Add support for AD4170 series of ADCs

Add device tree documentation for AD4170 and similar sigma-delta ADCs. The AD4170 is a 24-bit, multichannel, sigma-delta ADC.

Signed-off-by Marcelo Schmitt <[email protected]>

---
Change log v2 -> v3

[device tree changes]
- Removed unneeded allOf.
- Removed occurences of adi,sensor-type type re-declaration.
- Created type for the AD4170 channels, allowing to avoid dt doc repetition.

 .../bindings/iio/adc/adi,ad4170.yaml          | 544 ++++++++++++++++++
 MAINTAINERS                                   |   7 +
 2 files changed, 551 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml

Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml new file +28 -0

new file mode 100644
index 000000000000..0a06258b6631
@@ -0,0 +1,544 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/adc/adi,ad4170.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Analog Devices AD4170 and similar Analog to Digital Converters
+
+maintainers:
+  - Marcelo Schmitt <[email protected]>
+
+description: |
+  Analog Devices AD4170 series of Sigma-delta Analog to Digital Converters.
+  Specifications can be found at:
+    https://www.analog.com/media/en/technical-documentation/data-sheets/ad4170-4.pdf
+    https://www.analog.com/media/en/technical-documentation/data-sheets/ad4190-4.pdf
+    https://www.analog.com/media/en/technical-documentation/data-sheets/ad4195-4.pdf
+
+$ref: /schemas/spi/spi-peripheral-props.yaml#
+
+$defs:
+  ad4170-channel:
+    type: object
+    $ref: /schemas/iio/adc/adc.yaml#
+    description:
+      Common properties for configuring AD4170 channels.
+
+    properties:

Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml new file +34 -0

+
+
+  sensor-node:
+    type: object
+    $ref: '#/$defs/ad4170-channel'
+    description:
+      The AD4170 and similar designs have features to aid interfacing with weigh
+      scale, RTD, and thermocouple sensors. Each of those sensor types requires
+      either distinct wiring configuration or external circuitry for proper
+      sensor operation and can use different AD4170 functionality on their
+      setups. A key characteristic of those external sensors is that they must
+      be excited either by voltage supply or by AD4170 excitation signals. The
+      sensor can then be read through a pair of analog inputs. These properties
+      describe external sensor circuitry connected to the ADC.
+
+    properties:
+      reg:
+        description:
+          Channel number. Connects the sensor to the channel with this number
+          of the device.
+        minimum: 1
+        maximum: 16
+
+      diff-channels:
+        description:
+          Defines the ADC input pins used to read sensor data. Only regular
+          analog input pins can be used.
+        items:
+          enum: [0, 1, 2, 3, 4, 5, 6, 7, 8]
+
+      bipolar: true
+
+      adi,sensor-type:
+        description: |

Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml new file +22 -0

+
+      adi,excitation-pins:
+        $ref: /schemas/types.yaml#/definitions/uint32-array
+        description:
+          Pins used to excite the sensor or external circuit that contains the
+          sensor. Thermocouples and RTD sensors are excited either with one
+          current source or with a pair of current sources to minimize the
+          excitation current mismatch and the excitation current drift matching
+          on the ADC. E.g. <0>; <1>; <0 1>. Load cell weigh scales may be
+          excited with one current source, a pair of excitation currents, or two
+          pairs of excitation currents. When four pins are defined, the first
+          two values specify the first pair and the last ones specify the second
+          pair of excitation currents. E.g. <0>; <0 1>; <0 1 2 3>.
+        items:
+          minimum: 0
+          maximum: 20
+
+      adi,excitation-current-microamp:
+        description:
+          Excitation current in microamperes to be output to each excitation pin
+          specified by adi,excitation-pins property. If not provided and
+          adi,excitation-ac is true, use predefined ACX1, ACX1 negated, ACX2,

Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml new file +17 -0

+
+      adi,vbias:
+        type: boolean
+        description:
+          For unbiased thermocouple applications, the voltage generated by the
+          thermocouple must be biased around some DC voltage. When present, this
+          property specifies a bias voltage of (AVDD + AVSS)/2 to be applied as
+          common-mode voltage for the sensor.
+
+    required:
+      - reg
+      - diff-channels
+      - bipolar
+      - adi,sensor-type
+      - adi,reference-select
+
+

Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml new file +42 -0

+      (absolute value) of the negative voltage supplied to the AVSS pin. Since
+      AVSS must be −2.625V minimum and 0V maximum, the declared supply voltage
+      must be between 0 and 2.65V. If not provided, AVSS is assumed to be at
+      system ground (0V).
+
+  avdd-supply:
+    description:
+      A supply of 4.75V to 5.25V relative to AVSS that powers the chip (AVDD).
+
+  iovdd-supply:
+    description: 1.7V to 5.25V reference supply to the serial interface (IOVDD).
+
+  refin1p-supply:
+    description: REFIN+ supply that can be used as reference for conversion.
+
+  refin1n-supply:
+    description: REFIN- supply that can be used as reference for conversion. If
+      provided, describes the magnitude (absolute value) of the negative voltage
+      supplied to the REFIN- pin.
+
+  refin2p-supply:
+    description: REFIN2+ supply that can be used as reference for conversion.
+
+  refin2n-supply:
+    description: REFIN2- supply that can be used as reference for conversion. If
+      provided, describes the magnitude (absolute value) of the negative voltage
+      supplied to the REFIN2- pin.
+
+  spi-cpol: true
+
+  spi-cpha: true
+
+  interrupts:
+    maxItems: 1> +
+  interrupt-names:
+    description:
+      Specify which pin should be configured as Data Ready interrupt.
+    enum:
+      - sdo
+      - dig_aux1
+    default: sdo> +
+  clocks:

Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml new file +51 -0

+
+  gpio-controller: true
+
+  "#gpio-cells":
+    const: 2
+    description: |
+      The first cell is for the GPIO number: 0 to 3.
+      The second cell takes standard GPIO flags.
+
+  ldac-gpios:
+    description:
+      GPIO connected to DIG_AUX2 pin to be used as LDAC toggle to control the
+      transfer of data from the DAC_INPUT_A register to the DAC.
+    maxItems: 1
+
+  '#address-cells':
+    const: 1
+
+  '#size-cells':
+    const: 0
+
+patternProperties:
+  "^channel@[0-9a-f]$":
+    $ref: '#/$defs/ad4170-channel'
+    unevaluatedProperties: false
+    description:
+      Represents the external channels which are connected to the ADC.
+
+    properties:
+      reg:
+        description:
+          The channel number.
+        minimum: 0
+        maximum: 15
+
+      diff-channels:
+        description: |
+          This property is used for defining the inputs of a differential
+          voltage channel. The first value is the positive input and the second
+          value is the negative input of the channel.
+
+          Besides the analog input pins AIN0 to AIN8, there are special inputs
+          that can be selected with the following values:
+          17: Internal temperature sensor
+          18: (AVDD-AVSS)/5
+          19: (IOVDD-DGND)/5
+          20: DAC output
+          21: ALDO
+          22: DLDO
+          23: AVSS
+          24: DGND

Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml new file +34 -0

+
+      single-channel: true
+
+      common-mode-channel: true
+
+      bipolar: true
+
+      adi,buffered-positive:
+        description: |
+          Enable precharge buffer, full buffer, or skip reference buffering of
+          the positive voltage reference. Because the output impedance of the
+          source driving the voltage reference inputs may be dynamic, RC
+          combinations of those inputs can cause DC gain errors if the reference
+          inputs go unbuffered into the ADC. Enable reference buffering if the
+          provided reference source has dynamic high impedance output. Note the
+          absolute voltage allowed on positive reference inputs (REFIN+,
+          REFIN2+) is from AVSS − 50 mV to AVDD + 50 mV when the reference
+          buffers are disabled but narrows to AVSS to AVDD when reference
+          buffering is enabled or in precharge mode.
+          0: Reference precharge buffer.
+          1: Full Buffer.
+          2: Bypass reference buffers (buffering disabled).
+        $ref: /schemas/types.yaml#/definitions/uint8
+        enum: [0, 1, 2]
+        default: 1
+
+      adi,buffered-negative:
+        description: |
+          Enable precharge buffer, full buffer, or skip reference buffering of
+          the negative voltage reference. Because the output impedance of the
+          source driving the voltage reference inputs may be dynamic, RC
+          combinations of those inputs can cause DC gain errors if the reference
+          inputs go unbuffered into the ADC. Enable reference buffering if the
+          provided reference source has dynamic high impedance output. Note the

Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml new file +70 -0

+        properties:
+          diff-channels: false
+      - required: [diff-channels]
+        properties:
+          single-channel: false
+          common-mode-channel: false
+
+  "^weighscale@":
+    $ref: '#/$defs/sensor-node'
+    unevaluatedProperties: false
+
+    properties:
+      diff-channels: true
+      bipolar: true
+
+      adi,sensor-type:
+        description: Weigh scale sensor.
+        const: 0
+
+      adi,excitation-pins: true
+
+  "^rtd@":
+    $ref: '#/$defs/sensor-node'
+    unevaluatedProperties: false
+
+    properties:
+      diff-channels: true
+      bipolar: true
+
+      adi,sensor-type:
+        description: RTD sensor.
+        const: 1
+
+      adi,excitation-pins: true
+
+      adi,excitation-current-microamp: true
+
+    required:
+      - adi,excitation-pins
+      - adi,excitation-current-microamp
+
+  "^thermocouple@":
+    $ref: '#/$defs/sensor-node'
+    unevaluatedProperties: false
+
+    properties:
+      diff-channels: true
+      bipolar: true
+
+      adi,sensor-type:
+        description: Thermocouple sensor.
+        const: 2
+
+    required:
+      - adi,excitation-pins
+      - adi,excitation-current-microamp
+
+required:
+  - compatible
+  - reg
+  - avdd-supply
+  - iovdd-supply
+  - spi-cpol
+  - spi-cpha
+
+allOf:
+  # Some devices don't have integrated DAC
+  - if:
+      properties:
+        compatible:

Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml line 38

Quoted 12 lines

Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml new file +12 -0

+
+    properties:
+      adi,reference-select:
+        description: |
+          Selects the reference source to use when converting on the specific
+          channel. Valid values are:
+          0: Differential reference voltage REFIN+ - REFIN−.
+          1: Differential reference voltage REFIN2+ - REFIN2−.
+          2: Internal 2.5V referece (REFOUT) relative to AVSS.
+          3: Analog supply voltage (AVDD) relative AVSS.
+        $ref: /schemas/types.yaml#/definitions/uint8
+        enum: [0, 1, 2, 3]

Using strings instead of int for this and most of the other custom enums here would make them self-documenting and easier to use.

Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml line 82

Quoted 12 lines

Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml new file +12 -0

+      adi,sensor-type:
+        description: |
+          Type of sensor connected to the device. Depending on the sensor type
+          (weigh scale, RTD, or thermocouple) the values of sensor-node
+          properties have slightly different constraints. This property
+          specifies which particular external sensor is connected to the ADC so
+          the sensor-node properties can be properly parsed and verified. The
+          possible sensor types are:
+          0: weigh scale;
+          1: RTD;
+          2: thermocouple.
+        $ref: /schemas/types.yaml#/definitions/uint8

This property seems reduandant since it has to match the node name.

i.e. weighscale@... is is always adi,sensor-type = <0>; and so on.

Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml line 119

Quoted 6 lines

Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml new file +6 -0

+
+      adi,power-down-switch-pin:
+        description:
+          Number of the GPIO used as power-down switch for the bridge circuit.
+        $ref: /schemas/types.yaml#/definitions/uint8
+        enum: [0, 1]

This isn't required, so what is the default if omitted?

Quoted 16 lines

Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml new file +16 -0

+      diff-channels:
+        description: |
+          This property is used for defining the inputs of a differential
+          voltage channel. The first value is the positive input and the second
+          value is the negative input of the channel.
+
+          Besides the analog input pins AIN0 to AIN8, there are special inputs
+          that can be selected with the following values:
+          17: Internal temperature sensor
+          18: (AVDD-AVSS)/5
+          19: (IOVDD-DGND)/5
+          20: DAC output
+          21: ALDO
+          22: DLDO
+          23: AVSS
+          24: DGND

Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml line 267

Quoted 10 lines

Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml new file +10 -0

+          25: REFIN+
+          26: REFIN-
+          27: REFIN2+
+          28: REFIN2-
+          29: REFOUT
+          For the internal temperature sensor, use the input number for both
+          inputs (i.e. diff-channels = <17 17>).
+        items:
+          enum: [0, 1, 2, 3, 4, 5, 6, 7, 8, 17, 18, 19, 20, 21, 22, 23, 24, 25,
+                 26, 27, 28, 29]

A Header file with macros for these would be nice since it seems like we have to use the higher-numbered ones a lot with the common-mode-channel properties in the examples.

Quoted 38 lines

Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml new file +37 -0

+
+      single-channel: true
+
+      common-mode-channel: true
+
+      bipolar: true
+
+      adi,buffered-positive:
+        description: |
+          Enable precharge buffer, full buffer, or skip reference buffering of
+          the positive voltage reference. Because the output impedance of the
+          source driving the voltage reference inputs may be dynamic, RC
+          combinations of those inputs can cause DC gain errors if the reference
+          inputs go unbuffered into the ADC. Enable reference buffering if the
+          provided reference source has dynamic high impedance output. Note the
+          absolute voltage allowed on positive reference inputs (REFIN+,
+          REFIN2+) is from AVSS − 50 mV to AVDD + 50 mV when the reference
+          buffers are disabled but narrows to AVSS to AVDD when reference
+          buffering is enabled or in precharge mode.
+          0: Reference precharge buffer.
+          1: Full Buffer.
+          2: Bypass reference buffers (buffering disabled).
+        $ref: /schemas/types.yaml#/definitions/uint8
+        enum: [0, 1, 2]
+        default: 1
+
+      adi,buffered-negative:
+        description: |
+          Enable precharge buffer, full buffer, or skip reference buffering of
+          the negative voltage reference. Because the output impedance of the
+          source driving the voltage reference inputs may be dynamic, RC
+          combinations of those inputs can cause DC gain errors if the reference
+          inputs go unbuffered into the ADC. Enable reference buffering if the
+          provided reference source has dynamic high impedance output. Note the
+          absolute voltage allowed on negative reference inputs (REFIN-,
+          REFIN2-) is from AVSS − 50 mV to AVDD + 50 mV when the reference
+          buffers are disabled but narrows to AVSS to AVDD when reference

Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml line 292

Quoted 7 lines

Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml new file +7 -0

+          buffering is enabled or in precharge mode.
+          0: Reference precharge buffer.
+          1: Full Buffer.
+          2: Bypass reference buffers (buffering disabled).
+        $ref: /schemas/types.yaml#/definitions/uint8
+        enum: [0, 1, 2]
+        default: 1

Could make a $def for these too to reduce duplication.

