Correct location for ADC/DAC drivers

Hi all,

I'm in the stage of integrating some ADC and DAC drivers for the AMCC 405EZ 
PPC and looking for the correct location to place these drivers in the Linux 
source tree. The drivers are basically character-drivers, so my first thought 
is to put them in "drivers/char/adc/foo.c" or "drivers/char/adc_foo.c". Is 
this a good solution?

Any suggestions welcome (could be that I missed an already existing example).

BTW: I am aware of the hwmon subsystem, but I don't think it fits my needs in 
this case.

Best regards,
Stefan

On Tue, 1 May 2007, Stefan Roese wrote:

I'm in the stage of integrating some ADC and DAC drivers for the AMCC 405EZ 
PPC and looking for the correct location to place these drivers in the Linux 
source tree. The drivers are basically character-drivers, so my first thought 
is to put them in "drivers/char/adc/foo.c" or "drivers/char/adc_foo.c". Is 
this a good solution?

drivers/mfd following ucb1x00?

Thanks
Guennadi
---
Guennadi Liakhovetski

On Tuesday 01 May 2007 23:03, Guennadi Liakhovetski wrote:

On Tue, 1 May 2007, Stefan Roese wrote:

quoted

I'm in the stage of integrating some ADC and DAC drivers for the AMCC
405EZ PPC and looking for the correct location to place these drivers in
the Linux source tree. The drivers are basically character-drivers, so my
first thought is to put them in "drivers/char/adc/foo.c" or
"drivers/char/adc_foo.c". Is this a good solution?

drivers/mfd following ucb1x00?

Perhaps. Not sure though. I just checked again and I still think the drivers 
will better fit for "our" drivers because of the chrdev nature.

Is there a maintainer for this "drivers/mfd" directory?

Thanks.

Best regards,
Stefan

On Wed, May 02, 2007 at 12:25:53PM +0200, Stefan Roese wrote:

Is there a maintainer for this "drivers/mfd" directory?

rmk

Robert 
-- 
 Dipl.-Ing. Robert Schwebel | http://www.pengutronix.de
 Pengutronix - Linux Solutions for Science and Industry
   Handelsregister:  Amtsgericht Hildesheim, HRA 2686
     Hannoversche Str. 2, 31134 Hildesheim, Germany
   Phone: +49-5121-206917-0 |  Fax: +49-5121-206917-9

On Wed, May 02, 2007 at 03:35:12PM +0200, Robert Schwebel wrote:

On Wed, May 02, 2007 at 12:25:53PM +0200, Stefan Roese wrote:

quoted

Is there a maintainer for this "drivers/mfd" directory?

rmk

I wouldn't go that far.  There's no real infrastructure there
to maintain, so I'd actually say that the directory was
maintainerless.  However, I'll own up to the UCB/MCP drivers
in there.

-- 
Russell King
 Linux kernel    2.6 ARM Linux   - http://www.arm.linux.org.uk/
 maintainer of:

On Wednesday 02 May 2007 21:11, Russell King wrote:

quoted

quoted

Is there a maintainer for this "drivers/mfd" directory?

rmk

I wouldn't go that far.  There's no real infrastructure there
to maintain, so I'd actually say that the directory was
maintainerless.  However, I'll own up to the UCB/MCP drivers
in there.

So perhaps you could answer is you feel that these ADC & DAC chrdev device 
drivers would fit into this drivers/mfd directory, or are better suited for 
the drivers/char directory?

Thanks.

Best regards,
Stefan

On Fri, May 04, 2007 at 08:11:42AM +0200, Stefan Roese wrote:

On Wednesday 02 May 2007 21:11, Russell King wrote:

quoted

quoted

quoted

Is there a maintainer for this "drivers/mfd" directory?

rmk

I wouldn't go that far.  There's no real infrastructure there
to maintain, so I'd actually say that the directory was
maintainerless.  However, I'll own up to the UCB/MCP drivers
in there.

So perhaps you could answer is you feel that these ADC & DAC chrdev device 
drivers would fit into this drivers/mfd directory, or are better suited for 
the drivers/char directory?

No idea; firstly I've long since deleted the email, secondly I've not much
interest in the directory itself, and thirdly I've enough patches to review
already.  Finally, I'm out all day today, including the evening.  I doubt
I'll read any further email until the weekend.

