Re: [RFC v2] IIO: Add hardware triggers support to the AT91 ADC driver

[Jonathan Cameron <jic23@kernel.org>]

Firstly, sorry I didn't reply when you first raised this.  Read it,
thought I'll answer that later and then forgot!
> Hi Jonathan,
> 
> I think this is really something we should worry about if this is not
> already here.

I am unclear how this should be supported by the core?  Do we have any
real business getting involved.  We already have an explicit trigger
driver for timers on the blackfin.   Would something like that make
sense here?

>From the point of view of interfaces we also have the rtc driver
(which exits because I was using this as a dubious route to the
various timers on the pxa27x..  There have been various discussions
about generic support for these more general purpose timers but
no one has ever had the time to do anything about it.

> 
> Even though on the G20, the timer counters come from an external IP, so
> we can safely say it is not our job to setup these, on the later Atmel
> SoCs, the timer counters are embedded into the ADC, so we would
> definitely need to setup at least the period of these counters through IIO.
Right now we have as stated about a number of drivers doing this, but no
inkernel interfaces.  There have been various discussions about taking
the frequency control (that many chips that do data ready triggers have)
into the iio core more directly (to make them available
to in kernel users).  Perhaps that fits more with what you are after?

Jonathan
> 
> Maxime
> 
> On 07/12/2011 19:28, Maxime Ripard wrote:
>> I also have a question related to that.
>>
>> The SAM9G20 has timer counters as trigger sources for the ADC. Is there
>> some kind of integration for them in IIO, or should we do the setup of
>> these counters outside of IIO ?
>>
>> Thanks,
>> Maxime
>>
>> On 07/12/2011 19:25, Maxime Ripard wrote:
>>> Hi all,
>>>
>>> This is a follow-up of the previous patchset about hardware triggers for the
>>> ADC on AT91.
>>>
>>> This is still not for inclusion, as it relies on a duplication of !staging code.
>>> But basically, I'm submitting it for review and be sure I do everything right.
>>> Moreover, it will save some iterations when the time for it to be included will
>>> come.
>>>
>>> I should have addressed all the points made by Jonathan in the v1, but here is
>>> what changed:
>>>   - Fix the timestamp declaration. scan_timestamp was set to true, but no
>>> channel was declared for it. It is obviously wrong.
>>>   - Rebased on brand new patches, instead of outdated branch. This patch now
>>> requires the buffer clean ups and scan demux unit patchsets from Jonathan and
>>> the brand new wrapper functions introduced by Lars Peter.
>>>   - Renamed the triggers to be more explicit
>>>   - Lot of small fixes and improvements: use ALIGN, change the location of
>>> IRQ acknowledgements, etc.
>>>   - Added comments, switched to kernel doc for the structure declarations
>>>   - split the cosmetic changes into a new commit
>>>
>>> Thanks,
>>> Maxime
>>>
>>> Cc: Patrice Vilchez <patrice.vilchez@atmel.com>
>>> Cc: Nicolas Ferre <nicolas.ferre@atmel.com>
>>> Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
>>>
>>>
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>>
>>
> 
>