This is the devicetree schema for Microchip EMC1812/13/14/15/33
Multichannel Low-Voltage Remote Diode Sensor Family.
Signed-off-by: Marius Cristea <marius.cristea@microchip.com>
---
.../iio/temperature/microchip,emc1812.yaml | 223 +++++++++++++++++++++
MAINTAINERS | 6 +
2 files changed, 229 insertions(+)
diff --git a/Documentation/devicetree/bindings/iio/temperature/microchip,emc1812.yaml b/Documentation/devicetree/bindings/iio/temperature/microchip,emc1812.yaml
new file mode 100644
index 0000000000000000000000000000000000000000..898d6d246746e229cb004f447872ee6bd5a65074
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/temperature/microchip,emc1812.yaml
@@ -0,0 +1,223 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/temperature/microchip,emc1812.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Microchip EMC1812/13/14/15/33 multichannel temperature sensor
+
+maintainers:
+ - Marius Cristea <marius.cristea@microchip.com>
+
+description: |
+ The Microchip EMC1812/13/14/15/33 is a high-accuracy 2-wire multichannel
+ low-voltage remote diode temperature monitor.
+
+ The datasheet can be found here:
+ https://ww1.microchip.com/downloads/aemDocuments/documents/MSLD/ProductDocuments/DataSheets/EMC1812-3-4-5-33-Data-Sheet-DS20005751.pdf
+
+properties:
+ compatible:
+ enum:
+ - microchip,emc1812
+ - microchip,emc1813
+ - microchip,emc1814
+ - microchip,emc1815
+ - microchip,emc1833
+
+ reg:
+ maxItems: 1
+
+ interrupts:
+ maxItems: 2
+
+ interrupt-names:
+ description:
+ -alert-therm2 asserts when a diode temperature exceeds the ALERT
+ threshold.
+ -therm-addr asserts low when the hardware-set THERM limit threshold is
+ exceeded by one of the temperature sensors.
+ items:
+ - const: alert-therm2
+ - const: therm-addr
+
+ "#address-cells":
+ const: 1
+
+ "#size-cells":
+ const: 0
+
+ microchip,beta1:
+ description:
+ Set beta compensation value for external channel 1.
+ <0> 0.050
+ <1> 0.066
+ <2> 0.087
+ <3> 0.114
+ <4> 0.150
+ <5> 0.197
+ <6> 0.260
+ <7> 0.342
+ <8> 0.449
+ <9> 0.591
+ <10> 0.778
+ <11> 1.024
+ <12> 1.348
+ <13> 1.773
+ <14> 2.333
+ <15> Diode_Mode
+ <16> Auto
+ - Diode_Mode is used when measuring a discrete thermal diode
+ or a CPU diode that functions like a discrete thermal diode.
+ - Auto enables beta auto-detection. The chip monitors
+ external diode/transistor and determines the optimum
+ setting.
+ $ref: /schemas/types.yaml#/definitions/uint32
+ minimum: 0
+ maximum: 16
+ default: 16
+
+ microchip,beta2:
+ description:
+ Set beta compensation value for external channel 2.
+ $ref: /schemas/types.yaml#/definitions/uint32
+ minimum: 0
+ maximum: 16
+ default: 16
+
+ microchip,parasitic-res-on-channel1-2:
+ description:
+ Indicates that the chip and the diodes/transistors are sufficiently far
+ apart that a parasitic resistance is added to the wires, which can affect
+ the measurements. Due to the anti-parallel diode connections, channels
+ 1 and 2 are affected together.
+ type: boolean
+
+ microchip,parasitic-res-on-channel3-4:
+ description:
+ Indicates that the chip and the diodes/transistors are sufficiently far
+ apart that a parasitic resistance is added to the wires, which can affect
+ the measurements. Due to the anti-parallel diode connections, channels
+ 3 and 4 are affected together.
+ type: boolean
+
+ vdd-supply: true
+
+patternProperties:
+ "^channel@[1-4]$":
+ description:
+ Represents the external temperature channels to which
+ a remote diode is connected.
+ type: object
+
+ properties:
+ reg:
+ items:
+ minimum: 1
+ maximum: 4
+
+ microchip,ideality-factor:
+ description:
+ Each channel has an ideality factor.
+ Beta compensation and resistance error correction automatically
+ correct for most ideality errors. So ideality factor does not need
+ to be adjusted in general.
+ $ref: /schemas/types.yaml#/definitions/uint32
+ minimum: 8
+ maximum: 55
+ default: 18
+
+ label:
+ description: Unique name to identify which channel this is.