-- 
Russell King
 Linux kernel    2.6 ARM Linux   - http://www.arm.linux.org.uk/
 maintainer of:

On Tue, May 01, 2007 at 02:35:44PM +0200, Stefan Roese wrote:

I'm in the stage of integrating some ADC and DAC drivers for the AMCC
405EZ PPC and looking for the correct location to place these drivers
in the Linux source tree. The drivers are basically character-drivers,
so my first thought is to put them in "drivers/char/adc/foo.c" or
"drivers/char/adc_foo.c". Is this a good solution?

Any suggestions welcome (could be that I missed an already existing
example).

BTW: I am aware of the hwmon subsystem, but I don't think it fits my
needs in this case.

Could you elaborate the requirements a bit more? ADC is not ADC, because
slow i2c ADCs which measure a temperature every five minutes have other
requirements than multi-megabyte-per-second-dma-driven ADCs.

Robert
-- 
 Dipl.-Ing. Robert Schwebel | http://www.pengutronix.de
 Pengutronix - Linux Solutions for Science and Industry
   Handelsregister:  Amtsgericht Hildesheim, HRA 2686
     Hannoversche Str. 2, 31134 Hildesheim, Germany
   Phone: +49-5121-206917-0 |  Fax: +49-5121-206917-9

On Friday 04 May 2007 10:24, Robert Schwebel wrote:

On Tue, May 01, 2007 at 02:35:44PM +0200, Stefan Roese wrote:

quoted

I'm in the stage of integrating some ADC and DAC drivers for the AMCC
405EZ PPC and looking for the correct location to place these drivers
in the Linux source tree. The drivers are basically character-drivers,
so my first thought is to put them in "drivers/char/adc/foo.c" or
"drivers/char/adc_foo.c". Is this a good solution?

Any suggestions welcome (could be that I missed an already existing
example).

BTW: I am aware of the hwmon subsystem, but I don't think it fits my
needs in this case.

Could you elaborate the requirements a bit more? ADC is not ADC, because
slow i2c ADCs which measure a temperature every five minutes have other
requirements than multi-megabyte-per-second-dma-driven ADCs.

The hardware (PPC405EZ) actually implements an high speed, dma capable, ADC 
controller with 10-bit resolution and up to 4MHz sample rate. The current 
driver doesn't support all these features though (dma is not supported right 
now for example). Could be that this will be added in future releases. It 
would be good though, to have the driver located at the "correct" place in 
the kernel tree right away.

Best regards,
Stefan

On Fri 4 May 2007 04:54, Stefan Roese pondered:

On Friday 04 May 2007 10:24, Robert Schwebel wrote:

quoted

On Tue, May 01, 2007 at 02:35:44PM +0200, Stefan Roese wrote:

quoted

I'm in the stage of integrating some ADC and DAC drivers for the AMCC
405EZ PPC and looking for the correct location to place these drivers
in the Linux source tree. The drivers are basically character-drivers,
so my first thought is to put them in "drivers/char/adc/foo.c" or
"drivers/char/adc_foo.c". Is this a good solution?

Any suggestions welcome (could be that I missed an already existing
example).

BTW: I am aware of the hwmon subsystem, but I don't think it fits my
needs in this case.

Could you elaborate the requirements a bit more? ADC is not ADC, because
slow i2c ADCs which measure a temperature every five minutes have other
requirements than multi-megabyte-per-second-dma-driven ADCs.

The hardware (PPC405EZ) actually implements an high speed, dma capable, ADC
controller with 10-bit resolution and up to 4MHz sample rate. The current
driver doesn't support all these features though (dma is not supported
right now for example). Could be that this will be added in future
releases. It would be good though, to have the driver located at the
"correct" place in the kernel tree right away.

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 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 think that is the common TLA - at least according to 
http://en.wikipedia.org/wiki/Data_acquisition

?

-Robin

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? 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).
 

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.

Robert
-- 
 Dipl.-Ing. Robert Schwebel | http://www.pengutronix.de
 Pengutronix - Linux Solutions for Science and Industry
   Handelsregister:  Amtsgericht Hildesheim, HRA 2686
     Hannoversche Str. 2, 31134 Hildesheim, Germany
   Phone: +49-5121-206917-0 |  Fax: +49-5121-206917-9

On Fri 4 May 2007 16:52, Robert Schwebel pondered:

Robin,

On Fri, May 04, 2007 at 02:21:50PM -0400, Robin Getz wrote:

quoted

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.

quoted

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