[PATCH v5 00/20] iio: adc: Add AD7768/AD7768-4 ADC driver support

[PATCH v5 00/20] 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 automatic power mode selection.

Datasheet:
https://www.analog.com/media/en/technical-documentation/data-sheets/ad7768-ad7768-4.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.
- Automatic low-noise power mode selection (fast, median, low power)
  with associated decimation rate and output data rate tables.
- Per-channel offset, gain, and conversion delay 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.
- VCM common-mode output exposed through the regulator framework, with
  runtime PM management while the output is enabled.

**Patch Summary:**
1. Initialize the AXI ADC state mutex.
2. Add the AD7768 and AD7768-4 devicetree binding.
3. Add the IIO backend CRC operation.
4. Implement CRC control in the AXI ADC backend.
5. Add core AD7768 and AD7768-4 capture support.
6. Validate the master clock rate.
7. Add the power-mode configuration helper.
8. Derive output data rates and the data-clock divider.
9. Configure enabled channels across two sampling profiles.
10. Expose per-channel sampling-frequency controls.
11. Expose per-channel filter controls.
12. Wait for active digital filters to settle.
13. Add per-channel offset and gain calibration controls.
14. Add per-channel conversion delay.
15. Expose the VCM output through the regulator framework.
16. Register the GPIO auxiliary device from the parent driver.
17. Use regmap_test_bits() for single-bit gpio-regmap reads.
18. Add optional runtime PM support to gpio-regmap.
19. Add the AD7768 GPIO auxiliary driver.
20. Add 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.

Signed-off-by: Janani Sunil <janani.sunil@analog.com>
---
Changes in v5:
- Split configurable sampling support into focused patches for clock
  validation, power-mode setup, output-rate derivation, channel profiles,
  sampling-frequency controls, filter controls, and filter settling.
- Read the positive and negative reference supply voltages and report the
  resulting differential IIO scale for each channel group.
- Allow grounded REF1- and REF2- inputs to omit their regulator supplies,
  treating absent negative reference supplies as 0 V.
- Document the per-channel IIO scale attribute.
- Require a named master clock, remove the default clock source, and
  clarify why the LVDS clock is enabled only after device configuration.
- Clarify the clock-source, supply, and VCM descriptions in the
  Devicetree binding, and drop the unused sync-out-gpios property.
- Simplify scan-mask handling, register-range checks, channel parsing,
  reset timing, probe initialization, and error reporting.
- Use the exact 1.66 ms reset start-up delay and standard time-unit
  constants for fixed delays.
- Avoid runtime-PM references for cached IIO attributes and acquire them
  locally for calibration register accesses.
- Use regmap_assign_bits() for single-bit assignments and sizeof() for
  calibration byte-array transfers.
- Rework gpio-regmap runtime-PM guards and synchronize the pm_dev member
  and kernel-doc ordering.
- Simplify the AD7768 GPIO auxiliary driver's includes and probe setup,
  and drop its cross-tree MAINTAINERS update.
- Note that the AXI ADC mutex fix is already queued in the IIO fixes tree.
- Link to v4: https://lore.kernel.org/r/20260821-ad7768-driver-v4-0-bb8fbd06d4eb@analog.com

Changes in v4:
- Move the AXI ADC mutex initialization fix to the start of the series.
- Clarify the IIO backend CRC documentation for input and output paths.
- Add explicit MCLK, crystal, and LVDS clock-source handling and
  sequencing.
- Keep the required channel active for crystal excitation.
- Configure FILTER/GPIO4 for crystal and LVDS clock sources and reserve
  it from GPIO consumers while it is used for clock selection.
- Make AVSS optional.
- Validate MCLK, crystal, and LVDS clock rates against datasheet limits.
- Split each differential reference into positive and negative supplies.
- Correct AD7768-4 standby and channel-mode bit handling.
- Program the AD7768-4 channel mode-enable bits correctly.
- Use unshifted register values and FIELD_PREP() consistently.
- Use regmap single-bit helpers where appropriate.
- Use scoped runtime-PM guards and scoped loop variables.
- Use for_each_set_bit() and named channel-child iteration.
- Remove the redundant initial autosuspend request.
- Document the validated 20 ms wake-up delay.
- Make REGULATOR mandatory when VCM regulator support is introduced.
- Add feature dependencies and includes in their respective patches.
- Convert gpio-regmap runtime-PM handling to cleanup guards.
- Use active-only PM references for gpio-regmap operations.
- Mark GPIO chips using runtime PM as sleep-capable.
- Simplify the AD7768 GPIO auxiliary driver.
- Clean up IIO and kernel coding-style issues across the series.
- Drop the redundant Devicetree example.
- Update the link to the latest Rev. D datasheet, update table
  references.
- Address the remaining binding description comments.
- Link to v3: https://lore.kernel.org/r/20260813-ad7768-driver-v3-0-cb554399ad26@analog.com

