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

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Message-ID: <AANLkTikPnm1NK1wGGzbOuNoCOnAcSp=RC8mTW2yx3u0s@mail.gmail.com>
Date:	Wed, 20 Oct 2010 08:13:25 +0200
From:	Ohad Ben-Cohen <ohad@...ery.com>
To:	Daniel Walker <dwalker@...eaurora.org>
Cc:	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	akpm@...ux-foundation.org, Greg KH <greg@...ah.com>,
	Tony Lindgren <tony@...mide.com>,
	Benoit Cousson <b-cousson@...com>,
	Grant Likely <grant.likely@...retlab.ca>,
	Hari Kanigeri <h-kanigeri2@...com>, Suman Anna <s-anna@...com>,
	mattw@...eaurora.org
Subject: Re: [PATCH 0/3] Add OMAP hardware spinlock misc driver

On Wed, Oct 20, 2010 at 1:31 AM, Daniel Walker <dwalker@...eaurora.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.
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