduled, but how do you guarantee you enter 
this udelay code often enough?

Andrey