On 19 April 2016 00:50:15 BST, Guenter Roeck <linux@xxxxxxxxxxxx> 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. It's not an alarm on anything in particular but rather simply means 'something is wrong somewhere in the power supply startup'. > >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 -- Sent from my Android device with K-9 Mail. Please excuse my brevity. -- 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
