linux-kernel - Re: [PATCH RFC v2 2/5] spmi: Linux driver framework for SPMI

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Date:	Mon, 9 Sep 2013 16:52:24 +0100
From:	Mark Brown <broonie@...nel.org>
To:	Josh Cartwright <joshc@...eaurora.org>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Grant Likely <grant.likely@...aro.org>,
	Rob Herring <rob.herring@...xeda.com>,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linux-arm-msm@...r.kernel.org,
	Sagar Dharia <sdharia@...eaurora.org>,
	Gilad Avidov <gavidov@...eaurora.org>,
	Michael Bohan <mbohan@...eaurora.org>
Subject: Re: [PATCH RFC v2 2/5] spmi: Linux driver framework for SPMI

On Fri, Aug 23, 2013 at 11:06:25AM -0500, Josh Cartwright wrote:
> On Thu, Aug 22, 2013 at 04:10:54PM -0700, Greg Kroah-Hartman wrote:
> > On Fri, Aug 09, 2013 at 01:37:09PM -0700, Josh Cartwright wrote:

> > > +	"Example: Read 4 bytes starting at register address 0x1234 for SID 2\n"
> > > +	"\n"
> > > +	"echo 0x21234 > address\n"
> > > +	"echo 4 > count\n"
> > > +	"cat data\n"
> > > +	"\n"
> > > +	"Example: Write 3 bytes starting at register address 0x1008 for SID 1\n"
> > > +	"\n"
> > > +	"echo 0x11008 > address\n"
> > > +	"echo 0x01 0x02 0x03 > data\n"
> > > +	"\n"
> > > +	"Note that the count file is not used for writes.  Since 3 bytes are\n"
> > > +	"written to the 'data' file, then 3 bytes will be written across the\n"
> > > +	"SPMI bus.\n\n";

> > The help file within the kernel is a nice touch :)

> > Or is this only for "debugging"?  If so, please document it as such.

> It's there because it provides a useful interface for debugging of the
> controller code, and for simple peek/poke of the slave registers without
> having a full driver in place.  Will document this.

This looks awfully like a version of the debugfs interfaces that regmap
provides, and indeed the entire bus sounds like something that could
idiomatically be supported via regmap.  Have you considered doing that?
This would give access to standard tracepoints as well, plus the cache
infrastructure.

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