+
+ required:
+ - reg
+
+ additionalProperties: false
+
+required:
+ - compatible
+ - reg
+ - vdd-supply
+
+allOf:
+ - if:
+ properties:
+ compatible:
+ contains:
+ enum:
+ - microchip,emc1812
+ - microchip,emc1813
+ - microchip,emc1833
+ then:
+ properties:
+ microchip,beta2: false
+ microchip,parasitic-res-on-channel3-4: false
+ - if:
+ properties:
+ compatible:
+ pattern: "^microchip,emc1812"
+ then:
+ patternProperties:
+ "^channel@1$":
+ properties:
+ reg:
+ items:
+ maximum: 1
+ "^channel@[2-4]$": false
+ - if:
+ properties:
+ compatible:
+ pattern: "^microchip,emc18[13]3"
+ then:
+ patternProperties:
+ "^channel@[12]$":
+ properties:
+ reg:
+ items:
+ maximum: 1
+ "^channel@[34]$": false
+ - if:
+ properties:
+ compatible:
+ pattern: "^microchip,emc1814"
+ then:
+ patternProperties:
+ "^channel@[1-3]$":
+ properties:
+ reg:
+ items:
+ maximum: 1
+ "^channel@4$": false
+
+additionalProperties: false
+
+examples:
+ - |
+ i2c {
+ #address-cells = <1>;
+ #size-cells = <0>;
+
+ temperature-sensor@4c {
+ compatible = "microchip,emc1813";
+ reg = <0x4c>;
+
+ #address-cells = <1>;
+ #size-cells = <0>;
+
+ microchip,parasitic-res-on-channel1-2;
+
+ microchip,beta1 = <16>;
+ vdd-supply = <&vdd>;
+
+ channel@1 {
+ reg = <1>;
+ label = "External CH1 Temperature";
+ };
+
+ channel@2 {
+ reg = <2>;
+ label = "External CH2 Temperature";
+ };
+ };
+ };
diff --git a/MAINTAINERS b/MAINTAINERS
index a92290fffa163f9fe8fe3f04bf66426f9a894409..09efda36a17e398b3ad807ac47485e530154bae4 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -22862,6 +22862,12 @@ M: Nicolas Pitre <nico@fluxnic.net>
S: Odd Fixes
F: drivers/net/ethernet/smsc/smc91x.*
+MICROCHIP EMC1812 TEMPERATURE DRIVER
+M: Marius Cristea <marius.cristea@microchip.com>
+L: linux-iio@vger.kernel.org
+S: Supported
+F: Documentation/devicetree/bindings/iio/temperature/microchip,emc1812.yaml
+
SMSC EMC2103 HARDWARE MONITOR DRIVER
M: Steve Glendinning <steve.glendinning@shawell.net>
L: linux-hwmon@vger.kernel.org
--
2.48.1On 9/17/25 7:21 AM, Marius Cristea wrote: > This is the devicetree schema for Microchip EMC1812/13/14/15/33 > Multichannel Low-Voltage Remote Diode Sensor Family. > > Signed-off-by: Marius Cristea <marius.cristea@microchip.com> > --- > .../iio/temperature/microchip,emc1812.yaml | 223 +++++++++++++++++++++ > MAINTAINERS | 6 + > 2 files changed, 229 insertions(+) > > diff --git a/Documentation/devicetree/bindings/iio/temperature/microchip,emc1812.yaml b/Documentation/devicetree/bindings/iio/temperature/microchip,emc1812.yaml > new file mode 100644 > index 0000000000000000000000000000000000000000..898d6d246746e229cb004f447872ee6bd5a65074 > --- /dev/null > +++ b/Documentation/devicetree/bindings/iio/temperature/microchip,emc1812.yaml > @@ -0,0 +1,223 @@ > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause) > +%YAML 1.2 > +--- > +$id: http://devicetree.org/schemas/iio/temperature/microchip,emc1812.yaml# > +$schema: http://devicetree.org/meta-schemas/core.yaml# > + > +title: Microchip EMC1812/13/14/15/33 multichannel temperature sensor > + > +maintainers: > + - Marius Cristea <marius.cristea@microchip.com> > + > +description: | > + The Microchip EMC1812/13/14/15/33 is a high-accuracy 2-wire multichannel > + low-voltage remote diode temperature monitor. > + > + The datasheet can be found here: > + https://ww1.microchip.com/downloads/aemDocuments/documents/MSLD/ProductDocuments/DataSheets/EMC1812-3-4-5-33-Data-Sheet-DS20005751.pdf The pinouts of these chips look nearly identical to MCP998X. Would it make sense to share a single bindings document for these? Or maybe there would be too many if: blocks and keeping it separate is fine. https://lore.kernel.org/linux-iio/20250829143447.18893-2-victor.duicu@microchip.com/ > + > +properties: > + compatible: > + enum: > + - microchip,emc1812 > + - microchip,emc1813 > + - microchip,emc1814 > + - microchip,emc1815 > + - microchip,emc1833 > + > + reg: > + maxItems: 1 > + > + interrupts: > + maxItems: 2 > + > + interrupt-names: > + description: > + -alert-therm2 asserts when a diode temperature exceeds the ALERT > + threshold. > + -therm-addr asserts