Hello,
On 07/02/2013 03:28 PM, Alexandre Belloni wrote:
On 02/07/2013 14:58, Lars-Peter Clausen wrote:
On 07/02/2013 12:49 PM, Hector Palacios wrote:
Greetings,
The mxs-lradc has some hardware specific features like the DIVIDE_BY_TWO (an
analog divide by two circuit that can be activated per channel).
This is not currently implemented in the driver and I was wondering what would
be the way to expose and control such setting. A specific sysfs entry? Somehow
through the device tree?
Is there any example of how to control a hw-specific feature in other similar
iio drivers?
This sounds as if the channel scale is programmable. There are quite a few
drivers for devices which have similar features, just make the scale property
writable and provide a scale_available.
I was looking at that yesterday as I had to had a scale for the
temperature sensors. You'll have to be careful because the maximum
measured voltage when DIVIDE_BY_TWO is not set is 1.85V and when it is
set, it becomes VDDIO - 50mv.
Also, scaling for quite a lot of channels is fixed. You'll also get
channels with a fixed divider that can take DIVIDE_BY_TWO. That is quite
a mess ;)
Thank you, I checked and it's easy to add custom sysfs attributes using
IIO_DEVICE_ATTR(). I was thinking whether adding a divide_by_two attribute per channel:
divide_by_two0
divide_by_two1
...
divide_by_two7
or a unique divide_by_two descriptor that admits a mask value for all channels.
I think the first approach (one per channel) is cleaner. Opinions?
Best regards,
--
Hector Palacios
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