diff mbox series

[v1,8/9] dt-bindings: iio: afe: add binding for temperature-sense-current

Message ID 20210530005917.20953-9-liambeguin@gmail.com
State New
Headers show
Series iio: afe: add temperature rescaling support | expand

Commit Message

Liam Beguin May 30, 2021, 12:59 a.m. UTC 
From: Liam Beguin <lvb@xiphos.com>

An ADC is often used to measure other quantities indirectly. This
binding describe one cases, the measurement of a temperature through
a current sense amplifier (such as an AD590) and a sense resistor.

Signed-off-by: Liam Beguin <lvb@xiphos.com>
---
 .../iio/afe/temperature-sense-current.yaml    | 61 +++++++++++++++++++
 MAINTAINERS                                   |  1 +
 2 files changed, 62 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/afe/temperature-sense-current.yaml

Comments

Peter Rosin May 31, 2021, 7:28 a.m. UTC | #1 
Hi!

On 2021-05-30 02:59, Liam Beguin wrote:
> From: Liam Beguin <lvb@xiphos.com>

> 

> An ADC is often used to measure other quantities indirectly. This

> binding describe one cases, the measurement of a temperature through

> a current sense amplifier (such as an AD590) and a sense resistor.

> 

> Signed-off-by: Liam Beguin <lvb@xiphos.com>

> ---

>  .../iio/afe/temperature-sense-current.yaml    | 61 +++++++++++++++++++

>  MAINTAINERS                                   |  1 +

>  2 files changed, 62 insertions(+)

>  create mode 100644 Documentation/devicetree/bindings/iio/afe/temperature-sense-current.yaml

> 

> diff --git a/Documentation/devicetree/bindings/iio/afe/temperature-sense-current.yaml b/Documentation/devicetree/bindings/iio/afe/temperature-sense-current.yaml

> new file mode 100644

> index 000000000000..1bac74486102

> --- /dev/null

> +++ b/Documentation/devicetree/bindings/iio/afe/temperature-sense-current.yaml

> @@ -0,0 +1,61 @@

> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)

> +%YAML 1.2

> +---

> +$id: http://devicetree.org/schemas/iio/afe/temperature-sense-current.yaml#

> +$schema: http://devicetree.org/meta-schemas/core.yaml#

> +

> +title: Temperature Sense Current

> +

> +maintainers:

> +  - Liam Beguin <lvb@xiphos.com>

> +

> +description: |

> +  When an io-channel measures the output voltage for a temperature current

> +  sense amplifier such as the AD950, the interesting measurement is almost

> +  always the corresponding temperature, not the voltage output.

> +  This binding describes such a circuit.

> +

> +properties:

> +  compatible:

> +    const: temperature-sense-current

> +

> +  io-channels:

> +    maxItems: 1

> +    description: |

> +      Channel node of a voltage io-channel.

> +

> +  '#io-channel-cells':

> +    const: 1

> +

> +  sense-resistor-ohms:

> +    description: The sense resistance.

> +

> +  alpha-micro-amps-per-degree:

> +    description: |

> +      Linear output current gain of the temperature IC.

> +

> +  use-kelvin-scale:

> +    type: boolean

> +    description: |

> +      Boolean indicating if alpha uses Kelvin degrees instead of Celsius.


It's "kelvin", not "Kelvin degrees", and it's "degrees Celsius".

But what exactly is this property for? We always want degrees Celsius, don't we,
and any offset can be handled...with an offset. No?

Cheers,
Peter

> +

> +additionalProperties: false

> +required:

> +  - compatible

> +  - io-channels

> +  - sense-resistor-ohms

> +  - alpha-micro-amps-per-degree

> +

> +examples:

> +  - |

> +    ad590: iio-rescale0 {

> +        compatible = "temperature-sense-current";

> +        #io-channel-cells = <1>;

> +        io-channels = <&temp_adc 2>;

> +

> +        sense-resistor-ohms = <8060>;

> +        use-kelvin-scale;

> +        alpha-micro-amps-per-degree = <1>;

> +    };

> +

> +...