low when the hardware-set THERM limit threshold is > + exceeded by one of the temperature sensors. > + items: > + - const: alert-therm2 > + - const: therm-addr > + > + "#address-cells": > + const: 1 > + > + "#size-cells": > + const: 0 > + > + microchip,beta1: > + description: > + Set beta compensation value for external channel 1. > + <0> 0.050 > + <1> 0.066 > + <2> 0.087 > + <3> 0.114 > + <4> 0.150 > + <5> 0.197 > + <6> 0.260 > + <7> 0.342 > + <8> 0.449 > + <9> 0.591 > + <10> 0.778 > + <11> 1.024 > + <12> 1.348 > + <13> 1.773 > + <14> 2.333 > + <15> Diode_Mode > + <16> Auto > + - Diode_Mode is used when measuring a discrete thermal diode > + or a CPU diode that functions like a discrete thermal diode. > + - Auto enables beta auto-detection. The chip monitors > + external diode/transistor and determines the optimum > + setting. > + $ref: /schemas/types.yaml#/definitions/uint32 > + minimum: 0 > + maximum: 16 > + default: 16 > + > + microchip,beta2: > + description: > + Set beta compensation value for external channel 2. > + $ref: /schemas/types.yaml#/definitions/uint32 > + minimum: 0 > + maximum: 16 > + default: 16 This beta value sounds like something that might not belong in the devicetree. The datasheet says that auto is always the best. So that makes me wonder when would we want to use something else? Also, it says that in auto mode, that the value is recalculated on every conversion, so even if manually selecting a value, it sounds like something that could change at runtime, so having a fixed value might not cover all use cases. Having a boolean flag to say this is wired to a discrete thermal diode makes sense though (the driver would use this info to select diode mode). And if we can make the case that the beta value should be in the devicetree, then having the actual value instead of a lookup table would be preferred. There is a "basis points" standards unit (suffix "-bp") that can be used for non-integer values like this (assuming it is a unit-less value). It is 1/10,000 so it would make the property an enum with 15 values between 500 and 23330. Both properties would not be allowed at the same time and if both properties are omitted, the driver would know to use auto mode. Also, it would make more sense to have these as channel properties if they only apply to 1 channel each. > + > + microchip,parasitic-res-on-channel1-2: > + description: > + Indicates that the chip and the diodes/transistors are sufficiently far > + apart that a parasitic resistance is added to the wires, which can affect > + the measurements. Due to the anti-parallel diode connections, channels > + 1 and 2 are affected together. > + type: boolean > + > + microchip,parasitic-res-on-channel3-4: > + description: > + Indicates that the chip and the diodes/transistors are sufficiently far > + apart that a parasitic resistance is added to the wires, which can affect > + the measurements. Due to the anti-parallel diode connections, channels > + 3 and 4 are affected together. > + type: boolean > + > + vdd-supply: true > + > +patternProperties: > + "^channel@[1-4]$": > + description: > + Represents the external temperature channels to which > + a remote diode is connected. > + type: object > + > + properties: > + reg: > + items: > + minimum: 1 > + maximum: 4 > + I.e. beta-related properties would go here. > + microchip,ideality-factor: > + description: > + Each channel has an ideality factor. > + Beta compensation and resistance error correction automatically > + correct for most ideality errors. So ideality factor does not need > + to be adjusted in general. > + $ref: /schemas/types.yaml#/definitions/uint32 > + minimum: 8 > + maximum: 55 > + default: 18 > +
