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Date: Tue, 22 May 2007 16:16:55 -0500
From: Scott Wood <scottwood@freescale.com>
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To: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Subject: Re: [PATCH 10/13] mpc83xx: Power Management support
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	<Pine.LNX.4.60.0705222301070.4243@poirot.grange>
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Guennadi Liakhovetski wrote:
>>+	/* There can only be one fsl,mpc83xx-pmc device in the system;
>>+	 * it is assumed that it is the one that the pmc driver matches.
>>+	 */
>>+	if (of_device_is_compatible(sleep_controller, "fsl,mpc83xx-pmc")) {
>>+		sleep->sccr_mask = sleepdata[1];
>>+		ret = 0;
>>+	}
> 
> 
> Just wondering - do we really want to special-case 83xx-pmc here? What 
> when / if further "sleep controllers" get implemented? Shouldn't this be 
> some callback?

The quick and ugly thing would be more if checks.  The ideal solution 
would be a mechanism to look up a device by phandle, returning an ops 
struct corresponding to the requested class (if the device supports it).

> BTW, do we have an interface similar to platform-driver/device for of? 
> Like of_driver/device. This would be a use case for it. Just register a 
> of_driver, which would trigger a dt-scan (just a find_compatible), calling 
> driver's probe()... Would it make sense?

See asm-powerpc/of_platform.h.  However, that won't help find the driver 
  you need to talk to if all you have is a phandle.

-Scott