On Wed, Sep 24, 2014 at 05:00:42PM +0100, Ivan T. Ivanov wrote: > On Wed, 2014-09-24 at 15:55 +0100, Mark Rutland wrote: > > On Wed, Sep 24, 2014 at 02:58:23PM +0100, Ivan T. Ivanov wrote: > > > The current ADC is peripheral of Qualcomm SPMI PMIC chips. It has > > > 16 bits resolution and register space inside PMIC accessible across > > > SPMI bus. > > > > > > The driver registers itself through IIO interface. > > > > > > Signed-off-by: Ivan T. Ivanov <iivanov@xxxxxxxxxx> > > > --- > > > Changes: > > > - Fix Kconfig dependencies > > > - Reword Kconfig help text > > > - Replace IIO_CHAN_INFO_PROCESSED with IIO_CHAN_INFO_RAW and IIO_CHAN_INFO_SCALE, > > > This enable client drivers to use microampers precission, instead miliamps. > > > - Use const array for iio_schan_spec-fiers. > > > - Fix spelling errors and adress review comments. > > > > > > Previous version: > > > https://www.mail-archive.com/linux-kernel@xxxxxxxxxxxxxxx/msg728360.html > > > > > > .../devicetree/bindings/iio/adc/qcom,spmi-iadc.txt | 61 ++ > > > drivers/iio/adc/Kconfig | 11 + > > > drivers/iio/adc/Makefile | 1 + > > > drivers/iio/adc/qcom-spmi-iadc.c | 691 +++++++++++++++++++++ > > > 4 files changed, 764 insertions(+) > > > create mode 100644 Documentation/devicetree/bindings/iio/adc/qcom,spmi-iadc.txt > > > create mode 100644 drivers/iio/adc/qcom-spmi-iadc.c > > > > > > diff --git a/Documentation/devicetree/bindings/iio/adc/qcom,spmi-iadc.txt b/Documentation/devicetree/bindings/iio/adc/qcom,spmi-iadc.txt > > > new file mode 100644 > > > index 0000000..06e58b6 > > > --- /dev/null > > > +++ b/Documentation/devicetree/bindings/iio/adc/qcom,spmi-iadc.txt > > > @@ -0,0 +1,61 @@ > > > +Qualcomm's SPMI PMIC current ADC > > > + > > > +QPNP PMIC current ADC (IADC) provides interface to clients to read current. > > > +A 16 bit ADC is used for current measurements. > > > + > > > +IADC node: > > > + > > > +- compatible: > > > + Usage: required > > > + Value type: <string> > > > + Definition: Should contain "qcom,spmi-iadc". > > > + > > > +- reg: > > > + Usage: required > > > + Value type: <prop-encoded-array> > > > + Definition: IADC base address and length in the SPMI PMIC register map. > > > + TRIM_CNST_RDS register address and length(1) > > > > Are these two register regions? Please make the order explicit somehow > > (either say first/second/third/etc, or use reg-names). > > Will make order explicit. > > > > > Are they both part of the IADC, or is one part of an external/shared > > component? > > I think that this is shared component. If it's not a portion of the ADC itself, then that should probably be described as a separate unit, and referred to by phandle. What else is that unit, and what else is said unit used by? > > > > > > + > > > +- interrupts: > > > + Usage: optional > > > + Value type: <prop-encoded-array> > > > + Definition: End of conversion interrupt number. If property is > > > + missing driver will use polling to detect end of conversion > > > + completion. > > > > Driver details shouldn't be in the binding. If the driver can poll, > > that's good, but it should be dropped form this description. > > > > Will remove driver details. > > > Is this the only interrupt? > > > > Yes. > > > What do you mean be "End of conversion interrupt number"? Just describe > > what the interrupt logically is from the PoV of the device -- interrupts > > is a standard property so we don't need to be too explicit about the > > type. > > Badly worded. Just, "End of conversion interrupt"? The part I didn't understand was what was meant by "End of conversion", but dropping "number" is certainly better. > > > > > > + > > > +- qcom,rsense: > > > + Usage: optional > > > + Value type: <u32> > > > + Definition: External sense register value in Ohm. Defining this > > > + propery will instruct ADC to use external ADC sense channel. > > > + If property is not defined ADC will use internal sense channel. > > > > The latter two sentences sound like a driver description. > > > > What exactly is the difference between the internal and external > > channels, and what exactly is the value in the sense register used for? > > Internal - when using chip build-in resistor > External - when using off-chip resistor Would it be possible to use the internal channel when you have an external resistor? If so, does the device have a channel per resistor, or can either resistor be selected and applied to the single channel the device has? This might be better worded as "external-registor-ohms". > > > > > The binding should describe the logical properties of the device rather > > than the specific programming model details. > > > > > + > > > +- qcom,rds-trim: > > > + Usage: optional > > > + Value type: <u32> > > > + Definition: Calculate internal sense resistor value based TRIM_CNST_RDS, > > > + IADC RDS and manufacturer. > > > + 0: Read the IADC and SMBB trim register and apply the default > > > + RSENSE if conditions are met. > > > + 1: Read the IADC, SMBB trim register and manufacturer type and > > > + apply the default RSENSE if conditions are met. > > > + 2: Read the IADC, SMBB trim register and apply the default RSENSE > > > + if conditions are met. > > > + If property is not defined driver will use qcom,rsense value if > > > + defined or internal sense resistor value trimmed into register. > > > > Having read this a few times, I still don't understand which I would use > > and when. > > > > Which conditions need to be met in each of these cases? > > > > When does the manufacturer need to be taken into account and what does > > it even mean for that to be the case? That sounds very much like a > > driver detail rather than a HW property. > > > > Cases 0 and 2 seem to be the same, just with s/, / and /. I cannot > > figure out the intended difference between the two. > > > > The last sentence is very much a driver description. > > Sorry. I have tried to make it better. Now looking again DT files > in codeaurora tree I see that 0 is used in pm8941, 1 is used in > pm8110 and 2 is used for pm8226. So I will remove this property > and handle this inside driver based on chip version. Is this only to determine the value of the internal resistor? If that isn't probable in a standard way across all variations, would an "internal-resistor-ohms" property be sufficient? > > > > > > + > > > +Example: > > > + /* IADC node */ > > > + pmic_iadc: iadc@3600 { > > > + compatible = "qcom,spmi-iadc"; > > > + reg = <0x3600 0x100>, > > > + <0x12f1 0x1>; > > > + interrupts = <0x0 0x36 0x0 IRQ_TYPE_EDGE_RISING>; > > > + qcom,rds-trim = <0>; > > > + }; > > > + > > > + /* IIO client node */ > > > + bat { > > > + io-channels = <&pmic_iadc 0>; > > > + io-channel-names = "iadc"; > > > + }; > > > > Surely you need #iio-cells on the IADC node? > > Yes, I need to add it. > > > > > Given the client seems to pass a specifier value, does this have > > multiple channels, or only a single channel? > > Driver register only one IIO channel, so #io-channel-cells > should be <0>. Ok. Regardless of what the driver does, does the hardware have multi-channel capability? Thanks, Mark. -- 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