Hi David, Thank you for the feedback, On Wed, 2025-09-17 at 18:34 -0500, David Lechner wrote: > EXTERNAL EMAIL: Do not click links or open attachments unless you > know the content is safe > > On 9/17/25 7:21 AM, Marius Cristea wrote: > > This is the devicetree schema for Microchip EMC1812/13/14/15/33 > > Multichannel Low-Voltage Remote Diode Sensor Family. > > > > Signed-off-by: Marius Cristea <marius.cristea@microchip.com> > > --- > > .../iio/temperature/microchip,emc1812.yaml | 223 > > +++++++++++++++++++++ > > MAINTAINERS | 6 + > > 2 files changed, 229 insertions(+) > > > > diff --git > > a/Documentation/devicetree/bindings/iio/temperature/microchip,emc18 > > 12.yaml > > b/Documentation/devicetree/bindings/iio/temperature/microchip,emc18 > > 12.yaml > > new file mode 100644 > > index > > 0000000000000000000000000000000000000000..898d6d246746e229cb004f447 > > 872ee6bd5a65074 > > --- /dev/null > > +++ > > b/Documentation/devicetree/bindings/iio/temperature/microchip,emc18 > > 12.yaml > > @@ -0,0 +1,223 @@ > > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause) > > +%YAML 1.2 > > +--- > > +$id: > > http://devicetree.org/schemas/iio/temperature/microchip,emc1812.yaml# > > +$schema: http://devicetree.org/meta-schemas/core.yaml# > > + > > +title: Microchip EMC1812/13/14/15/33 multichannel temperature > > sensor > > + > > +maintainers: > > + - Marius Cristea <marius.cristea@microchip.com> > > + > > +description: | > > + The Microchip EMC1812/13/14/15/33 is a high-accuracy 2-wire > > multichannel > > + low-voltage remote diode temperature monitor. > > + > > + The datasheet can be found here: > > + > > https://ww1.microchip.com/downloads/aemDocuments/documents/MSLD/ProductDocuments/DataSheets/EMC1812-3-4-5-33-Data-Sheet-DS20005751.pdf > > The pinouts of these chips look nearly identical to MCP998X. > Would it make sense to share a single bindings document for these? > Or maybe there would be too many if: blocks and keeping it separate > is fine. > > https://lore.kernel.org/linux-iio/20250829143447.18893-2-victor.duicu@microchip.com/ > > I know that the chip looks nearly identical with MCP998X, but being two different family of devices and having different functions inside, I would like to keep the binding separate, otherwise there will be too many conditions. Thanks, Marius
On Wed, 17 Sep 2025 15:21:57 +0300, Marius Cristea wrote:
> This is the devicetree schema for Microchip EMC1812/13/14/15/33
> Multichannel Low-Voltage Remote Diode Sensor Family.
>
> Signed-off-by: Marius Cristea <marius.cristea@microchip.com>
> ---
> .../iio/temperature/microchip,emc1812.yaml | 223 +++++++++++++++++++++
> MAINTAINERS | 6 +
> 2 files changed, 229 insertions(+)
>
My bot found errors running 'make dt_binding_check' on your patch:
yamllint warnings/errors:
dtschema/dtc warnings/errors:
/builds/robherring/dt-review-ci/linux/Documentation/devicetree/bindings/iio/temperature/microchip,emc1812.yaml: allOf:1:then:patternProperties: '^channel@1$' should not be valid under {'pattern': '^\\^[a-zA-Z0-9,\\-._#@]+\\$$'}
hint: Fixed strings belong in 'properties', not 'patternProperties'
from schema $id: http://devicetree.org/meta-schemas/keywords.yaml#
/builds/robherring/dt-review-ci/linux/Documentation/devicetree/bindings/iio/temperature/microchip,emc1812.yaml: allOf:3:then:patternProperties: '^channel@4$' should not be valid under {'pattern': '^\\^[a-zA-Z0-9,\\-._#@]+\\$$'}
hint: Fixed strings belong in 'properties', not 'patternProperties'
from schema $id: http://devicetree.org/meta-schemas/keywords.yaml#
/builds/robherring/dt-review-ci/linux/Documentation/devicetree/bindings/iio/temperature/microchip,emc1812.example.dtb: temperature-sensor@4c (microchip,emc1813): channel@2:reg:0:0: 2 is greater than the maximum of 1
from schema $id: http://devicetree.org/schemas/iio/temperature/microchip,emc1812.yaml#
doc reference errors (make refcheckdocs):
See https://patchwork.ozlabs.org/project/devicetree-bindings/patch/20250917-iio-emc1812-v1-1-0b1f74cea7ab@microchip.com
The base for the series is generally the latest rc1. A different dependency
should be noted in *this* patch.
If you already ran 'make dt_binding_check' and didn't see the above
error(s), then make sure 'yamllint' is installed and dt-schema is up to
date:
pip3 install dtschema --upgrade
Please check and re-submit after running the above command yourself. Note
that DT_SCHEMA_FILES can be set to your schema file to speed up checking
your schema. However, it must be unset to test all examples with your schema.
© 2016 - 2025 Red Hat, Inc.