| Message ID | 20180403153635.8228-2-peda@axentia.se (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, 3 Apr 2018 17:36:34 +0200 Peter Rosin <peda@axentia.se> wrote: circuit in the patch title is spelled wrong. > An ADC is often used to measure other quantities indirectly. These > bindings describe two cases, a current through a sense resistor, and > a "big" voltage measured with the help of a voltage divider. > > Signed-off-by: Peter Rosin <peda@axentia.se> Will definitely be wanting wide opinions on this one - Rob in particularly for the binding side. One comment inline. What we have here is nice and generic, but is it what would be 'expected' for current sense circuit? Should we also be more specific in the naming. There are lots of options for current sense circuits and this is just the simplest (current loop for example). One option would be to use current-sense-shunt perhaps? https://en.wikipedia.org/wiki/Current_sensing_techniques Gives a few that I didn't think of beyond current loops etc. > --- > .../bindings/iio/afe/current-sense-circuit.txt | 45 ++++++++++++++++++++++ > .../bindings/iio/afe/voltage-divider.txt | 45 ++++++++++++++++++++++ > MAINTAINERS | 7 ++++ > 3 files changed, 97 insertions(+) > create mode 100644 Documentation/devicetree/bindings/iio/afe/current-sense-circuit.txt > create mode 100644 Documentation/devicetree/bindings/iio/afe/voltage-divider.txt > > diff --git a/Documentation/devicetree/bindings/iio/afe/current-sense-circuit.txt b/Documentation/devicetree/bindings/iio/afe/current-sense-circuit.txt > new file mode 100644 > index 000000000000..0bc7d89387c0 > --- /dev/null > +++ b/Documentation/devicetree/bindings/iio/afe/current-sense-circuit.txt > @@ -0,0 +1,45 @@ > +Current Sense Curcuit > +===================== > + > +When an io-channel measures the voltage over a current sense resistor, > +the interesting mesaurement is often the current through the resistor, > +not the voltage over it. This binding describes such a current sense > +curcuit. > + > +Required properties: > +- compatible : "current-sense-circuit" > +- io-channels : Channel node of a voltage io-channel. > + > +Optional properties: > +- numerator : The io-channel scale is multiplied by this value (default 1). > +- denominator : The io-channel scale is divided by this value (default 1). > + > +Example: > +The system current is measured by measuring the voltage over a > +3.3 ohms sense resistor. Hmm. It sort of feels like the binding doesn't really reflect the hardware as directly as it might. Should we be explicitly having the resistance in this case? (with some more mapping logic needed in the driver to figure out the scaling this causes). > + > +sysi { > + compatible = "current-sense-circuit"; > + io-channels = <&tiadc 0>; > + > + /* Divide the ADC voltage by 33/10 (i.e. 3.3) to get the current. */ > + numerator = <10>; > + denominator = <33>; > +}; > + > +&i2c { > + tiadc: adc@48 { > + compatible = "ti,ads1015"; > + reg = <0x48>; > + #io-channel-cells = <1>; > + > + #address-cells = <1>; > + #size-cells = <0>; > + > + channel@0 { /* IN0,IN1 differential */ > + reg = <0>; > + ti,gain = <1>; > + ti,datarate = <4>; > + }; > + }; > +}; > diff --git a/Documentation/devicetree/bindings/iio/afe/voltage-divider.txt b/Documentation/devicetree/bindings/iio/afe/voltage-divider.txt > new file mode 100644 > index 000000000000..fd4a215d9e6d > --- /dev/null > +++ b/Documentation/devicetree/bindings/iio/afe/voltage-divider.txt > @@ -0,0 +1,45 @@ > +Voltage divider > +=============== > + > +When an io-channel measures the midpoint of a voltage divider, the > +interesting voltage is often the voltage over the full resistance > +of the divider. This binding describes the voltage divider in such > +a curcuit. > + > +Required properties: > +- compatible : "voltage-divider" > +- io-channels : Channel node of a voltage io-channel. > + > +Optional properties: > +- numerator : The io-channel scale is multiplied by this value (default 1). > +- denominator : The io-channel scale is divided by this value (default 1). > + > +Example: > +The system voltage is circa 12V, but divided down with a 22/200 > +voltage divider to adjust it to the ADC range. > + > +SYSV ADC GND > + + + + > + | .