linux-kernel - Re: [lm-sensors] [RFC 5/5] hwmon: add support for Technologic Systems TS-5500 A-D converter

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Date:	Tue, 3 May 2011 10:33:06 -0700
From:	Guenter Roeck <guenter.roeck@...csson.com>
To:	Vivien Didelot <vivien.didelot@...oirfairelinux.com>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"lm-sensors@...sensors.org" <lm-sensors@...sensors.org>,
	"linux-serial@...r.kernel.org" <linux-serial@...r.kernel.org>,
	Jonas Fonseca <jonas.fonseca@...oirfairelinux.com>,
	"platform-driver-x86@...r.kernel.org" 
	<platform-driver-x86@...r.kernel.org>,
	linux-iio <linux-iio@...r.kernel.org>
Subject: Re: [lm-sensors] [RFC 5/5] hwmon: add support for Technologic
 Systems TS-5500 A-D converter

On Tue, 2011-05-03 at 11:55 -0400, Vivien Didelot wrote:
> Hi Guenter,
> 
> Excerpts from Guenter Roeck's message of 2011-04-29 23:39:38 -0400:
> > Hi Vivien,
> > 
> > The headline and file name are a bit misleading, since the driver is really
> > for MAX197 on a TS-5500 board.
> > 
> > You should split the driver into two parts, a generic driver
> > for the MAX197 and a platform driver (residing somewhere in arch/
> > or possibly drivers/platform/) to instantiate it.
> > 
> > There should be a platform data include file, probably in
> > include/linux/platform_data/.
> > 
> > .ioaddr in platform data should not be necessary. The driver's probe
> > function should get the values using platform_get_resource().
> > 
> > Having said that, from reading the code it looks like the chip is not really
> > used for hardware monitoring, but for generic ADC functionality. A quick look
> > into the TS-5500 user manual confirms this. So this should not be a hwmon
> > driver in the first place, but a generic ADC driver. Given the ADC conversion rate
> > of the MAX197, the hwmon ABI is not optimal anyway. You should move this driver
> > into the iio subsystem, probably to drivers/staging/iio/adc. Copying the iio
> > mailing list for input.
> > 
> > Thanks,
> > Guenter
> 
> I've took a closer look to the manual and that's right, in fact the
> driver doesn't talk to the MAX197 directly. The board uses a CPLD to
> abstract the interface to the MAX197. So all the MAX197 logic is hidden
> by the CPLD.  Therefore, the driver files should probably not have
> function and structure names with a "max197_" prefix. I'll make the code
> a bit clearer. What do you think?
> 
The original driver for the chip on http://mcrapet.free.fr/ has a
platform dependent and a platform independent part. Other than coding
style issues, that approach seems to be cleaner to me.

Thanks,
Guenter


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