From: Robin Getz <rgetz@blackfin.uclinux.org>
Organization: Blackfin uClinux org
To: "Robert Schwebel" <r.schwebel@pengutronix.de>
Subject: Re: Correct location for ADC/DAC drivers
Date: Fri, 4 May 2007 18:16:01 -0400
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Cc: "Stefan Roese" <ml@stefan-roese.de>, linuxppc-dev@ozlabs.org,
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On Fri 4 May 2007 16:52, Robert Schwebel pondered:
> Robin,
>
> On Fri, May 04, 2007 at 02:21:50PM -0400, Robin Getz wrote:
> > We also have DAC and ADC drivers (up to 16 bits @ 64MS/s, via DMA),
> > that would be nice to put in the "right" place  - I don't think that
> > drivers/char is the right place, nor drivers/misc - I also don't think
> > that /adc is a descriptive place for DAC or mixed signal front ends
> > (MxFE).
>
> What userspace interface do your drivers have?

Right now, it is a little rudimentary char interface, it needs a little care 
to be a bit more general purpose, but it suited needs of what the people who 
were using it.

http://blackfin.uclinux.org/gf/project/linux-kernel/scmsvn/?view=markup&path=/trunk/drivers/char/ad9960.c

> I don't think that there 
> is anything generic available at the moment, other than COMEDI (which is
> rather outdated as far as I know).

I would be interested in having a detailed discussion/random thoughts on 
this - what is the best way to expose these types of devices?

I never actually used COMEDI, to understand the pro/cons of what it did.

> > What about /drivers/char/daq or just drivers/daq - drivers for
> > non-PCI/USB/ISA/PCMCIA Data Acquisition Hardware, D/A and A/D
> > converters, Analog Front ends, etc.
>
> I'd like drivers/daq better, because it doesn't have anything to do with
> the bus it is connected to; a chipselect bus connectable ADC may be
> connected to a SoC CS-bus or to a PCI bridge and you want to use the
> same driver for it.

That makes sense - I have seen more and more parts with selectable interfaces 
(I2C or SPI), and you should be able to use the same base driver, independent 
of the bus - so drivers/daq would suite me fine. 

-Robin
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