ST driver - ad-hoc allocation of trigger interrupt

ST driver - ad-hoc allocation of trigger interrupt

[simon]

Hi all,
A friend and I were attempting to get a LSM303DLHC breakout board hooked
up to the expansion header on the RaspPi yesterday - it was him doing the
work and me offering suggestions from afar (unfortunately the blind
leading the blind)...

Anyhow 'we' got reasonably far and could read raw value and trigger the
buffer via the 'iio-sysfs-trig'. The problem came when we wanted the
device to trigger itself at the set sample frequency.

We infer that we need to connect the DRDY signal to a CPU interrupt line,
but can't see how we tell the ST iio driver which one.

I did find this is the source:
https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/drivers/iio/common/st_sensors/st_sensors_trigger.c?id=refs/tags/v4.1-rc8#n21

Which shows that the 'sdata->get_irq_data_ready()' can be pre-defined in
the data structure passed on driver init. But how can we do that from the
command line, or even a little script/app once the kernel is up and
running?


The story of our attempt is documented here:
https://groups.google.com/forum/?hl=en#!topic/richards-tech-user-forum/BjQpWjTmims

Any suggestions on how we can succeed?

Many thanks,
Simon.

Re: ST driver - ad-hoc allocation of trigger interrupt

[Jonathan Cameron]

On 15 June 2015 16:04:58 BST, simon@mungewell.org wrote:
>Hi all,
>A friend and I were attempting to get a LSM303DLHC breakout board
>hooked
>up to the expansion header on the RaspPi yesterday - it was him doing
>the
>work and me offering suggestions from afar (unfortunately the blind
>leading the blind)...
>
>Anyhow 'we' got reasonably far and could read raw value and trigger the
>buffer via the 'iio-sysfs-trig'. The problem came when we wanted the
>device to trigger itself at the set sample frequency.
>
>We infer that we need to connect the DRDY signal to a CPU interrupt
>line,
>but can't see how we tell the ST iio driver which one.
>
>I did find this is the source:
>https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/drivers/iio/common/st_sensors/st_sensors_trigger.c?id=refs/tags/v4.1-rc8#n21
>
>Which shows that the 'sdata->get_irq_data_ready()' can be pre-defined
>in
>the data structure passed on driver init. But how can we do that from
>the
>command line, or even a little script/app once the kernel is up and
>running?
>
>
>The story of our attempt is documented here:
>https://groups.google.com/forum/?hl=en#!topic/richards-tech-user-forum/BjQpWjTmims
>
>Any suggestions on how we can succeed?

Looks like you basically got there with the DT file at the end. Adhoc arrangements
 like this are often done with device tree overlays (which can be added to a
 running device). A quick Google suggests the raspberry pi uses these for standard hats.

Good luck.

Jonathan

>
>Many thanks,
>Simon.
>
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Re: ST driver - ad-hoc allocation of trigger interrupt

[simon]

>>The story of our attempt is documented here:
>>https://groups.google.com/forum/?hl=en#!topic/richards-tech-user-forum/BjQpWjTmims
>>
>>Any suggestions on how we can succeed?
>
> Looks like you basically got there with the DT file at the end. Adhoc
> arrangements
>  like this are often done with device tree overlays (which can be added to
> a
>  running device). A quick Google suggests the raspberry pi uses these for
> standard hats.

A little follow-up that you might like; Richard was able to get the IIO
devices configured via Device Tree, even to the point of getting a full
sensor fusion working to give pose and heading.

https://richardstechnotes.wordpress.com/2015/06/17/rteiioimu-driving-a-9-dof-imu-via-industrial-io-iio/

Simon.

Re: ST driver - ad-hoc allocation of trigger interrupt

[Jonathan Cameron]

On 18 June 2015 21:53:53 BST, simon@mungewell.org wrote:
>
>>>The story of our attempt is documented here:
>>>https://groups.google.com/forum/?hl=en#!topic/richards-tech-user-forum/BjQpWjTmims
>>>
>>>Any suggestions on how we can succeed?
>>
>> Looks like you basically got there with the DT file at the end. Adhoc
>> arrangements
>>  like this are often done with device tree overlays (which can be
>added to
>> a
>>  running device). A quick Google suggests the raspberry pi uses these
>for
>> standard hats.
>
>A little follow-up that you might like; Richard was able to get the IIO
>devices configured via Device Tree, even to the point of getting a full
>sensor fusion working to give pose and heading.
>
>https://richardstechnotes.wordpress.com/2015/06/17/rteiioimu-driving-a-9-dof-imu-via-industrial-io-iio/
>
>Simon.
Nice.

Thanks for the heads up!
>
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>the body of a message to majordomo@vger.kernel.org
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