[PATCH 0/6] iio: adc: Add AD7768/AD7768-4 ADC driver support

[PATCH 0/6] iio: adc: Add AD7768/AD7768-4 ADC driver support

[Janani Sunil]

Add support for Analog Devices AD7768 and AD7768-4, 24-bit simultaneous
sampling Sigma-Delta ADCs with configurable power and performance modes.

Datasheet:
https://www.analog.com/media/en/technical-documentation/data-sheets/ad7768.pdf

**Device Overview:**
The AD7768 is an 8-channel, 24-bit simultaneous sampling ADC. The
AD7768-4 is a 4-channel variant. Both support configurable power modes,
programmable decimation filters, and a high-speed serial interface with
1, 2, 4, or 8 data output lines. Per-channel offset, gain, and phase
calibration registers are available.

**Features Implemented:**
- Support for AD7768 (8-channel) and AD7768-4 (4-channel) via device
  match data.
- Configurable power modes (fast, median, low power) with associated
  decimation rate and output data rate tables.
- Per-channel offset, gain, and phase calibration via IIO attributes.
- SPI communication with custom regmap bus for the device's protocol.
- IIO backend integration with adi-axi-adc for high-speed data capture.
- CRC data integrity verification over the serial interface.
- GPIO auxiliary driver to expose the 5 on-chip GPIO pins.

**Patch Summary:**
1. **dt-bindings**: Binding documentation for AD7768 and AD7768-4,
   covering SPI interface, clock, power supplies, reference voltage,
   reset GPIO, serial data lane count, and on-chip GPIO controller.
2. **iio: backend**: Add CRC enable/disable backend operation for data
   integrity verification over the high-speed serial interface.
3. **iio: adi-axi-adc**: Implement the new CRC backend operation.
4. **driver**: Core IIO driver for AD7768/AD7768-4 with regmap, power
   mode, calibration, and IIO backend support. Registers an auxiliary
   device to expose the GPIO functionality.
5. **gpio**: Auxiliary bus GPIO driver for the AD7768's 5 general-purpose
   I/O pins, reusing the parent's regmap and runtime PM.
6. **docs**: Driver documentation.

**Testing:**
The driver was compiled and tested on the EVAL-AD7768FMCZ using a
Zedboard with a mainline kernel.

**Driver Rationale:**
The AD7768/AD7768-4 warrants its own driver due to several
device-specific characteristics:

1. A custom SPI framing protocol: register reads and writes use 16-bit
   frames with embedded read/write bits and register address fields,
   requiring a custom regmap bus implementation rather than the standard
   SPI regmap backend.

2. A coupled power mode / sample rate model: available output data rates
   are not a flat list but depend on the active power mode (fast, median,
   low power), each with its own set of valid decimation rates. This
   relationship must be managed in the driver.

3. Simultaneous sampling across all channels with per-channel calibration
   registers (24-bit offset, gain, and phase) that are laid out
   differently between the 8-channel AD7768 and the 4-channel AD7768-4,
   requiring device-specific register mapping.

4. IIO backend integration for high-speed data capture via adi-axi-adc,
   including CRC data integrity verification over the serial interface.

5. On-chip GPIO: 5 general-purpose I/O pins exposed via an auxiliary bus
   driver, sharing the parent's regmap and runtime PM.

To: Nuno Sá <nuno.sa@analog.com>
To: Michael Hennerich <Michael.Hennerich@analog.com>
To: Jonathan Cameron <jic23@kernel.org>
To: David Lechner <dlechner@baylibre.com>
To: Andy Shevchenko <andy@kernel.org>
To: Rob Herring <robh@kernel.org>
To: Krzysztof Kozlowski <krzk+dt@kernel.org>
To: Conor Dooley <conor+dt@kernel.org>
To: Olivier Moysan <olivier.moysan@foss.st.com>
To: Philipp Zabel <p.zabel@pengutronix.de>
To: Linus Walleij <linusw@kernel.org>
To: Bartosz Golaszewski <brgl@kernel.org>
To: Jonathan Corbet <corbet@lwn.net>
To: Shuah Khan <skhan@linuxfoundation.org>
Cc: linux@analog.com
Cc: linux-iio@vger.kernel.org
Cc: devicetree@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-gpio@vger.kernel.org
Cc: linux-doc@vger.kernel.org
Cc: jananisunil.dev@gmail.com

Signed-off-by: Janani Sunil <janani.sunil@analog.com>
---
Janani Sunil (6):
      dt-bindings: iio: adc: Add AD7768
      iio: backend: Add support for CRC
      iio: adc: adi-axi-adc: Add support for CRC
      iio: adc: Add AD7768 IIO Driver support
      gpio: ad7768: Add AD7768 GPIO auxiliary driver
      Documentation: iio: Add AD7768 Documentation

 .../devicetree/bindings/iio/adc/adi,ad7768.yaml    |  285 +++++
 Documentation/iio/ad7768.rst                       |  207 ++++
 Documentation/iio/index.rst                        |    1 +
 MAINTAINERS                                        |   10 +
 drivers/gpio/Kconfig                               |   10 +
 drivers/gpio/Makefile                              |    1 +
 drivers/gpio/gpio-ad7768.c                         |  208 ++++
 drivers/iio/adc/Kconfig                            |   16 +
 drivers/iio/adc/Makefile                           |    1 +
 drivers/iio/adc/ad7768.c                           | 1291 ++++++++++++++++++++
 drivers/iio/adc/adi-axi-adc.c                      |   20 +
 drivers/iio/industrialio-backend.c                 |   33 +
 include/linux/iio/backend.h                        |    4 +
 13 files changed, 2087 insertions(+)
---
base-commit: b75697ef53e435d894833dad2a8c2fa882cb9b19
change-id: 20260708-ad7768-driver-10cd15296c20

Best regards,
-- 
Janani Sunil <janani.sunil@analog.com>

[PATCH 1/6] dt-bindings: iio: adc: Add AD7768

[Janani Sunil]

Devicetree Bindings for AD7768-4 (4 channel) and AD7768 (8 channel)
simultaneous sampling ADC

Signed-off-by: Janani Sunil <janani.sunil@analog.com>
---
 .../devicetree/bindings/iio/adc/adi,ad7768.yaml    | 285 +++++++++++++++++++++
 MAINTAINERS                                        |   7 +
 2 files changed, 292 insertions(+)

diff --git a/Documentation/devicetree/bindings/iio/adc/adi,ad7768.yaml b/Documentation/devicetree/bindings/iio/adc/adi,ad7768.yaml
new file mode 100644
index 000000000000..b74fe6aef01c
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/adc/adi,ad7768.yaml
@@ -0,0 +1,285 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/adc/adi,ad7768.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Analog Devices AD7768 and AD7768-4 ADC
+
+maintainers:
+  - Janani Sunil <janani.sunil@analog.com>
+
+description: |
+  The AD7768 is a 8-channel, 24-bit simultaneous sampling ADC with configurable
+  power and performance modes. The AD7768-4 is a 4-channel version.
+
+  Datasheet at:
+    https://www.analog.com/media/en/technical-documentation/data-sheets/ad7768.pdf
+
+properties:
+  compatible:
+    enum:
+      - adi,ad7768
+      - adi,ad7768-4
+
+  reg:
+    maxItems: 1
+
+  clocks:
+    maxItems: 1
+    description: Master clock (MCLK)
+
+  avdd-supply:
+    description: Analog power supply AVDD1 (4.5V to 5.5V)
+
+  avss-supply:
+    description: Analog ground/negative supply AVSS (0V to -2.75V)
+
+  dvdd-supply:
+    description: Analog power supply AVDD2 (2.0V to 5.5V)
+
+  iovdd-supply:
+    description: Digital I/O power supply (1.8V or 2.25V to 3.6V)
+
+  vref-supply:
+    description: ADC reference voltage supply
+
+  reset-gpios:
+    maxItems: 1
+    description: GPIO connected to the active-low RESET pin
+
+  gpio-controller: true
+
+  '#gpio-cells':
+    const: 2
+
+  adi,data-lines-number:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    enum: [1, 2, 4, 8]
+    description:
+      Number of data output lines used for serial interface.
+      AD7768 supports 1, 2, or 8 lines. AD7768-4 supports 1 or 4 lines.
+
+  adi,common-mode-output:
+    $ref: /schemas/types.yaml#/definitions/string
+    enum:
+      - avdd-avss-half
+      - 1.65V
+      - 2.5V
+      - 2.14V
+    description:
+      Common mode voltage output selection.
+
+  adi,vcm-power-down:
+    type: boolean
+    description: Power down the common mode output buffer
+
+  adi,power-mode:
+    $ref: /schemas/types.yaml#/definitions/string
+    enum:
+      - low
+      - median
+      - fast
+    description:
+      Power mode selection.
+
+  io-backends:
+    maxItems: 1
+
+  '#address-cells':
+    const: 1
+
+  '#size-cells':
+    const: 0
+
+patternProperties:
+  "^channel@[0-7]$":
+    type: object
+    description: |
+      Represents the external channels which are connected to the device.
+      AD7768 supports channels 0-7, AD7768-4 supports channels 0-3.
+
+    properties:
+      reg:
+        minimum: 0
+        maximum: 7
+        description: The channel number
+
+      adi,ch-mode:
+        $ref: /schemas/types.yaml#/definitions/uint32
+        minimum: 0
+        maximum: 1
+        description: |
+          Channel mode selection. The AD7768 supports two independent
+          configuration profiles (Mode A and Mode B) for filter and
+          decimation settings. Each channel can be assigned to either mode:
+            0 - Channel uses Mode A filter and decimation settings
+            1 - Channel uses Mode B filter and decimation settings
+
+      adi,prebuf-pos-en:
+        type: boolean
+        description: Enable positive input precharge buffer
+
+      adi,prebuf-neg-en:
+        type: boolean
+        description: Enable negative input precharge buffer
+
+      adi,refbuf-pos-en:
+        type: boolean
+        description: Enable positive reference buffer
+
+      adi,refbuf-neg-en:
+        type: boolean
+        description: Enable negative reference buffer
+
+    required:
+      - reg
+      - adi,ch-mode
+
+    additionalProperties: false
+
+required:
+  - compatible
+  - reg
+  - clocks
+  - avdd-supply
+  - avss-supply
+  - dvdd-supply
+  - iovdd-supply
+  - vref-supply
+  - adi,data-lines-number
+  - adi,common-mode-output
+  - io-backends
+
+dependencies:
+  gpio-controller:
+    - '#gpio-cells'
+  '#gpio-cells':
+    - gpio-controller
+
+allOf:
+  - $ref: /schemas/spi/spi-peripheral-props.yaml#
+  - if:
+      properties:
+        compatible:
+          contains:
+            const: adi,ad7768-4
+    then:
+      properties:
+        adi,data-lines-number:
+          enum: [1, 4]
+      patternProperties:
+        "^channel@[0-3]$":
+          properties:
+            reg:
+              maximum: 3
+        "^channel@[4-7]$": false
+    else:
+      properties:
+        adi,data-lines-number:
+          enum: [1, 2, 8]
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+
+    spi {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        adc@0 {
+            compatible = "adi,ad7768";
+            reg = <0>;
+            spi-max-frequency = <1000000>;
+
+            avdd-supply = <&avdd_regulator>;
+            avss-supply = <&avss_regulator>;
+            dvdd-supply = <&dvdd_regulator>;
+            iovdd-supply = <&iovdd_regulator>;
+            vref-supply = <&vref_regulator>;
+            reset-gpios = <&gpio0 86 GPIO_ACTIVE_LOW>;
+
+            clocks = <&ad7768_mclk>;
+
+            adi,data-lines-number = <8>;
+            adi,common-mode-output = "2.5V";
+            adi,vcm-power-down;
+            adi,power-mode = "median";
+            gpio-controller;
+            #gpio-cells = <2>;
+
+            io-backends = <&iio_backend>;
+
+            #address-cells = <1>;
+            #size-cells = <0>;
+
+            channel@0 {
+                reg = <0>;
+                adi,ch-mode = <0>;
+                adi,prebuf-pos-en;
+                adi,refbuf-pos-en;
+            };
+
+            channel@1 {
+                reg = <1>;
+                adi,ch-mode = <1>;
+                adi,prebuf-pos-en;
+                adi,prebuf-neg-en;
+                adi,refbuf-pos-en;
+                adi,refbuf-neg-en;
+            };
+
+            channel@7 {
+                reg = <7>;
+                adi,ch-mode = <1>;
+                adi,prebuf-pos-en;
+                adi,refbuf-pos-en;
+            };
+        };
+    };
+
+  - |
+    spi {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        adc@1 {
+            compatible = "adi,ad7768-4";
+            reg = <1>;
+            spi-max-frequency = <1000000>;
+
+            avdd-supply = <&avdd_regulator>;
+            avss-supply = <&avss_regulator>;
+            dvdd-supply = <&dvdd_regulator>;
+            iovdd-supply = <&iovdd_regulator>;
+            vref-supply = <&vref_regulator>;
+
+            clocks = <&ad7768_mclk>;
+
+            adi,data-lines-number = <4>;
+            adi,common-mode-output = "2.14V";
+            adi,power-mode = "fast";
+
+            io-backends = <&iio_backend>;
+
+            #address-cells = <1>;
+            #size-cells = <0>;
+
+            channel@0 {
+                reg = <0>;
+                adi,ch-mode = <0>;
+                adi,prebuf-pos-en;
+                adi,refbuf-pos-en;
+            };
+
+            channel@3 {
+                reg = <3>;
+                adi,ch-mode = <1>;
+                adi,prebuf-pos-en;
+                adi,refbuf-pos-en;
+            };
+        };
+    };
+...
diff --git a/MAINTAINERS b/MAINTAINERS
index 2b1ec46c5919..d667a0411f28 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1633,6 +1633,13 @@ F:	Documentation/devicetree/bindings/iio/adc/adi,ad7768-1.yaml
 F:	drivers/iio/adc/ad7768-1.c
 F:	include/dt-bindings/iio/adc/adi,ad7768-1.h
 
+ANALOG DEVICES INC AD7768 DRIVER
+M:	Janani Sunil <janani.sunil@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,ad7768.yaml
+
 ANALOG DEVICES INC AD7780 DRIVER
 M:	Michael Hennerich <Michael.Hennerich@analog.com>
 M:	Renato Lui Geh <renatogeh@gmail.com>

-- 
2.43.0

Re: [PATCH 1/6] dt-bindings: iio: adc: Add AD7768

[David Lechner]

On 7/9/26 3:50 AM, Janani Sunil wrote:
> Devicetree Bindings for AD7768-4 (4 channel) and AD7768 (8 channel)
> simultaneous sampling ADC
> 
> Signed-off-by: Janani Sunil <janani.sunil@analog.com>
> ---
>  .../devicetree/bindings/iio/adc/adi,ad7768.yaml    | 285 +++++++++++++++++++++
>  MAINTAINERS                                        |   7 +
>  2 files changed, 292 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/iio/adc/adi,ad7768.yaml b/Documentation/devicetree/bindings/iio/adc/adi,ad7768.yaml
> new file mode 100644
> index 000000000000..b74fe6aef01c
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/adc/adi,ad7768.yaml
> @@ -0,0 +1,285 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/iio/adc/adi,ad7768.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Analog Devices AD7768 and AD7768-4 ADC
> +
> +maintainers:
> +  - Janani Sunil <janani.sunil@analog.com>
> +
> +description: |
> +  The AD7768 is a 8-channel, 24-bit simultaneous sampling ADC with configurable
> +  power and performance modes. The AD7768-4 is a 4-channel version.

Probably worth mentioning that this binding is for SPI mode, not for pin control
mode.

And that the io-backend is for the data output interface, so consumes the DOUTx,
DCLK, DRDY. Maybe also START? And SYNC_{IN,OUT}?

> +
> +  Datasheet at:
> +    https://www.analog.com/media/en/technical-documentation/data-sheets/ad7768.pdf

A link to the example HDL project for the io-backend would be helpful too.

> +
> +properties:
> +  compatible:
> +    enum:
> +      - adi,ad7768
> +      - adi,ad7768-4
> +
> +  reg:
> +    maxItems: 1
> +
> +  clocks:
> +    maxItems: 1
> +    description: Master clock (MCLK)

Could also be XTAL{1,2}.

> +
> +  avdd-supply:
> +    description: Analog power supply AVDD1 (4.5V to 5.5V)
> +
> +  avss-supply:
> +    description: Analog ground/negative supply AVSS (0V to -2.75V)
> +

What about AV{DD,SS}{1,2}{A,B} supplies?

> +  dvdd-supply:
> +    description: Analog power supply AVDD2 (2.0V to 5.5V)
> +
> +  iovdd-supply:
> +    description: Digital I/O power supply (1.8V or 2.25V to 3.6V)
> +
> +  vref-supply:
> +    description: ADC reference voltage supply

There is more that one reference voltage input. so ref1-supply, ref2-supply.

vref is the name of an internal signal, so doesn't make sense here.

> +
> +  reset-gpios:
> +    maxItems: 1
> +    description: GPIO connected to the active-low RESET pin
> +
> +  gpio-controller: true
> +
> +  '#gpio-cells':
> +    const: 2
> +
> +  adi,data-lines-number:
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    enum: [1, 2, 4, 8]
> +    description:
> +      Number of data output lines used for serial interface.

This could be made a bit more clear that this is a secondary data
output interface, not the SPI lines.

> +      AD7768 supports 1, 2, or 8 lines. AD7768-4 supports 1 or 4 lines.
> +
> +  adi,common-mode-output:
> +    $ref: /schemas/types.yaml#/definitions/string
> +    enum:
> +      - avdd-avss-half
> +      - 1.65V
> +      - 2.5V
> +      - 2.14V
> +    description:
> +      Common mode voltage output selection.

Why not using standard regulator provider bindings for this?

> +
> +  adi,vcm-power-down:
> +    type: boolean
> +    description: Power down the common mode output buffer

Is the buffer separate from the output? In that case I would expect
buffer to be in the property name, otherwise this should just be
part of the enum options above (and the default one at that).

> +
> +  adi,power-mode:
> +    $ref: /schemas/types.yaml#/definitions/string
> +    enum:
> +      - low
> +      - median
> +      - fast
> +    description:
> +      Power mode selection.

Unless there are pins that control this, it seems like it should be
left up to the driver to decide how to set this.

In this case, it looks like the power mode also influences sample rate
which is normally something controlled at runtime.