Also another case where string type would make more sense.

Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml line 130

Quoted 3 lines

Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml new file +3 -0

+
+    required:
+      - reg

reg is already required by adc.yaml

Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml line 317

Quoted 3 lines

Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml new file +3 -0

+
+    oneOf:
+      - required: [single-channel]

Is there a default for common-mode-channel if it isn't required in this case?

...

Quoted 12 lines

Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml line 38

Quoted 12 lines

Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml new file +12 -0

+
+    properties:
+      adi,reference-select:
+        description: |
+          Selects the reference source to use when converting on the specific
+          channel. Valid values are:
+          0: Differential reference voltage REFIN+ - REFIN−.
+          1: Differential reference voltage REFIN2+ - REFIN2−.
+          2: Internal 2.5V referece (REFOUT) relative to AVSS.
+          3: Analog supply voltage (AVDD) relative AVSS.
+        $ref: /schemas/types.yaml#/definitions/uint8
+        enum: [0, 1, 2, 3]

Quoted 2 lines

Using strings instead of int for this and most of the other custom enums here would make them self-documenting and easier to use.

The numbers match the values that are documented in the datasheet for each option of voltage reference available to use with a channel. So we would be using numbers mostly to define values of some unit and pin numbers (e.g. 100 for the microamp property)? Not really excited about doing this change because I think it will make the dtb a bit larger and the driver code a bit more lengthy, but can do that for v4.

...

Quoted 6 lines

Quoted 6 lines

Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml new file +6 -0

+
+      adi,power-down-switch-pin:
+        description:
+          Number of the GPIO used as power-down switch for the bridge circuit.
+        $ref: /schemas/types.yaml#/definitions/uint8
+        enum: [0, 1]

Quoted 1 line

This isn't required, so what is the default if omitted?

We don't care about it when the property is omitted.
Do we need a default even when the property is not required and we don't care when it's not set?

...

Quoted 27 lines

Quoted 26 lines

Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml new file +26 -0

+      diff-channels:
+        description: |
+          This property is used for defining the inputs of a differential
+          voltage channel. The first value is the positive input and the second
+          value is the negative input of the channel.
+
+          Besides the analog input pins AIN0 to AIN8, there are special inputs
+          that can be selected with the following values:
+          17: Internal temperature sensor
+          18: (AVDD-AVSS)/5
+          19: (IOVDD-DGND)/5
+          20: DAC output
+          21: ALDO
+          22: DLDO
+          23: AVSS
+          24: DGND
+          25: REFIN+
+          26: REFIN-
+          27: REFIN2+
+          28: REFIN2-
+          29: REFOUT
+          For the internal temperature sensor, use the input number for both
+          inputs (i.e. diff-channels = <17 17>).
+        items:
+          enum: [0, 1, 2, 3, 4, 5, 6, 7, 8, 17, 18, 19, 20, 21, 22, 23, 24, 25,
+                 26, 27, 28, 29]

Quoted 3 lines

A Header file with macros for these would be nice since it seems like we have to use the higher-numbered ones a lot with the common-mode-channel properties in the examples.

The RFC set had a header with macros for those numbers, but making dt properties "look nice" was said to no be a reason to have binding headers.

https://lore.kernel.org/linux-iio/ikq55kcfu2lmxzeeobu4zwf67xypyikadnpycw2m4d7o6gvmi2@tkepvcvzqzoh/

Also, no other binding would use those values. So, we would have a header specific for adi,ad4170?

Quoted 39 lines

Quoted 39 lines

Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml new file +37 -0

+
+      single-channel: true
+
+      common-mode-channel: true
+
+      bipolar: true
+
+      adi,buffered-positive:
+        description: |
+          Enable precharge buffer, full buffer, or skip reference buffering of
+          the positive voltage reference. Because the output impedance of the
+          source driving the voltage reference inputs may be dynamic, RC
+          combinations of those inputs can cause DC gain errors if the reference
+          inputs go unbuffered into the ADC. Enable reference buffering if the
+          provided reference source has dynamic high impedance output. Note the
+          absolute voltage allowed on positive reference inputs (REFIN+,
+          REFIN2+) is from AVSS − 50 mV to AVDD + 50 mV when the reference
+          buffers are disabled but narrows to AVSS to AVDD when reference
+          buffering is enabled or in precharge mode.
+          0: Reference precharge buffer.
+          1: Full Buffer.
+          2: Bypass reference buffers (buffering disabled).
+        $ref: /schemas/types.yaml#/definitions/uint8
+        enum: [0, 1, 2]
+        default: 1
+
+      adi,buffered-negative:
+        description: |
+          Enable precharge buffer, full buffer, or skip reference buffering of
+          the negative voltage reference. Because the output impedance of the
+          source driving the voltage reference inputs may be dynamic, RC
+          combinations of those inputs can cause DC gain errors if the reference
+          inputs go unbuffered into the ADC. Enable reference buffering if the
+          provided reference source has dynamic high impedance output. Note the
+          absolute voltage allowed on negative reference inputs (REFIN-,
+          REFIN2-) is from AVSS − 50 mV to AVDD + 50 mV when the reference
+          buffers are disabled but narrows to AVSS to AVDD when reference

Quoted 8 lines

Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml line 292

Quoted 7 lines

Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml new file +7 -0

+          buffering is enabled or in precharge mode.
+          0: Reference precharge buffer.
+          1: Full Buffer.
+          2: Bypass reference buffers (buffering disabled).
+        $ref: /schemas/types.yaml#/definitions/uint8
+        enum: [0, 1, 2]
+        default: 1

Could make a $def for these too to reduce duplication.

I think so, but how? They are only documented here. I can merge them into a single adi,buffered property. That will also reduce duplication.

...

Quoted 12 lines

Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml line 38

Quoted 12 lines

Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml new file +12 -0

+
+    properties:
+      adi,reference-select:
+        description: |
+          Selects the reference source to use when converting on the specific
+          channel. Valid values are:
+          0: Differential reference voltage REFIN+ - REFIN−.
+          1: Differential reference voltage REFIN2+ - REFIN2−.
+          2: Internal 2.5V referece (REFOUT) relative to AVSS.
+          3: Analog supply voltage (AVDD) relative AVSS.
+        $ref: /schemas/types.yaml#/definitions/uint8
+        enum: [0, 1, 2, 3]

Quoted 2 lines

Using strings instead of int for this and most of the other custom enums here would make them self-documenting and easier to use.

The numbers match the values that are documented in the datasheet for each option of voltage reference available to use with a channel. So we would be using numbers mostly to define values of some unit and pin numbers (e.g. 100 for the microamp property)? Not really excited about doing this change because I think it will make the dtb a bit larger and the driver code a bit more lengthy, but can do that for v4.

