Hi Guenter,
On 04/18/2016 06:50 PM, Guenter Roeck wrote:
On Mon, Apr 18, 2016 at 09:06:02PM +0100, Jonathan Cameron wrote:
On 18/04/16 20:43, Thor Thayer wrote:
On 04/18/2016 11:41 AM, Lars-Peter Clausen wrote:
On 04/18/2016 06:14 PM, Thor Thayer wrote:
Hi,
The Arria10 System Resource chip (A10SR) is a SPI based MFD implementing a
GPIO expander, reset controller, and power supply monitoring. I'm not sure
where the driver for the A10SR power monitoring driver should reside and I'm
hoping someone can offer some advice.
I'd originally submitted the RFC to the HWMON list but the maintainer
pointed out that it wasn't a good fit because the A10SR only indicates
boolean power supply status - not the voltage level as required by HWMON.
I read that IIO acts as a bridge between IO and HWMON but I'm also not sure
this fits those drivers (although I did find some power supply supervistors
there). It isn't quite a power supply supervisor - the A10SR is a comparator
instead of an Analog-to-Digital Converter.
One additional thing, the A10SR also had a number of enable bits for
enabling devices external to Altera's SoC (but still on the development
board). These don't quite fit into the reset controller framework but would
seem to fit a MISC directory driver better.
If neither IIO or MISC is a good fit, can someone suggest a more appropriate
place?
How does the device work, does it generate an interrupt when the voltage
level goes below the threshold? I'd like to pass the ball back and say that
this sounds like something that should go into hwmon.
Good question but no, there is no interrupt.
The chip is actually a power supply sequencer for bringing up the
power supplies in the correct order. Since the sequence, timings, and
thresholds are hard coded in the chip and can't be changed
programatically, I assume it was decided that a power fail interrupt
was not needed. However, the status of the power (OK/Fail) can be
read from the chip.
I was directed to look at Documentation/hwmon/sysfs-interface which
states the units are in millivolts and I didn't see any references to
a boolean output so I'm leaning away from hwmon.
That's one impressively uninformative output... Hmm.
Please clarify what you mean with "impressively uninformative output".
FWIW, hwmon alarm attributes are boolean.
Thanks,
Guenter
Thank you for pointing out the alarms - I missed that but they would
fit. I'll investigate further.
Thanks!
Not obvious where to put it - it doesn't fit in IIO really either.
Could report as a power supply? There is 'health' support in there.
See Documentation/power/power_supply_class.txt
and include/linux/power_supply.h
though I'm not sure which type a fail on this would count as...
perhaps UNSPEC_FAILURE.
It's intended for batteries really - not sure how far you can stretch
that.
Cc'd linux-pm and maintainers. Perhaps they will have a better idea!
Thank you for your reply!
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