> +
> +  io-backends:
> +    maxItems: 1
> +
> +  '#address-cells':
> +    const: 1
> +
> +  '#size-cells':
> +    const: 0
> +
> +patternProperties:
> +  "^channel@[0-7]$":
> +    type: object
> +    description: |
> +      Represents the external channels which are connected to the device.
> +      AD7768 supports channels 0-7, AD7768-4 supports channels 0-3.
> +
> +    properties:
> +      reg:
> +        minimum: 0
> +        maximum: 7
> +        description: The channel number
> +
> +      adi,ch-mode:
> +        $ref: /schemas/types.yaml#/definitions/uint32
> +        minimum: 0
> +        maximum: 1
> +        description: |
> +          Channel mode selection. The AD7768 supports two independent
> +          configuration profiles (Mode A and Mode B) for filter and
> +          decimation settings. Each channel can be assigned to either mode:
> +            0 - Channel uses Mode A filter and decimation settings
> +            1 - Channel uses Mode B filter and decimation settings

This could probably be handled in the driver. E.g. allow per-channel settings
that just get stored in a data structure. Then when starting a buffered read
check that all enabled channels have at most 2 different groups of settings.
Then do all of the required register config at that time.

> +
> +      adi,prebuf-pos-en:
> +        type: boolean
> +        description: Enable positive input precharge buffer
> +
> +      adi,prebuf-neg-en:
> +        type: boolean
> +        description: Enable negative input precharge buffer
> +
> +      adi,refbuf-pos-en:
> +        type: boolean
> +        description: Enable positive reference buffer
> +
> +      adi,refbuf-neg-en:
> +        type: boolean
> +        description: Enable negative reference buffer
> +
> +    required:
> +      - reg
> +      - adi,ch-mode
> +
> +    additionalProperties: false
> +
> +required:
> +  - compatible
> +  - reg
> +  - clocks
> +  - avdd-supply
> +  - avss-supply
> +  - dvdd-supply
> +  - iovdd-supply
> +  - vref-supply

> +  - adi,data-lines-number

Suggest making the highest number of lines the default instead
of making this property required.


> +  - adi,common-mode-output

Should probably default to disabled, unless it is always used?
Changing it to a regulator provider makes this not relevant.

> +  - io-backends
> +

Re: [PATCH 1/6] dt-bindings: iio: adc: Add AD7768

[Jonathan Cameron]

> > +  adi,common-mode-output:
> > +    $ref: /schemas/types.yaml#/definitions/string
> > +    enum:
> > +      - avdd-avss-half
> > +      - 1.65V
> > +      - 2.5V
> > +      - 2.14V
> > +    description:
> > +      Common mode voltage output selection.  
> 
> Why not using standard regulator provider bindings for this?

Interesting question.  If that was done there would need to be
a consumer which means explicit modelling of any analog circuit.
We do that in a few cases but so far (and yup this is a driver thing
in a dt-binding) I don't think we have any way to consumer data when
a backend is involved.
	
> 
> > +
> > +  adi,vcm-power-down:
> > +    type: boolean
> > +    description: Power down the common mode output buffer  
> 
> Is the buffer separate from the output? In that case I would expect
> buffer to be in the property name, otherwise this should just be
> part of the enum options above (and the default one at that).
> 

Re: [PATCH 1/6] dt-bindings: iio: adc: Add AD7768

[Jonathan Cameron]

> +
> +      adi,prebuf-pos-en:

Spell out precharge and probably enable as well so
adi,prechargebuf-pos-enable


> +        type: boolean
> +        description: Enable positive input precharge buffer
> +
> +      adi,prebuf-neg-en:
> +        type: boolean
> +        description: Enable negative input precharge buffer
> +
> +      adi,refbuf-pos-en:
> +        type: boolean
> +        description: Enable positive reference buffer
> +
> +      adi,refbuf-neg-en:
> +        type: boolean
> +        description: Enable negative reference buffer

[PATCH 2/6] iio: backend: Add support for CRC

[Janani Sunil]

Add a backend operation to enable or disable Cyclic Redundancy Check
processing for data integrity verification. When enabled, the backend
will generate, verify, or process CRC information for data samples
transmitted over the interface, allowing the host to detect corrupted
samples.

Signed-off-by: Janani Sunil <janani.sunil@analog.com>
---
 drivers/iio/industrialio-backend.c | 33 +++++++++++++++++++++++++++++++++
 include/linux/iio/backend.h        |  4 ++++
 2 files changed, 37 insertions(+)

diff --git a/drivers/iio/industrialio-backend.c b/drivers/iio/industrialio-backend.c
index f7a4be8ec320..379a426931cd 100644
--- a/drivers/iio/industrialio-backend.c
+++ b/drivers/iio/industrialio-backend.c
@@ -886,6 +886,39 @@ int iio_backend_num_lanes_set(struct iio_backend *back, unsigned int num_lanes)
 }
 EXPORT_SYMBOL_NS_GPL(iio_backend_num_lanes_set, "IIO_BACKEND");
 
+/**
+ * iio_backend_crc_enable - Enable the CRC generation.
+ * @back: Backend device
+ *
+ * Enable Cyclic Redundancy Check processing for data integrity
+ * verification. When enabled, the backend will generate, verify, or process
+ * CRC information for data samples transmitted over the interface.
+ *
+ * RETURNS:
+ * 0 on success, negative error number on failure.
+ */
+int iio_backend_crc_enable(struct iio_backend *back)
+{
+	return iio_backend_op_call(back, crc_enable);
+}
+EXPORT_SYMBOL_NS_GPL(iio_backend_crc_enable, "IIO_BACKEND");
+
+/**
+ * iio_backend_crc_disable - Disable the CRC generation.
+ * @back: Backend device
+ *
+ * Disable Cyclic Redundancy Check processing. When disabled, the backend
+ * will stop generating, verifying, or processing CRC information for data samples.
+ *
+ * RETURNS:
+ * 0 on success, negative error number on failure.
+ */
+int iio_backend_crc_disable(struct iio_backend *back)
+{
+	return iio_backend_op_call(back, crc_disable);
+}
+EXPORT_SYMBOL_NS_GPL(iio_backend_crc_disable, "IIO_BACKEND");
+
 /**
  * iio_backend_ddr_enable - Enable interface DDR (Double Data Rate) mode
  * @back: Backend device
diff --git a/include/linux/iio/backend.h b/include/linux/iio/backend.h
index 3f95ed1fdf9e..197cf1ad5e68 100644
--- a/include/linux/iio/backend.h
+++ b/include/linux/iio/backend.h
@@ -189,6 +189,8 @@ struct iio_backend_ops {
 			       enum iio_backend_filter_type type);
 	int (*interface_data_align)(struct iio_backend *back, u32 timeout_us);
 	int (*num_lanes_set)(struct iio_backend *back, unsigned int num_lanes);
+	int (*crc_enable)(struct iio_backend *back);
+	int (*crc_disable)(struct iio_backend *back);
 	int (*ddr_enable)(struct iio_backend *back);
 	int (*ddr_disable)(struct iio_backend *back);
 	int (*data_stream_enable)(struct iio_backend *back);
@@ -237,6 +239,8 @@ int iio_backend_filter_type_set(struct iio_backend *back,
 				enum iio_backend_filter_type type);
 int iio_backend_interface_data_align(struct iio_backend *back, u32 timeout_us);
 int iio_backend_num_lanes_set(struct iio_backend *back, unsigned int num_lanes);
+int iio_backend_crc_enable(struct iio_backend *back);
+int iio_backend_crc_disable(struct iio_backend *back);
 int iio_backend_ddr_enable(struct iio_backend *back);
 int iio_backend_ddr_disable(struct iio_backend *back);
 int iio_backend_data_stream_enable(struct iio_backend *back);

-- 
2.43.0

Re: [PATCH 2/6] iio: backend: Add support for CRC

[Jonathan Cameron]

On Thu, 9 Jul 2026 10:50:13 +0200
Janani Sunil <janani.sunil@analog.com> wrote:

> Add a backend operation to enable or disable Cyclic Redundancy Check
> processing for data integrity verification. When enabled, the backend
> will generate, verify, or process CRC information for data samples
> transmitted over the interface, allowing the host to detect corrupted
> samples.
> 
> Signed-off-by: Janani Sunil <janani.sunil@analog.com>
> ---
>  drivers/iio/industrialio-backend.c | 33 +++++++++++++++++++++++++++++++++
>  include/linux/iio/backend.h        |  4 ++++
>  2 files changed, 37 insertions(+)
> 
> diff --git a/drivers/iio/industrialio-backend.c b/drivers/iio/industrialio-backend.c
> index f7a4be8ec320..379a426931cd 100644
> --- a/drivers/iio/industrialio-backend.c
> +++ b/drivers/iio/industrialio-backend.c
> @@ -886,6 +886,39 @@ int iio_backend_num_lanes_set(struct iio_backend *back, unsigned int num_lanes)
>  }
>  EXPORT_SYMBOL_NS_GPL(iio_backend_num_lanes_set, "IIO_BACKEND");
>  
> +/**
> + * iio_backend_crc_enable - Enable the CRC generation.
> + * @back: Backend device
> + *
> + * Enable Cyclic Redundancy Check processing for data integrity
> + * verification. When enabled, the backend will generate, verify, or process

Verification should be on previous line - under 80 chars.

> + * CRC information for data samples transmitted over the interface.
> + *
> + * RETURNS:
> + * 0 on success, negative error number on failure.
> + */
> +int iio_backend_crc_enable(struct iio_backend *back)
> +{
> +	return iio_backend_op_call(back, crc_enable);
> +}
> +EXPORT_SYMBOL_NS_GPL(iio_backend_crc_enable, "IIO_BACKEND");
> +
> +/**
> + * iio_backend_crc_disable - Disable the CRC generation.
> + * @back: Backend device
> + *
> + * Disable Cyclic Redundancy Check processing. When disabled, the backend
> + * will stop generating, verifying, or processing CRC information for data samples.

Odd line wrap.  Keep to a consistent <= 80 chars unless there is a reason
to do otherwise.

> + *
> + * RETURNS:
> + * 0 on success, negative error number on failure.
> + */

[PATCH 3/6] iio: adc: adi-axi-adc: Add support for CRC

[Janani Sunil]

Add support for enabling and disabling Cyclic Redundancy Check (CRC)
processing in the AXI ADC backend. CRC provides data integrity verification
for high-speed ADC data streams, ensuring reliable data transfer between
the ADC frontend and backend processing systems.

Signed-off-by: Janani Sunil <janani.sunil@analog.com>
---
 drivers/iio/adc/adi-axi-adc.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/drivers/iio/adc/adi-axi-adc.c b/drivers/iio/adc/adi-axi-adc.c
index 26b9c75bd4d8..8af42d26aac0 100644
--- a/drivers/iio/adc/adi-axi-adc.c
+++ b/drivers/iio/adc/adi-axi-adc.c
@@ -47,6 +47,8 @@
 #define    ADI_AXI_ADC_CTRL_DDR_EDGESEL_MASK	BIT(1)
 
 #define ADI_AXI_ADC_REG_CNTRL_3			0x004c
+#define    ADI_AXI_ADC_REG_CNTRL3_CRC_EN_MASK	BIT(8)
+
 #define   AXI_AD485X_CNTRL_3_OS_EN_MSK		BIT(2)
 #define   AXI_AD485X_CNTRL_3_PACKET_FORMAT_MSK	GENMASK(1, 0)
 #define   AXI_AD485X_PACKET_FORMAT_20BIT	0x0
@@ -567,6 +569,22 @@ static int axi_adc_reg_access(struct iio_backend *back, unsigned int reg,
 	return regmap_write(st->regmap, reg, writeval);
 }
 
+static int axi_adc_crc_enable(struct iio_backend *back)
+{
+	struct adi_axi_adc_state *st = iio_backend_get_priv(back);
+
+	return regmap_set_bits(st->regmap, ADI_AXI_ADC_REG_CNTRL_3,
+			       ADI_AXI_ADC_REG_CNTRL3_CRC_EN_MASK);
+}
+
+static int axi_adc_crc_disable(struct iio_backend *back)
+{
+	struct adi_axi_adc_state *st = iio_backend_get_priv(back);
+
+	return regmap_clear_bits(st->regmap, ADI_AXI_ADC_REG_CNTRL_3,
+				 ADI_AXI_ADC_REG_CNTRL3_CRC_EN_MASK);
+}
+
 static const struct regmap_config axi_adc_regmap_config = {
 	.val_bits = 32,
 	.reg_bits = 32,
@@ -615,6 +633,8 @@ static const struct iio_backend_ops adi_axi_adc_ops = {
 	.num_lanes_set = axi_adc_num_lanes_set,
 	.debugfs_reg_access = iio_backend_debugfs_ptr(axi_adc_reg_access),
 	.debugfs_print_chan_status = iio_backend_debugfs_ptr(axi_adc_debugfs_print_chan_status),
+	.crc_enable = axi_adc_crc_enable,
+	.crc_disable = axi_adc_crc_disable,
 };
 
 static const struct iio_backend_info adi_axi_adc_generic = {

-- 
2.43.0

Re: [PATCH 3/6] iio: adc: adi-axi-adc: Add support for CRC

[David Lechner]

On 7/9/26 3:50 AM, Janani Sunil wrote:
> Add support for enabling and disabling Cyclic Redundancy Check (CRC)
> processing in the AXI ADC backend. CRC provides data integrity verification
> for high-speed ADC data streams, ensuring reliable data transfer between
> the ADC frontend and backend processing systems.
> 
> Signed-off-by: Janani Sunil <janani.sunil@analog.com>
> ---
>  drivers/iio/adc/adi-axi-adc.c | 20 ++++++++++++++++++++
>  1 file changed, 20 insertions(+)
> 
> diff --git a/drivers/iio/adc/adi-axi-adc.c b/drivers/iio/adc/adi-axi-adc.c
> index 26b9c75bd4d8..8af42d26aac0 100644
> --- a/drivers/iio/adc/adi-axi-adc.c
> +++ b/drivers/iio/adc/adi-axi-adc.c
> @@ -47,6 +47,8 @@
>  #define    ADI_AXI_ADC_CTRL_DDR_EDGESEL_MASK	BIT(1)
>  
>  #define ADI_AXI_ADC_REG_CNTRL_3			0x004c
> +#define    ADI_AXI_ADC_REG_CNTRL3_CRC_EN_MASK	BIT(8)

	ADI_AXI_ADC_CNTRL_3_CRC_EN_MASK

to match the existing naming pattern.

Also, add a comment that bit 8 is shared by all AXI ADC cores while bits
7-0 are custom per HDL project. (That is why they have names like AD485X
instead of AXI_ADC).

> +
>  #define   AXI_AD485X_CNTRL_3_OS_EN_MSK		BIT(2)
>  #define   AXI_AD485X_CNTRL_3_PACKET_FORMAT_MSK	GENMASK(1, 0)
>  #define   AXI_AD485X_PACKET_FORMAT_20BIT	0x0
> @@ -567,6 +569,22 @@ static int axi_adc_reg_access(struct iio_backend *back, unsigned int reg,
>  	return regmap_write(st->regmap, reg, writeval);
>  }
>  

Re: [PATCH 3/6] iio: adc: adi-axi-adc: Add support for CRC

[Jonathan Cameron]

On Thu, 9 Jul 2026 10:50:14 +0200
Janani Sunil <janani.sunil@analog.com> wrote:

> Add support for enabling and disabling Cyclic Redundancy Check (CRC)
> processing in the AXI ADC backend. CRC provides data integrity verification
> for high-speed ADC data streams, ensuring reliable data transfer between
> the ADC frontend and backend processing systems.
> 
> Signed-off-by: Janani Sunil <janani.sunil@analog.com>
> ---
>  drivers/iio/adc/adi-axi-adc.c | 20 ++++++++++++++++++++
>  1 file changed, 20 insertions(+)

>  static const struct regmap_config axi_adc_regmap_config = {
>  	.val_bits = 32,
>  	.reg_bits = 32,
> @@ -615,6 +633,8 @@ static const struct iio_backend_ops adi_axi_adc_ops = {
>  	.num_lanes_set = axi_adc_num_lanes_set,
>  	.debugfs_reg_access = iio_backend_debugfs_ptr(axi_adc_reg_access),
>  	.debugfs_print_chan_status = iio_backend_debugfs_ptr(axi_adc_debugfs_print_chan_status),
Sashiko caught that this needs kernel-doc.
https://sashiko.dev/#/patchset/20260709-ad7768-driver-v1-0-44e1194fd96a%40analog.com

> +	.crc_enable = axi_adc_crc_enable,
> +	.crc_disable = axi_adc_crc_disable,
>  };
>  
>  static const struct iio_backend_info adi_axi_adc_generic = {
> 

Re: [PATCH 3/6] iio: adc: adi-axi-adc: Add support for CRC

[Jonathan Cameron]

On Thu, 9 Jul 2026 10:50:14 +0200
Janani Sunil <janani.sunil@analog.com> wrote:

> Add support for enabling and disabling Cyclic Redundancy Check (CRC)
> processing in the AXI ADC backend. CRC provides data integrity verification
> for high-speed ADC data streams, ensuring reliable data transfer between
> the ADC frontend and backend processing systems.
> 
> Signed-off-by: Janani Sunil <janani.sunil@analog.com>
The 'other things' I found bit from Sashiko is interesting. Far as I can
tell it is right and [devm_]mutex_init() is missing for lock
in struct adi_axi_adc_state().  

Nuno, looks like it was from:
7ecb8ee5c93b ("iio: adc: adi-axi-adc: support digital interface calibration")

Which indeed adds the lock with a mutex_init()

Jonathan

>  static const struct iio_backend_info adi_axi_adc_generic = {
> 

[PATCH 4/6] iio: adc: Add AD7768 IIO Driver support

[Janani Sunil]

Add support for AD7768 4/8 channel,simultaneous sampling Sigma-Delta
ADC, supporting configurable power modes, decimation filters and data
output lines

Signed-off-by: Janani Sunil <janani.sunil@analog.com>
---
 MAINTAINERS              |    1 +
 drivers/iio/adc/Kconfig  |   16 +
 drivers/iio/adc/Makefile |    1 +
 drivers/iio/adc/ad7768.c | 1291 ++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 1309 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index d667a0411f28..dc94e7803a7c 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1639,6 +1639,7 @@ L:	linux-iio@vger.kernel.org
 S:	Supported
 W:	https://ez.analog.com/linux-software-drivers
 F:	Documentation/devicetree/bindings/iio/adc/adi,ad7768.yaml
+F:	drivers/iio/adc/ad7768.c
 
 ANALOG DEVICES INC AD7780 DRIVER
 M:	Michael Hennerich <Michael.Hennerich@analog.com>
diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index d1b198cb8a80..1325cdbedea4 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -429,6 +429,22 @@ config AD7766
 	  To compile this driver as a module, choose M here: the module will be
 	  called ad7766.
 
