Re: [PATCH 0/3] Add OMAP hardware spinlock misc driver

Ohad Ben-Cohen
2010-10-20T10:00:59Z

[resubmitting due to l-o being dropped from this discussion fork.
Thanks Russell for catching this]

On Wed, Oct 20, 2010 at 1:31 AM, Daniel Walker <dwalker@codeaurora.org> wrote:
> On Mon, 2010-10-18 at 09:44 +0200, Ohad Ben-Cohen wrote:
>> OMAP4 introduces a Spinlock hardware module, which provides hardware
>> assistance for synchronization and mutual exclusion between heterogeneous
>> processors and those not operating under a single, shared operating system
>> (e.g. OMAP4 has dual Cortex-A9, dual Cortex-M3 and a C64x+ DSP).
>>
>> The intention of this hardware module is to allow remote processors,
>> that have no alternative mechanism to accomplish synchronization and mutual
>> exclusion operations, to share resources (such as memory and/or any other
>> hardware resource).
>>
>> This patchset adds a new misc driver for this OMAP hwspinlock module.
>
> Does this code interface with some hardware unit (other than the other
> processors) to accomplish this locking ?

Yes, it's a special-purpose hardware peripheral.

> The reason I ask is because MSM has similar code, and from what I can
> tell the MSM version has some structures in memory but that's all. It
> just operates on the structures in memory.

That's interesting.

We did have thoughts of making this a generic framework, in the hope
that it would be useful for other vendors too, but we didn't find
additional users.

> It might be worth looking over the two implementation so we aren't both
> remaking the wheel.

Indeed. Where is that MSM code ?

Thanks,
Ohad.