...

Quoted 12 lines

Quoted 12 lines

Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml new file +12 -0

+      adi,sensor-type:
+        description: |
+          Type of sensor connected to the device. Depending on the sensor type
+          (weigh scale, RTD, or thermocouple) the values of sensor-node
+          properties have slightly different constraints. This property
+          specifies which particular external sensor is connected to the ADC so
+          the sensor-node properties can be properly parsed and verified. The
+          possible sensor types are:
+          0: weigh scale;
+          1: RTD;
+          2: thermocouple.
+        $ref: /schemas/types.yaml#/definitions/uint8

Quoted 3 lines

This property seems reduandant since it has to match the node name.

i.e. weighscale@... is is always adi,sensor-type = <0>; and so on.

Yes, can we rely on node names I'll do that for v4.

Add device tree documentation for AD4170 and similar sigma-delta ADCs. The AD4170 is a 24-bit, multichannel, sigma-delta ADC.

Signed-off-by Marcelo Schmitt <[email protected]>

---
Change log v2 -> v3

[device tree changes]
- Removed unneeded allOf.
- Removed occurences of adi,sensor-type type re-declaration.
- Created type for the AD4170 channels, allowing to avoid dt doc repetition.

 .../bindings/iio/adc/adi,ad4170.yaml          | 544 ++++++++++++++++++
 MAINTAINERS                                   |   7 +
 2 files changed, 551 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml

Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml new file +30 -0

new file mode 100644
index 000000000000..0a06258b6631
@@ -0,0 +1,544 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/adc/adi,ad4170.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Analog Devices AD4170 and similar Analog to Digital Converters
+
+maintainers:
+  - Marcelo Schmitt <[email protected]>
+
+description: |
+  Analog Devices AD4170 series of Sigma-delta Analog to Digital Converters.
+  Specifications can be found at:
+    https://www.analog.com/media/en/technical-documentation/data-sheets/ad4170-4.pdf
+    https://www.analog.com/media/en/technical-documentation/data-sheets/ad4190-4.pdf
+    https://www.analog.com/media/en/technical-documentation/data-sheets/ad4195-4.pdf
+
+$ref: /schemas/spi/spi-peripheral-props.yaml#
+
+$defs:
+  ad4170-channel:
+    type: object
+    $ref: /schemas/iio/adc/adc.yaml#
+    description:
+      Common properties for configuring AD4170 channels.
+
+    properties:
+      adi,reference-select:
+        description: |

Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml new file +17 -0

+    description:
+      The AD4170 and similar designs have features to aid interfacing with weigh
+      scale, RTD, and thermocouple sensors. Each of those sensor types requires
+      either distinct wiring configuration or external circuitry for proper
+      sensor operation and can use different AD4170 functionality on their
+      setups. A key characteristic of those external sensors is that they must
+      be excited either by voltage supply or by AD4170 excitation signals. The
+      sensor can then be read through a pair of analog inputs. These properties
+      describe external sensor circuitry connected to the ADC.
+
+    properties:
+      reg:
+        description:
+          Channel number. Connects the sensor to the channel with this number
+          of the device.
+        minimum: 1
+        maximum: 16

Quoted 1 line

+patternProperties:

Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml new file +35 -0

+  "^channel@[0-9a-f]$":
+    $ref: '#/$defs/ad4170-channel'
+    unevaluatedProperties: false
+    description:
+      Represents the external channels which are connected to the ADC.
+
+    properties:
+      reg:
+        description:
+          The channel number.
+        minimum: 0
+        maximum: 15
+
+      diff-channels:
+        description: |
+          This property is used for defining the inputs of a differential
+          voltage channel. The first value is the positive input and the second
+          value is the negative input of the channel.
+
+          Besides the analog input pins AIN0 to AIN8, there are special inputs
+          that can be selected with the following values:
+          17: Internal temperature sensor
+          18: (AVDD-AVSS)/5
+          19: (IOVDD-DGND)/5
+          20: DAC output
+          21: ALDO
+          22: DLDO
+          23: AVSS
+          24: DGND
+          25: REFIN+
+          26: REFIN-
+          27: REFIN2+
+          28: REFIN2-
+          29: REFOUT
+          For the internal temperature sensor, use the input number for both

Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml new file +9 -0

+
+      adi,buffered-positive:
+        description: |
+          Enable precharge buffer, full buffer, or skip reference buffering of
+          the positive voltage reference. Because the output impedance of the
+          source driving the voltage reference inputs may be dynamic, RC
+          combinations of those inputs can cause DC gain errors if the reference
+          inputs go unbuffered into the ADC. Enable reference buffering if the
+          provided reference source has dynamic high impedance output. Note the

Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml line 43

Quoted 4 lines

Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml new file +3 -0

+  sensor-node:
+    type: object
+    $ref: '#/$defs/ad4170-channel'

I do not understand this binding. channel@ node is a channel and sensors like rtd@ is also channel but also sensor. What is the point of channel@ which is not a sensor?

...

Quoted 9 lines

Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml line 43

Quoted 4 lines

Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml new file +3 -0

+  sensor-node:
+    type: object
+    $ref: '#/$defs/ad4170-channel'  

I do not understand this binding. channel@ node is a channel and sensors like rtd@ is also channel but also sensor. What is the point of channel@ which is not a sensor?

The sensor node is meant to describe a channel that has extra setup configuration. For example, a common ADC channel could look like this

-------- +VREF ------ +-------------------+

    ´ `       ´ `              /                    |
  /     \   /     \   /   --- <  IN+                |
         `-´       `-´         |                    |
  -------- -VREF ------        |                    |
                               |            ADC     |
  -------- +VREF ------        |                    |
        ´ `       ´ `          |                    |
  \   /     \   /     \   --- <  IN-                |
   `-´       `-´               \       +VREF  -VREF |

-------- -VREF ------ +-------------------+
^ ^
| +---- External -VREF
External +VREF

The the channel@ node for that would look like

    adc@0 {
        ...
        channel@0 {
            reg = <0>;
            bipolar;
            diff-channels = <0 1>;
        };
    };

Though, some sigma-delta ADCs (including AD4170) are fancy and have features that relate to what is connected to the ADC inputs. For example, an RTD would be connected like

                                     External +VREF
                                          |
       +----------------------------------|-------+---- External -VREF
       |           +----------------------+       |
       +---Rref----+                +-----v-------v----+
       |           |               /    REFIN+  REFIN- |
   +---+-----------|------------> <  IN+               |
   |               |              |                    |
3-wire RTD         |              |            ADC     |
   |               |              |                    |
   +--------------------+-------> <  IN-               |
   |               |    |          \      GPIO2 GPIO3  |
   v               |    |           +-------v-----v----+
  GND              |    +-------------------+     |
                   |       <--- IOUT1             |
                   +------------------------------+
                           <--- IOUT0

A better drawing can be found in AD4170 datasheet Figure 115. 3-Wire RTD Application.
https://www.analog.com/media/en/technical-documentation/data-sheets/ad4170-4.pdf#unique_151_Connect_42_ID10430

Since the RTD sensor requires additional hardware connections, the proposed dt-binding describes those differently, e.g.

    adc@0 {
        ...
        rtd@0 {
            reg = <0>;
            bipolar;
            diff-channels = <0 1>;
            adi,sensor-type = /bits/ 8 <1>;
            adi,reference-select = <0>;
            adi,excitation-pins = <19 20>;
            adi,excitation-current-microamp = <500>;
        };

That allows the ADC chip to be configured to provide the excitation signals to properly handle the RTD sensor. Because the hardware connections and operation requirements vary among those external sensor types (RTDs, thermocouples, load cell weigh scales), some properties are only applicable to specific sensor types. Also, because those are extra connections, the related properties are not meaningful to typical ADC channels.