+config AD7768
+	tristate "Analog Devices AD7768/AD7768-4 ADC driver"
+	depends on SPI
+	depends on REGULATOR || COMPILE_TEST
+	select AUXILIARY_BUS
+	select IIO_BUFFER
+	select IIO_BACKEND
+	select REGMAP
+	help
+	  Say yes here to build support for Analog Devices AD7768 and AD7768-4
+	  SPI analog to digital converters.
+
+	  To compile this driver as a module, choose M here: the module will be
+	  called ad7768.
+
+
 config AD7768_1
 	tristate "Analog Devices AD7768-1 ADC driver"
 	depends on SPI
diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index 0f90b75577ff..3e896c8aa7c3 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -39,6 +39,7 @@ obj-$(CONFIG_AD7606_IFACE_SPI) += ad7606_spi.o
 obj-$(CONFIG_AD7606) += ad7606.o
 obj-$(CONFIG_AD7625) += ad7625.o
 obj-$(CONFIG_AD7766) += ad7766.o
+obj-$(CONFIG_AD7768) += ad7768.o
 obj-$(CONFIG_AD7768_1) += ad7768-1.o
 obj-$(CONFIG_AD7779) += ad7779.o
 obj-$(CONFIG_AD7780) += ad7780.o
diff --git a/drivers/iio/adc/ad7768.c b/drivers/iio/adc/ad7768.c
new file mode 100644
index 000000000000..f76a7081090e
--- /dev/null
+++ b/drivers/iio/adc/ad7768.c
@@ -0,0 +1,1291 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Analog Devices AD7768 ADC driver
+ *
+ * Copyright 2018-2026 Analog Devices Inc.
+ */
+
+#include <linux/array_size.h>
+#include <linux/auxiliary_bus.h>
+#include <linux/bitfield.h>
+#include <linux/bitops.h>
+#include <linux/cleanup.h>
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/math.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/pm_runtime.h>
+#include <linux/property.h>
+#include <linux/regmap.h>
+#include <linux/regulator/consumer.h>
+#include <linux/reset.h>
+#include <linux/spi/spi.h>
+#include <linux/types.h>
+
+#include <linux/iio/backend.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/types.h>
+
+#define AD7768_AUX_DEV_GPIO_NAME	"gpio"
+#define AD7768_REG_GPIO_CONTROL		0x0E
+
+/* AD7768 registers definition */
+#define AD7768_REG_CH_STANDBY			0x00
+#define AD7768_REG_CH_MODE(x)			(0x01 + (x))
+#define AD7768_REG_CH_MODE_SEL			0x03
+#define AD7768_REG_POWER_MODE			0x04
+#define AD7768_REG_GENERAL_CONFIG		0x05
+#define AD7768_REG_DATA_CONTROL			0x06
+#define AD7768_REG_INTERFACE_CFG		0x07
+#define AD7768_REG_REV_ID			0x0A
+#define AD7768_REG_PRECHARGE_BUF1		0x11
+#define AD7768_REG_PRECHARGE_BUF2		0x12
+#define AD7768_REG_REFP_BUF			0x13
+#define AD7768_REG_REFN_BUF			0x14
+#define AD7768_REG_OFFSET_BASE			0x1E
+#define AD7768_REG_GAIN_BASE			0x36
+#define AD7768_REG_PHASE_BASE			0x4E
+#define AD7768_REG_OFFSET(ch)			((AD7768_REG_OFFSET_BASE + (3 * (ch))))
+#define AD7768_REG_GAIN(ch)			((AD7768_REG_GAIN_BASE + (3 * (ch))))
+#define AD7768_REG_PHASE(ch)			((AD7768_REG_PHASE_BASE + (ch)))
+#define __AD7768_4_REG_MAP(ch)		((ch) < 2 ? (ch) : ((ch) + 2))
+#define AD7768_4_REG_OFFSET(ch) \
+	(AD7768_REG_OFFSET_BASE + (3 * __AD7768_4_REG_MAP(ch)))
+#define AD7768_4_REG_GAIN(ch) \
+	(AD7768_REG_GAIN_BASE + (3 * __AD7768_4_REG_MAP(ch)))
+#define AD7768_4_REG_PHASE(ch)		(AD7768_REG_PHASE_BASE + __AD7768_4_REG_MAP(ch))
+#define AD7768_REG_DIAGNOSTIC_RX		0x56
+#define AD7768_REG_DIAGNOSTIC_MUX_CTRL		0x57
+#define AD7768_REG_MODULATOR_DELAY_CTRL		0x58
+#define AD7768_REG_CHOP_CTRL			0x59
+
+/* AD7768_REG_CH_MODE */
+#define   AD7768_CH_MODE_FILTER_TYPE_MSK	BIT(3)
+#define   AD7768_CH_MODE_FILTER_TYPE_MODE(x)	(((x) & 0x1) << 3)
+#define   AD7768_CH_MODE_GET_FILTER_TYPE(x)	(((x) >> 3) & 0x1)
+#define   AD7768_CH_MODE_DEC_RATE_MSK		GENMASK(2, 0)
+#define   AD7768_CH_MODE_DEC_RATE_MODE(x)	(((x) & 0x7) << 0)
+
+/* AD7768_REG_CH_MODE_SEL */
+#define   AD7768_CH_MODE_READ_MSK		GENMASK(7, 0)
+#define   AD7768_CH_MODE_READ_MODE(x)		((x) & 0xFF)
+#define   AD7768_CH_MODE_READ_GET(x)		((x) & 0xFF)
+#define   AD7768_CH_MODE_SEL_8CH(ch)		BIT(ch)
+#define   AD7768_CH_MODE_READ_CHN(n)		BIT(n)
+#define   AD7768_GET_CH_MODE_8CH(ch, x)		(!!((x) & BIT(ch)))
+
+/* AD7768_REG_POWER_MODE */
+#define   AD7768_SLEEP_MODE_MSK			BIT(7)
+#define   AD7768_POWER_MODE_POWER_MODE_MSK	GENMASK(5, 4)
+#define   AD7768_POWER_MODE_POWER_MODE(x)	(((x) & 0x3) << 4)
+#define   AD7768_POWER_MODE_GET_POWER_MODE(x)	(((x) >> 4) & 0x3)
+#define   AD7768_POWER_MODE_MCLK_DIV_MSK	GENMASK(1, 0)
+#define   AD7768_POWER_MODE_MCLK_DIV_MODE(x)	(((x) & 0x3) << 0)
+
+/* AD7768_REG_DATA_CONTROL */
+#define   AD7768_DATA_CONTROL_SPI_RESET_MSK	GENMASK(1, 0)
+#define   AD7768_DATA_CONTROL_SPI_RESET_1	0x03
+#define   AD7768_DATA_CONTROL_SPI_RESET_2	0x02
+#define   AD7768_DATA_CONTROL_SPI_SYNC_MSK	BIT(7)
+#define   AD7768_DATA_CONTROL_SPI_SYNC		BIT(7)
+#define   AD7768_DATA_CONTROL_SPI_SYNC_CLEAR	0
+
+/* AD7768_REG_INTERFACE_CFG */
+#define   AD7768_INTERFACE_CFG_DCLK_DIV_MSK	GENMASK(1, 0)
+#define   AD7768_INTERFACE_CFG_DCLK_DIV_MODE(x)	(4 - ffs(x))
+#define   AD7768_MAX_DCLK_DIV			8
+
+#define   AD7768_INTERFACE_CFG_CRC_SELECT_MSK	GENMASK(3, 2)
+/* only 4 samples CRC calculation support exists */
+#define   AD7768_INTERFACE_CFG_CRC_SELECT	FIELD_PREP(GENMASK(3, 2), 0x01)
+
+/* AD7768_REG_GENERAL_CONFIG */
+#define   AD7768_GEN_CONFIG_VCM_SEL_MSK		GENMASK(1, 0)
+#define   AD7768_GEN_CONFIG_VCM_PD		BIT(4)
+
+/* AD7768_REG_PRECHARGE_BUF1 and 2*/
+#define   AD7768_PRECHARGE_BUF1_MSK(val)	((val) & GENMASK(7, 0))
+#define   AD7768_PRECHARGE_BUF2_MSK(val)	(((val) & GENMASK(15, 8)) >> 8)
+#define   AD7768_4_PRECHARGE_BUF1_MSK(val)	((val) & GENMASK(3, 0))
+#define   AD7768_4_PRECHARGE_BUF2_MSK(val)	(((val) & GENMASK(7, 4)) >> 4)
+#define   AD7768_PREBUF_POS_EN(ch)	BIT((ch) * 2)
+#define   AD7768_PREBUF_NEG_EN(ch)	BIT(((ch) * 2) + 1)
+
+#define   AD7768_SPI_READ_CMD			BIT(15)
+#define   AD7768_SPI_REG_MASK			GENMASK(14, 8)
+#define   AD7768_SPI_DATA_MASK			GENMASK(7, 0)
+#define   AD7768_OUTPUT_MODE_TWOS_COMPLEMENT	0x01
+#define   AD7768_SAMPLE_SIZE				32
+#define   MAX_FREQ_PER_MODE			6
+#define   AD7768_MAX_CHANNEL  8
+#define   AD7768_NUM_CHANNEL_MODES		2
+#define   AD7768_CALIB_REG_MSB_MASK(val)		(((val) & 0xFF0000) >> 16)
+#define   AD7768_CALIB_REG_MID_MASK(val)		(((val) & 0x00FF00) >> 8)
+#define   AD7768_CALIB_REG_LSB_MASK(val)		((val) & 0x0000FF)
+#define   AD7768_REV_ID_VAL			0x06
+
+enum ad7768_filter_type {
+	AD7768_FILTER_TYPE_WIDEBAND,
+	AD7768_FILTER_TYPE_SINC5,
+};
+
+enum ad7768_power_modes {
+	AD7768_LOW_POWER_MODE,
+	AD7768_MEDIAN_MODE,
+	AD7768_FAST_MODE,
+	AD7768_NUM_POWER_MODES
+};
+
+struct ad7768_precharge_config {
+	bool prebufp_en;
+	bool prebufn_en;
+	bool refbufp;
+	bool refbufn;
+};
+
+struct ad7768_freq_config {
+	unsigned int freq;
+	unsigned int dec_rate;
+};
+
+struct ad7768_avail_freq {
+	unsigned int n_freqs;
+	struct ad7768_freq_config freq_cfg[MAX_FREQ_PER_MODE];
+};
+
+struct ad7768_chip_info {
+	const char *name;
+	unsigned int num_channels;
+	const struct iio_chan_spec channel[AD7768_MAX_CHANNEL];
+	const struct regmap_config *regmap_config;
+	const unsigned int *available_datalines;
+	unsigned int num_datalines;
+};
+
+struct ad7768_state {
+	struct spi_device *spi;
+	struct regmap *regmap;
+	struct mutex lock; /* Protects device register access and configuration */
+	struct clk *mclk;
+	unsigned int datalines;
+	unsigned int sampling_freq;
+	enum ad7768_power_modes power_mode;
+	const struct ad7768_chip_info *chip_info;
+	struct ad7768_avail_freq avail_freq[AD7768_NUM_POWER_MODES];
+	unsigned int chn_mode[AD7768_MAX_CHANNEL];
+	unsigned int mode_freq[AD7768_NUM_CHANNEL_MODES];
+	unsigned int active_modes;
+	struct iio_backend *back;
+
+	__be16 d16 __aligned(IIO_DMA_MINALIGN);
+};
+
+static const char * const ad7768_vcm_sel_str[] = {
+	"avdd-avss-half", "1.65V", "2.5V", "2.14V"
+};
+
+static const char * const ad7768_power_mode_str[] = {
+	"low", "median", "fast"
+};
+
+static const int ad7768_dec_rate[MAX_FREQ_PER_MODE] = {
+	32, 64, 128, 256, 512, 1024
+};
+
+static const int ad7768_mclk_div[3] = {
+	32, 8, 4
+};
+
+static const unsigned int ad7768_available_datalines[] = {
+	1, 2, 8
+};
+
+static const unsigned int ad7768_4_available_datalines[] = {
+	1, 4
+};
+
+static const char * const ad7768_supply_names[] = {
+	"avdd", "avss", "dvdd", "iovdd", "vref"
+};
+
+static u8 ad7768_map_power_mode_to_regval(u8 x)
+{
+	return x ? (x + 1) : 0;
+}
+
+static u8 ad7768_4_get_refbuf(u8 ch)
+{
+	return (ch < 2) ? BIT(ch) : BIT(ch + 2);
+}
+
+static u8 ad7768_ch_mode_sel_4ch(u8 ch)
+{
+	return (ch < 2) ? BIT(ch) : BIT(ch + 2);
+}
+
+static int ad7768_regmap_read(void *context, const void *reg_buf,
+			      size_t reg_size, void *val_buf, size_t val_size)
+{
+	struct spi_device *spi = context;
+	struct ad7768_state *st = spi_get_drvdata(spi);
+	unsigned int reg;
+	int ret;
+	struct spi_transfer t[] = {
+		{
+			.tx_buf = &st->d16,
+			.len = 2,
+			.cs_change = 1,
+		}, {
+			.tx_buf = &st->d16,
+			.rx_buf = &st->d16,
+			.len = 2,
+		},
+	};
+
+	reg = *(const u8 *)reg_buf;
+
+	st->d16 = cpu_to_be16(AD7768_SPI_READ_CMD |
+			      FIELD_PREP(AD7768_SPI_REG_MASK, reg));
+
+	ret = spi_sync_transfer(spi, t, ARRAY_SIZE(t));
+	if (ret < 0)
+		return ret;
+
+	*(u8 *)val_buf = FIELD_GET(AD7768_SPI_DATA_MASK, be16_to_cpu(st->d16));
+
+	return ret;
+}
+
+static int ad7768_regmap_write(void *context, const void *data, size_t count)
+{
+	struct spi_device *spi = context;
+
+	return spi_write(spi, data, count);
+}
+
+static const struct regmap_bus ad7768_regmap_bus = {
+	.read = ad7768_regmap_read,
+	.write = ad7768_regmap_write,
+	.reg_format_endian_default = REGMAP_ENDIAN_BIG,
+	.val_format_endian_default = REGMAP_ENDIAN_BIG,
+};
+
+static bool ad7768_readable_reg(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case AD7768_REG_CH_STANDBY ... AD7768_REG_REV_ID:
+	case AD7768_REG_GPIO_CONTROL ... AD7768_REG_REFN_BUF:
+		return true;
+	case AD7768_REG_OFFSET(0) ... AD7768_REG_OFFSET(7) + 2:
+	case AD7768_REG_GAIN(0) ... AD7768_REG_GAIN(7) + 2:
+	case AD7768_REG_PHASE(0) ... AD7768_REG_PHASE(7):
+	case AD7768_REG_DIAGNOSTIC_RX ... AD7768_REG_CHOP_CTRL:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static bool ad7768_4_readable_reg(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	case AD7768_REG_CH_STANDBY ... AD7768_REG_REV_ID:
+	case AD7768_REG_GPIO_CONTROL ... AD7768_REG_REFN_BUF:
+		return true;
+	case AD7768_4_REG_OFFSET(0) ... AD7768_4_REG_OFFSET(1) + 2:
+	case AD7768_4_REG_OFFSET(2) ... AD7768_4_REG_OFFSET(3) + 2:
+	case AD7768_4_REG_GAIN(0) ... AD7768_4_REG_GAIN(1) + 2:
+	case AD7768_4_REG_GAIN(2) ... AD7768_4_REG_GAIN(3) + 2:
+	case AD7768_4_REG_PHASE(0) ... AD7768_4_REG_PHASE(1):
+	case AD7768_4_REG_PHASE(2) ... AD7768_4_REG_PHASE(3):
+	case AD7768_REG_DIAGNOSTIC_RX ... AD7768_REG_CHOP_CTRL:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static const struct regmap_config ad7768_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.max_register = AD7768_REG_CHOP_CTRL,
+	.readable_reg = ad7768_readable_reg,
+};
+
+static const struct regmap_config ad7768_4_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.max_register = AD7768_REG_CHOP_CTRL,
+	.readable_reg = ad7768_4_readable_reg,
+};
+
+static unsigned int ad7768_get_calib_reg_base(struct ad7768_state *st,
+					      const struct iio_chan_spec *chan,
+					      bool is_gain)
+{
+	if (is_gain) {
+		if (st->chip_info->num_channels == AD7768_MAX_CHANNEL)
+			return AD7768_REG_GAIN(chan->address);
+		return AD7768_4_REG_GAIN(chan->address);
+	}
+
+	if (st->chip_info->num_channels == AD7768_MAX_CHANNEL)
+		return AD7768_REG_OFFSET(chan->address);
+	return AD7768_4_REG_OFFSET(chan->address);
+}
+
+static int ad7768_read_calib_value(struct ad7768_state *st,
+				   unsigned int base_reg, int *val)
+{
+	unsigned int msb, mid, lsb;
+	int ret;
+
+	guard(mutex)(&st->lock);
+
+	ret = regmap_read(st->regmap, base_reg + 0, &msb);
+	if (ret)
+		return ret;
+
+	ret = regmap_read(st->regmap, base_reg + 1, &mid);
+	if (ret)
+		return ret;
+
+	ret = regmap_read(st->regmap, base_reg + 2, &lsb);
+	if (ret)
+		return ret;
+
+	*val = (msb << 16) | (mid << 8) | lsb;
+
+	return 0;
+}
+
+static int ad7768_write_calib_value(struct ad7768_state *st,
+				    unsigned int base_reg, int val)
+{
+	int ret;
+
+	guard(mutex)(&st->lock);
+
+	ret = regmap_write(st->regmap, base_reg, AD7768_CALIB_REG_MSB_MASK(val));
+	if (ret)
+		return ret;
+
+	ret = regmap_write(st->regmap, base_reg + 1,
+			   AD7768_CALIB_REG_MID_MASK(val));
+	if (ret)
+		return ret;
+
+	return regmap_write(st->regmap, base_reg + 2,
+			    AD7768_CALIB_REG_LSB_MASK(val));
+}
+
+static int ad7768_reg_access(struct iio_dev *indio_dev,
+			     unsigned int reg,
+			     unsigned int writeval,
+			     unsigned int *readval)
+{
+	struct ad7768_state *st = iio_priv(indio_dev);
+	int ret;
+
+	PM_RUNTIME_ACQUIRE_IF_ENABLED_AUTOSUSPEND(&st->spi->dev, pm);
+	ret = PM_RUNTIME_ACQUIRE_ERR(&pm);
+	if (ret)
+		return ret;
+
+	if (readval)
+		return regmap_read(st->regmap, reg, readval);
+
+	return regmap_write(st->regmap, reg, writeval);
+}
+
+static int ad7768_sync(struct ad7768_state *st)
+{
+	int ret;
+
+	ret = regmap_update_bits(st->regmap, AD7768_REG_DATA_CONTROL,
+				 AD7768_DATA_CONTROL_SPI_SYNC_MSK,
+				 AD7768_DATA_CONTROL_SPI_SYNC_CLEAR);
+	if (ret < 0)
+		return ret;
+
+	return regmap_update_bits(st->regmap, AD7768_REG_DATA_CONTROL,
+				  AD7768_DATA_CONTROL_SPI_SYNC_MSK,
+				  AD7768_DATA_CONTROL_SPI_SYNC);
+}
+
+static int ad7768_set_clk_divs(struct ad7768_state *st,
+			       unsigned int freq, unsigned int ch)
+{
+	unsigned int mclk, dclk, dclk_div, i;
+	struct ad7768_freq_config f_cfg = {};
+	unsigned int chan_per_doutx;
+
+	mclk = clk_get_rate(st->mclk);
+
+	chan_per_doutx = st->chip_info->num_channels / st->datalines;
+	if (!chan_per_doutx)
+		return -EINVAL;
+
+	for (i = 0; i < st->avail_freq[st->power_mode].n_freqs; i++) {
+		f_cfg = st->avail_freq[st->power_mode].freq_cfg[i];
+		if (freq == f_cfg.freq)
+			break;
+	}
+
+	if (i == st->avail_freq[st->power_mode].n_freqs)
+		return -EINVAL;
+
+	dclk = f_cfg.freq * AD7768_SAMPLE_SIZE * chan_per_doutx;
+	if (dclk > mclk)
+		return -EINVAL;
+
+	/* Set dclk_div to the nearest power of 2 less than the original value */
+	dclk_div = DIV_ROUND_CLOSEST_ULL(mclk, dclk);
+	if (dclk_div > AD7768_MAX_DCLK_DIV)
+		dclk_div = AD7768_MAX_DCLK_DIV;
+	else if (dclk_div > 0 && hweight32(dclk_div) != 1)
+		dclk_div = 1 << (fls(dclk_div) - 1);
+
+	return regmap_update_bits(st->regmap, AD7768_REG_INTERFACE_CFG,
+				  AD7768_INTERFACE_CFG_DCLK_DIV_MSK,
+				  AD7768_INTERFACE_CFG_DCLK_DIV_MODE(dclk_div));
+}
+
+static int ad7768_set_channel_decimation(struct ad7768_state *st,
+					 unsigned int freq, unsigned int ch)
+{
+	struct ad7768_freq_config f_cfg = {};
+	unsigned int i;
+
+	for (i = 0; i < st->avail_freq[st->power_mode].n_freqs; i++) {
+		f_cfg = st->avail_freq[st->power_mode].freq_cfg[i];
+		if (freq == f_cfg.freq)
+			break;
+	}
+
+	if (i == st->avail_freq[st->power_mode].n_freqs)
+		return -EINVAL;
+
+	return regmap_update_bits(st->regmap, AD7768_REG_CH_MODE(st->chn_mode[ch]),
+				  AD7768_CH_MODE_DEC_RATE_MSK,
+				  AD7768_CH_MODE_DEC_RATE_MODE(f_cfg.dec_rate));
+}
+
+static unsigned int ad7768_get_max_mode_freq(const struct ad7768_state *st,
+					     unsigned int mode,
+					     unsigned int mode_freq)
+{
+	unsigned int max_freq = 0;
+	unsigned int i, freq;
+
+	for (i = 0; i < AD7768_NUM_CHANNEL_MODES; i++) {
+		if (!(st->active_modes & BIT(i)))
+			continue;
+
+		freq = i == mode ? mode_freq : st->mode_freq[i];
+		if (freq > max_freq)
+			max_freq = freq;
+	}
+
+	return max_freq;
+}
+
+static int ad7768_set_sampling_freq(struct iio_dev *indio_dev,
+				    unsigned int freq, unsigned int ch)
+{
+	struct ad7768_state *st = iio_priv(indio_dev);
+	unsigned int mode = st->chn_mode[ch];
+	int ret = 0;
+	unsigned int max_freq;
+
+	if (!freq)
+		return -EINVAL;
+
+	guard(mutex)(&st->lock);
+
+	max_freq = ad7768_get_max_mode_freq(st, mode, freq);
+
+	ret = ad7768_set_clk_divs(st, max_freq, ch);
+	if (ret < 0)
+		return ret;
+
+	ret = ad7768_set_channel_decimation(st, freq, ch);
+	if (ret < 0)
+		return ret;
+
+	ret = ad7768_sync(st);
+	if (ret)
+		return ret;
+
+	st->mode_freq[mode] = freq;
+	return 0;
+}
+
+static int ad7768_set_channel_mode(struct iio_dev *indio_dev, unsigned int ch,
+				   unsigned int mode)
+{
+	struct ad7768_state *st = iio_priv(indio_dev);
+	int ret;
+	unsigned int mask;
+
+	if (st->chip_info->num_channels == AD7768_MAX_CHANNEL)
+		mask = AD7768_CH_MODE_SEL_8CH(ch);
+	else
+		mask = ad7768_ch_mode_sel_4ch(ch);
+
+	guard(mutex)(&st->lock);
+
+	ret = regmap_update_bits(st->regmap, AD7768_REG_CH_MODE_SEL, mask,
+				 mode ? mask : 0);
+	if (ret)
+		return ret;
+
+	st->chn_mode[ch] = mode;
+
+	return 0;
+}
+
+static int ad7768_set_power_mode(struct iio_dev *indio_dev, unsigned int mode)
+{
+	struct ad7768_state *st = iio_priv(indio_dev);
+	struct ad7768_avail_freq avail_freq;
+	int max_mode_freq;
+	unsigned int regval;
+	int ret;
+
+	if (mode >= AD7768_NUM_POWER_MODES)
+		return -EINVAL;
+
+	guard(mutex)(&st->lock);
+
+	st->power_mode = mode;
+
+	regval = ad7768_map_power_mode_to_regval(mode);
+	ret = regmap_update_bits(st->regmap, AD7768_REG_POWER_MODE,
+				 AD7768_POWER_MODE_POWER_MODE_MSK,
+				 AD7768_POWER_MODE_POWER_MODE(regval));
+	if (ret < 0)
+		return ret;
+
+	ret = regmap_update_bits(st->regmap, AD7768_REG_POWER_MODE,
+				 AD7768_POWER_MODE_MCLK_DIV_MSK,
+				 AD7768_POWER_MODE_MCLK_DIV_MODE(regval));
+	if (ret < 0)
+		return ret;
+
+	avail_freq = st->avail_freq[mode];
+	max_mode_freq = avail_freq.freq_cfg[avail_freq.n_freqs - 1].freq;
+
+	st->sampling_freq = max_mode_freq;
+
+	return ad7768_sync(st);
+}
+
+static int ad7768_read_raw(struct iio_dev *indio_dev,
+			   const struct iio_chan_spec *chan,
+			   int *val, int *val2, long info)
+{
+	struct ad7768_state *st = iio_priv(indio_dev);
+	unsigned int base_reg;
+	int ret;
+
+	PM_RUNTIME_ACQUIRE_IF_ENABLED_AUTOSUSPEND(&st->spi->dev, pm);
+	ret = PM_RUNTIME_ACQUIRE_ERR(&pm);
+	if (ret)
+		return ret;
+
+	switch (info) {
+	case IIO_CHAN_INFO_SAMP_FREQ: {
+		guard(mutex)(&st->lock);
+		*val = st->mode_freq[st->chn_mode[chan->channel]];
+		return IIO_VAL_INT;
+	}
+
+	case IIO_CHAN_INFO_CALIBBIAS:
+		base_reg = ad7768_get_calib_reg_base(st, chan, false);
+		ret = ad7768_read_calib_value(st, base_reg, val);
+		if (ret)
+			return ret;
+		return IIO_VAL_INT;
+
+	case IIO_CHAN_INFO_CALIBSCALE:
+		base_reg = ad7768_get_calib_reg_base(st, chan, true);
