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Date: Mon, 2 Oct 2023 13:46:53 +0000
From: "Miclaus, Antoniu" <Antoniu.Miclaus@...log.com>
To: Conor Dooley <conor@...nel.org>
CC: Jean Delvare <jdelvare@...e.com>,
Guenter Roeck <linux@...ck-us.net>,
Rob Herring <robh+dt@...nel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
Conor Dooley <conor+dt@...nel.org>,
Jonathan Corbet <corbet@....net>,
"linux-hwmon@...r.kernel.org" <linux-hwmon@...r.kernel.org>,
"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>
Subject: RE: [PATCH v2 1/2] dt-bindings: hwmon: ltc2991: add bindings
--
Antoniu Miclăuş
> -----Original Message-----
> From: Conor Dooley <conor@...nel.org>
> Sent: Monday, October 2, 2023 4:01 PM
> To: Miclaus, Antoniu <Antoniu.Miclaus@...log.com>
> Cc: Jean Delvare <jdelvare@...e.com>; Guenter Roeck <linux@...ck-
> us.net>; Rob Herring <robh+dt@...nel.org>; Krzysztof Kozlowski
> <krzysztof.kozlowski+dt@...aro.org>; Conor Dooley
> <conor+dt@...nel.org>; Jonathan Corbet <corbet@....net>; linux-
> hwmon@...r.kernel.org; devicetree@...r.kernel.org; linux-
> kernel@...r.kernel.org; linux-doc@...r.kernel.org
> Subject: Re: [PATCH v2 1/2] dt-bindings: hwmon: ltc2991: add bindings
>
> [External]
>
> Hey,
>
> On Mon, Oct 02, 2023 at 01:18:14PM +0300, Antoniu Miclaus wrote:
> > Add dt-bindings for ltc2991 octal i2c voltage, current and temperature
> > monitor.
> >
> > Signed-off-by: Antoniu Miclaus <antoniu.miclaus@...log.com>
> > ---
> > changes in v2:
> > - make compatible const type
> > - remove `|` where not necessary
> > - switch to micro-ohms for the shunt resistor property
> > - add vendor prefix for temperature-enable
>
> Thanks for the updates...
>
> > .../bindings/hwmon/adi,ltc2991.yaml | 114 ++++++++++++++++++
> > 1 file changed, 114 insertions(+)
> > create mode 100644
> Documentation/devicetree/bindings/hwmon/adi,ltc2991.yaml
> >
> > diff --git a/Documentation/devicetree/bindings/hwmon/adi,ltc2991.yaml
> b/Documentation/devicetree/bindings/hwmon/adi,ltc2991.yaml
> > new file mode 100644
> > index 000000000000..3811ea07a04f
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/hwmon/adi,ltc2991.yaml
> > @@ -0,0 +1,114 @@
> > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +
> > +$id: http://devicetree.org/schemas/hwmon/adi,ltc2991.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: Analog Devices LTC2991 Octal I2C Voltage, Current and Temperature
> Monitor
> > +
> > +maintainers:
> > + - Antoniu Miclaus <antoniu.miclaus@...log.com>
> > +
> > +description: |
> > + The LTC2991 is used to monitor system temperatures, voltages and
> currents.
> > + Through the I2C serial interface, the eight monitors can individually
> measure
> > + supply voltages and can be paired for differential measurements of
> current
> > + sense resistors or temperature sensing transistors.
> > +
> > + Datasheet:
> > + https://www.analog.com/en/products/ltc2991.html
> > +
> > +properties:
> > + compatible:
> > + const: adi,ltc2991
> > +
> > + reg:
> > + maxItems: 1
> > +
> > + '#address-cells':
> > + const: 1
> > +
> > + '#size-cells':
> > + const: 0
> > +
> > + vcc-supply: true
> > +
> > +patternProperties:
> > + "^channel@[0-3]$":
> > + type: object
> > + description:
> > + Represents the differential/temperature channels.
> > +
> > + properties:
> > + reg:
> > + description:
> > + The channel number. LTC2991 can monitor 4 currents/temperatures.
> > + items:
> > + minimum: 0
> > + maximum: 3
> > +
> > + shunt-resistor-micro-ohms:
> > + description:
> > + The value of curent sense resistor in miliohms. Enables differential
> > + input pair.
> > +
> > + adi,temperature-enable:
> > + description:
> > + Enables temperature readings for a input pair.
> > + type: boolean
>
> ...but I did not see an answer to my question on v1:
> TBH, this seems like it is used just to control software behaviour.
> Why would you want to actually disable this in DT?
> In other words, is there something in that hardware that precludes
> measuring temperature for channels that do not contain this property?
>
> Thanks,
> Conor.
>
Sorry for missing that. I took in consideration this approach based on the pin functions
described in the datasheet (page 8 of 32). For example the V1 pin of the part can support
3 different configurations: "V1 (Pin 1): First Monitor Input. This pin can be configured
as a single-ended input (0V to 4.9V) or the positive inputfor a differential or remote diode
temperature measurement (in combination with V2)."
Moreover, looking at the multiple typical applications examples at the end of the datasheet
there is a specific adjacent hardware circuit connected to this part for the temperature
measurements configurations.
Thank you,
Antoniu
> > +
> > +required:
> > + - compatible
> > + - reg
> > + - vcc-supply
> > +
> > +additionalProperties: false
> > +
> > +examples:
> > + - |
> > + i2c {
> > + #address-cells = <1>;
> > + #size-cells = <0>;
> > +
> > + hwmon@48 {
> > + compatible = "adi,ltc2991";
> > + reg = <0x48>;
> > + vcc-supply = <&vcc>;
> > + };
> > + };
> > + - |
> > + i2c {
> > + #address-cells = <1>;
> > + #size-cells = <0>;
> > +
> > + hwmon@48 {
> > + #address-cells = <1>;
> > + #size-cells = <0>;
> > +
> > + compatible = "adi,ltc2991";
> > + reg = <0x48>;
> > + vcc-supply = <&vcc>;
> > +
> > + channel@0 {
> > + reg = <0x0>;
> > + shunt-resistor-micro-ohms = <100000>;
> > + };
> > +
> > + channel@1 {
> > + reg = <0x1>;
> > + shunt-resistor-micro-ohms = <100000>;
> > + };
> > +
> > + channel@2 {
> > + reg = <0x2>;
> > + temperature-enable;
> > + };
> > +
> > + channel@3 {
> > + reg = <0x3>;
> > + temperature-enable;
> > + };
> > + };
> > + };
> > +...
> > --
> > 2.42.0
> >
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