[PATCH v2 12/13] ARM: move sp804 and integrator timers to drivers/clocksource

[Linus Walleij]

On Tue, Apr 2, 2013 at 9:49 PM, Rob Herring <robherring2 at gmail.com> wrote:
> On 04/01/2013 06:26 PM, John Stultz wrote:

>> So, most of the code here is really clockevent code and not clocksource
>> code. I realize they were combined in the mach directory you're copying
>> them from, but if we're going to move all this code out of the arch
>> directory and into drivers/, I'd like to propose we not dump it all into
>> drivers/clocksource.
>
> Arguably, half the h/w is used for clocksource and half for clockevent
> so it is equal. :) The sp804 and integrator are somewhat separated that
> carving them up may be possible, but there are examples like i.MX timers
> where the implementations are tied more closely together (the clockevent
> compare value is the clocksource counter + delta).
>
> Where do I put the init functions which need to know about both?
>
> What about all the other timers that are already in drivers/clocksource?

The other day I thought about this because I remembered discussing
it with John, and thinking about how some drivers (like ours) combine
clock source, clock event, sched_clock() hook and delay timers. The
same hardware is incidentally used for all four.

Driver writers really like to think about a driver pertaining to a certain
memory segment in the hardware, and that's causing some strain
here and there in the kernel.

Anyway, I was thinking that the four classes of drivers were somehow
related but not the same thing.

So what about renaming
drivers/clocksource -> drivers/timer

Then create a subdirectory drivers/timer/clocksource
for the pure clocksource code and any drivers falling into that
category.

Thus drivers/timer/clockevent, drivers/timer/schedclock
and drivers/timer/delay can be created to handle specialized
hardware blocks.

But the best thing with that scheme would be that combined
drivers doing several things at once could live directly in
drivers/timer/* and not pollute drivers/clocksource.

Yes/No/Insane?

Yours,
Linus Walleij