+		ret = ad7768_read_calib_value(st, base_reg, val);
+		if (ret)
+			return ret;
+		return IIO_VAL_INT;
+
+	case IIO_CHAN_INFO_PHASE:
+		if (st->chip_info->num_channels == AD7768_MAX_CHANNEL)
+			base_reg = AD7768_REG_PHASE(chan->address);
+		else
+			base_reg = AD7768_4_REG_PHASE(chan->address);
+
+		ret = regmap_read(st->regmap, base_reg, val);
+		if (ret)
+			return ret;
+
+		return IIO_VAL_INT;
+	default:
+		return -EINVAL;
+	}
+}
+
+static int ad7768_write_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan,
+			    int val, int val2, long info)
+{
+	struct ad7768_state *st = iio_priv(indio_dev);
+	unsigned int base_reg;
+	int ret;
+
+	PM_RUNTIME_ACQUIRE_IF_ENABLED_AUTOSUSPEND(&st->spi->dev, pm);
+	ret = PM_RUNTIME_ACQUIRE_ERR(&pm);
+	if (ret)
+		return ret;
+
+	switch (info) {
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		return ad7768_set_sampling_freq(indio_dev, val, chan->channel);
+
+	case IIO_CHAN_INFO_CALIBBIAS:
+		return ad7768_write_calib_value(st,
+			ad7768_get_calib_reg_base(st, chan, false), val);
+
+	case IIO_CHAN_INFO_CALIBSCALE:
+		return ad7768_write_calib_value(st,
+			ad7768_get_calib_reg_base(st, chan, true), val);
+
+	case IIO_CHAN_INFO_PHASE:
+		if (st->chip_info->num_channels == AD7768_MAX_CHANNEL)
+			base_reg = AD7768_REG_PHASE(chan->address);
+		else
+			base_reg = AD7768_4_REG_PHASE(chan->address);
+
+		return regmap_write(st->regmap, base_reg, val);
+
+	default:
+		return -EINVAL;
+	}
+}
+
+static int ad7768_update_scan_mode(struct iio_dev *indio_dev,
+				   const unsigned long *scan_mask)
+{
+	struct ad7768_state *st = iio_priv(indio_dev);
+	unsigned int c;
+	int ret;
+
+	for (c = 0; c < st->chip_info->num_channels; c++) {
+		if (test_bit(c, scan_mask))
+			ret = iio_backend_chan_enable(st->back, c);
+		else
+			ret = iio_backend_chan_disable(st->back, c);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+static const struct ad7768_chip_info ad7768_chip_info = {
+	.name = "ad7768",
+	.num_channels = 8,
+	.regmap_config = &ad7768_regmap_config,
+	.available_datalines = ad7768_available_datalines,
+	.num_datalines = ARRAY_SIZE(ad7768_available_datalines),
+};
+
+static const struct ad7768_chip_info ad7768_4_chip_info = {
+	.name = "ad7768-4",
+	.num_channels = 4,
+	.regmap_config = &ad7768_4_regmap_config,
+	.available_datalines = ad7768_4_available_datalines,
+	.num_datalines = ARRAY_SIZE(ad7768_4_available_datalines),
+};
+
+static int ad7768_buffer_preenable(struct iio_dev *indio_dev)
+{
+	struct ad7768_state *st = iio_priv(indio_dev);
+
+	return pm_runtime_resume_and_get(&st->spi->dev);
+}
+
+static int ad7768_buffer_postdisable(struct iio_dev *indio_dev)
+{
+	struct ad7768_state *st = iio_priv(indio_dev);
+
+	pm_runtime_mark_last_busy(&st->spi->dev);
+	pm_runtime_put_autosuspend(&st->spi->dev);
+	return 0;
+}
+
+static const struct iio_buffer_setup_ops ad7768_buffer_ops = {
+	.preenable = ad7768_buffer_preenable,
+	.postdisable = ad7768_buffer_postdisable,
+};
+
+static const struct iio_info ad7768_info = {
+	.debugfs_reg_access = ad7768_reg_access,
+	.read_raw = ad7768_read_raw,
+	.write_raw = ad7768_write_raw,
+	.update_scan_mode = ad7768_update_scan_mode,
+};
+
+static void ad7768_set_available_sampl_freq(struct ad7768_state *st)
+{
+	unsigned int mode;
+	unsigned int dec;
+	unsigned int mclk = clk_get_rate(st->mclk);
+	struct ad7768_avail_freq *avail_freq;
+
+	for (mode = 0; mode < AD7768_NUM_POWER_MODES; mode++) {
+		avail_freq = &st->avail_freq[mode];
+		for (dec = ARRAY_SIZE(ad7768_dec_rate); dec > 0; dec--) {
+			struct ad7768_freq_config freq_cfg;
+
+			freq_cfg.dec_rate = dec - 1;
+			freq_cfg.freq = mclk / (ad7768_dec_rate[dec - 1] *
+					ad7768_mclk_div[mode]);
+			avail_freq->freq_cfg[avail_freq->n_freqs++] = freq_cfg;
+		}
+	}
+
+	/* The max frequency is not supported in one data line configuration */
+	if (st->datalines == 1)
+		st->avail_freq[AD7768_FAST_MODE].n_freqs--;
+}
+
+static int ad7768_gpio_adev_init(struct ad7768_state *st)
+{
+	struct device *dev = &st->spi->dev;
+	struct auxiliary_device *adev;
+	int id;
+
+	if (!device_property_read_bool(dev, "gpio-controller"))
+		return 0;
+
+	id = (st->spi->controller->bus_num << 8) | spi_get_chipselect(st->spi, 0);
+	adev = __devm_auxiliary_device_create(dev, KBUILD_MODNAME,
+					      AD7768_AUX_DEV_GPIO_NAME,
+					      (void *)st->chip_info->name, id);
+	if (!adev)
+		return dev_err_probe(dev, -ENODEV,
+				     "Failed to create GPIO auxiliary device\n");
+
+	return 0;
+}
+
+static int ad7768_set_filter_mode(struct iio_dev *indio_dev,
+				  const struct iio_chan_spec *chan,
+				  unsigned int mode)
+{
+	struct ad7768_state *st = iio_priv(indio_dev);
+	int ret;
+
+	PM_RUNTIME_ACQUIRE_IF_ENABLED_AUTOSUSPEND(&st->spi->dev, pm);
+	ret = PM_RUNTIME_ACQUIRE_ERR(&pm);
+	if (ret)
+		return ret;
+
+	guard(mutex)(&st->lock);
+
+	ret = regmap_update_bits(st->regmap,
+				 AD7768_REG_CH_MODE(st->chn_mode[chan->address]),
+				 AD7768_CH_MODE_FILTER_TYPE_MSK,
+				 AD7768_CH_MODE_FILTER_TYPE_MODE(mode));
+	if (ret < 0)
+		return ret;
+
+	return ad7768_sync(st);
+}
+
+static int ad7768_get_filter_mode(struct iio_dev *indio_dev,
+				  const struct iio_chan_spec *chan)
+{
+	struct ad7768_state *st = iio_priv(indio_dev);
+	unsigned int regval;
+	int ret;
+
+	PM_RUNTIME_ACQUIRE_IF_ENABLED_AUTOSUSPEND(&st->spi->dev, pm);
+	ret = PM_RUNTIME_ACQUIRE_ERR(&pm);
+	if (ret)
+		return ret;
+
+	ret = regmap_read(st->regmap,
+			  AD7768_REG_CH_MODE(st->chn_mode[chan->address]),
+			  &regval);
+	if (ret < 0)
+		return ret;
+
+	return AD7768_CH_MODE_GET_FILTER_TYPE(regval);
+}
+
+static int ad7768_configure_precharge_buffers(struct iio_dev *indio_dev,
+					      struct ad7768_precharge_config *precharge_cfg)
+{
+	struct ad7768_state *st = iio_priv(indio_dev);
+	int ret;
+	u8 ch;
+	u8 prebuf1_val, prebuf2_val;
+	u16 prebuf_mask = 0;
+	u8 refbufp_val = 0;
+	u8 refbufn_val = 0;
+
+	if (st->chip_info->num_channels == AD7768_MAX_CHANNEL) {
+		for (ch = 0; ch < indio_dev->num_channels; ch++) {
+			u8 channel = indio_dev->channels[ch].channel;
+
+			if (precharge_cfg[channel].prebufp_en)
+				prebuf_mask |= AD7768_PREBUF_POS_EN(channel);
+
+			if (precharge_cfg[channel].prebufn_en)
+				prebuf_mask |= AD7768_PREBUF_NEG_EN(channel);
+
+			if (precharge_cfg[channel].refbufp)
+				refbufp_val |= BIT(channel);
+
+			if (precharge_cfg[channel].refbufn)
+				refbufn_val |= BIT(channel);
+		}
+
+		prebuf1_val = AD7768_PRECHARGE_BUF1_MSK(prebuf_mask);
+		prebuf2_val = AD7768_PRECHARGE_BUF2_MSK(prebuf_mask);
+	} else {
+		for (ch = 0; ch < indio_dev->num_channels; ch++) {
+			u8 channel = indio_dev->channels[ch].channel;
+
+			if (precharge_cfg[channel].prebufp_en)
+				prebuf_mask |= AD7768_PREBUF_POS_EN(channel);
+
+			if (precharge_cfg[channel].prebufn_en)
+				prebuf_mask |= AD7768_PREBUF_NEG_EN(channel);
+
+			if (precharge_cfg[channel].refbufp)
+				refbufp_val |= ad7768_4_get_refbuf(channel);
+
+			if (precharge_cfg[channel].refbufn)
+				refbufn_val |= ad7768_4_get_refbuf(channel);
+		}
+
+		prebuf1_val = AD7768_4_PRECHARGE_BUF1_MSK(prebuf_mask);
+		prebuf2_val = AD7768_4_PRECHARGE_BUF2_MSK(prebuf_mask);
+	}
+
+	ret = regmap_write(st->regmap, AD7768_REG_PRECHARGE_BUF1, prebuf1_val);
+	if (ret < 0)
+		return ret;
+
+	ret = regmap_write(st->regmap, AD7768_REG_PRECHARGE_BUF2, prebuf2_val);
+	if (ret < 0)
+		return ret;
+
+	ret = regmap_write(st->regmap, AD7768_REG_REFP_BUF, refbufp_val);
+	if (ret < 0)
+		return ret;
+
+	return regmap_write(st->regmap, AD7768_REG_REFN_BUF, refbufn_val);
+}
+
+static const char *const ad7768_filter_types[] = {
+	[AD7768_FILTER_TYPE_WIDEBAND] = "wideband",
+	[AD7768_FILTER_TYPE_SINC5] = "sinc5",
+};
+
+static const struct iio_enum ad7768_filter_types_enum = {
+	.items = ad7768_filter_types,
+	.num_items = ARRAY_SIZE(ad7768_filter_types),
+	.set = ad7768_set_filter_mode,
+	.get = ad7768_get_filter_mode,
+};
+
+static struct iio_chan_spec_ext_info ad7768_ext_info[] = {
+	IIO_ENUM("filter_type", IIO_SEPARATE,
+		 &ad7768_filter_types_enum),
+	IIO_ENUM_AVAILABLE("filter_type", IIO_SEPARATE, &ad7768_filter_types_enum),
+	{ },
+};
+
+static const struct iio_chan_spec ad7768_channel_template = {
+	.type = IIO_VOLTAGE,
+	.info_mask_separate =	BIT(IIO_CHAN_INFO_CALIBBIAS) |
+				BIT(IIO_CHAN_INFO_CALIBSCALE) |
+				BIT(IIO_CHAN_INFO_PHASE) |
+				BIT(IIO_CHAN_INFO_SAMP_FREQ),
+	.indexed = 1,
+	.scan_type = {
+		.sign = 's',
+		.realbits = 24,
+		.storagebits = 32,
+	},
+	.ext_info = ad7768_ext_info,
+};
+
+static void ad7768_init_chan(struct iio_chan_spec *chan, unsigned int channel)
+{
+	*chan = ad7768_channel_template;
+	chan->address = channel;
+	chan->channel = channel;
+	chan->scan_index = channel;
+}
+
+static int ad7768_parse_config(struct iio_dev *indio_dev,
+			       struct device *dev)
+{
+	struct ad7768_state *st = iio_priv(indio_dev);
+	const unsigned int *available_datalines;
+	struct ad7768_precharge_config precharge_cfg[AD7768_MAX_CHANNEL] = {};
+	struct iio_chan_spec *chan;
+	unsigned int num_channels;
+	unsigned int channel;
+	unsigned int i, len, vcm_sel, vcm_pd, ch_mode, pwr_mode;
+	int chan_idx = 0;
+	int ret;
+
+	num_channels = device_get_child_node_count(dev);
+
+	if (!num_channels || num_channels > st->chip_info->num_channels)
+		return dev_err_probe(dev, -EINVAL, "Invalid number of channels\n");
+
+	chan = devm_kcalloc(indio_dev->dev.parent, num_channels,
+			    sizeof(*chan), GFP_KERNEL);
+	if (!chan)
+		return -ENOMEM;
+
+	indio_dev->channels = chan;
+	indio_dev->num_channels = num_channels;
+
+	ret = regmap_write(st->regmap, AD7768_REG_CH_STANDBY,
+			   GENMASK(st->chip_info->num_channels - 1, 0));
+	if (ret < 0)
+		return ret;
+
+	device_for_each_child_node_scoped(dev, child) {
+		ret = fwnode_property_read_u32(child, "reg", &channel);
+		if (ret)
+			return dev_err_probe(dev, ret,
+					     "Failed to parse reg property of %pfwP\n", child);
+
+		if (channel >= st->chip_info->num_channels)
+			return dev_err_probe(dev, -EINVAL,
+					     "Invalid channel number %d\n", channel);
+
+		ret = regmap_update_bits(st->regmap, AD7768_REG_CH_STANDBY,
+					 BIT(channel), 0);
+		if (ret < 0)
+			return ret;
+
+		ret = fwnode_property_read_u32(child, "adi,ch-mode", &ch_mode);
+		if (ret)
+			return dev_err_probe(dev, ret,
+					     "Failed to parse property adi,ch-mode %pfwP\n",
+					     child);
+
+		if (ch_mode >= AD7768_NUM_CHANNEL_MODES)
+			return dev_err_probe(dev, -EINVAL,
+					     "Invalid adi,ch-mode %u for channel %u\n",
+					     ch_mode, channel);
+
+		ret = ad7768_set_channel_mode(indio_dev, channel, ch_mode);
+		if (ret)
+			return ret;
+
+		st->active_modes |= BIT(ch_mode);
+
+		if (fwnode_property_read_bool(child, "adi,prebuf-pos-en"))
+			precharge_cfg[channel].prebufp_en = true;
+
+		if (fwnode_property_read_bool(child, "adi,prebuf-neg-en"))
+			precharge_cfg[channel].prebufn_en = true;
+
+		if (fwnode_property_read_bool(child, "adi,refbuf-pos-en"))
+			precharge_cfg[channel].refbufp = true;
+
+		if (fwnode_property_read_bool(child, "adi,refbuf-neg-en"))
+			precharge_cfg[channel].refbufn = true;
+
+		ad7768_init_chan(&chan[chan_idx], channel);
+		chan_idx++;
+	}
+
+	ret = ad7768_configure_precharge_buffers(indio_dev, precharge_cfg);
+	if (ret < 0)
+		return ret;
+
+	st->datalines = 1;
+	ret = device_property_read_u32(&st->spi->dev, "adi,data-lines-number",
+				       &st->datalines);
+	if (ret)
+		return dev_err_probe(&st->spi->dev, ret,
+				     "Missing \"adi,data-lines-number\" property\n");
+
+	ad7768_set_available_sampl_freq(st);
+
+	ret = device_property_match_property_string(&st->spi->dev,
+						    "adi,common-mode-output",
+						    ad7768_vcm_sel_str,
+						    ARRAY_SIZE(ad7768_vcm_sel_str));
+	if (ret < 0)
+		return dev_err_probe(&st->spi->dev, ret,
+				     "Missing or invalid \"adi,common-mode-output\" property\n");
+	vcm_sel = ret;
+
+	ret = regmap_update_bits(st->regmap,
+				 AD7768_REG_GENERAL_CONFIG,
+				 AD7768_GEN_CONFIG_VCM_SEL_MSK,
+				 vcm_sel);
+	if (ret < 0)
+		return ret;
+
+	vcm_pd = device_property_read_bool(&st->spi->dev, "adi,vcm-power-down");
+
+	ret = regmap_update_bits(st->regmap,
+				 AD7768_REG_GENERAL_CONFIG,
+				 AD7768_GEN_CONFIG_VCM_PD,
+				 vcm_pd ? AD7768_GEN_CONFIG_VCM_PD : 0);
+	if (ret < 0)
+		return ret;
+
+	ret = device_property_match_property_string(&st->spi->dev,
+						    "adi,power-mode",
+						    ad7768_power_mode_str,
+						    ARRAY_SIZE(ad7768_power_mode_str));
+	if (ret < 0) {
+		if (ret != -ENODATA)
+			return dev_err_probe(&st->spi->dev, ret,
+					     "Invalid \"adi,power-mode\" property\n");
+
+		pwr_mode = AD7768_LOW_POWER_MODE;
+	} else {
+		pwr_mode = ret;
+	}
+
+	ret = ad7768_set_power_mode(indio_dev, pwr_mode);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to set power mode\n");
+
+	for (i = 0; i < indio_dev->num_channels; i++) {
+		ret = ad7768_set_sampling_freq(indio_dev, st->sampling_freq,
+					       indio_dev->channels[i].channel);
+		if (ret < 0)
+			return dev_err_probe(dev, ret,
+					     "Failed to set sampling freq for channel %d\n",
+					     indio_dev->channels[i].channel);
+	}
+
+	available_datalines = st->chip_info->available_datalines;
+	len = st->chip_info->num_datalines;
+
+	for (i = 0; i < len; i++) {
+		if (available_datalines[i] == st->datalines)
+			return 0;
+	}
+
+	return dev_err_probe(&st->spi->dev, -EINVAL,
+			     "Invalid data-lines-number %d for %s\n",
+			     st->datalines, st->chip_info->name);
+}
+
+static int ad7768_reset(struct ad7768_state *st)
+{
+	struct reset_control *reset_ctrl;
+	int ret;
+
+	reset_ctrl = devm_reset_control_get_optional_exclusive(&st->spi->dev, NULL);
+	if (IS_ERR(reset_ctrl))
+		return PTR_ERR(reset_ctrl);
+
+	if (reset_ctrl) {
+		ret = reset_control_assert(reset_ctrl);
+		if (ret)
+			return ret;
+
+		ret = reset_control_deassert(reset_ctrl);
+		if (ret)
+			return ret;
+	} else {
+		ret = regmap_write(st->regmap, AD7768_REG_DATA_CONTROL,
+				   AD7768_DATA_CONTROL_SPI_RESET_1);
+		if (ret)
+			return ret;
+
+		ret = regmap_write(st->regmap, AD7768_REG_DATA_CONTROL,
+				   AD7768_DATA_CONTROL_SPI_RESET_2);
+		if (ret)
+			return ret;
+	}
+
+	/* ADC start-up time after reset: 1.66 ms max (datasheet Table 1) */
+	fsleep(2000);
+
+	return 0;
+}
+
+static int ad7768_probe(struct spi_device *spi)
+{
+	struct device *dev = &spi->dev;
+	unsigned int spi_readback, rev_id;
+	struct iio_dev *indio_dev;
+	struct ad7768_state *st;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*st));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	st = iio_priv(indio_dev);
+	st->spi = spi;
+	spi_set_drvdata(spi, st);
+
+	ret = devm_mutex_init(dev, &st->lock);
+	if (ret)
+		return ret;
+
+	st->chip_info = spi_get_device_match_data(spi);
+
+	ret = devm_regulator_bulk_get_enable(dev,
+					     ARRAY_SIZE(ad7768_supply_names),
+					     ad7768_supply_names);
+	if (ret)
+		return ret;
+
+	st->mclk = devm_clk_get_enabled(dev, NULL);
+	if (IS_ERR(st->mclk))
+		return PTR_ERR(st->mclk);
+
+	st->regmap = devm_regmap_init(dev, &ad7768_regmap_bus, spi,
+				      st->chip_info->regmap_config);
+	if (IS_ERR(st->regmap))
+		return PTR_ERR(st->regmap);
+
+	ret = regmap_attach_dev(dev, st->regmap, st->chip_info->regmap_config);
+	if (ret)
+		return ret;
+
+	ret = ad7768_reset(st);
+	if (ret)
+		return ret;
+
+	/* Dummy SPI register read to discard the Reset response from the chip */
+	ret = regmap_read(st->regmap, AD7768_REG_REV_ID, &spi_readback);
+	if (ret)
+		return ret;
+
+	ret = regmap_read(st->regmap, AD7768_REG_REV_ID, &rev_id);
+	if (ret)
+		return ret;
+
+	if (rev_id != AD7768_REV_ID_VAL)
+		dev_warn(dev, "Unexpected revision ID 0x%02x\n", rev_id);
+
+	ret = ad7768_parse_config(indio_dev, dev);
+	if (ret < 0)
+		return ret;
+
+	ret = regmap_update_bits(st->regmap, AD7768_REG_INTERFACE_CFG,
+				 AD7768_INTERFACE_CFG_CRC_SELECT_MSK,
+				 AD7768_INTERFACE_CFG_CRC_SELECT);
+	if (ret < 0)
+		return ret;
+
+	indio_dev->name = st->chip_info->name;
+	indio_dev->info = &ad7768_info;
+
+	st->back = devm_iio_backend_get(dev, NULL);
+	if (IS_ERR(st->back))
+		return PTR_ERR(st->back);
+
+	ret = devm_iio_backend_request_buffer(dev, st->back, indio_dev);
+	if (ret)
+		return ret;
+
+	ret = iio_backend_num_lanes_set(st->back, st->datalines);
+	if (ret)
+		return ret;
+
+	ret = iio_backend_crc_enable(st->back);
+	if (ret)
+		return ret;
+
+	ret = devm_iio_backend_enable(dev, st->back);
+	if (ret)
+		return ret;
+
+	pm_runtime_set_autosuspend_delay(dev, 2000);
+	pm_runtime_use_autosuspend(dev);
+	pm_runtime_set_active(dev);
+
+	ret = devm_pm_runtime_enable(dev);
+	if (ret)
+		return ret;
+
+	indio_dev->setup_ops = &ad7768_buffer_ops;
+
+	ret = ad7768_gpio_adev_init(st);
+	if (ret)
+		return ret;
+
+	return devm_iio_device_register(dev, indio_dev);
+}
+
+static int ad7768_runtime_suspend(struct device *dev)
+{
+	struct ad7768_state *st = dev_get_drvdata(dev);
+
+	return regmap_update_bits(st->regmap, AD7768_REG_POWER_MODE,
+				  AD7768_SLEEP_MODE_MSK,
+				  AD7768_SLEEP_MODE_MSK);
+}
+
+static int ad7768_runtime_resume(struct device *dev)
+{
+	struct ad7768_state *st = dev_get_drvdata(dev);
+	int ret;
+
+	ret = regmap_update_bits(st->regmap, AD7768_REG_POWER_MODE,
+				 AD7768_SLEEP_MODE_MSK, 0);
+	if (ret)
+		return ret;
+
+	fsleep(20000);
+
+	return 0;
+}
+
+static DEFINE_RUNTIME_DEV_PM_OPS(ad7768_pm_ops, ad7768_runtime_suspend,
+	ad7768_runtime_resume, NULL);
+
+static const struct of_device_id ad7768_of_match[]  = {
+	{ .compatible = "adi,ad7768", .data = &ad7768_chip_info },
+	{ .compatible = "adi,ad7768-4", .data = &ad7768_4_chip_info },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, ad7768_of_match);
+
+static const struct spi_device_id ad7768_spi_id[] = {
+	{"ad7768", (kernel_ulong_t)&ad7768_chip_info},
+	{"ad7768-4", (kernel_ulong_t)&ad7768_4_chip_info},
+	{ }
+};
+MODULE_DEVICE_TABLE(spi, ad7768_spi_id);
+
+static struct spi_driver ad7768_driver = {
+	.probe = ad7768_probe,
+	.driver = {
+		.name = "ad7768",
+		.of_match_table = ad7768_of_match,
+		.pm = pm_ptr(&ad7768_pm_ops),
+	},
+	.id_table = ad7768_spi_id,
+};
+module_spi_driver(ad7768_driver);
+
+MODULE_AUTHOR("Stefan Popa <stefan.popa@analog.com>");
+MODULE_AUTHOR("Janani Sunil <janani.sunil@analog.com>");
+MODULE_DESCRIPTION("Analog Devices AD7768 ADC driver");
+MODULE_LICENSE("GPL");
+MODULE_IMPORT_NS("IIO_BACKEND");