-----. | .----. | > + '--| 200 |-+-| 22 |--' > + '-----' '----' > + > +sysv { > + compatible = "voltage-divider"; > + io-channels = <&maxadc 1>; > + > + /* Multiply the ADC voltage by 222/22 to get the system voltage. */ > + numerator = <222>; /* 200 + 22 */ > + denominator = <22>; > +}; > + > +&spi { > + maxadc: adc@0 { > + compatible = "maxim,max1027"; > + reg = <0>; > + #io-channel-cells = <1>; > + interrupt-parent = <&gpio5>; > + interrupts = <15 IRQ_TYPE_EDGE_RISING>; > + spi-max-frequency = <1000000>; > + }; > +}; > diff --git a/MAINTAINERS b/MAINTAINERS > index 36a28e979e9a..9dbe5019c6bd 100644 > --- a/MAINTAINERS > +++ b/MAINTAINERS > @@ -6889,6 +6889,13 @@ F: drivers/staging/iio/ > F: include/linux/iio/ > F: tools/iio/ > > +IIO UNIT CONVERTER > +M: Peter Rosin <peda@axentia.se> > +L: linux-iio@vger.kernel.org > +S: Maintained > +F: Documentation/devicetree/bindings/iio/afe/current-sense-circuit.txt > +F: Documentation/devicetree/bindings/iio/afe/voltage-divider.txt > + > IKANOS/ADI EAGLE ADSL USB DRIVER > M: Matthieu Castet <castet.matthieu@free.fr> > M: Stanislaw Gruszka <stf_xl@wp.pl> -- 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
On Tue, Apr 3, 2018 at 12:36 PM, Peter Rosin <peda@axentia.se> wrote: > diff --git a/Documentation/devicetree/bindings/iio/afe/current-sense-circuit.txt b/Documentation/devicetree/bindings/iio/afe/current-sense-circuit.txt > new file mode 100644 > index 000000000000..0bc7d89387c0 > --- /dev/null > +++ b/Documentation/devicetree/bindings/iio/afe/current-sense-circuit.txt > @@ -0,0 +1,45 @@ > +Current Sense Curcuit s/Curcuit/Circuit > +===================== > + > +When an io-channel measures the voltage over a current sense resistor, > +the interesting mesaurement is often the current through the resistor, > +not the voltage over it. This binding describes such a current sense > +curcuit. s/curcuit/circuit -- 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
On 2018-04-08 18:50, Jonathan Cameron wrote: > On Tue, 3 Apr 2018 17:36:34 +0200 > Peter Rosin <peda@axentia.se> wrote: > > circuit in the patch title is spelled wrong. > >> An ADC is often used to measure other quantities indirectly. These >> bindings describe two cases, a current through a sense resistor, and >> a "big" voltage measured with the help of a voltage divider. >> >> Signed-off-by: Peter Rosin <peda@axentia.se> > > Will definitely be wanting wide opinions on this one - Rob in particularly > for the binding side. > > One comment inline. What we have here is nice and generic, but is > it what would be 'expected' for current sense circuit? Should we > also be more specific in the naming. There are lots of options for > current sense circuits and this is just the simplest (current loop > for example). > > One option would be to use current-sense-shunt perhaps? Heh, I'm obviously happy to not use anything "circuit", because I fail to type it correctly most of the time. I don't know how many instances I fixed before sending and there were still a few lingering. Anyway, I have fixed those locally and I have also locally removed the error message on registration failure in patch 2/2 so that will be in v3. But I'm holding off that v3, since I expect more input on the naming. > https://en.wikipedia.org/wiki/Current_sensing_techniques > Gives a few that I didn't think of beyond current loops etc. I'll give it a read. Cheers, Peter >> --- >> .../bindings/iio/afe/current-sense-circuit.txt | 45 ++++++++++++++++++++++ >> .../bindings/iio/afe/voltage-divider.txt | 45 ++++++++++++++++++++++ >> MAINTAINERS | 7 ++++ >> 3 files changed, 97 insertions(+) >> create mode 100644 Documentation/devicetree/bindings/iio/afe/current-sense-circuit.txt >> create mode 100644 Documentation/devicetree/bindings/iio/afe/voltage-divider.txt >> >> diff --git a/Documentation/devicetree/bindings/iio/afe/current-sense-circuit.txt b/Documentation/devicetree/bindings/iio/afe/current-sense-circuit.txt >> new file mode 100644 >> index 000000000000..0bc7d89387c0 >> --- /dev/null >> +++ b/Documentation/devicetree/bindings/iio/afe/current-sense-circuit.txt >> @@ -0,0 +1,45 @@ >> +Current Sense Curcuit >> +===================== >> + >> +When an io-channel measures the voltage over a current sense resistor, >> +the interesting mesaurement is often the current through the resistor, >> +not the voltage over it. This binding describes such a current sense >> +curcuit. >> + >> +Required properties: >> +- compatible : "current-sense-circuit" >> +- io-channels : Channel node of a voltage io-channel. >> + >> +Optional properties: >> +- numerator : The io-channel scale is multiplied by this value (default 1). >> +- denominator : The io-channel scale is divided by this value (default 1). >> + >> +Example: >> +The system current is measured by measuring the voltage over a >> +3.3 ohms sense resistor. > > Hmm. It sort of feels like the binding doesn't really reflect the > hardware as directly as it might. Should we be explicitly having the > resistance in this case? (with some more mapping logic needed in the > driver to figure out the scaling this causes). > >> + >> +sysi { >> + compatible = "current-sense-circuit"; >> + io-channels = <&tiadc 0>; >> + >> + /* Divide the ADC voltage by 33/10 (i.e. 3.3) to get the current. */ >> + numerator = <10>; >> + denominator = <33>; >> +}; >> + >> +&i2c { >> + tiadc: adc@48 { >> + compatible = "ti,ads1015"; >> + reg = <0x48>; >> + #io-channel-cells = <1>; >> + >> + #address-cells = <1>; >> + #size-cells = <0>; >> + >> + channel@0 { /* IN0,IN1 differential */ >> + reg = <0>; >> + ti,gain = <1>; >> + ti,datarate = <4>; >> + }; >> + }; >> +}; >> diff --git a/Documentation/devicetree/bindings/iio/afe/voltage-divider.txt b/Documentation/devicetree/bindings/iio/afe/voltage-divider.txt >> new file mode 100644 >> index 000000000000..fd4a215d9e6d >> --- /dev/null >> +++ b/Documentation/devicetree/bindings/iio/afe/voltage-divider.txt >> @@ -0,0 +1,45 @@ >> +Voltage divider >> +=============== >> + >> +When an io-channel measures the midpoint of a voltage divider, the >> +interesting voltage is often the voltage over the full resistance >> +of the divider. This binding describes the voltage divider in such >> +a curcuit. >> + >> +Required properties: >> +- compatible : "voltage-divider" >> +- io-channels : Channel node of a voltage io-channel. >> + >> +Optional properties: >> +- numerator : The io-channel scale is multiplied by this value (default 1). >> +- denominator : The io-channel scale is divided by this value (default 1). >> + >> +Example: >> +The system voltage is circa 12V, but divided down with a 22/200 >> +voltage divider to adjust it to the ADC range. >> + >> +SYSV ADC GND >> + + + + >> + | .-----. | .