Writing I2C Sensor Kernel Modules

Writing I2C Sensor Kernel Modules

[Robin Müller-Bady]

Hi,

I have a (architectural design) question about I2C drivers in kernel space.
Currently, I'm writing userspace software for using external sensors
on an raspberry pi via bcm2835's I2C bus with the help of
wiringPi/ioctl, e.g. the barometric pressure with the MPL115A2 sensor.

I now had the idea to write the software directly in kernel space,
providing a device, e.g. /dev/mpl115a2, for polling the sensor data.
Does this idea fit into the architectural design of the I2C subsystem
/ the sensors ? Or should code for handling I2C clients stay in
userspace?
Is there any good documentation for writing such drivers except the
kernel Documentation? I found some information in the kernel wiki
which is unfortunately not that detailed.

Regards,

Robin

Re: Writing I2C Sensor Kernel Modules

[Peter Meerwald]

Hello Robin,

> wiringPi/ioctl, e.g. the barometric pressure with the MPL115A2 sensor.
> I now had the idea to write the software directly in kernel space,
> providing a device, e.g. /dev/mpl115a2, for polling the sensor data.
> Does this idea fit into the architectural design of the I2C subsystem
> / the sensors ? Or should code for handling I2C clients stay in

have a look at the IIO subsystem which provides an interface for various 
sensors (adc, light, accelerometer) attached via spi or i2c; pressure was 
very recently added

regards, p.

-- 

Peter Meerwald
+43-664-2444418 (mobile)

Re: Writing I2C Sensor Kernel Modules

[Sylwester Nawrocki]

Hi,

On 06/27/2013 04:33 PM, Robin Müller-Bady wrote:
> I have a (architectural design) question about I2C drivers in kernel space.
> Currently, I'm writing userspace software for using external sensors
> on an raspberry pi via bcm2835's I2C bus with the help of
> wiringPi/ioctl, e.g. the barometric pressure with the MPL115A2 sensor.

AFAIK the IIO framework should be use nowadays sensors like this one.
Unfortunately I'm not aware of any detailed documentation of this
subsystem. This presentation [1] might be helpful.

I think you could get some help asking on linux-iio-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
mailing list.

> I now had the idea to write the software directly in kernel space,
> providing a device, e.g. /dev/mpl115a2, for polling the sensor data.
> Does this idea fit into the architectural design of the I2C subsystem
> / the sensors ? Or should code for handling I2C clients stay in
> userspace?
> Is there any good documentation for writing such drivers except the
> kernel Documentation? I found some information in the kernel wiki
> which is unfortunately not that detailed.

[1] http://tinyurl.com/o6yxwrm

Regards,
Sylwester

Writing I2C Sensor Kernel Modules

[Robin Müller-Bady]

Hi,

this iio subsystem is a good hint.
Thank you both very much!

Regards,
Robin

Am 27.06.2013 16:57 schrieb "Sylwester Nawrocki" <s.nawrocki-Sze3O3UU22KIwRZHo2/mJg@public.gmane.orgm>:
>
> Hi,
>
> On 06/27/2013 04:33 PM, Robin Müller-Bady wrote:
> > I have a (architectural design) question about I2C drivers in kernel space.
> > Currently, I'm writing userspace software for using external sensors
> > on an raspberry pi via bcm2835's I2C bus with the help of
> > wiringPi/ioctl, e.g. the barometric pressure with the MPL115A2 sensor.
>
> AFAIK the IIO framework should be use nowadays sensors like this one.
> Unfortunately I'm not aware of any detailed documentation of this
> subsystem. This presentation [1] might be helpful.
>
> I think you could get some help asking on linux-iio-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
> mailing list.
>
> > I now had the idea to write the software directly in kernel space,
> > providing a device, e.g. /dev/mpl115a2, for polling the sensor data.
> > Does this idea fit into the architectural design of the I2C subsystem
> > / the sensors ? Or should code for handling I2C clients stay in
> > userspace?
> > Is there any good documentation for writing such drivers except the
> > kernel Documentation? I found some information in the kernel wiki
> > which is unfortunately not that detailed.
>
> [1] http://tinyurl.com/o6yxwrm
>
> Regards,
> Sylwester
>