-- 
2.43.0

Re: [PATCH 4/6] iio: adc: Add AD7768 IIO Driver support

[Jonathan Cameron]

On Thu, 9 Jul 2026 10:50:15 +0200
Janani Sunil <janani.sunil@analog.com> wrote:

> Add support for AD7768 4/8 channel,simultaneous sampling Sigma-Delta
> ADC, supporting configurable power modes, decimation filters and data
> output lines
> 
> Signed-off-by: Janani Sunil <janani.sunil@analog.com>
Hi Janani.

Various things inline.

> ---
>  MAINTAINERS              |    1 +
>  drivers/iio/adc/Kconfig  |   16 +
>  drivers/iio/adc/Makefile |    1 +
>  drivers/iio/adc/ad7768.c | 1291 ++++++++++++++++++++++++++++++++++++++++++++++
>  4 files changed, 1309 insertions(+)

> diff --git a/drivers/iio/adc/ad7768.c b/drivers/iio/adc/ad7768.c
> new file mode 100644
> index 000000000000..f76a7081090e
> --- /dev/null
> +++ b/drivers/iio/adc/ad7768.c
> @@ -0,0 +1,1291 @@
...
> +
> +#define AD7768_AUX_DEV_GPIO_NAME	"gpio"

Can this just go inline?

> +#define AD7768_REG_GPIO_CONTROL		0x0E

> +/* AD7768_REG_POWER_MODE */
> +#define   AD7768_SLEEP_MODE_MSK			BIT(7)
> +#define   AD7768_POWER_MODE_POWER_MODE_MSK	GENMASK(5, 4)
> +#define   AD7768_POWER_MODE_POWER_MODE(x)	(((x) & 0x3) << 4)
> +#define   AD7768_POWER_MODE_GET_POWER_MODE(x)	(((x) >> 4) & 0x3)
> +#define   AD7768_POWER_MODE_MCLK_DIV_MSK	GENMASK(1, 0)
> +#define   AD7768_POWER_MODE_MCLK_DIV_MODE(x)	(((x) & 0x3) << 0)

FIELD_GET() inline. This define doesn't give us anything wrt
to readability over that.

> +
> +/* AD7768_REG_DATA_CONTROL */
> +#define   AD7768_DATA_CONTROL_SPI_RESET_MSK	GENMASK(1, 0)
> +#define   AD7768_DATA_CONTROL_SPI_RESET_1	0x03
> +#define   AD7768_DATA_CONTROL_SPI_RESET_2	0x02
> +#define   AD7768_DATA_CONTROL_SPI_SYNC_MSK	BIT(7)
> +#define   AD7768_DATA_CONTROL_SPI_SYNC		BIT(7)

No need for define, use FIELD_PREP(AD7768_DATA_CONTROL_SPI_SYNC_MASK, 1)
inline
> +#define   AD7768_DATA_CONTROL_SPI_SYNC_CLEAR	0
Not obvious why a define is needed for this. 
> +
> +/* AD7768_REG_INTERFACE_CFG */
> +#define   AD7768_INTERFACE_CFG_DCLK_DIV_MSK	GENMASK(1, 0)
> +#define   AD7768_INTERFACE_CFG_DCLK_DIV_MODE(x)	(4 - ffs(x))
> +#define   AD7768_MAX_DCLK_DIV			8
> +
> +#define   AD7768_INTERFACE_CFG_CRC_SELECT_MSK	GENMASK(3, 2)
> +/* only 4 samples CRC calculation support exists */

Exists where?  In the backend, or if the hardware. Good to be more specific.