Though, the supported features are not different from those described in Documentation/devicetree/bindings/iio/adc/adi,ad4130.yaml.
In that binding, the properties related to external sensor support are set on the device node (not related to any channel). The binding proposed on AD4170 RFC patch was more similar to adi,ad4130.yaml and somehow avoiding to introduce custom/new properties, but that lead to a lot of duplication.

The currently proposed dt-binding for ad4170 avoids repetition and, to some degree, tries to provide better description of connected bridge sensors and their related properties as that seemed to be one of Jonathan's suggestions to the RFC version.
https://lore.kernel.org/linux-iio/20241219140353.787ffccc@jic23-huawei/

Even though I'm naturally biased in favor of my own code, I see this is fairly different from bindings describing the exact same features and that can lead to confusion. I'll use the same types for properties that describe the same things/features. Would it also be preferred to drop the defs and just have channel nodes?

Thanks,
Marcelo

Add device tree documentation for AD4170 and similar sigma-delta ADCs. The AD4170 is a 24-bit, multichannel, sigma-delta ADC.

Signed-off-by Marcelo Schmitt <[email protected]>

---
Change log v2 -> v3

[device tree changes]
- Removed unneeded allOf.
- Removed occurences of adi,sensor-type type re-declaration.
- Created type for the AD4170 channels, allowing to avoid dt doc repetition.

 .../bindings/iio/adc/adi,ad4170.yaml          | 544 ++++++++++++++++++
 MAINTAINERS                                   |   7 +
 2 files changed, 551 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml

Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml new file +1 -0

new file mode 100644
index 000000000000..0a06258b6631
@@ -0,0 +1,544 @@
 
+  sensor-node:

Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml new file +8 -0

+    required:
+      - reg
+      - diff-channels
+      - bipolar
+      - adi,sensor-type
+      - adi,reference-select
+
+

Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml new file +9 -0

+
+  interrupt-names:
+    description:
+      Specify which pin should be configured as Data Ready interrupt.
+    enum:
+      - sdo
+      - dig_aux1
+    default: sdo
+

Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml line 82

Quoted 12 lines

Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml new file +12 -0

+      adi,sensor-type:
+        description: |
+          Type of sensor connected to the device. Depending on the sensor type
+          (weigh scale, RTD, or thermocouple) the values of sensor-node
+          properties have slightly different constraints. This property
+          specifies which particular external sensor is connected to the ADC so
+          the sensor-node properties can be properly parsed and verified. The
+          possible sensor types are:
+          0: weigh scale;
+          1: RTD;
+          2: thermocouple.
+        $ref: /schemas/types.yaml#/definitions/uint8

I think this should be an enum of strings. That will give us a clean way to extend it for other sensor types in future.

Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml line 180

Quoted 3 lines

Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml new file +3 -0

+
+  interrupts:
+    maxItems: 1

What if they are both wired? At that point shouldn't software make up it's mind which to use?

Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml line 189

Quoted 9 lines

Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml new file +9 -0

+
+  interrupt-names:
+    description:
+      Specify which pin should be configured as Data Ready interrupt.
+    enum:
+      - sdo
+      - dig_aux1
+    default: sdo
+

Hi Jonathan,

I'm still working on the changes suggested for this set.
Just to mention, I've updated the dt-binding to declare only channel nodes under the ADC node.

...

Quoted 13 lines

Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml line 82

Quoted 12 lines

Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml new file +12 -0

+      adi,sensor-type:
+        description: |
+          Type of sensor connected to the device. Depending on the sensor type
+          (weigh scale, RTD, or thermocouple) the values of sensor-node
+          properties have slightly different constraints. This property
+          specifies which particular external sensor is connected to the ADC so
+          the sensor-node properties can be properly parsed and verified. The
+          possible sensor types are:
+          0: weigh scale;
+          1: RTD;
+          2: thermocouple.
+        $ref: /schemas/types.yaml#/definitions/uint8  

Quoted 2 lines

I think this should be an enum of strings. That will give us a clean way to extend it for other sensor types in future.

Ack

...

Quoted 6 lines

Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml line 180

Quoted 3 lines

Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml new file +3 -0

+
+  interrupts:
+    maxItems: 1  

What if they are both wired? At that point shouldn't software make up it's mind which to use?

Not sure I understand the concern here. Is 'interrupt-names' property expected to precede 'interrupts' in dt-doc? For AD4170 and similar parts, the data ready signal (/RDY) is by default provided on the SDO line after the completion of a conversion. Alternatively, it can be provided on the DIG_AUX1 pin in which case the chip disables the RDY function on SDO. So, there can only be one data ready interrupt enabled at a time. Guess I'll add some description to make clear only one interrupt can be enabled.

Quoted 10 lines

Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml line 189

Quoted 10 lines

Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml new file +9 -0

+
+  interrupt-names:
+    description:
+      Specify which pin should be configured as Data Ready interrupt.
+    enum:
+      - sdo
+      - dig_aux1
+    default: sdo
+  

Thanks,
Marcelo

From: Ana-Maria Cusco <[email protected]>

The AD4170 is a multichannel, low noise, 24-bit precision sigma-delta analog to digital converter. The AD4170 design offers a flexible data aquisition solution with crosspoint multiplexed analog inputs, configurable ADC voltage reference inputs, ultra-low noise integrated PGA, digital filtering, wide range of configurable output data rates, internal oscillator and temperature sensor, four GPIOs, and integrated features for interfacing with load cell weigh scales, RTD, and thermocouple sensors.

Add basic support for the AD4170 ADC with the following features:
- Single-shot read.
- Analog front end PGA configuration.
- Differential and pseudo-differential input configuration.

