[PATCH v2 1/7] dt-bindings: iio: adc: Add TI ADS126x ADC family

[Kurt Borja <kuurtb@gmail.com>]

The ADS1262 and ADS1263 are 32-bit, 38.4-kSPS delta-sigma ADCs with an
integrated PGA, internal reference, excitation and burn-out current
sources for sensor biasing and diagnostics. The ADS1263 adds a second,
24-bit delta-sigma ADC (ADC2) for background measurements.

Each can configure it's own voltage reference source, the two excitation
current sources (IDAC), plus input and excitation channels rotation for
offset and IDAC mismatch cancellation. This lets the device drive and
ratiometrically measure RTDs and other resistive sensors.

Signed-off-by: Kurt Borja <kuurtb@gmail.com>
---
 .../devicetree/bindings/iio/adc/ti,ads1262.yaml    | 309 +++++++++++++++++++++
 MAINTAINERS                                        |   6 +
 2 files changed, 315 insertions(+)

diff --git a/Documentation/devicetree/bindings/iio/adc/ti,ads1262.yaml b/Documentation/devicetree/bindings/iio/adc/ti,ads1262.yaml
new file mode 100644
index 0000000000000000..2f4e812ae2af135a
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/adc/ti,ads1262.yaml
@@ -0,0 +1,309 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/adc/ti,ads1262.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: TI ADS1262/ADS1263 analog to digital converter
+
+maintainers:
+  - Kurt Borja <kuurtb@gmail.com>
+
+description: |
+  The ADS1262 and ADS1263 are 38.4-kSPS, delta-sigma (ΔΣ) ADCs with an
+  integrated PGA, reference, and internal fault monitors. The ADS1263 integrates
+  an auxiliary, 24-bit, ΔΣ ADC intended for background measurements.
+
+  Datasheets:
+    - ADS126x: https://www.ti.com/lit/ds/symlink/ads1262.pdf
+
+properties:
+  compatible:
+    oneOf:
+      - const: ti,ads1262
+      - items:
+          - const: ti,ads1263
+          - const: ti,ads1262
+
+  reg:
+    maxItems: 1
+
+  '#address-cells':
+    const: 1
+
+  '#size-cells':
+    const: 0
+
+  spi-max-frequency:
+    maximum: 8000000
+
+  spi-cpha: true
+
+  interrupts:
+    description: Data ready (DRDY) interrupt line.
+    maxItems: 1
+
+  start-gpios:
+    description: Start conversion control.
+    maxItems: 1
+
+  reset-gpios:
+    maxItems: 1
+
+  dvdd-supply:
+    description: Digital power supply.
+
+  avdd-supply:
+    description: Analog power supply.
+
+  refp-supply:
+    description: External positive voltage reference.
+
+  refn-supply:
+    description: External negative voltage reference.
+
+  ti,vbias:
+    $ref: /schemas/types.yaml#/definitions/flag
+    description: Enables the level-shift voltage on the AINCOM pin.
+
+  clocks:
+    maxItems: 1
+
+  '#io-channel-cells':
+    minimum: 1
+    maximum: 2
+
+  '#gpio-cells':
+    const: 2
+
+  gpio-controller: true
+
+patternProperties:
+  "^channel@[0-9]+$":
+    $ref: /schemas/iio/adc/adc.yaml#
+    unevaluatedProperties: false
+
+    properties:
+      reg:
+        maxItems: 1
+
+      diff-channels:
+        description: |
+          Selects the analog input configuration for this channel. The first
+          value is the positive input and the second is the negative input.
+          The following values are available:
+          0: AIN0 pin
+          1: AIN1 pin
+          2: AIN2 pin
+          3: AIN3 pin
+          4: AIN4 pin
+          5: AIN5 pin
+          6: AIN6 pin
+          7: AIN7 pin
+          8: AIN8 pin
+          9: AIN9 pin
+          10: AINCOM pin
+          11: Temperature sensor monitor
+          12: Analog power supply monitor
+          13: Digital power supply monitor
+          14: TDAC test signal
+          15: Float (open connection)
+        items:
+          minimum: 0
+          maximum: 15
+
+      reference-sources:
+        minItems: 2
+        description:
+          Indicates the reference sources for this channel. The first and second
+          items are the positive and negative sources of the main ADC (ADC1).
+          The third item is the reference source of the secondary ADC (ADC2).
+        items:
+          - enum: [internal, ain0, ain2, ain4, avdd]
+          - enum: [internal, ain1, ain3, ain5, avss]
+          - enum: [internal, ain0-ain1, ain2-ain3, ain4-ain5, avdd-avss]
+
+      excitation-channels:
+        $ref: /schemas/types.yaml#/definitions/uint32-array
+        minItems: 2
+        maxItems: 2
+        description: |
+          Selects pins for the IDAC sources from the following options:
+            0: AIN0
+            1: AIN1
+            2: AIN2
+            3: AIN3
+            4: AIN4
+            5: AIN5
+            6: AIN6
+            7: AIN7
+            8: AIN8
+            9: AIN9
+            10: AINCOM
+            11: No Connection
+          The first value corresponds to IDAC1 and the second to IDAC2.
+        items:
+          minimum: 0
+          maximum: 11
+
+      excitation-current-nanoamp:
+        minItems: 2
+        maxItems: 2
+        description:
+          The first value corresponds to IDAC1 and the second to IDAC2.
+        items:
+          enum: [0, 50000, 100000, 250000, 500000, 750000, 1000000, 1500000,
+                 2000000, 2500000, 3000000]
