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. 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
