Hi Maxime,
> I'm currently writing a driver for the ADCs present in Atmel AT91 SoC
> using iio. I will of course submit it once it is ready.
>
> For now, I have the basic integration into iio, and I am beginning to
> integrate the hardware logic in it. However, this integration raises few
> questions, and I didn't found any answers to it. (The dummy driver is of
> great help btw)
cool. Any feedback on that particularly welcome given we haven't merged
it yet.
>
> - While the registers are all the same on the AT91 platform for the
> ADCs, the number of channels available is not the same from one board to
> another. For now, I'm declaring the number of channels available through
> the board definition and platform_data, and I'm declaring the channels
> to iio using :
>
> idev->channels = kzalloc(sizeof(struct iio_chan_spec) * nb_chan,
> GFP_KERNEL);
> for(i = 0; i < nb_chan; i++) {
> struct iio_chan_spec *chan = idev->channels + i;
> chan->type = IIO_IN;
> chan->indexed = 1;
> chan->channel = i;
> }
>
> While it seems to work nicely, it generates a warning, as iio_dev's
> channels field is declared const. Is there a better solution ?
As an aside
IIO_IN -> IIO_VOLTAGE. I've push a patch to GregKH today that scraps
IIO_IN once and for all.
Are you using the latest published tree (currently on github)?
There's at least one driver that does the same in tree and it doesn't
give a warning (there were some core changes to avoid it). ad7280a.
The other option is to have a single array of all channels and set
num_channels lower than the size of the array. Couple of drivers
do that for some of the parts they support.
>
> - For now, I don't really want to rely on hardware triggers, but
> instead use only software triggers. I've taken a look to sysfs triggers,
> and while the module for sysfs trigger is compiled and loaded, and added
> to the platform_devices of the board, the file trigger_now is nowhere to
> be found. I guess that I need to declare triggers in my driver, but I
> have found no clue on how to do that. How can we achieve it ?
Hmm.. clearly need some documentation for that driver.
What you should have is a directory called:
/sys/bus/iio/devices/iio_sysfs_trigger (it's a rather 'unusual device').
In there are the userspace controls for creating and destroying sysfs
triggers.
echo N to > add_trigger and you should find it has created a trigger
called sysfstrigN the controls for which (including the trigger_now) file
can be found in /sys/bus/iio/devices/triggerY (where Y is id of the
trigger - counting from 0).
Hope that helps,
Jonathan
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