+
+      burn-out-current-nanoamp:
+        description:
+          The ADC incorporates a sensor bias current source that can be used to
+          apply a small test current to diagnose broken sensor leads or problems
+          existing in the sensor.
+        enum: [0, 500, 2000, 10000, 50000, 200000]
+
+      ti,burn-out-resistor:
+        $ref: /schemas/types.yaml#/definitions/flag
+        description: |
+          Instead of a fixed current, the sensor bias (burn-out) current source
+          can be pulled using an internal 10 MΩ resistor.
+
+      ti,burn-out-polarity:
+        $ref: /schemas/types.yaml#/definitions/string
+        description:
+          The sensor bias can be configured to either pull-up or pull-down mode.
+          In pull-up mode, the current flows into the positive input and flows
+          out of the negative input. In pull-down mode, the polarities are
+          reversed.
+        enum: [pull-up, pull-down]
+
+      input-chopping:
+        $ref: /schemas/types.yaml#/definitions/flag
+        description:
+          When enabled, the ADC performs two internal conversions to cancel the
+          input offset voltage. The first conversion is taken with normal input
+          polarity. The ADC reverses the internal input polarity for the second
+          conversion. The difference of the two conversions is computed to yield
+          the final corrected result with the offset voltage removed.
+
+      ti,idac-chopping:
+        $ref: /schemas/types.yaml#/definitions/flag
+        description:
+          Automatically swap the IDAC1 and IDAC2 connections of alternate
+          conversions. The ADC averages the alternate conversions to eliminate
+          IDAC mismatch.
+
+      ti,pga-bypass:
+        $ref: /schemas/types.yaml#/definitions/flag
+        description: Bypass the Programmable Gain Amplifier (PGA).
+
+    dependencies:
+      excitation-channels: [excitation-current-nanoamp]
+      excitation-current-nanoamp: [excitation-channels]
+      burn-out-current-nanoamp:
+        not:
+          required:
+            - ti,burn-out-resistor
+
+    required:
+      - reg
+
+dependencies:
+  refn-supply: [refp-supply]
+
+required:
+  - compatible
+  - reg
+  - avdd-supply
+  - dvdd-supply
+  - '#address-cells'
+  - '#size-cells'
+
+allOf:
+  - $ref: /schemas/spi/spi-peripheral-props.yaml#
+  - if:
+      properties:
+        compatible:
+          contains:
+            const: ti,ads1263
+    then:
+      properties:
+        '#io-channel-cells':
+          const: 2
+      patternProperties:
+        "^channel@[0-9]+$":
+          properties:
+            reference-sources:
+              minItems: 3
+    else:
+      properties:
+        '#io-channel-cells':
+          const: 1
+      patternProperties:
+        "^channel@[0-9]+$":
+          properties:
+            reference-sources:
+              maxItems: 2
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+    #include <dt-bindings/interrupt-controller/irq.h>
+
+    spi {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        adc@0 {
+            compatible = "ti,ads1262";
+            reg = <0>;
+            spi-max-frequency = <8000000>;
+            spi-cpha;
+            avdd-supply = <&avdd>;
+            dvdd-supply = <&dvdd>;
+            #address-cells = <1>;
+            #size-cells = <0>;
+
+            reset-gpios = <&gpio 18 GPIO_ACTIVE_LOW>;
+            interrupts-extended = <&gpio 10 IRQ_TYPE_EDGE_FALLING>;
+
+            channel@0 {
+                reg = <0>;
+                diff-channels = <0x0 0xA>;
+            };
+        };
+    };
+
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+    #include <dt-bindings/interrupt-controller/irq.h>
+
+    spi {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        adc@0 {
+            compatible = "ti,ads1263", "ti,ads1262";
+            reg = <0>;
+            spi-max-frequency = <8000000>;
+            spi-cpha;
+            avdd-supply = <&avdd>;
+            dvdd-supply = <&dvdd>;
+            refp-supply = <&refp>;
+            #address-cells = <1>;
+            #size-cells = <0>;
+
+            reset-gpios = <&gpio 18 GPIO_ACTIVE_LOW>;
+            interrupts-extended = <&gpio 10 IRQ_TYPE_EDGE_FALLING>;
+
+            channel@0 {
+                reg = <0>;
+                diff-channels = <0x4 0x5>;
+                reference-sources = "ain2", "ain3", "ain2-ain3";
+                excitation-channels = <0x1 0x6>;
+                excitation-current-nanoamp = <500000 500000>;
+            };
+        };
+    };
diff --git a/MAINTAINERS b/MAINTAINERS
index 6c0471487974f145..9b83d294734b574d 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -26923,6 +26923,12 @@ S:	Maintained
 F:	Documentation/devicetree/bindings/iio/adc/ti,ads1018.yaml
 F:	drivers/iio/adc/ti-ads1018.c
 
+TI ADS1262 ADC DRIVER
+M:	Kurt Borja <kuurtb@gmail.com>
+L:	linux-iio@vger.kernel.org
+S:	Maintained
+F:	Documentation/devicetree/bindings/iio/adc/ti,ads1262.yaml
+
 TI ADS7924 ADC DRIVER
 M:	Hugo Villeneuve <hvilleneuve@dimonoff.com>
 L:	linux-iio@vger.kernel.org

-- 
2.54.0