> +#define   AD7768_INTERFACE_CFG_CRC_SELECT	FIELD_PREP(GENMASK(3, 2), 0x01)

> +/* AD7768_REG_PRECHARGE_BUF1 and 2*/
> +#define   AD7768_PRECHARGE_BUF1_MSK(val)	((val) & GENMASK(7, 0))
> +#define   AD7768_PRECHARGE_BUF2_MSK(val)	(((val) & GENMASK(15, 8)) >> 8)
> +#define   AD7768_4_PRECHARGE_BUF1_MSK(val)	((val) & GENMASK(3, 0))
> +#define   AD7768_4_PRECHARGE_BUF2_MSK(val)	(((val) & GENMASK(7, 4)) >> 4)


> +#define   AD7768_CALIB_REG_MSB_MASK(val)		(((val) & 0xFF0000) >> 16)

That seems unlikely to be the mask. It's the value. So just define the mask
and let FIELD_GET() deal with the shift.


> +#define   AD7768_CALIB_REG_MID_MASK(val)		(((val) & 0x00FF00) >> 8)
> +#define   AD7768_CALIB_REG_LSB_MASK(val)		((val) & 0x0000FF)
> +#define   AD7768_REV_ID_VAL			0x06


...
> +
> +static const unsigned int ad7768_4_available_datalines[] = {
> +	1, 4
> +};
> +
> +static const char * const ad7768_supply_names[] = {
> +	"avdd", "avss", "dvdd", "iovdd", "vref"
> +};

Add trailing commas to these.  They aren't terminated in
any way so in theory at least we might get more elements
on the next line.

> +
> +static int ad7768_regmap_read(void *context, const void *reg_buf,
> +			      size_t reg_size, void *val_buf, size_t val_size)
> +{
> +	struct spi_device *spi = context;
> +	struct ad7768_state *st = spi_get_drvdata(spi);
> +	unsigned int reg;
> +	int ret;
> +	struct spi_transfer t[] = {
> +		{
> +			.tx_buf = &st->d16,
> +			.len = 2,
> +			.cs_change = 1,
> +		}, {
> +			.tx_buf = &st->d16,

Sashiko moaned about this.  Add a comment on why tx_buf is
set to the same thing.

> +			.rx_buf = &st->d16,
> +			.len = 2,
> +		},
> +	};
> +
> +	reg = *(const u8 *)reg_buf;
> +
> +	st->d16 = cpu_to_be16(AD7768_SPI_READ_CMD |
> +			      FIELD_PREP(AD7768_SPI_REG_MASK, reg));
> +
> +	ret = spi_sync_transfer(spi, t, ARRAY_SIZE(t));
> +	if (ret < 0)
> +		return ret;
> +
> +	*(u8 *)val_buf = FIELD_GET(AD7768_SPI_DATA_MASK, be16_to_cpu(st->d16));
I'd prefer seeing a local pointer variable for the correct size

	u8 *data_val = val_buf;
...

> +
> +	return ret;
> +}

> +
> +static int ad7768_read_calib_value(struct ad7768_state *st,
> +				   unsigned int base_reg, int *val)
> +{
> +	unsigned int msb, mid, lsb;
> +	int ret;
> +
> +	guard(mutex)(&st->lock);
> +
> +	ret = regmap_read(st->regmap, base_reg + 0, &msb);
> +	if (ret)
> +		return ret;
> +
> +	ret = regmap_read(st->regmap, base_reg + 1, &mid);
> +	if (ret)
> +		return ret;
> +
> +	ret = regmap_read(st->regmap, base_reg + 2, &lsb);
> +	if (ret)
> +		return ret;
> +
> +	*val = (msb << 16) | (mid << 8) | lsb;

No bulk read?  

> +
> +	return 0;
> +}


> +static unsigned int ad7768_get_max_mode_freq(const struct ad7768_state *st,
> +					     unsigned int mode,
> +					     unsigned int mode_freq)
> +{
> +	unsigned int max_freq = 0;
> +	unsigned int i, freq;
> +
> +	for (i = 0; i < AD7768_NUM_CHANNEL_MODES; i++) {
> +		if (!(st->active_modes & BIT(i)))
> +			continue;
> +
> +		freq = i == mode ? mode_freq : st->mode_freq[i];
> +		if (freq > max_freq)
> +			max_freq = freq;
		max_freq = max(max_freq, freq);

> +	}
> +
> +	return max_freq;
> +}
> +
> +static int ad7768_set_sampling_freq(struct iio_dev *indio_dev,
> +				    unsigned int freq, unsigned int ch)
> +{
> +	struct ad7768_state *st = iio_priv(indio_dev);
> +	unsigned int mode = st->chn_mode[ch];
> +	int ret = 0;

Always set before use so don't init.

> +	unsigned int max_freq;
> +
> +	if (!freq)
> +		return -EINVAL;
> +
> +	guard(mutex)(&st->lock);
> +
> +	max_freq = ad7768_get_max_mode_freq(st, mode, freq);
> +
> +	ret = ad7768_set_clk_divs(st, max_freq, ch);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = ad7768_set_channel_decimation(st, freq, ch);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = ad7768_sync(st);
> +	if (ret)
> +		return ret;
> +
> +	st->mode_freq[mode] = freq;

blank line before simple returns like this one.

> +	return 0;
> +}

> +
> +static int ad7768_read_raw(struct iio_dev *indio_dev,
> +			   const struct iio_chan_spec *chan,
> +			   int *val, int *val2, long info)
> +{

...

> +	case IIO_CHAN_INFO_PHASE:
> +		if (st->chip_info->num_channels == AD7768_MAX_CHANNEL)
> +			base_reg = AD7768_REG_PHASE(chan->address);
> +		else
> +			base_reg = AD7768_4_REG_PHASE(chan->address);
> +
> +		ret = regmap_read(st->regmap, base_reg, val);

As below. Check units.

> +		if (ret)
> +			return ret;
> +
> +		return IIO_VAL_INT;
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static int ad7768_write_raw(struct iio_dev *indio_dev,
> +			    struct iio_chan_spec const *chan,
> +			    int val, int val2, long info)
> +{
> +	struct ad7768_state *st = iio_priv(indio_dev);
> +	unsigned int base_reg;
> +	int ret;
> +
> +	PM_RUNTIME_ACQUIRE_IF_ENABLED_AUTOSUSPEND(&st->spi->dev, pm);
> +	ret = PM_RUNTIME_ACQUIRE_ERR(&pm);
> +	if (ret)
> +		return ret;
> +
> +	switch (info) {
> +	case IIO_CHAN_INFO_SAMP_FREQ:
> +		return ad7768_set_sampling_freq(indio_dev, val, chan->channel);
> +
> +	case IIO_CHAN_INFO_CALIBBIAS:
> +		return ad7768_write_calib_value(st,
> +			ad7768_get_calib_reg_base(st, chan, false), val);

Probably use a local variable for the reg base as you do for
phase so you can align easily after the (

> +
> +	case IIO_CHAN_INFO_CALIBSCALE:
> +		return ad7768_write_calib_value(st,
> +			ad7768_get_calib_reg_base(st, chan, true), val);
> +
> +	case IIO_CHAN_INFO_PHASE:
> +		if (st->chip_info->num_channels == AD7768_MAX_CHANNEL)
> +			base_reg = AD7768_REG_PHASE(chan->address);
> +		else
> +			base_reg = AD7768_4_REG_PHASE(chan->address);
> +
> +		return regmap_write(st->regmap, base_reg, val);

Is val in the units the ABI expects? Seems unlikely given that's radians.


> +
> +	default:
> +		return -EINVAL;
> +	}
> +}

> +
> +static int ad7768_buffer_postdisable(struct iio_dev *indio_dev)
> +{
> +	struct ad7768_state *st = iio_priv(indio_dev);
> +
> +	pm_runtime_mark_last_busy(&st->spi->dev);

Look up what the next call does.

> +	pm_runtime_put_autosuspend(&st->spi->dev);
> +	return 0;
> +}

> +
> +static void ad7768_set_available_sampl_freq(struct ad7768_state *st)
> +{
> +	unsigned int mode;
> +	unsigned int dec;
> +	unsigned int mclk = clk_get_rate(st->mclk);
> +	struct ad7768_avail_freq *avail_freq;
> +
> +	for (mode = 0; mode < AD7768_NUM_POWER_MODES; mode++) {
	for (unsigned int mode = 0;  
> +		avail_freq = &st->avail_freq[mode];
> +		for (dec = ARRAY_SIZE(ad7768_dec_rate); dec > 0; dec--) {

for (unsigned int dec = ...


> +			struct ad7768_freq_config freq_cfg;
> +
> +			freq_cfg.dec_rate = dec - 1;
> +			freq_cfg.freq = mclk / (ad7768_dec_rate[dec - 1] *
> +					ad7768_mclk_div[mode]);
> +			avail_freq->freq_cfg[avail_freq->n_freqs++] = freq_cfg;
> +		}
> +	}
> +
> +	/* The max frequency is not supported in one data line configuration */
> +	if (st->datalines == 1)
> +		st->avail_freq[AD7768_FAST_MODE].n_freqs--;
> +}
> +
> +static int ad7768_gpio_adev_init(struct ad7768_state *st)
> +{
> +	struct device *dev = &st->spi->dev;
> +	struct auxiliary_device *adev;
> +	int id;
> +
> +	if (!device_property_read_bool(dev, "gpio-controller"))
> +		return 0;
> +
> +	id = (st->spi->controller->bus_num << 8) | spi_get_chipselect(st->spi, 0);

Why that particular ID?  Add some comment.

> +	adev = __devm_auxiliary_device_create(dev, KBUILD_MODNAME,
> +					      AD7768_AUX_DEV_GPIO_NAME,
> +					      (void *)st->chip_info->name, id);

Why is the cast to void * needed?  Suggests perhaps the type is wrong for name.


> +	if (!adev)
> +		return dev_err_probe(dev, -ENODEV,
> +				     "Failed to create GPIO auxiliary device\n");
> +
> +	return 0;
> +}

> +
> +static int ad7768_configure_precharge_buffers(struct iio_dev *indio_dev,
> +					      struct ad7768_precharge_config *precharge_cfg)
> +{
> +	struct ad7768_state *st = iio_priv(indio_dev);
> +	int ret;
> +	u8 ch;
> +	u8 prebuf1_val, prebuf2_val;

Prefer reverse xmas tree where the ordering isn't really enforced by anything else.

> +	u16 prebuf_mask = 0;
> +	u8 refbufp_val = 0;
> +	u8 refbufn_val = 0;
> +
> +	if (st->chip_info->num_channels == AD7768_MAX_CHANNEL) {

This match is odd. Encode what you need in chip_info, don't use the
number of channels as a place holder for which chip it is.
Maybe via a callback, or maybe via data. I haven't messed around
with it to see how bad the data version is (masks etc)

> +		for (ch = 0; ch < indio_dev->num_channels; ch++) {
> +			u8 channel = indio_dev->channels[ch].channel;
> +
> +			if (precharge_cfg[channel].prebufp_en)
> +				prebuf_mask |= AD7768_PREBUF_POS_EN(channel);
> +
> +			if (precharge_cfg[channel].prebufn_en)
> +				prebuf_mask |= AD7768_PREBUF_NEG_EN(channel);
> +
> +			if (precharge_cfg[channel].refbufp)
> +				refbufp_val |= BIT(channel);
> +
> +			if (precharge_cfg[channel].refbufn)
> +				refbufn_val |= BIT(channel);
> +		}
> +
> +		prebuf1_val = AD7768_PRECHARGE_BUF1_MSK(prebuf_mask);
> +		prebuf2_val = AD7768_PRECHARGE_BUF2_MSK(prebuf_mask);
> +	} else {
> +		for (ch = 0; ch < indio_dev->num_channels; ch++) {
> +			u8 channel = indio_dev->channels[ch].channel;
> +
> +			if (precharge_cfg[channel].prebufp_en)
> +				prebuf_mask |= AD7768_PREBUF_POS_EN(channel);
> +
> +			if (precharge_cfg[channel].prebufn_en)
> +				prebuf_mask |= AD7768_PREBUF_NEG_EN(channel);
> +
> +			if (precharge_cfg[channel].refbufp)
> +				refbufp_val |= ad7768_4_get_refbuf(channel);
> +
> +			if (precharge_cfg[channel].refbufn)
> +				refbufn_val |= ad7768_4_get_refbuf(channel);
> +		}
> +
> +		prebuf1_val = AD7768_4_PRECHARGE_BUF1_MSK(prebuf_mask);
> +		prebuf2_val = AD7768_4_PRECHARGE_BUF2_MSK(prebuf_mask);
> +	}
> +
> +	ret = regmap_write(st->regmap, AD7768_REG_PRECHARGE_BUF1, prebuf1_val);
Mentioned below, but if (ret) is more appropriate for regmap calls because...
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = regmap_write(st->regmap, AD7768_REG_PRECHARGE_BUF2, prebuf2_val);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = regmap_write(st->regmap, AD7768_REG_REFP_BUF, refbufp_val);
> +	if (ret < 0)
> +		return ret;
> +

If ret did go positive ever the following would treat it differently to
every other call.

> +	return regmap_write(st->regmap, AD7768_REG_REFN_BUF, refbufn_val);
> +}

> +
> +static struct iio_chan_spec_ext_info ad7768_ext_info[] = {
> +	IIO_ENUM("filter_type", IIO_SEPARATE,
> +		 &ad7768_filter_types_enum),
> +	IIO_ENUM_AVAILABLE("filter_type", IIO_SEPARATE, &ad7768_filter_types_enum),
> +	{ },

No trailing comma on a terminating entry like that one.


> +};
> +
> +static const struct iio_chan_spec ad7768_channel_template = {
> +	.type = IIO_VOLTAGE,
> +	.info_mask_separate =	BIT(IIO_CHAN_INFO_CALIBBIAS) |
> +				BIT(IIO_CHAN_INFO_CALIBSCALE) |
> +				BIT(IIO_CHAN_INFO_PHASE) |
> +				BIT(IIO_CHAN_INFO_SAMP_FREQ),
> +	.indexed = 1,
> +	.scan_type = {
> +		.sign = 's',
> +		.realbits = 24,
> +		.storagebits = 32,
> +	},
> +	.ext_info = ad7768_ext_info,
> +};
> +
> +static void ad7768_init_chan(struct iio_chan_spec *chan, unsigned int channel)
> +{
> +	*chan = ad7768_channel_template;
I'd replace where this is called with
		chan[chan_idx] = (struct iio_chan_spec) {
			.type = IIO_VOLTAGE,
etc.
  Generally ends up easier to read than a template and modify.

> +	chan->address = channel;
> +	chan->channel = channel;
> +	chan->scan_index = channel;
> +}
> +
> +static int ad7768_parse_config(struct iio_dev *indio_dev,
> +			       struct device *dev)
> +{
> +	struct ad7768_state *st = iio_priv(indio_dev);
> +	const unsigned int *available_datalines;
> +	struct ad7768_precharge_config precharge_cfg[AD7768_MAX_CHANNEL] = {};

Trivial but { }; would be my preference for style of that.

> +	struct iio_chan_spec *chan;
> +	unsigned int num_channels;
> +	unsigned int channel;
> +	unsigned int i, len, vcm_sel, vcm_pd, ch_mode, pwr_mode;

What you combine and what you don't combine here seems a bit random. Maybe
take another look and see if there is a more logical combination.
(or maybe this makes sense after a later patch, in which case ignore
this comment).

> +	int chan_idx = 0;
> +	int ret;
> +
> +	num_channels = device_get_child_node_count(dev);
> +

Given following is a check on the value returned, no blank line here would
keep that association more obvious.

> +	if (!num_channels || num_channels > st->chip_info->num_channels)
> +		return dev_err_probe(dev, -EINVAL, "Invalid number of channels\n");
> +
> +	chan = devm_kcalloc(indio_dev->dev.parent, num_channels,
> +			    sizeof(*chan), GFP_KERNEL);
> +	if (!chan)
> +		return -ENOMEM;
> +
> +	indio_dev->channels = chan;
> +	indio_dev->num_channels = num_channels;
> +
> +	ret = regmap_write(st->regmap, AD7768_REG_CH_STANDBY,
> +			   GENMASK(st->chip_info->num_channels - 1, 0));
> +	if (ret < 0)
> +		return ret;

regmap is always 0 or negative, so these can be if (ret)

> +
> +	device_for_each_child_node_scoped(dev, child) {
> +		ret = fwnode_property_read_u32(child, "reg", &channel);
> +		if (ret)
> +			return dev_err_probe(dev, ret,
> +					     "Failed to parse reg property of %pfwP\n", child);
> +
> +		if (channel >= st->chip_info->num_channels)
> +			return dev_err_probe(dev, -EINVAL,
> +					     "Invalid channel number %d\n", channel);

maybe put "from firmware" in that error message.

> +
> +		ret = regmap_update_bits(st->regmap, AD7768_REG_CH_STANDBY,
> +					 BIT(channel), 0);
> +		if (ret < 0)
> +			return ret;
> +
> +		ret = fwnode_property_read_u32(child, "adi,ch-mode", &ch_mode);

David covered this when reviewing the binding. There is quite a bit of precedence
of smaller sets of config registers than channels. Usually we just make it a userspace
thing and fail if too many configs are requested.

