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 > 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! > > -- > > 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 > -- 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