Signed-off-by Ana-Maria Cusco <[email protected]>

Co-developed-by Marcelo Schmitt <[email protected]>

Signed-off-by Marcelo Schmitt <[email protected]>

drivers/iio/adc/ad4170.c new file +46 -0

new file mode 100644
index 000000000000..bf19b31095ee
 
+
+/*
+ * Verifies whether the channel configuration is valid by checking the provided
+ * input type, polarity, and voltage references result in a sane input range.
+ * Returns negative error code on failure.
+ */
+static int ad4170_get_input_range(struct ad4170_state *st,
+				  struct iio_chan_spec const *chan,
+				  unsigned int ch_reg, unsigned int ref_sel)
+{
+	bool bipolar = chan->scan_type.sign == 's';
+	struct device *dev = &st->spi->dev;
+	int refp, refn, ain_voltage, ret;
+
+	switch (ref_sel) {
+	case AD4170_REF_REFIN1:
+		if (st->vrefs_uv[AD4170_REFIN1P_SUP] == -ENODEV ||
+		    st->vrefs_uv[AD4170_REFIN1N_SUP] == -ENODEV)
+			return dev_err_probe(dev, -ENODEV,
+					     "REFIN± selected but not provided\n");
+
+		refp = st->vrefs_uv[AD4170_REFIN1P_SUP];
+		refn = st->vrefs_uv[AD4170_REFIN1N_SUP];
+		break;
+	case AD4170_REF_REFIN2:
+		if (st->vrefs_uv[AD4170_REFIN2P_SUP] == -ENODEV ||
+		    st->vrefs_uv[AD4170_REFIN2N_SUP] == -ENODEV)
+			return dev_err_probe(dev, -ENODEV,
+					     "REFIN2± selected but not provided\n");
+
+		refp = st->vrefs_uv[AD4170_REFIN2P_SUP];
+		refn = st->vrefs_uv[AD4170_REFIN2N_SUP];
+		break;
+	case AD4170_REF_AVDD:
+		refp = st->vrefs_uv[AD4170_AVDD_SUP];
+		refn = st->vrefs_uv[AD4170_AVSS_SUP];
+		break;
+	case AD4170_REF_REFOUT:
+		/* REFOUT is 2.5 V relative to AVSS */
+		refp = st->vrefs_uv[AD4170_AVSS_SUP] + AD4170_INT_REF_2_5V;
+		refn = st->vrefs_uv[AD4170_AVSS_SUP];
+		break;
+	default:
+		return -EINVAL;
+	}
+

drivers/iio/adc/ad4170.c new file +12 -0

+					     "Channel %u differential unipolar\n",
+					     ch_reg);
+
+		/*
+		 * Differential bipolar channel.
+		 * avss-supply is never above 0V.
+		 * Assuming refin1n-supply not above 0V.
+		 * Assuming refin2n-supply not above 0V.
+		 */
+		return refp + abs(refn);
+	}
+	/*

drivers/iio/adc/ad4170.c new file +6 -0

+				     "REF+ <= GND for pseudo-diff chan %u\n",
+				     ch_reg);
+
+	if (bipolar)
+		return refp;
+

drivers/iio/adc/ad4170.c new file +5 -0

+				     "Negative input >= REF+ for pseudo-diff chan %u\n",
+				     ch_reg);
+
+	return refp - ain_voltage;
+}
 
 

drivers/iio/adc/ad4170.c new file +15 -0

+	ret = fwnode_property_read_u8(child, "adi,reference-select", &aux);
+	if (!ret) {
+		if (aux > AD4170_REF_AVDD)
+			return dev_err_probe(dev, -EINVAL,
+					     "Invalid reference selected %u\n",
+					     aux);
+	}
+	setup->afe |= FIELD_PREP(AD4170_AFE_REF_SELECT_MSK, aux);
+
+	return 0;
+}
+
+static int ad4170_parse_adc_channel_type(struct device *dev,
+					 struct fwnode_handle *child,
+					 struct iio_chan_spec *chan)

drivers/iio/adc/ad4170.c new file +19 -0

+	if (!ret) {
+		chan->differential = false;
+		chan->channel = pins[0];
+		chan->channel2 = pins[1];
+		return 0;
+	}
+
+	/* Parse differential channel configuration */
+	ret = fwnode_property_read_u32_array(child, "diff-channels", pins,
+					     ARRAY_SIZE(pins));
+	if (!ret) {
+		chan->differential = true;
+		chan->channel = pins[0];
+		chan->channel2 = pins[1];
+		return 0;
+	}
+	return dev_err_probe(dev, ret,
+		"Channel must define one of diff-channels or single-channel.\n");
+}

drivers/iio/adc/ad4170.c new file +8 -0

+				       &ad4170_irq_handler, IRQF_ONESHOT,
+				       indio_dev->name, indio_dev);
+		if (ret)
+			return ret;
+	}
+
+	return devm_iio_device_register(dev, indio_dev);
+}

From: Ana-Maria Cusco <[email protected]>

The AD4170 is a multichannel, low noise, 24-bit precision sigma-delta analog to digital converter. The AD4170 design offers a flexible data aquisition solution with crosspoint multiplexed analog inputs, configurable ADC voltage reference inputs, ultra-low noise integrated PGA, digital filtering, wide range of configurable output data rates, internal oscillator and temperature sensor, four GPIOs, and integrated features for interfacing with load cell weigh scales, RTD, and thermocouple sensors.

Add basic support for the AD4170 ADC with the following features:
- Single-shot read.
- Analog front end PGA configuration.
- Differential and pseudo-differential input configuration.

Signed-off-by Ana-Maria Cusco <[email protected]>

Co-developed-by Marcelo Schmitt <[email protected]>

Signed-off-by Marcelo Schmitt <[email protected]>

---

Change log v2 -> v3
- Updated Copyright year.
- Separated handling of channel setup cases for better understanding of code flow.
- Now comparing setups field by field instead of using memcmp().
- Disable channel on ad4170_read_sample() error path.
- Reinit completion before entering single conversion mode.
- Organized ad4170_sinc3_filt_fs_tbl.
- Used clamp to simplify configuration value checking.
- Returned earlier whenever possible.
- Used HZ_PER_KHZ/MHZ.
- Declared internal voltage reference constant AD4170_INT_REF_2_5V
- Many other minor code style and readability improvements.

 MAINTAINERS              |    1 +
 drivers/iio/adc/Kconfig  |   12 +
 drivers/iio/adc/Makefile |    1 +
 drivers/iio/adc/ad4170.c | 1553 ++++++++++++++++++++++++++++++++++++++

 4 files changed, 1567 insertions(+)

 create mode 100644 drivers/iio/adc/ad4170.c

MAINTAINERS +0 -0

index 0a8f2c7a139c..541e37ed304e 100644
@@ -1352,6 +1352,7 @@ L:	[email protected]

 S: Supported
 W: https://ez.analog.com/linux-software-drivers
 F: Documentation/devicetree/bindings/iio/adc/adi,ad4170.yaml
+F: drivers/iio/adc/ad4170.c

 ANALOG DEVICES INC AD4695 DRIVER
 M: Michael Hennerich <[email protected]>

drivers/iio/adc/Kconfig +0 -0

index 0fe6601e59ed..594b9f55ec0a 100644
@@ -70,6 +70,18 @@ config AD4130

    To compile this driver as a module, choose M here: the module will be
    called ad4130.

