Re: adc-jack-driver opinion related to IIO

[Lars-Peter Clausen <lars@xxxxxxxxxx>]

On 07/06/2012 06:45 PM, anish kumar wrote:
> On Fri, 2012-07-06 at 14:25 +0100, Jonathan Cameron wrote:
>> On 7/6/2012 1:00 PM, anish singh wrote:
>>> Hello Jonathan,
>>>
>>> I would be extremely happy if I can get your opinion on this.
>>>
>>> Recently Myungjoo Ham had posted Extcon: adc-jack driver patch.
>>>
>>> Description of this driver:
>>> This is basically a Headset(jack) driver.Once the headset is inserted
>>> a irq_handler is called and in this handler we have a callback(this
>>> callback calls into pmic driver to get the adc value) to get
>>> the adc value to determine the kind of headset: This headset could
>>> be headset with mic, headset without mic or headset with
>>> keys(volume-up/down) attached to it.One we have found out the kind
>>> of headset we use extcon framework to notify the other interested drivers or
>>> userspace that a headset with so and so capabilities has been inserted.
>>>
>>> Question:
>>> Does this driver fall into IIO as pointed by Mark Brown in his review comments?
>> The driver itself probably doesn't, but the adc part does in that IIO
>> provides a means of talking to the relevant adc.
>>>
>>> Why do we need to use IIO to get the adc value?As for different boards the
>>> method of getting adc is different.How does IIO help in this?
>> Ultimately, IIO in this case is acting as an infrastructure for ALL 
>> adcs. E.g. for different boards you'll need a mapping to tell it which
>> adc channel is connected but that is it.  Hence you don't need a 
>> specific callback for each pmic as you will be using generic interfaces 
>> to query it.
> After having a brief glance at IIO below is my understanding:
> IIO is used to provide standard interfaces in the form of sysfs to
> userspace _ONLY_.
> 
> My requirement:
> ADC-JACK-Driver should get the adc value from other driver i.e. PMIC
> driver.Here the requirement is communication between two drivers in
> kernel.Can IIO be used here?
> 
> I had a look at drivers/staging/iio/Documentation/Overview.txt and some
> ADC drivers.

Hi,

There is a new experimental in kernel API, which lets you write IIO clients
in the kernel.

See: drivers/iio/inkern.h
and drivers/staging/iio/iio_hwmon.c

- Lars

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