> diff --git a/MAINTAINERS b/MAINTAINERS

> index a7279af85adb..0eb7fcd94b66 100644

> --- a/MAINTAINERS

> +++ b/MAINTAINERS

> @@ -8721,6 +8721,7 @@ L:	linux-iio@vger.kernel.org

>  S:	Maintained

>  F:	Documentation/devicetree/bindings/iio/afe/current-sense-amplifier.yaml

>  F:	Documentation/devicetree/bindings/iio/afe/current-sense-shunt.yaml

> +F:	Documentation/devicetree/bindings/iio/afe/temperature-sense-current.yaml

>  F:	Documentation/devicetree/bindings/iio/afe/temperature-sense-rtd.yaml

>  F:	Documentation/devicetree/bindings/iio/afe/voltage-divider.yaml

>  F:	drivers/iio/afe/iio-rescale.c

> 


-- 
Peter Rosin
+46 730 746 224
Axentia Technologies AB
Peter Rosin May 31, 2021, 8:58 a.m. UTC | #2 
On 2021-05-31 09:28, Peter Rosin wrote:
>> +  use-kelvin-scale:

>> +    type: boolean

>> +    description: |

>> +      Boolean indicating if alpha uses Kelvin degrees instead of Celsius.

> 

> It's "kelvin", not "Kelvin degrees", and it's "degrees Celsius".

> 

> But what exactly is this property for? We always want degrees Celsius, don't we,

> and any offset can be handled...with an offset. No?


Ahh, I hit send too soon. I now see that you calculate the offset in the driver
instead of requiring the devicetree author to do it "by hand".

Cheers,
Peter
Liam Beguin May 31, 2021, 1:41 p.m. UTC | #3 
Hi Peter,

On Mon May 31, 2021 at 4:58 AM EDT, Peter Rosin wrote:
>

>

> On 2021-05-31 09:28, Peter Rosin wrote:

> >> +  use-kelvin-scale:

> >> +    type: boolean

> >> +    description: |

> >> +      Boolean indicating if alpha uses Kelvin degrees instead of Celsius.

> > 

> > It's "kelvin", not "Kelvin degrees", and it's "degrees Celsius".


I'll rephrase the description base on your comment.

I also thought of using alpha-micro-amps-per-degree-celsius and
alpha-micro-amps-kelvin instead. I don't know if that would be better.

Thanks,
Liam

> > 

> > But what exactly is this property for? We always want degrees Celsius, don't we,

> > and any offset can be handled...with an offset. No?

>

> Ahh, I hit send too soon. I now see that you calculate the offset in the

> driver

> instead of requiring the devicetree author to do it "by hand".

>

> Cheers,

> Peter
Jonathan Cameron June 1, 2021, 4:47 p.m. UTC | #4 
On Sat, 29 May 2021 20:59:16 -0400
Liam Beguin <liambeguin@gmail.com> wrote:

> From: Liam Beguin <lvb@xiphos.com>

> 

> An ADC is often used to measure other quantities indirectly. This

> binding describe one cases, the measurement of a temperature through

> a current sense amplifier (such as an AD590) and a sense resistor.

> 

> Signed-off-by: Liam Beguin <lvb@xiphos.com>

> ---

>  .../iio/afe/temperature-sense-current.yaml    | 61 +++++++++++++++++++

>  MAINTAINERS                                   |  1 +

>  2 files changed, 62 insertions(+)

>  create mode 100644 Documentation/devicetree/bindings/iio/afe/temperature-sense-current.yaml

> 

> diff --git a/Documentation/devicetree/bindings/iio/afe/temperature-sense-current.yaml b/Documentation/devicetree/bindings/iio/afe/temperature-sense-current.yaml

> new file mode 100644

> index 000000000000..1bac74486102

> --- /dev/null

> +++ b/Documentation/devicetree/bindings/iio/afe/temperature-sense-current.yaml

> @@ -0,0 +1,61 @@

> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)

> +%YAML 1.2

> +---

> +$id: http://devicetree.org/schemas/iio/afe/temperature-sense-current.yaml#

> +$schema: http://devicetree.org/meta-schemas/core.yaml#

> +

> +title: Temperature Sense Current

> +

> +maintainers:

> +  - Liam Beguin <lvb@xiphos.com>

> +

> +description: |

> +  When an io-channel measures the output voltage for a temperature current

> +  sense amplifier such as the AD950, the interesting measurement is almost

> +  always the corresponding temperature, not the voltage output.

> +  This binding describes such a circuit.

> +

> +properties:

> +  compatible:

> +    const: temperature-sense-current


What about such a sensor connected to a current ADC? That was what I was
immediately expecting when I saw the naming.