----. | >> + '--| 200 |-+-| 22 |--' >> + '-----' '----' >> + >> +sysv { >> + compatible = "voltage-divider"; >> + io-channels = <&maxadc 1>; >> + >> + /* Multiply the ADC voltage by 222/22 to get the system voltage. */ >> + numerator = <222>; /* 200 + 22 */ >> + denominator = <22>; >> +}; >> + >> +&spi { >> + maxadc: adc@0 { >> + compatible = "maxim,max1027"; >> + reg = <0>; >> + #io-channel-cells = <1>; >> + interrupt-parent = <&gpio5>; >> + interrupts = <15 IRQ_TYPE_EDGE_RISING>; >> + spi-max-frequency = <1000000>; >> + }; >> +}; >> diff --git a/MAINTAINERS b/MAINTAINERS >> index 36a28e979e9a..9dbe5019c6bd 100644 >> --- a/MAINTAINERS >> +++ b/MAINTAINERS >> @@ -6889,6 +6889,13 @@ F: drivers/staging/iio/ >> F: include/linux/iio/ >> F: tools/iio/ >> >> +IIO UNIT CONVERTER >> +M: Peter Rosin <peda@axentia.se> >> +L: linux-iio@vger.kernel.org >> +S: Maintained >> +F: Documentation/devicetree/bindings/iio/afe/current-sense-circuit.txt >> +F: Documentation/devicetree/bindings/iio/afe/voltage-divider.txt >> + >> IKANOS/ADI EAGLE ADSL USB DRIVER >> M: Matthieu Castet <castet.matthieu@free.fr> >> M: Stanislaw Gruszka <stf_xl@wp.pl> > -- 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
On Sun, Apr 08, 2018 at 05:50:31PM +0100, Jonathan Cameron wrote: > On Tue, 3 Apr 2018 17:36:34 +0200 > Peter Rosin <peda@axentia.se> wrote: > > circuit in the patch title is spelled wrong. > > > An ADC is often used to measure other quantities indirectly. These > > bindings describe two cases, a current through a sense resistor, and > > a "big" voltage measured with the help of a voltage divider. > > > > Signed-off-by: Peter Rosin <peda@axentia.se> > > Will definitely be wanting wide opinions on this one - Rob in particularly > for the binding side. > > One comment inline. What we have here is nice and generic, but is > it what would be 'expected' for current sense circuit? Should we > also be more specific in the naming. There are lots of options for > current sense circuits and this is just the simplest (current loop > for example). > > One option would be to use current-sense-shunt perhaps? > > https://en.wikipedia.org/wiki/Current_sensing_techniques > Gives a few that I didn't think of beyond current loops etc. > > > > --- > > .../bindings/iio/afe/current-sense-circuit.txt | 45 ++++++++++++++++++++++ > > .../bindings/iio/afe/voltage-divider.txt | 45 ++++++++++++++++++++++ > > MAINTAINERS | 7 ++++ > > 3 files changed, 97 insertions(+) > > create mode 100644 Documentation/devicetree/bindings/iio/afe/current-sense-circuit.txt > > create mode 100644 Documentation/devicetree/bindings/iio/afe/voltage-divider.txt > > > > diff --git a/Documentation/devicetree/bindings/iio/afe/current-sense-circuit.txt b/Documentation/devicetree/bindings/iio/afe/current-sense-circuit.txt > > new file mode 100644 > > index 000000000000..0bc7d89387c0 > > --- /dev/null > > +++ b/Documentation/devicetree/bindings/iio/afe/current-sense-circuit.txt > > @@ -0,0 +1,45 @@ > > +Current Sense Curcuit > > +===================== > > + > > +When an io-channel measures the voltage over a current sense resistor, > > +the interesting mesaurement is often the current through the resistor, > > +not the voltage over it. This binding describes such a current sense > > +curcuit. > > + > > +Required properties: > > +- compatible : "current-sense-circuit" > > +- io-channels : Channel node of a voltage io-channel. > > + > > +Optional properties: > > +- numerator : The io-channel scale is multiplied by this value (default 1). > > +- denominator : The io-channel scale is divided by this value (default 1). > > + > > +Example: > > +The system current is measured by measuring the voltage over a > > +3.3 ohms sense resistor. > > Hmm. It sort of feels like the binding doesn't really reflect the > hardware as directly as it might. Should we be explicitly having the > resistance in this case? (with some more mapping logic needed in the > driver to figure out the scaling this causes). I think having the resistance would be better as least in this case. For other cases like voltage dividers I'm not sure though. Those would be different compatibles so the associated properties don't necessarily need to be the same. Rob -- 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
