dt-bindings: iio: adc: add AD4691 family

Add DT bindings for the Analog Devices AD4691 family of multichannel
SAR ADCs (AD4691, AD4692, AD4693, AD4694).

The four variants are not compatible with each other: AD4691/AD4692 have
16 analog input channels while AD4693/AD4694 have 8, and AD4691/AD4693
top out at 500 kSPS while AD4692/AD4694 reach 1 MSPS. These differences
in channel count and maximum sample rate require distinct compatible
strings so the driver can select the correct channel configuration and
rate limits.

Acked-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Radu Sabau <radu.sabau@analog.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

Documentation/devicetree/bindings/iio/adc/adi,ad4691.yaml

@@ -0,0 +1,180 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/adc/adi,ad4691.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Analog Devices AD4691 Family Multichannel SAR ADCs
+
+maintainers:
+  - Radu Sabau <radu.sabau@analog.com>
+
+description: |
+  The AD4691 family are high-speed, low-power, multichannel successive
+  approximation register (SAR) analog-to-digital converters (ADCs) with
+  an SPI-compatible serial interface. The ADC supports CNV Burst Mode,
+  where an external PWM drives the CNV pin, and Manual Mode, where CNV
+  is directly tied to the SPI chip-select.
+
+  Datasheets:
+    * https://www.analog.com/en/products/ad4691.html
+    * https://www.analog.com/en/products/ad4692.html
+    * https://www.analog.com/en/products/ad4693.html
+    * https://www.analog.com/en/products/ad4694.html
+
+$ref: /schemas/spi/spi-peripheral-props.yaml#
+
+properties:
+  compatible:
+    enum:
+      - adi,ad4691
+      - adi,ad4692
+      - adi,ad4693
+      - adi,ad4694
+
+  reg:
+    maxItems: 1
+
+  spi-max-frequency:
+    maximum: 40000000
+
+  spi-cpol: true
+  spi-cpha: true
+
+  avdd-supply:
+    description: Analog power supply (4.5V to 5.5V).
+
+  vdd-supply:
+    description:
+      External 1.8V digital core supply. When present, the internal LDO is
+      disabled (LDO_EN = 0). Mutually exclusive with ldo-in-supply.
+
+  ldo-in-supply:
+    description:
+      LDO input supply (2.4V to 5.5V). When present and vdd-supply is absent,
+      the internal LDO generates 1.8V VDD from this input (LDO_EN = 1).
+      Mutually exclusive with vdd-supply.
+
+  vio-supply:
+    description: I/O voltage supply (1.71V to 1.89V or VDD).
+
+  ref-supply:
+    description: External reference voltage supply (2.4V to 5.25V).
+
+  refin-supply:
+    description: Internal reference buffer input supply.
+
+  reset-gpios:
+    description:
+      GPIO line controlling the hardware reset pin (active-low).
+    maxItems: 1
+
+  pwms:
+    description:
+      PWM connected to the CNV pin. When present, selects CNV Burst Mode where
+      the PWM drives the conversion rate. When absent, Manual Mode is used
+      (CNV tied to SPI CS).
+    maxItems: 1
+
+  interrupts:
+    description:
+      Interrupt lines connected to the ADC GP pins. Each GP pin can be
+      physically wired to an interrupt-capable input on the SoC.
+    maxItems: 4
+
+  interrupt-names:
+    description: Names of the interrupt lines, matching the GP pin names.
+    minItems: 1
+    maxItems: 4
+    items:
+      enum:
+        - gp0
+        - gp1
+        - gp2
+        - gp3
+
+  gpio-controller: true
+
+  '#gpio-cells':
+    const: 2
+
+  '#trigger-source-cells':
+    description:
+      This node can act as a trigger source. The single cell in a consumer
+      reference specifies the GP pin number (0-3) used as the trigger output.
+    const: 1
+
+required:
+  - compatible
+  - reg
+  - avdd-supply
+  - vio-supply
+
+allOf:
+  # vdd-supply and ldo-in-supply are mutually exclusive, one is required:
+  # either an external 1.8V VDD is provided or the internal LDO is fed from
+  # ldo-in-supply to generate VDD.
+  - oneOf:
+      - required:
+          - vdd-supply
+      - required:
+          - ldo-in-supply
+  # ref-supply and refin-supply are mutually exclusive, one is required
+  - oneOf:
+      - required:
+          - ref-supply
+      - required:
+          - refin-supply
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+    /* AD4692 in CNV Burst Mode with SPI offload */
+    spi {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        adc@0 {
+            compatible = "adi,ad4692";
+            reg = <0>;
+            spi-cpol;
+            spi-cpha;
+            spi-max-frequency = <40000000>;
+
+            avdd-supply = <&avdd_supply>;
+            ldo-in-supply = <&avdd_supply>;
+            vio-supply = <&vio_supply>;
+            ref-supply = <&ref_5v>;
+
+            reset-gpios = <&gpio0 15 GPIO_ACTIVE_LOW>;
+
+            pwms = <&pwm_gen 0 0>;
+
+            #trigger-source-cells = <1>;
+        };
+    };
+
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+    /* AD4692 in Manual Mode (CNV tied to SPI CS) */
+    spi {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        adc@0 {
+            compatible = "adi,ad4692";
+            reg = <0>;
+            spi-cpol;
+            spi-cpha;
+            spi-max-frequency = <31250000>;
+
+            avdd-supply = <&avdd_supply>;
+            ldo-in-supply = <&avdd_supply>;
+            vio-supply = <&vio_supply>;
+            refin-supply = <&refin_supply>;
+
+            reset-gpios = <&gpio0 15 GPIO_ACTIVE_LOW>;
+        };
+    };

MAINTAINERS

@@ -1476,6 +1476,13 @@ W:	https://ez.analog.com/linux-software-drivers
 F:	Documentation/devicetree/bindings/iio/adc/adi,ad4170-4.yaml
 F:	drivers/iio/adc/ad4170-4.c
 
+ANALOG DEVICES INC AD4691 DRIVER
+M:	Radu Sabau <radu.sabau@analog.com>
+L:	linux-iio@vger.kernel.org
+S:	Supported
+W:	https://ez.analog.com/linux-software-drivers
+F:	Documentation/devicetree/bindings/iio/adc/adi,ad4691.yaml
+
 ANALOG DEVICES INC AD4695 DRIVER
 M:	Michael Hennerich <michael.hennerich@analog.com>
 M:	Nuno Sá <nuno.sa@analog.com>