You could daisy chain this with the current-sense-resistor AFE though
that does seem overly messy.

Anyhow this should be called something that reflects the presence of
that sense resitor.

> +

> +  io-channels:

> +    maxItems: 1

> +    description: |

> +      Channel node of a voltage io-channel.

> +

> +  '#io-channel-cells':

> +    const: 1

> +

> +  sense-resistor-ohms:

> +    description: The sense resistance.

> +

> +  alpha-micro-amps-per-degree:

> +    description: |

> +      Linear output current gain of the temperature IC.

> +

> +  use-kelvin-scale:

> +    type: boolean

> +    description: |

> +      Boolean indicating if alpha uses Kelvin degrees instead of Celsius.

> +

> +additionalProperties: false

> +required:

> +  - compatible

> +  - io-channels

> +  - sense-resistor-ohms

> +  - alpha-micro-amps-per-degree

> +

> +examples:

> +  - |

> +    ad590: iio-rescale0 {

> +        compatible = "temperature-sense-current";

> +        #io-channel-cells = <1>;

> +        io-channels = <&temp_adc 2>;

> +

> +        sense-resistor-ohms = <8060>;

> +        use-kelvin-scale;

> +        alpha-micro-amps-per-degree = <1>;

> +    };

> +

> +...

> diff --git a/MAINTAINERS b/MAINTAINERS

> index a7279af85adb..0eb7fcd94b66 100644

> --- a/MAINTAINERS

> +++ b/MAINTAINERS

> @@ -8721,6 +8721,7 @@ L:	linux-iio@vger.kernel.org

>  S:	Maintained

>  F:	Documentation/devicetree/bindings/iio/afe/current-sense-amplifier.yaml

>  F:	Documentation/devicetree/bindings/iio/afe/current-sense-shunt.yaml

> +F:	Documentation/devicetree/bindings/iio/afe/temperature-sense-current.yaml

>  F:	Documentation/devicetree/bindings/iio/afe/temperature-sense-rtd.yaml

>  F:	Documentation/devicetree/bindings/iio/afe/voltage-divider.yaml

>  F:	drivers/iio/afe/iio-rescale.c
Rob Herring June 4, 2021, 9:21 p.m. UTC | #5 
On Sat, May 29, 2021 at 08:59:16PM -0400, Liam Beguin wrote:
> From: Liam Beguin <lvb@xiphos.com>

> 

> An ADC is often used to measure other quantities indirectly. This

> binding describe one cases, the measurement of a temperature through

> a current sense amplifier (such as an AD590) and a sense resistor.

> 

> Signed-off-by: Liam Beguin <lvb@xiphos.com>

> ---

>  .../iio/afe/temperature-sense-current.yaml    | 61 +++++++++++++++++++

>  MAINTAINERS                                   |  1 +

>  2 files changed, 62 insertions(+)

>  create mode 100644 Documentation/devicetree/bindings/iio/afe/temperature-sense-current.yaml

> 

> diff --git a/Documentation/devicetree/bindings/iio/afe/temperature-sense-current.yaml b/Documentation/devicetree/bindings/iio/afe/temperature-sense-current.yaml

> new file mode 100644

> index 000000000000..1bac74486102

> --- /dev/null

> +++ b/Documentation/devicetree/bindings/iio/afe/temperature-sense-current.yaml

> @@ -0,0 +1,61 @@

> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)

> +%YAML 1.2

> +---

> +$id: http://devicetree.org/schemas/iio/afe/temperature-sense-current.yaml#

> +$schema: http://devicetree.org/meta-schemas/core.yaml#

> +

> +title: Temperature Sense Current

> +

> +maintainers:

> +  - Liam Beguin <lvb@xiphos.com>

> +

> +description: |

> +  When an io-channel measures the output voltage for a temperature current

> +  sense amplifier such as the AD950, the interesting measurement is almost

> +  always the corresponding temperature, not the voltage output.

> +  This binding describes such a circuit.

> +

> +properties:

> +  compatible:

> +    const: temperature-sense-current

> +

> +  io-channels:

> +    maxItems: 1

> +    description: |

> +      Channel node of a voltage io-channel.

> +

> +  '#io-channel-cells':

> +    const: 1


Belongs in provider unless this is a consumer and provider.

> +

> +  sense-resistor-ohms:

> +    description: The sense resistance.

