On 25/03/15 17:00, Daniel Baluta wrote: > This file wants to be a starting point document for anyone wanting > to use IIO configfs support or adding new IIO configfs functionality. > > Signed-off-by: Daniel Baluta <daniel.baluta@xxxxxxxxx> Looks like a good flexible structure to me. Thanks! > --- > Documentation/iio/iio_configfs.txt | 74 ++++++++++++++++++++++++++++++++++++++ > 1 file changed, 74 insertions(+) > create mode 100644 Documentation/iio/iio_configfs.txt > > diff --git a/Documentation/iio/iio_configfs.txt b/Documentation/iio/iio_configfs.txt > new file mode 100644 > index 0000000..494f4ff > --- /dev/null > +++ b/Documentation/iio/iio_configfs.txt > @@ -0,0 +1,74 @@ > +Industrial IIO configfs support > + > +1. Overview > + > +Configfs is a filesystem-based manager of kernel objects. IIO uses some > +objects that could be easily configured using configfs (e.g: devices, > +triggers). > + > +See Documentation/filesystems/configfs/configfs.txt for more information about > +how configfs works. > + > +2. Usage > + > +In order to use configfs support in IIO we need to select it at compile time > +via CONFIG_IIO_CONFIGFS config option. > + > +Then, mount the configfs filesystem (usually under /config directory): > + > +$ mkdir /config > +$ mount -t configfs none /config > + > +At this point, all default IIO groups will be creatd and can be accessed under > +/config/iio. Next chapters will describe available IIO configurable objects. > + > +2.1. Software triggers creation and destruction > + > +One of the IIO default configfs groups is the "triggers" groups. It is > +automagically accessible when the configfs is mounted and can be found under > +/config/iio/triggers. > + > +2.1.1. Trigger creation > + > +As simply as: > + > +$ mkdir /config/triggers/my_trigger > + > +This will create a directory associated with a trigger. To understand how this > +works we first need to see "my_triggers"'s attributes: > + > +$ ls /config/triggers/my_trigger > +activate sampling_frequency type > + > +Available types for triggers are: > + * none, this is a default dummy trigger that does nothing. > + * hrtimer, this is trigger based on high resolution timer. > + > +Order of operations in order to create a "hrtimer" trigger: > + > +$ echo hrtimer > /config/triggers/my_trigger/type > +$ echo 1 > /config/triggers/my_trigger/activate > +$ echo 100 > /config/triggers/my_trigger/sampling_frequency > + > +At this point the trigger can be used by an IIO device. > + > +2.1.2 Trigger destruction > + > +$ echo 1 > /config/triggers/my_trigger/activate > + > +3. Misc > + > +In order to add a new trigger type, one need to implement a driver that creates > +an instance of struct iio_configfs_ops (see iio_configfs_trigger.h header file > +in include/linux/iio) and then support it in iio_trigger_set_configfs_ops > +function from industrialiio-configfs.c file. > + > +These are the existing drivers implementing new trigger types: > + * hrtimer => iio/trigger/iio-trig-hrtimer.c > + > +4. Further work > + > +* IIO dummy device creation > +* Mappings to 'soft' in kernel users such as iio_input and iio_hwmon > +* IIO on IIO drivers > + > -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