drivers/iio/adc/Kconfig +10 -0

+
+config AD4170
+	tristate "Analog Device AD4170 ADC Driver"
+	depends on SPI
+	select REGMAP_SPI
+	help
+	  Say yes here to build support for Analog Devices AD4170 SPI analog
+	  to digital converters (ADC).
+
+	  To compile this driver as a module, choose M here: the module will

be

drivers/iio/adc/Kconfig +2 -0

+	  called ad4170.
+

 config AD4695
  tristate "Analog Device AD4695 ADC Driver" depends on SPI

drivers/iio/adc/Makefile +0 -0

index 07d4b832c42e..d3a1376d1f96 100644
@@ -11,6 +11,7 @@ obj-$(CONFIG_AD_SIGMA_DELTA) += ad_sigma_delta.o

 obj-$(CONFIG_AD4000) += ad4000.o
 obj-$(CONFIG_AD4030) += ad4030.o
 obj-$(CONFIG_AD4130) += ad4130.o
+obj-$(CONFIG_AD4170) += ad4170.o
 obj-$(CONFIG_AD4695) += ad4695.o
 obj-$(CONFIG_AD4851) += ad4851.o
 obj-$(CONFIG_AD7091R) += ad7091r-base.o

drivers/iio/adc/ad4170.c new file +26 -0

new file mode 100644
index 000000000000..bf19b31095ee
@@ -0,0 +1,1553 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2025 Analog Devices, Inc.
+ * Author: Ana-Maria Cusco <[email protected]>
+ * Author: Marcelo Schmitt <[email protected]>
+ */
+
+#include <linux/bitfield.h>
+#include <linux/bitmap.h>
+#include <linux/bitops.h>
+#include <linux/bits.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/iio/iio.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/math64.h>
+#include <linux/module.h>
+#include <linux/property.h>
+#include <linux/regmap.h>
+#include <linux/regulator/consumer.h>
+#include <linux/spi/spi.h>
+#include <linux/unaligned.h>
+#include <linux/units.h>
+#include <linux/util_macros.h>

drivers/iio/adc/ad4170.c new file +11 -0

+
+/*
+ * Sets the ADC operating mode. Supported modes are
+ * - Single conversion mode
+ * - Idle mode
+ */
+static int ad4170_set_mode(struct ad4170_state *st, unsigned int mode)
+{
+	return regmap_update_bits(st->regmap, AD4170_ADC_CTRL_REG,
+				  AD4170_ADC_CTRL_MODE_MSK,
+				  FIELD_PREP(AD4170_ADC_CTRL_MODE_MSK,

mode));
+}

Add support for ADC calibration gain configuration.

Signed-off-by Marcelo Schmitt <[email protected]>

---
Change log v2 -> v3
- New patch spun out of the base driver patch.

 drivers/iio/adc/ad4170.c | 29 ++++++++++++++++++++++++++++-

 1 file changed, 28 insertions(+), 1 deletion(-)

drivers/iio/adc/ad4170.c +0 -0

index bf19b31095ee..1df214f7fdec 100644
@@ -642,7 +642,8 @@ static const struct iio_chan_spec ad4170_channel_template
 = {
  	.differential = 1,

  .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE) |

drivers/iio/adc/ad4170.c +2 -1

-			      BIT(IIO_CHAN_INFO_OFFSET),
+			      BIT(IIO_CHAN_INFO_OFFSET) |
+			      BIT(IIO_CHAN_INFO_CALIBSCALE),

  .info_mask_separate_available = BIT(IIO_CHAN_INFO_SCALE), .scan_type = {
  .realbits = 24,

Add support for ADC calibration bias/offset configuration.

Signed-off-by Marcelo Schmitt <[email protected]>

---
Change log v2 -> v3
- New patch spun out of the base driver patch.

 drivers/iio/adc/ad4170.c | 26 ++++++++++++++++++++++++++

 1 file changed, 26 insertions(+)

drivers/iio/adc/ad4170.c +0 -0

index 1df214f7fdec..b02fdd25b4c8 100644
@@ -643,6 +643,7 @@ static const struct iio_chan_spec ad4170_channel_template
 = {

  .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_OFFSET) |

drivers/iio/adc/ad4170.c +1 -0

+			      BIT(IIO_CHAN_INFO_CALIBBIAS) |

        BIT(IIO_CHAN_INFO_CALIBSCALE), .info_mask_separate_available = BIT(IIO_CHAN_INFO_SCALE), .scan_type = {

drivers/iio/adc/ad4170.c +1 -0

+		return IIO_VAL_INT;

  case IIO_CHAN_INFO_CALIBSCALE:
  *val = setup->gain;
  return IIO_VAL_INT;

drivers/iio/adc/ad4170.c +0 -0

@@ -1083,6 +1087,25 @@ static int ad4170_set_pga(struct ad4170_state *st,
  	return 0;
  }

drivers/iio/adc/ad4170.c +1 -0

+static int ad4170_set_calib_offset(struct ad4170_state *st,

drivers/iio/adc/ad4170.c +2 -0

+}
+

 static int ad4170_set_calib_gain(struct ad4170_state *st, struct iio_chan_spec const *chan, int val) {

drivers/iio/adc/ad4170.c +0 -0

@@ -1111,6 +1134,8 @@ static int __ad4170_write_raw(struct iio_dev *indio_dev,
  	switch (info) {

  case IIO_CHAN_INFO_SCALE:
  return ad4170_set_pga(st, chan, val, val2);

drivers/iio/adc/ad4170.c +2 -0

+	case IIO_CHAN_INFO_CALIBBIAS:
+		return ad4170_set_calib_offset(st, chan, val);

  case IIO_CHAN_INFO_CALIBSCALE:
  return ad4170_set_calib_gain(st, chan, val); default:

drivers/iio/adc/ad4170.c +0 -0

@@ -1139,6 +1164,7 @@ static int ad4170_write_raw_get_fmt(struct iio_dev
 *indio_dev,
  	switch (info) {

  case IIO_CHAN_INFO_SCALE:
  return IIO_VAL_INT_PLUS_NANO;

drivers/iio/adc/ad4170.c +1 -0

+	case IIO_CHAN_INFO_CALIBBIAS:

  case IIO_CHAN_INFO_CALIBSCALE:
  return IIO_VAL_INT;
  default:

Add support for sinc3, sinc5, and averaged sinc5 digital filters along with sample frequency configuration.

Signed-off-by Marcelo Schmitt <[email protected]>

drivers/iio/adc/ad4170.c +18 -0

+static int ad4170_set_filter_type(struct iio_dev *indio_dev,
+				  struct iio_chan_spec const *chan,
+				  unsigned int val)
+{
+	struct ad4170_state *st = iio_priv(indio_dev);
+	struct ad4170_chan_info *chan_info = &st->chan_infos[chan->address];
+	struct ad4170_setup *setup = &chan_info->setup;
+	unsigned int old_filter_fs, old_filter, filter_type_conf;
+	int ret;
+
+	switch (val) {
+	case AD4170_SINC5_AVG:
+		filter_type_conf = AD4170_FILTER_FILTER_TYPE_SINC5_AVG;
+		break;
+	case AD4170_SINC5:
+		filter_type_conf = AD4170_FILTER_FILTER_TYPE_SINC5;
+		break;
+	case AD4170_SINC3:

drivers/iio/adc/ad4170.c +30 -0

+	/*
+	 * The filters provide the same ODR for a given filter_fs value but
+	 * there are different minimum and maximum filter_fs limits for each
+	 * filter. The filter_fs value will be adjusted if the current filter_fs
+	 * is out of the limits of the just requested filter. Since the
+	 * filter_fs value affects the ODR (sampling_frequency), changing the
+	 * filter may lead to a change in the sampling frequency.
+	 */
+	old_filter = setup->filter;
+	old_filter_fs = setup->filter_fs;
+	if (val == AD4170_SINC5_AVG || val == AD4170_SINC3)
+		setup->filter_fs = clamp(val, AD4170_SINC3_MIN_FS,
+					 AD4170_SINC3_MAX_FS);
+	else
+		setup->filter_fs = clamp(val, AD4170_SINC5_MIN_FS,
+					 AD4170_SINC5_MAX_FS);
+
+	setup->filter &= ~AD4170_FILTER_FILTER_TYPE_MSK;
+	setup->filter |= FIELD_PREP(AD4170_FILTER_FILTER_TYPE_MSK,
+				    filter_type_conf);
+
+	ret = ad4170_write_channel_setup(st, chan->address, false);
+	if (ret) {
+		setup->filter = old_filter;
+		setup->filter_fs = old_filter_fs;
+	}
+
+	iio_device_release_direct(indio_dev);
+	return ret;
+}

Extend the AD4170 driver to allow buffered data capture in continuous read mode. In continuous read mode, the chip skips the instruction phase and outputs just ADC sample data, enabling faster sample rates to be reached. The internal channel sequencer always starts sampling from channel 0 and channel 0 must be enabled if more than one channel is selected for data capture. The scan mask validation callback checks if the aforementioned condition is met.