> +		if (ret)
> +			return dev_err_probe(dev, ret,
> +					     "Failed to parse property adi,ch-mode %pfwP\n",
> +					     child);

> +
> +	ret = regmap_update_bits(st->regmap,
> +				 AD7768_REG_GENERAL_CONFIG,
> +				 AD7768_GEN_CONFIG_VCM_PD,
> +				 vcm_pd ? AD7768_GEN_CONFIG_VCM_PD : 0);

regmap_assign_bits()

> +	if (ret < 0)
> +		return ret;
> +
> +	ret = device_property_match_property_string(&st->spi->dev,
> +						    "adi,power-mode",
> +						    ad7768_power_mode_str,
> +						    ARRAY_SIZE(ad7768_power_mode_str));
> +	if (ret < 0) {
> +		if (ret != -ENODATA)

Check for device property existing before reading it. Avoids need for caring
about the specific return value.

	if (device_property_present()) {
		ret = device_property_match...
...
	} else {
		pwr_mode = AD7768_LOW_POWER_MODE;
	}

> +			return dev_err_probe(&st->spi->dev, ret,
> +					     "Invalid \"adi,power-mode\" property\n");
> +
> +		pwr_mode = AD7768_LOW_POWER_MODE;
> +	} else {
> +		pwr_mode = ret;
> +	}
> +
> +	ret = ad7768_set_power_mode(indio_dev, pwr_mode);
> +	if (ret)
> +		return dev_err_probe(dev, ret, "Failed to set power mode\n");
> +
> +	for (i = 0; i < indio_dev->num_channels; i++) {
> +		ret = ad7768_set_sampling_freq(indio_dev, st->sampling_freq,
> +					       indio_dev->channels[i].channel);
> +		if (ret < 0)
> +			return dev_err_probe(dev, ret,
> +					     "Failed to set sampling freq for channel %d\n",
> +					     indio_dev->channels[i].channel);
> +	}
> +
> +	available_datalines = st->chip_info->available_datalines;
> +	len = st->chip_info->num_datalines;
> +
> +	for (i = 0; i < len; i++) {
> +		if (available_datalines[i] == st->datalines)
> +			return 0;
I'd be tempted to not do something so specific to it being the last bit
of the function and keep the error case as clearly out of line.
		if (...)
			break;
	}
	if (i == len)
		return dev_err_probe();

	return 0;
> +	}
> +
> +	return dev_err_probe(&st->spi->dev, -EINVAL,

use dev

> +			     "Invalid data-lines-number %d for %s\n",
> +			     st->datalines, st->chip_info->name);
> +}
> +
> +static int ad7768_reset(struct ad7768_state *st)
> +{
> +	struct reset_control *reset_ctrl;
> +	int ret;
> +
> +	reset_ctrl = devm_reset_control_get_optional_exclusive(&st->spi->dev, NULL);
> +	if (IS_ERR(reset_ctrl))
> +		return PTR_ERR(reset_ctrl);
> +
> +	if (reset_ctrl) {
> +		ret = reset_control_assert(reset_ctrl);
> +		if (ret)
> +			return ret;

Probably do need a delay of some type here. See if you can find anything in the
data sheet on what it should be (sashiko)

> +
> +		ret = reset_control_deassert(reset_ctrl);
> +		if (ret)
> +			return ret;
> +	} else {
> +		ret = regmap_write(st->regmap, AD7768_REG_DATA_CONTROL,
> +				   AD7768_DATA_CONTROL_SPI_RESET_1);
> +		if (ret)
> +			return ret;
> +
> +		ret = regmap_write(st->regmap, AD7768_REG_DATA_CONTROL,
> +				   AD7768_DATA_CONTROL_SPI_RESET_2);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	/* ADC start-up time after reset: 1.66 ms max (datasheet Table 1) */
> +	fsleep(2000);
> +
> +	return 0;
> +}
> +
> +static int ad7768_probe(struct spi_device *spi)
> +{

...

> +	ret = devm_iio_backend_enable(dev, st->back);
> +	if (ret)
> +		return ret;
> +
> +	pm_runtime_set_autosuspend_delay(dev, 2000);
> +	pm_runtime_use_autosuspend(dev);
> +	pm_runtime_set_active(dev);
> +
> +	ret = devm_pm_runtime_enable(dev);

I'm fairly sure the sashiko comment here is incorrect but do check it.

> +	if (ret)
> +		return ret;
> +
> +	indio_dev->setup_ops = &ad7768_buffer_ops;
> +
> +	ret = ad7768_gpio_adev_init(st);
> +	if (ret)
> +		return ret;
> +
> +	return devm_iio_device_register(dev, indio_dev);
> +}
> +
> +static int ad7768_runtime_suspend(struct device *dev)
> +{
> +	struct ad7768_state *st = dev_get_drvdata(dev);
> +
> +	return regmap_update_bits(st->regmap, AD7768_REG_POWER_MODE,
> +				  AD7768_SLEEP_MODE_MSK,
> +				  AD7768_SLEEP_MODE_MSK);

regmap_set_bits()

> +}
> +
> +static int ad7768_runtime_resume(struct device *dev)
> +{
> +	struct ad7768_state *st = dev_get_drvdata(dev);
> +	int ret;
> +
> +	ret = regmap_update_bits(st->regmap, AD7768_REG_POWER_MODE,
> +				 AD7768_SLEEP_MODE_MSK, 0);

regmap_clear_bits()

> +	if (ret)
> +		return ret;

Re: [PATCH 4/6] iio: adc: Add AD7768 IIO Driver support

[Uwe Kleine-König]

[-- Attachment #1: Type: text/plain, Size: 232 bytes --]

On Thu, Jul 09, 2026 at 10:50:15AM +0200, Janani Sunil wrote:
> +#include <linux/mod_devicetable.h>

Please don't add new users for this header file. Only use those
<linux/device-id/*.h> that you actually need (if any).

Thanks
Uwe

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 488 bytes --]

[PATCH 5/6] gpio: ad7768: Add AD7768 GPIO auxiliary driver

[Janani Sunil]

The AD7768/AD7768-4 ADC exposes 5 general-purpose I/O pins that can be
independently configured as inputs or outputs. Add an auxiliary bus driver
to expose these pins as a GPIO chip, registered by the parent IIO driver.

The driver uses the parent's regmap for register access and delegates
runtime power management to the parent device.

Signed-off-by: Janani Sunil <janani.sunil@analog.com>
---
 MAINTAINERS                |   1 +
 drivers/gpio/Kconfig       |  10 +++
 drivers/gpio/Makefile      |   1 +
 drivers/gpio/gpio-ad7768.c | 208 +++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 220 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index dc94e7803a7c..3de7ebcc4ee7 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1639,6 +1639,7 @@ L:	linux-iio@vger.kernel.org
 S:	Supported
 W:	https://ez.analog.com/linux-software-drivers
 F:	Documentation/devicetree/bindings/iio/adc/adi,ad7768.yaml
+F:	drivers/gpio/gpio-ad7768.c
 F:	drivers/iio/adc/ad7768.c
 
 ANALOG DEVICES INC AD7780 DRIVER
diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 28cf6d2e83c2..12ebbdb16982 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -1796,6 +1796,16 @@ endmenu
 menu "Auxiliary Bus GPIO drivers"
 	depends on AUXILIARY_BUS
 
+config GPIO_AD7768
+	tristate "Analog Devices AD7768 GPIO support"
+	depends on AD7768 && GPIOLIB
+	help
+	  Say yes here to expose the AD7768 utility pins as GPIOs when the
+	  device tree node is marked as a GPIO controller.
+
+	  To compile this driver as a module, choose M here: the module will be
+	  called gpio-ad7768.
+
 config GPIO_LTC4283
 	tristate "Analog Devices LTC4283 GPIO support"
 	depends on SENSORS_LTC4283
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index 4d0e900402fc..d2921963efc7 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -27,6 +27,7 @@ obj-$(CONFIG_GPIO_104_IDI_48)		+= gpio-104-idi-48.o
 obj-$(CONFIG_GPIO_104_IDIO_16)		+= gpio-104-idio-16.o
 obj-$(CONFIG_GPIO_74X164)		+= gpio-74x164.o
 obj-$(CONFIG_GPIO_74XX_MMIO)		+= gpio-74xx-mmio.o
+obj-$(CONFIG_GPIO_AD7768)		+= gpio-ad7768.o
 obj-$(CONFIG_GPIO_ADNP)			+= gpio-adnp.o
 obj-$(CONFIG_GPIO_ADP5520)		+= gpio-adp5520.o
 obj-$(CONFIG_GPIO_ADP5585)		+= gpio-adp5585.o
diff --git a/drivers/gpio/gpio-ad7768.c b/drivers/gpio/gpio-ad7768.c
new file mode 100644
index 000000000000..c2f01b1abd7c
--- /dev/null
+++ b/drivers/gpio/gpio-ad7768.c
@@ -0,0 +1,208 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Analog Devices AD7768 GPIO auxiliary driver
+ *
+ * Copyright 2026 Analog Devices Inc.
+ */
+
+#include <linux/auxiliary_bus.h>
+#include <linux/cleanup.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/gpio/driver.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/pm_runtime.h>
+#include <linux/regmap.h>
+
+#define AD7768_REG_GPIO_CONTROL		0x0E
+#define AD7768_REG_GPIO_WRITE		0x0F
+#define AD7768_REG_GPIO_READ		0x10
+
+#define AD7768_GPIO_UGPIO_ENABLE	BIT(7)
+#define AD7768_GPIO_INPUT		0x00
+#define AD7768_GPIO_OUTPUT(x)		BIT(x)
+
+#define AD7768_NUM_GPIOS		5
+
+struct ad7768_gpio_state {
+	struct device *parent;
+	struct regmap *regmap;
+	struct mutex lock; /* protects regmap accesses */
+	struct gpio_chip gc;
+};
+
+static int ad7768_gpio_direction_input(struct gpio_chip *chip,
+				       unsigned int offset)
+{
+	struct ad7768_gpio_state *st = gpiochip_get_data(chip);
+
+	PM_RUNTIME_ACQUIRE_IF_ENABLED_AUTOSUSPEND(st->parent, pm);
+	int ret = PM_RUNTIME_ACQUIRE_ERR(&pm);
+
+	if (ret)
+		return ret;
+
+	return regmap_update_bits(st->regmap, AD7768_REG_GPIO_CONTROL,
+				  BIT(offset), AD7768_GPIO_INPUT);
+}
+
+static int ad7768_gpio_get_direction(struct gpio_chip *chip,
+				     unsigned int offset)
+{
+	struct ad7768_gpio_state *st = gpiochip_get_data(chip);
+	unsigned int val;
+	int ret;
+
+	PM_RUNTIME_ACQUIRE_IF_ENABLED_AUTOSUSPEND(st->parent, pm);
+	ret = PM_RUNTIME_ACQUIRE_ERR(&pm);
+	if (ret)
+		return ret;
+
+	ret = regmap_read(st->regmap, AD7768_REG_GPIO_CONTROL, &val);
+	if (ret)
+		return ret;
+
+	return !!(val & BIT(offset)) ? GPIO_LINE_DIRECTION_OUT :
+				       GPIO_LINE_DIRECTION_IN;
+}
+
+static int ad7768_gpio_direction_output(struct gpio_chip *chip,
+					unsigned int offset, int value)
+{
+	struct ad7768_gpio_state *st = gpiochip_get_data(chip);
+	int ret;
+
+	PM_RUNTIME_ACQUIRE_IF_ENABLED_AUTOSUSPEND(st->parent, pm);
+	ret = PM_RUNTIME_ACQUIRE_ERR(&pm);
+	if (ret)
+		return ret;
+
+	guard(mutex)(&st->lock);
+
+	ret = regmap_update_bits(st->regmap, AD7768_REG_GPIO_CONTROL,
+				 BIT(offset), AD7768_GPIO_OUTPUT(offset));
+	if (ret)
+		return ret;
+
+	return regmap_update_bits(st->regmap, AD7768_REG_GPIO_WRITE,
+				  BIT(offset), value << offset);
+}
+
+static int ad7768_gpio_get(struct gpio_chip *chip, unsigned int offset)
+{
+	struct ad7768_gpio_state *st = gpiochip_get_data(chip);
+	unsigned int val;
+	int ret;
+
+	PM_RUNTIME_ACQUIRE_IF_ENABLED_AUTOSUSPEND(st->parent, pm);
+	ret = PM_RUNTIME_ACQUIRE_ERR(&pm);
+	if (ret)
+		return ret;
+
+	guard(mutex)(&st->lock);
+
+	ret = regmap_read(st->regmap, AD7768_REG_GPIO_CONTROL, &val);
+	if (ret)
+		return ret;
+
+	if (val & BIT(offset))
+		ret = regmap_read(st->regmap, AD7768_REG_GPIO_WRITE, &val);
+	else
+		ret = regmap_read(st->regmap, AD7768_REG_GPIO_READ, &val);
+	if (ret)
+		return ret;
+
+	return !!(val & BIT(offset));
+}
+
+static int ad7768_gpio_set(struct gpio_chip *chip, unsigned int offset,
+			   int value)
+{
+	struct ad7768_gpio_state *st = gpiochip_get_data(chip);
+	unsigned int val;
+	int ret;
+
+	PM_RUNTIME_ACQUIRE_IF_ENABLED_AUTOSUSPEND(st->parent, pm);
+	ret = PM_RUNTIME_ACQUIRE_ERR(&pm);
+	if (ret)
+		return ret;
+
+	guard(mutex)(&st->lock);
+
+	ret = regmap_read(st->regmap, AD7768_REG_GPIO_CONTROL, &val);
+	if (ret)
+		return ret;
+
+	if (!(val & BIT(offset)))
+		return 0;
+
+	return regmap_update_bits(st->regmap, AD7768_REG_GPIO_WRITE,
+				  BIT(offset), value << offset);
+}
+
+static int ad7768_gpio_probe(struct auxiliary_device *adev,
+			     const struct auxiliary_device_id *id)
+{
+	struct device *dev = &adev->dev;
+	const char *label = dev_get_platdata(dev);
+	struct ad7768_gpio_state *st;
+	struct gpio_chip *gc;
+	int ret;
+
+	st = devm_kzalloc(dev, sizeof(*st), GFP_KERNEL);
+	if (!st)
+		return -ENOMEM;
+
+	st->parent = dev->parent;
+	st->regmap = dev_get_regmap(dev->parent, NULL);
+
+	ret = devm_mutex_init(dev, &st->lock);
+	if (ret)
+		return ret;
+
+	ret = pm_runtime_resume_and_get(st->parent);
+	if (ret < 0)
+		return ret;
+
+	ret = regmap_update_bits(st->regmap, AD7768_REG_GPIO_CONTROL,
+				 AD7768_GPIO_UGPIO_ENABLE,
+				 AD7768_GPIO_UGPIO_ENABLE);
+
+	pm_runtime_mark_last_busy(st->parent);
+	pm_runtime_put_autosuspend(st->parent);
+
+	if (ret < 0)
+		return ret;
+
+	gc = &st->gc;
+	gc->label = label;
+	gc->base = -1;
+	gc->ngpio = AD7768_NUM_GPIOS;
+	gc->parent = dev;
+	gc->owner = THIS_MODULE;
+	gc->can_sleep = true;
+	gc->get_direction = ad7768_gpio_get_direction;
+	gc->direction_input = ad7768_gpio_direction_input;
+	gc->direction_output = ad7768_gpio_direction_output;
+	gc->get = ad7768_gpio_get;
+	gc->set = ad7768_gpio_set;
+
+	return devm_gpiochip_add_data(dev, &st->gc, st);
+}
+
+static const struct auxiliary_device_id ad7768_gpio_ids[] = {
+	{ .name = "ad7768.gpio" },
+	{ }
+};
+MODULE_DEVICE_TABLE(auxiliary, ad7768_gpio_ids);
+
+static struct auxiliary_driver ad7768_gpio_driver = {
+	.probe = ad7768_gpio_probe,
+	.id_table = ad7768_gpio_ids,
+};
+module_auxiliary_driver(ad7768_gpio_driver);
+
+MODULE_AUTHOR("Janani Sunil <janani.sunil@analog.com>");
+MODULE_DESCRIPTION("Analog Devices AD7768 GPIO auxiliary driver");
+MODULE_LICENSE("GPL");

-- 
2.43.0

Re: [PATCH 5/6] gpio: ad7768: Add AD7768 GPIO auxiliary driver

[Andy Shevchenko]

On Thu, Jul 09, 2026 at 10:50:16AM +0200, Janani Sunil wrote:
> The AD7768/AD7768-4 ADC exposes 5 general-purpose I/O pins that can be
> independently configured as inputs or outputs. Add an auxiliary bus driver
> to expose these pins as a GPIO chip, registered by the parent IIO driver.
> 
> The driver uses the parent's regmap for register access and delegates
> runtime power management to the parent device.

...

> +config GPIO_AD7768
> +	tristate "Analog Devices AD7768 GPIO support"
> +	depends on AD7768 && GPIOLIB

Make depend on GPIOLIB on a separate line (it helps a lot when grepping for
the users of GPIOLIB).

> +	help
> +	  Say yes here to expose the AD7768 utility pins as GPIOs when the
> +	  device tree node is marked as a GPIO controller.
> +
> +	  To compile this driver as a module, choose M here: the module will be
> +	  called gpio-ad7768.

>  config GPIO_LTC4283

Shouldn't Kconfig entry be aligned by order with Makefile ordering?

...

> +#include <linux/auxiliary_bus.h>

+ bits.h

> +#include <linux/cleanup.h>
> +#include <linux/device.h>
> +#include <linux/err.h>
> +#include <linux/gpio/driver.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/pm_runtime.h>
> +#include <linux/regmap.h>

Please, IWYU! I believe AD knows this very well and again same mistake from AD!

...

> +struct ad7768_gpio_state {
> +	struct device *parent;
> +	struct regmap *regmap;

As far as I can see these two are dups. One may be derived from the other.
Try both and check (with probably bloat-o-meter) which one is better.

> +	struct mutex lock; /* protects regmap accesses */

This is not fully correct comment. This protects GPIO IO which may require more
than one regmap call in a row.

> +	struct gpio_chip gc;
> +};

...

> +static int ad7768_gpio_direction_input(struct gpio_chip *chip,
> +				       unsigned int offset)
> +{
> +	struct ad7768_gpio_state *st = gpiochip_get_data(chip);
> +
> +	PM_RUNTIME_ACQUIRE_IF_ENABLED_AUTOSUSPEND(st->parent, pm);

> +	int ret = PM_RUNTIME_ACQUIRE_ERR(&pm);

No, declare it usual way.

> +

And drop this blank line.

> +	if (ret)
> +		return ret;
> +
> +	return regmap_update_bits(st->regmap, AD7768_REG_GPIO_CONTROL,
> +				  BIT(offset), AD7768_GPIO_INPUT);
> +}

...

So, I briefly looked at the implementation and I don't understand why
gpio-regmap can't be used. Do you need PM runtime there? It can be
done for all (if absent).

...