> +

> +  alpha-micro-amps-per-degree:

> +    description: |

> +      Linear output current gain of the temperature IC.

> +

> +  use-kelvin-scale:

> +    type: boolean

> +    description: |

> +      Boolean indicating if alpha uses Kelvin degrees instead of Celsius.

> +

> +additionalProperties: false


blank line

> +required:

> +  - compatible

> +  - io-channels

> +  - sense-resistor-ohms

> +  - alpha-micro-amps-per-degree

> +

> +examples:

> +  - |

> +    ad590: iio-rescale0 {

> +        compatible = "temperature-sense-current";

> +        #io-channel-cells = <1>;

> +        io-channels = <&temp_adc 2>;

> +

> +        sense-resistor-ohms = <8060>;

> +        use-kelvin-scale;

> +        alpha-micro-amps-per-degree = <1>;

> +    };

> +

> +...

> diff --git a/MAINTAINERS b/MAINTAINERS

> index a7279af85adb..0eb7fcd94b66 100644

> --- a/MAINTAINERS

> +++ b/MAINTAINERS

> @@ -8721,6 +8721,7 @@ L:	linux-iio@vger.kernel.org

>  S:	Maintained

>  F:	Documentation/devicetree/bindings/iio/afe/current-sense-amplifier.yaml

>  F:	Documentation/devicetree/bindings/iio/afe/current-sense-shunt.yaml

> +F:	Documentation/devicetree/bindings/iio/afe/temperature-sense-current.yaml

>  F:	Documentation/devicetree/bindings/iio/afe/temperature-sense-rtd.yaml

>  F:	Documentation/devicetree/bindings/iio/afe/voltage-divider.yaml

>  F:	drivers/iio/afe/iio-rescale.c

> -- 

> 2.30.1.489.g328c10930387
diff mbox series

Patch

diff --git a/Documentation/devicetree/bindings/iio/afe/temperature-sense-current.yaml b/Documentation/devicetree/bindings/iio/afe/temperature-sense-current.yaml
new file mode 100644
index 000000000000..1bac74486102
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/afe/temperature-sense-current.yaml
@@ -0,0 +1,61 @@ 
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/afe/temperature-sense-current.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Temperature Sense Current
+
+maintainers:
+  - Liam Beguin <lvb@xiphos.com>
+
+description: |
+  When an io-channel measures the output voltage for a temperature current
+  sense amplifier such as the AD950, the interesting measurement is almost
+  always the corresponding temperature, not the voltage output.
+  This binding describes such a circuit.
+
+properties:
+  compatible:
+    const: temperature-sense-current
+
+  io-channels:
+    maxItems: 1
+    description: |
+      Channel node of a voltage io-channel.
+
+  '#io-channel-cells':
+    const: 1
+
+  sense-resistor-ohms:
+    description: The sense resistance.
+
+  alpha-micro-amps-per-degree:
+    description: |
+      Linear output current gain of the temperature IC.
+
+  use-kelvin-scale:
+    type: boolean
+    description: |
+      Boolean indicating if alpha uses Kelvin degrees instead of Celsius.
+
+additionalProperties: false
+required:
+  - compatible
+  - io-channels
+  - sense-resistor-ohms
+  - alpha-micro-amps-per-degree
+
+examples:
+  - |
+    ad590: iio-rescale0 {
+        compatible = "temperature-sense-current";
+        #io-channel-cells = <1>;
+        io-channels = <&temp_adc 2>;
+
+        sense-resistor-ohms = <8060>;
+        use-kelvin-scale;
+        alpha-micro-amps-per-degree = <1>;
+    };
+
+...
diff --git a/MAINTAINERS b/MAINTAINERS
index a7279af85adb..0eb7fcd94b66 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -8721,6 +8721,7 @@  L:	linux-iio@vger.kernel.org
 S:	Maintained
 F:	Documentation/devicetree/bindings/iio/afe/current-sense-amplifier.yaml
 F:	Documentation/devicetree/bindings/iio/afe/current-sense-shunt.yaml
+F:	Documentation/devicetree/bindings/iio/afe/temperature-sense-current.yaml
 F:	Documentation/devicetree/bindings/iio/afe/temperature-sense-rtd.yaml
 F:	Documentation/devicetree/bindings/iio/afe/voltage-divider.yaml
 F:	drivers/iio/afe/iio-rescale.c