On Tue, 10 Apr 2018 08:13:38 -0500 Rob Herring <robh@kernel.org> wrote: > On Sun, Apr 08, 2018 at 05:50:31PM +0100, Jonathan Cameron wrote: > > On Tue, 3 Apr 2018 17:36:34 +0200 > > Peter Rosin <peda@axentia.se> wrote: > > > > circuit in the patch title is spelled wrong. > > > > > An ADC is often used to measure other quantities indirectly. These > > > bindings describe two cases, a current through a sense resistor, and > > > a "big" voltage measured with the help of a voltage divider. > > > > > > Signed-off-by: Peter Rosin <peda@axentia.se> > > > > Will definitely be wanting wide opinions on this one - Rob in particularly > > for the binding side. > > > > One comment inline. What we have here is nice and generic, but is > > it what would be 'expected' for current sense circuit? Should we > > also be more specific in the naming. There are lots of options for > > current sense circuits and this is just the simplest (current loop > > for example). > > > > One option would be to use current-sense-shunt perhaps? > > > > https://en.wikipedia.org/wiki/Current_sensing_techniques > > Gives a few that I didn't think of beyond current loops etc. > > > > > > > --- > > > .../bindings/iio/afe/current-sense-circuit.txt | 45 ++++++++++++++++++++++ > > > .../bindings/iio/afe/voltage-divider.txt | 45 ++++++++++++++++++++++ > > > MAINTAINERS | 7 ++++ > > > 3 files changed, 97 insertions(+) > > > create mode 100644 Documentation/devicetree/bindings/iio/afe/current-sense-circuit.txt > > > create mode 100644 Documentation/devicetree/bindings/iio/afe/voltage-divider.txt > > > > > > diff --git a/Documentation/devicetree/bindings/iio/afe/current-sense-circuit.txt b/Documentation/devicetree/bindings/iio/afe/current-sense-circuit.txt > > > new file mode 100644 > > > index 000000000000..0bc7d89387c0 > > > --- /dev/null > > > +++ b/Documentation/devicetree/bindings/iio/afe/current-sense-circuit.txt > > > @@ -0,0 +1,45 @@ > > > +Current Sense Curcuit > > > +===================== > > > + > > > +When an io-channel measures the voltage over a current sense resistor, > > > +the interesting mesaurement is often the current through the resistor, > > > +not the voltage over it. This binding describes such a current sense > > > +curcuit. > > > + > > > +Required properties: > > > +- compatible : "current-sense-circuit" > > > +- io-channels : Channel node of a voltage io-channel. > > > + > > > +Optional properties: > > > +- numerator : The io-channel scale is multiplied by this value (default 1). > > > +- denominator : The io-channel scale is divided by this value (default 1). > > > + > > > +Example: > > > +The system current is measured by measuring the voltage over a > > > +3.3 ohms sense resistor. > > > > Hmm. It sort of feels like the binding doesn't really reflect the > > hardware as directly as it might. Should we be explicitly having the > > resistance in this case? (with some more mapping logic needed in the > > driver to figure out the scaling this causes). > > I think having the resistance would be better as least in this case. For > other cases like voltage dividers I'm not sure though. Those would be > different compatibles so the associated properties don't necessarily > need to be the same. Agreed, that was my thought as well. Given with divider it really is the ratios that matter, I'd keep it defined in terms of them. We'll have some slightly interesting bindings to interpret to get to what matters internally, but I don't think that will be too bad. So nicer bindings at the slight cost of driver complexity. Sounds fine to me! > > Rob > -- > 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 -- 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
