From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Reply-To: Subject: Re: Driver directory selection for Power Supply Status chip References: <571507DE.3080408@opensource.altera.com> <57150E47.4020503@metafoo.de> <571538D5.5020209@opensource.altera.com> <57153E2A.7030207@kernel.org> <20160418235015.GA20720@roeck-us.net> To: Guenter Roeck , Jonathan Cameron CC: Lars-Peter Clausen , , , , linux-pm , Sebastian Reichel , Dmitry , David Woodhouse From: Thor Thayer Message-ID: <57165A5B.4050909@opensource.altera.com> Date: Tue, 19 Apr 2016 11:18:35 -0500 MIME-Version: 1.0 In-Reply-To: <20160418235015.GA20720@roeck-us.net> Content-Type: text/plain; charset="windows-1252"; format=flowed List-ID: 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! >>> -- >>> To unsubscribe from this list: send the line "unsubscribe linux-iio" in >>> the body of a message to majordomo@vger.kernel.org >>> More majordomo info at http://vger.kernel.org/majordomo-info.html >> From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thor Thayer Subject: Re: Driver directory selection for Power Supply Status chip Date: Tue, 19 Apr 2016 11:18:35 -0500 Message-ID: <57165A5B.4050909@opensource.altera.com> References: <571507DE.3080408@opensource.altera.com> <57150E47.4020503@metafoo.de> <571538D5.5020209@opensource.altera.com> <57153E2A.7030207@kernel.org> <20160418235015.GA20720@roeck-us.net> Reply-To: Mime-Version: 1.0 Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20160418235015.GA20720-0h96xk9xTtrk1uMJSBkQmQ@public.gmane.org> Sender: linux-iio-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Guenter Roeck , Jonathan Cameron Cc: Lars-Peter Clausen , linux-iio-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, arnd-r2nGTMty4D4@public.gmane.org, gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org, linux-pm , Sebastian Reichel , Dmitry , David Woodhouse List-Id: linux-pm@vger.kernel.org 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! >>> -- >>> To unsubscribe from this list: send the line "unsubscribe linux-iio" in >>> the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org >>> More majordomo info at http://vger.kernel.org/majordomo-info.html >>