Signed-off-by Marcelo Schmitt <[email protected]>

drivers/iio/adc/ad4170.c +0 -0

index 218f768042fe..e8856c911dfd 100644
 
 
 enum ad4170_ref_buf {

@@ -309,9 +322,13 @@ struct ad4170_state {
 	struct spi_device *spi;

drivers/iio/adc/ad4170.c +0 -0

 	/*

The AD4170 chip can use an externally supplied clock at the XTAL2 pin, or an external crystal connected to the XTAL1 and XTAL2 pins. Alternatively, the AD4170 can provide its 16 MHz internal clock at the XTAL2 pin. Extend the AD4170 driver so it effectively uses the provided external clock, if any, or supplies its own clock as a clock provider.

Reviewed-by Nuno Sá <[email protected]>

Signed-off-by Marcelo Schmitt <[email protected]>

---

drivers/iio/adc/ad4170.c +1 -0

+	unsigned int clock_ctrl;
 	/*
 	 * DMA (thus cache coherency maintenance) requires the transfer buffers
 	 * to live in their own cache lines.

@@ -1656,6 +1678,120 @@ static int ad4170_parse_channels(struct iio_dev *indio_dev)
 	return 0;
 }
 

drivers/iio/adc/ad4170.c +37 -0

+	return regmap_write(st->regmap, AD4170_CLOCK_CTRL_REG, st->clock_ctrl);
+}
+
+static unsigned long ad4170_clk_recalc_rate(struct clk_hw *hw,
+					    unsigned long parent_rate)
+{
+	return AD4170_INT_CLOCK_16MHZ;
+}
+
+static int ad4170_clk_output_is_enabled(struct clk_hw *hw)
+{
+	struct ad4170_state *st = clk_hw_to_ad4170(hw);
+	u32 clk_sel;
+
+	clk_sel = FIELD_GET(AD4170_CLOCK_CTRL_CLOCKSEL_MSK, st->clock_ctrl);
+	return clk_sel == AD4170_CLOCK_CTRL_CLOCKSEL_INT_OUT;
+}
+
+static int ad4170_clk_output_prepare(struct clk_hw *hw)
+{
+	struct ad4170_state *st = clk_hw_to_ad4170(hw);
+
+	return ad4170_sel_clk(st, AD4170_CLOCK_CTRL_CLOCKSEL_INT_OUT);
+}
+
+static void ad4170_clk_output_unprepare(struct clk_hw *hw)
+{
+	struct ad4170_state *st = clk_hw_to_ad4170(hw);
+
+	ad4170_sel_clk(st, AD4170_CLOCK_CTRL_CLOCKSEL_INT);
+}
+
+static const struct clk_ops ad4170_int_clk_ops = {
+	.recalc_rate = ad4170_clk_recalc_rate,
+	.is_enabled = ad4170_clk_output_is_enabled,
+	.prepare = ad4170_clk_output_prepare,
+	.unprepare = ad4170_clk_output_unprepare,

drivers/iio/adc/ad4170.c +17 -0

+		return 0;
+
+	if (device_property_read_string(dev, "clock-output-names", &init.name)) {
+		init.name = devm_kasprintf(dev, GFP_KERNEL, "%pfw",
+					   dev_fwnode(dev));
+		if (!init.name)
+			return -ENOMEM;
+	}
+
+	init.ops = &ad4170_int_clk_ops;
+
+	st->int_clk_hw.init = &init;
+	ret = devm_clk_hw_register(dev, &st->int_clk_hw);
+	if (ret)
+		return ret;
+
+	return devm_of_clk_add_hw_provider(dev, of_clk_hw_simple_get,

drivers/iio/adc/ad4170.c +23 -0

+		return ad4170_register_clk_provider(indio_dev);
+	}
+
+	/* Use external clock reference */
+	st->ext_clk = devm_clk_get_enabled(dev, ad4170_clk_sel[ret]);
+	if (IS_ERR(st->ext_clk))
+		return dev_err_probe(dev, PTR_ERR(st->ext_clk),
+				     "Failed to get external clock\n");
+
+	st->clock_ctrl |= FIELD_PREP(AD4170_CLOCK_CTRL_CLOCKSEL_MSK,
+				     AD4170_CLOCK_CTRL_CLOCKSEL_EXT + ret);
+
+	st->mclk_hz = clk_get_rate(st->ext_clk);
+	if (st->mclk_hz < AD4170_EXT_CLOCK_MHZ_MIN ||
+	    st->mclk_hz > AD4170_EXT_CLOCK_MHZ_MAX) {
+		return dev_err_probe(dev, -EINVAL,
+				     "Invalid external clock frequency %u\n",
+				     st->mclk_hz);
+	}
+
+	return 0;
+}
+
 static int ad4170_parse_firmware(struct iio_dev *indio_dev)
 {
 	struct ad4170_state *st = iio_priv(indio_dev);

@@ -1663,7 +1799,13 @@ static int ad4170_parse_firmware(struct iio_dev *indio_dev)
 	int reg_data, ret;

drivers/iio/adc/ad4170.c +0 -0

 	for (i = 0; i < AD4170_NUM_ANALOG_PINS; i++)
 		st->pins_fn[i] = AD4170_PIN_UNASIGNED;

The AD4170 has four multifunctional pins that can be used as GPIOs. The GPIO functionality can be accessed when the AD4170 chip is not busy performing continuous data capture or handling any other register read/write request. Also, the AD4170 does not provide any interrupt based on GPIO pin states so AD4170 GPIOs can't be used as interrupt sources.

Implement gpio_chip callbacks to make AD4170 GPIO pins controllable through the gpiochip interface.

Signed-off-by Marcelo Schmitt <[email protected]>

---
Change log v2 -> v3
- Defined masks for updating GPIO mode register.
- Replaced regmap_clear/set_bits() by regmap_update_bits() to set GPIO direction.
- Removed GPIO direction check before setting GPIO output values.
- Made use of regmap_assign_bits() to set GPIO output reg bits.
- Made value to be set as GPIO output state be either 0 or 1.
- No longer locking on state mutex on GPIO set since GPIO output should not conflict with other direct mode functionality (e.g. single-shot read).

 drivers/iio/adc/Kconfig  |   1 +
 drivers/iio/adc/ad4170.c | 224 ++++++++++++++++++++++++++++++++++++++-
 2 files changed, 224 insertions(+), 1 deletion(-)

drivers/iio/adc/Kconfig +0 -0

index 6e4b14243599..a328f03eea34 100644