diff --git a/Documentation/devicetree/bindings/iio/afe/current-sense-circuit.txt b/Documentation/devicetree/bindings/iio/afe/current-sense-circuit.txt new file mode 100644 index 000000000000..0bc7d89387c0 --- /dev/null +++ b/Documentation/devicetree/bindings/iio/afe/current-sense-circuit.txt @@ -0,0 +1,45 @@ +Current Sense Curcuit +===================== + +When an io-channel measures the voltage over a current sense resistor, +the interesting mesaurement is often the current through the resistor, +not the voltage over it. This binding describes such a current sense +curcuit. + +Required properties: +- compatible : "current-sense-circuit" +- io-channels : Channel node of a voltage io-channel. + +Optional properties: +- numerator : The io-channel scale is multiplied by this value (default 1). +- denominator : The io-channel scale is divided by this value (default 1). + +Example: +The system current is measured by measuring the voltage over a +3.3 ohms sense resistor. + +sysi { + compatible = "current-sense-circuit"; + io-channels = <&tiadc 0>; + + /* Divide the ADC voltage by 33/10 (i.e. 3.3) to get the current. */ + numerator = <10>; + denominator = <33>; +}; + +&i2c { + tiadc: adc@48 { + compatible = "ti,ads1015"; + reg = <0x48>; + #io-channel-cells = <1>; + + #address-cells = <1>; + #size-cells = <0>; + + channel@0 { /* IN0,IN1 differential */ + reg = <0>; + ti,gain = <1>; + ti,datarate = <4>; + }; + }; +}; diff --git a/Documentation/devicetree/bindings/iio/afe/voltage-divider.txt b/Documentation/devicetree/bindings/iio/afe/voltage-divider.txt new file mode 100644 index 000000000000..fd4a215d9e6d --- /dev/null +++ b/Documentation/devicetree/bindings/iio/afe/voltage-divider.txt @@ -0,0 +1,45 @@ +Voltage divider +=============== + +When an io-channel measures the midpoint of a voltage divider, the +interesting voltage is often the voltage over the full resistance +of the divider. This binding describes the voltage divider in such +a curcuit. + +Required properties: +- compatible : "voltage-divider" +- io-channels : Channel node of a voltage io-channel. + +Optional properties: +- numerator : The io-channel scale is multiplied by this value (default 1). +- denominator : The io-channel scale is divided by this value (default 1). + +Example: +The system voltage is circa 12V, but divided down with a 22/200 +voltage divider to adjust it to the ADC range. + +SYSV ADC GND + + + + + | .-----. | .----. | + '--| 200 |-+-| 22 |--' + '-----' '----' + +sysv { + compatible = "voltage-divider"; + io-channels = <&maxadc 1>; + + /* Multiply the ADC voltage by 222/22 to get the system voltage. */ + numerator = <222>; /* 200 + 22 */ + denominator = <22>; +}; + +&spi { + maxadc: adc@0 { + compatible = "maxim,max1027"; + reg = <0>; + #io-channel-cells = <1>; + interrupt-parent = <&gpio5>; + interrupts = <15 IRQ_TYPE_EDGE_RISING>; + spi-max-frequency = <1000000>; + }; +}; diff --git a/MAINTAINERS b/MAINTAINERS index 36a28e979e9a..9dbe5019c6bd 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -6889,6 +6889,13 @@ F: drivers/staging/iio/ F: include/linux/iio/ F: tools/iio/ +IIO UNIT CONVERTER +M: Peter Rosin <peda@axentia.se> +L: linux-iio@vger.kernel.org +S: Maintained +F: Documentation/devicetree/bindings/iio/afe/current-sense-circuit.txt +F: Documentation/devicetree/bindings/iio/afe/voltage-divider.txt + IKANOS/ADI EAGLE ADSL USB DRIVER M: Matthieu Castet <castet.matthieu@free.fr> M: Stanislaw Gruszka <stf_xl@wp.pl>
An ADC is often used to measure other quantities indirectly. These bindings describe two cases, a current through a sense resistor, and a "big" voltage measured with the help of a voltage divider. Signed-off-by: Peter Rosin <peda@axentia.se> --- .../bindings/iio/afe/current-sense-circuit.txt | 45 ++++++++++++++++++++++ .../bindings/iio/afe/voltage-divider.txt | 45 ++++++++++++++++++++++ MAINTAINERS | 7 ++++ 3 files changed, 97 insertions(+) create mode 100644 Documentation/devicetree/bindings/iio/afe/current-sense-circuit.txt create mode 100644 Documentation/devicetree/bindings/iio/afe/voltage-divider.txt