> +static int ad7768_gpio_probe(struct auxiliary_device *adev,
> +			     const struct auxiliary_device_id *id)
> +{
> +	struct device *dev = &adev->dev;
> +	const char *label = dev_get_platdata(dev);
> +	struct ad7768_gpio_state *st;
> +	struct gpio_chip *gc;
> +	int ret;
> +
> +	st = devm_kzalloc(dev, sizeof(*st), GFP_KERNEL);
> +	if (!st)
> +		return -ENOMEM;
> +
> +	st->parent = dev->parent;
> +	st->regmap = dev_get_regmap(dev->parent, NULL);
> +
> +	ret = devm_mutex_init(dev, &st->lock);
> +	if (ret)
> +		return ret;
> +
> +	ret = pm_runtime_resume_and_get(st->parent);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = regmap_update_bits(st->regmap, AD7768_REG_GPIO_CONTROL,
> +				 AD7768_GPIO_UGPIO_ENABLE,
> +				 AD7768_GPIO_UGPIO_ENABLE);
> +

> +	pm_runtime_mark_last_busy(st->parent);

For a few releases this is a dup call.

> +	pm_runtime_put_autosuspend(st->parent);
> +
> +	if (ret < 0)
> +		return ret;
> +
> +	gc = &st->gc;
> +	gc->label = label;
> +	gc->base = -1;
> +	gc->ngpio = AD7768_NUM_GPIOS;
> +	gc->parent = dev;
> +	gc->owner = THIS_MODULE;
> +	gc->can_sleep = true;
> +	gc->get_direction = ad7768_gpio_get_direction;
> +	gc->direction_input = ad7768_gpio_direction_input;
> +	gc->direction_output = ad7768_gpio_direction_output;
> +	gc->get = ad7768_gpio_get;
> +	gc->set = ad7768_gpio_set;
> +
> +	return devm_gpiochip_add_data(dev, &st->gc, st);
> +}

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH 5/6] gpio: ad7768: Add AD7768 GPIO auxiliary driver

[Jonathan Cameron]

On Thu, 9 Jul 2026 10:50:16 +0200
Janani Sunil <janani.sunil@analog.com> wrote:

> The AD7768/AD7768-4 ADC exposes 5 general-purpose I/O pins that can be
> independently configured as inputs or outputs. Add an auxiliary bus driver
> to expose these pins as a GPIO chip, registered by the parent IIO driver.
> 
> The driver uses the parent's regmap for register access and delegates
> runtime power management to the parent device.
> 
> Signed-off-by: Janani Sunil <janani.sunil@analog.com>
A few things inline.

> diff --git a/drivers/gpio/gpio-ad7768.c b/drivers/gpio/gpio-ad7768.c
> new file mode 100644
> index 000000000000..c2f01b1abd7c
> --- /dev/null
> +++ b/drivers/gpio/gpio-ad7768.c
...

> +static int ad7768_gpio_probe(struct auxiliary_device *adev,
> +			     const struct auxiliary_device_id *id)
> +{
> +	struct device *dev = &adev->dev;
> +	const char *label = dev_get_platdata(dev);
> +	struct ad7768_gpio_state *st;
> +	struct gpio_chip *gc;
> +	int ret;
> +
> +	st = devm_kzalloc(dev, sizeof(*st), GFP_KERNEL);
> +	if (!st)
> +		return -ENOMEM;
> +
> +	st->parent = dev->parent;
> +	st->regmap = dev_get_regmap(dev->parent, NULL);
> +
> +	ret = devm_mutex_init(dev, &st->lock);
> +	if (ret)
> +		return ret;
> +
> +	ret = pm_runtime_resume_and_get(st->parent);
I'd use the ACQUIRE stuff you used else where and not worry about
maybe keeping power on a tiny bit long.


> +	if (ret < 0)
> +		return ret;
> +
> +	ret = regmap_update_bits(st->regmap, AD7768_REG_GPIO_CONTROL,
> +				 AD7768_GPIO_UGPIO_ENABLE,
> +				 AD7768_GPIO_UGPIO_ENABLE);

set_bits()

> +
> +	pm_runtime_mark_last_busy(st->parent);

As before this is wrong.

> +	pm_runtime_put_autosuspend(st->parent);
> +
> +	if (ret < 0)
> +		return ret;
> +
> +	gc = &st->gc;
> +	gc->label = label;
> +	gc->base = -1;
> +	gc->ngpio = AD7768_NUM_GPIOS;
> +	gc->parent = dev;
> +	gc->owner = THIS_MODULE;
> +	gc->can_sleep = true;
> +	gc->get_direction = ad7768_gpio_get_direction;
> +	gc->direction_input = ad7768_gpio_direction_input;
> +	gc->direction_output = ad7768_gpio_direction_output;
> +	gc->get = ad7768_gpio_get;
> +	gc->set = ad7768_gpio_set;
> +
> +	return devm_gpiochip_add_data(dev, &st->gc, st);
use gc given you have it.

> +}

> 

Re: [PATCH 5/6] gpio: ad7768: Add AD7768 GPIO auxiliary driver

[Linus Walleij]

Hi Janani,

thanks for your patch!

On Thu, Jul 9, 2026 at 10:51 AM Janani Sunil <janani.sunil@analog.com> wrote:

> The AD7768/AD7768-4 ADC exposes 5 general-purpose I/O pins that can be
> independently configured as inputs or outputs. Add an auxiliary bus driver
> to expose these pins as a GPIO chip, registered by the parent IIO driver.
>
> The driver uses the parent's regmap for register access and delegates
> runtime power management to the parent device.
>
> Signed-off-by: Janani Sunil <janani.sunil@analog.com>

(...)

When I look at these functions I see they are very close to something
the GPIO_REGMAP helpers should be able to do.

Bascically all that stops you from doing this is:

> +static int ad7768_gpio_direction_input(struct gpio_chip *chip,
> +                                      unsigned int offset)
> +{
> +       struct ad7768_gpio_state *st = gpiochip_get_data(chip);
> +
> +       PM_RUNTIME_ACQUIRE_IF_ENABLED_AUTOSUSPEND(st->parent, pm);
> +       int ret = PM_RUNTIME_ACQUIRE_ERR(&pm);

These two things.

> +static int ad7768_gpio_get_direction(struct gpio_chip *chip,
> +                                    unsigned int offset)
> +{
> +       struct ad7768_gpio_state *st = gpiochip_get_data(chip);
> +       unsigned int val;
> +       int ret;
> +
> +       PM_RUNTIME_ACQUIRE_IF_ENABLED_AUTOSUSPEND(st->parent, pm);
> +       ret = PM_RUNTIME_ACQUIRE_ERR(&pm);
> +       if (ret)
> +               return ret;

Here again, etc.

Can't we just add a

struct device *pm_dev; to struct gpio_regmap_config, pass
st->parent there at init, modify drivers/gpio/gpio-regmap.c adding:

static int gpio_regmap_pm(struct gpio_regmap *gpio)
{
    PM_RUNTIME_ACQUIRE_IF_ENABLED_AUTOSUSPEND(gpio->pm_device, pm);
    ret = PM_RUNTIME_ACQUIRE_ERR(&pm);
    if (ret)
        return ret;
    return 0;
}

And call this in each of the standard callbacks so gpio-regmap.c
can handle PM as well for free? The above can be an ifdef stub if
runtime PM is not enabled.

Yours,
Linus Walleij

[PATCH 6/6] Documentation: iio: Add AD7768 Documentation

[Janani Sunil]

Add driver documentation for AD7768

Signed-off-by: Janani Sunil <janani.sunil@analog.com>
---
 Documentation/iio/ad7768.rst | 207 +++++++++++++++++++++++++++++++++++++++++++
 Documentation/iio/index.rst  |   1 +
 MAINTAINERS                  |   1 +
 3 files changed, 209 insertions(+)

diff --git a/Documentation/iio/ad7768.rst b/Documentation/iio/ad7768.rst
new file mode 100644
index 000000000000..438e33d4f375
--- /dev/null
+++ b/Documentation/iio/ad7768.rst
@@ -0,0 +1,207 @@
+.. SPDX-License-Identifier: GPL-2.0-only
+
+=============
+AD7768 driver
+=============
+
+ADC driver for Analog Devices Inc. AD7768 and AD7768-4 devices. The module name
+is ``ad7768``.
+
+Supported devices
+=================
+
+The following chips are supported by this driver:
+
+* `AD7768 <https://www.analog.com/en/products/ad7768.html>`_ - 8-channel, 24-bit simultaneous sampling ADC
+* `AD7768-4 <https://www.analog.com/en/products/ad7768-4.html>`_ - 4-channel, 24-bit simultaneous sampling ADC
+
+Supported features
+==================
+
+Power modes
+-----------
+
+The AD7768 family supports three configurable power and performance modes:
+
+* **Low power mode** - Optimized for lowest power consumption
+* **Median mode** - Balanced power and performance
+* **Fast mode** - Highest performance with maximum sampling rates
+
+The power mode affects the available sampling frequencies and power consumption.
+Set via the ``adi,power-mode`` device tree property.
+
+Data output configuration
+-------------------------
+
+The devices support flexible serial data output configurations:
+
+AD7768 data lines
+^^^^^^^^^^^^^^^^^
+
+* 1 data line (DOUT0) - Standard single-lane output
+* 2 data lines (DOUT0, DOUT1) - Dual-lane output for higher throughput
+* 8 data lines (DOUT0-DOUT7) - Maximum throughput, one line per channel
+
+AD7768-4 data lines
+^^^^^^^^^^^^^^^^^^^
+
+* 1 data line (DOUT0) - Standard single-lane output
+* 4 data lines (DOUT0-DOUT3) - Maximum throughput, one line per channel
+
+The number of data lines is configured via the ``adi,data-lines-number``
+device tree property.
+
+Channel configuration
+---------------------
+
+Each channel can be individually configured with:
+
+Channel modes
+^^^^^^^^^^^^^
+
+* **Mode A** - First set of filter and decimation settings
+* **Mode B** - Second set of filter and decimation settings
+
+Each channel can be assigned to either Mode A or Mode B via the
+``adi,ch-mode`` device tree property.
+
+Channels assigned to the same mode share the same runtime filter and
+decimation configuration. The per-channel IIO attributes for sampling
+frequency and filter type are aliases to the channel's assigned mode
+profile rather than independent per-channel settings.
+
+Precharge and reference buffers
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Per-channel buffer control for optimal signal integrity:
+
+* Positive input precharge buffer (``adi,prebuf-pos-en``)
+* Negative input precharge buffer (``adi,prebuf-neg-en``)
+* Positive reference buffer (``adi,refbuf-pos-en``)
+* Negative reference buffer (``adi,refbuf-neg-en``)
+
+Common mode voltage
+-------------------
+
+Configurable common mode output voltage levels:
+
+* (AVDD - AVSS) / 2V
+* 1.65V
+* 2.5V
+* 2.14V
+
+Set via the ``adi,common-mode-output`` device tree property.
+The common mode buffer can be powered down using ``adi,vcm-power-down``.
+
+Filter types
+------------
+
+Two digital filter types are available:
+
+* **Wideband** - Optimized for wide bandwidth applications
+* **Sinc5** - Fifth-order sinc filter for high rejection of out-of-band noise
+
+IIO backend support
+-------------------
+
+The driver integrates with IIO backends (e.g., AXI ADC) for high-speed data
+capture and DMA operations. Features include:
+
+* Automatic channel enable/disable based on scan mask
+* CRC on data interface. CRC replaces the header every 4th output sample.
+* High-throughput buffered data acquisition
+
+GPIO controller
+---------------
+
+The AD7768 includes a 5-pin GPIO controller for auxiliary digital I/O
+operations. The GPIO pins can be configured as inputs or outputs.
+
+Device attributes
+=================
+
+The following IIO attributes are available for each enabled channel:
+
+Sampling frequency
+------------------
+
++---------------------------------------+--------------------------------------------------------------+
+| Attribute                             | Description                                                  |
++=======================================+==============================================================+
+| ``in_voltage<N>_sampling_frequency``  | Current sampling frequency in Hz for channel N. Channels     |
+|                                       | assigned to the same mode profile read back the same value.  |
++---------------------------------------+--------------------------------------------------------------+
+
+Filter configuration
+---------------------
+
++---------------------------------------+--------------------------------------------------------------+
+| Attribute                             | Description                                                  |
++=======================================+==============================================================+
+| ``in_voltage<N>_filter_type``         | Current filter type for channel N: "wideband" or "sinc5".    |
+|                                       | Channels assigned to the same mode profile share this value. |
++---------------------------------------+--------------------------------------------------------------+
+| ``in_voltage<N>_filter_type_          | Available filter types for channel N: "wideband sinc5".      |
+| available``                           |                                                              |
++---------------------------------------+--------------------------------------------------------------+
+
+Per-channel calibration
+-----------------------
+
++---------------------------------------+--------------------------------------------------------------+
+| Attribute                             | Description                                                  |
++=======================================+==============================================================+
+| ``in_voltage<N>_calibbias``           | Channel offset calibration value                             |
++---------------------------------------+--------------------------------------------------------------+
+| ``in_voltage<N>_calibscale``          | Channel gain calibration value                               |
++---------------------------------------+--------------------------------------------------------------+
+| ``in_voltage<N>_phase``               | Channel phase calibration value.                             |
++---------------------------------------+--------------------------------------------------------------+
+
+Device buffers
+==============
+
+This driver supports IIO buffered data acquisition through IIO backends.
+When used with compatible backends like the AXI ADC, it provides:
+
+* High-speed simultaneous sampling across all enabled channels
+* Hardware-triggered data capture
+* DMA-based data transfer for minimal CPU overhead
+* CRC error detection
+
+See :doc:`iio_devbuf` for more information about IIO device buffers.
+
+Example usage
+=============
+
+.. code-block:: bash
+
+	# Read current sampling frequency for channel 0
+	cat /sys/bus/iio/devices/iio:device0/in_voltage0_sampling_frequency
+
+	# Update sampling frequency for channel 0
+	echo 8000 > /sys/bus/iio/devices/iio:device0/in_voltage0_sampling_frequency
+
+	# Read current filter type for channel 0
+	cat /sys/bus/iio/devices/iio:device0/in_voltage0_filter_type
+
+	# List available filter types for channel 0
+	cat /sys/bus/iio/devices/iio:device0/in_voltage0_filter_type_available
+
+	# Update filter type for channel 0 to wideband
+	echo wideband > /sys/bus/iio/devices/iio:device0/in_voltage0_filter_type
+
+	# Updating one channel also updates all channels assigned to the same
+	# mode profile (Mode A or Mode B) selected by adi,ch-mode in devicetree
+
+	# Read calibration scale for channel 0
+	cat /sys/bus/iio/devices/iio:device0/in_voltage0_calibscale
+
+	# Read phase calibration for channel 0
+	cat /sys/bus/iio/devices/iio:device0/in_voltage0_phase
+
+
+Unimplemented features
+======================
+
+* CRC message every 16 samples (CRC_SEL configuration) - currently only supports CRC every 4 samples
diff --git a/Documentation/iio/index.rst b/Documentation/iio/index.rst
index b02b879b053a..73c58cec7620 100644
--- a/Documentation/iio/index.rst
+++ b/Documentation/iio/index.rst
@@ -29,6 +29,7 @@ Industrial I/O Kernel Drivers
    ad7380
    ad7606
    ad7625
+   ad7768
    ad7944
    ade9000
    adf41513
diff --git a/MAINTAINERS b/MAINTAINERS
index 3de7ebcc4ee7..b93c77d3a4c3 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1639,6 +1639,7 @@ L:	linux-iio@vger.kernel.org
 S:	Supported
 W:	https://ez.analog.com/linux-software-drivers
 F:	Documentation/devicetree/bindings/iio/adc/adi,ad7768.yaml
+F:	Documentation/iio/ad7768.rst
 F:	drivers/gpio/gpio-ad7768.c
 F:	drivers/iio/adc/ad7768.c
 

-- 
2.43.0

Re: [PATCH 6/6] Documentation: iio: Add AD7768 Documentation

[Jonathan Cameron]

On Thu, 9 Jul 2026 10:50:17 +0200
Janani Sunil <janani.sunil@analog.com> wrote:

> Add driver documentation for AD7768
> 
> Signed-off-by: Janani Sunil <janani.sunil@analog.com>
> ---
>  Documentation/iio/ad7768.rst | 207 +++++++++++++++++++++++++++++++++++++++++++
>  Documentation/iio/index.rst  |   1 +
>  MAINTAINERS                  |   1 +
>  3 files changed, 209 insertions(+)
> 
> diff --git a/Documentation/iio/ad7768.rst b/Documentation/iio/ad7768.rst
> new file mode 100644
> index 000000000000..438e33d4f375
> --- /dev/null
> +++ b/Documentation/iio/ad7768.rst
> @@ -0,0 +1,207 @@
> +.. SPDX-License-Identifier: GPL-2.0-only
> +
> +=============
> +AD7768 driver
> +=============
> +
> +ADC driver for Analog Devices Inc. AD7768 and AD7768-4 devices. The module name
> +is ``ad7768``.
> +
> +Supported devices
> +=================
> +
> +The following chips are supported by this driver:
> +
> +* `AD7768 <https://www.analog.com/en/products/ad7768.html>`_ - 8-channel, 24-bit simultaneous sampling ADC
> +* `AD7768-4 <https://www.analog.com/en/products/ad7768-4.html>`_ - 4-channel, 24-bit simultaneous sampling ADC

Too long. Wrap those.  In general keep to 80 chars for docs
unless you are breaking up some thing greppable like a file name.


> +
> +Supported features
> +==================
> +
> +Power modes
> +-----------
> +
> +The AD7768 family supports three configurable power and performance modes:
> +
> +* **Low power mode** - Optimized for lowest power consumption
> +* **Median mode** - Balanced power and performance
> +* **Fast mode** - Highest performance with maximum sampling rates
> +
> +The power mode affects the available sampling frequencies and power consumption.
> +Set via the ``adi,power-mode`` device tree property.

Control it from the sampling frequency probably as David suggested.

> +
> +Per-channel calibration
> +-----------------------
> +
> ++---------------------------------------+--------------------------------------------------------------+
> +| Attribute                             | Description                                                  |
> ++=======================================+==============================================================+
> +| ``in_voltage<N>_calibbias``           | Channel offset calibration value                             |
> ++---------------------------------------+--------------------------------------------------------------+
> +| ``in_voltage<N>_calibscale``          | Channel gain calibration value                               |
> ++---------------------------------------+--------------------------------------------------------------+
> +| ``in_voltage<N>_phase``               | Channel phase calibration value.                             |
Be consistent on .

Also does this mean the phase offset is a tweak, or do we know the scaling?

> ++---------------------------------------+--------------------------------------------------------------+
> +