Changes in v3:
- Split the IIO driver into core support and focused patches for sampling
  modes, calibration, conversion delay, VCM, and GPIO registration.
- Split AXI ADC mutex initialization into a separate preparatory patch.
- Use PSEC_PER_SEC, explicit frequency units, unsigned frequency storage,
  32-bit divider arithmetic, and rounddown_pow_of_two().
- Use endian helpers and bulk regmap operations for calibration transfers,
  while retaining single-register writes for the custom SPI protocol.
- Validate the MCLK rate during probe and reject a zero computed DCLK rate.
- Remove redundant SPI and channel-template state, regmap_attach_dev(),
  unused includes, and a forward declaration, unused chn_mode assignment.
- Move regulators additionalProperties and drop redundant GPIO
  dependencies from the Devicetree binding.
- Split the gpio-regmap changes and add the regmap_test_bits() conversion
  as a separate cleanup.
- Limit the generic gpio-regmap extension to optional runtime PM support.
- Use an AD7768 reg_mask_xlate() callback to select the output latch for
  output GPIOs and document why it is required.
- Use regmap_test_bits() when reading the VCM enable state.
- Use descriptive runtime PM cleanup labels and verify structure layout
  with pahole.
- Set the VCM regulator's regulators_node so constraints from the nested
  vcm-output node are parsed.
- Mark gpio-regmap GPIO chips as sleep-capable when a runtime PM device is
  configured.
- Reword the conversion-delay and buffered-capture documentation to
  clarify their operation.
- Link to v2: https://lore.kernel.org/r/20260806-ad7768-driver-v2-0-027ac5e2a641@analog.com

Changes in v2:
- Renamed and expanded supply descriptions, split reference to
  ref1-supply and ref2-supply.
- Added START and synchronization signal descriptions.
- Added variant-specific channel and data-line validation.
- Made adi,data-lines-number optional, defaulting to the maximum.
- Renamed the precharge and reference-buffer properties, removed channel
  mode and power mode properties.
- Exposed the VCM output through the regulator framework and updated
  documentation accordingly.
- Improved runtime PM initialization and requested initial autosuspend
  after probe.
- Automatically assigned channels to two hardware mode profiles.
- Selected the lowest noise compatible power mode when ODR ranges overlap.
- Replaced the raw phase attribute with the standard conversion-delay
  attribute.
- Added filter-settling delays based on the selected filter and ODR.
- Fixed AD7768-4 register and channel-bit mapping, including standby,
  calibration, phase, precharge and reference-buffer handling.
- Added direct-mode protection around runtime channel configuration.
- Added calibration register range validation and documented
  calibration values as raw unsigned 24-bit values.
- Added the required reset pulse delay derived from MCLK.
- Added a generic GPIO-regmap patch providing runtime-PM integration
  and separate output-register readback.
- Converted the AD7768 GPIO auxiliary driver to use gpio-regmap.
- Documented that AXI ADC CRC control bit 8 is common to the AXI ADC
  cores.
- Added the missing AXI ADC mutex initialization.
- Expanded the driver documentation to describe dynamic channel
  grouping, power-mode selection, VCM regulation and conversion delay.
- Link to v1: https://lore.kernel.org/r/20260709-ad7768-driver-v1-0-44e1194fd96a@analog.com

---
Janani Sunil (20):
      iio: adc: adi-axi-adc: Initialize state mutex
      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 and AD7768-4 core support
      iio: adc: ad7768: Validate master clock rate
      iio: adc: ad7768: Add power mode helper
      iio: adc: ad7768: Derive output data rates
      iio: adc: ad7768: Configure channel sampling profiles
      iio: adc: ad7768: Add sampling frequency controls
      iio: adc: ad7768: Add per-channel filter controls
      iio: adc: ad7768: Wait for digital filters to settle
      iio: adc: ad7768: Add calibration controls
      iio: adc: ad7768: Add per-channel conversion delay
      iio: adc: ad7768: Add VCM regulator support
      iio: adc: ad7768: Register GPIO auxiliary device
      gpio: regmap: Use regmap_test_bits() for single bit reads
      gpio: regmap: Add optional runtime PM support
      gpio: ad7768: Add AD7768 GPIO auxiliary driver
      Documentation: iio: Add AD7768 Documentation

 .../devicetree/bindings/iio/adc/adi,ad7768.yaml    |  270 +++
 Documentation/iio/ad7768.rst                       |  273 +++
 Documentation/iio/index.rst                        |    1 +
 MAINTAINERS                                        |    9 +
 drivers/gpio/Kconfig                               |   12 +
 drivers/gpio/Makefile                              |    1 +
 drivers/gpio/gpio-ad7768.c                         |  118 ++
 drivers/gpio/gpio-regmap.c                         |   87 +-
 drivers/iio/adc/Kconfig                            |   15 +
 drivers/iio/adc/Makefile                           |    1 +
 drivers/iio/adc/ad7768.c                           | 1872 ++++++++++++++++++++
 drivers/iio/adc/adi-axi-adc.c                      |   25 +
 drivers/iio/industrialio-backend.c                 |   33 +
 include/linux/gpio/regmap.h                        |    2 +
 include/linux/iio/backend.h                        |    6 +
 15 files changed, 2713 insertions(+), 12 deletions(-)
---
base-commit: b75697ef53e435d894833dad2a8c2fa882cb9b19
change-id: 20260708-ad7768-driver-10cd15296c20

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

[PATCH v5 01/20] iio: adc: adi-axi-adc: Initialize state mutex

[Janani Sunil]

The AXI ADC register access paths serialize transactions with st->lock,
but probe does not initialize it. Initialize the mutex before registering
the backend.

Fixes: 7ecb8ee5c93b ("iio: adc: adi-axi-adc: support digital interface calibration")
Signed-off-by: Janani Sunil <janani.sunil@analog.com>
---
This patch is already queued in the IIO fixes-togreg branch as commit
040c2514b25b ("iio: adc: adi-axi-adc: Initialize state mutex").
---
 drivers/iio/adc/adi-axi-adc.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/iio/adc/adi-axi-adc.c b/drivers/iio/adc/adi-axi-adc.c
index 26b9c75bd4d8..b5e59b1871b6 100644
--- a/drivers/iio/adc/adi-axi-adc.c
+++ b/drivers/iio/adc/adi-axi-adc.c
@@ -684,6 +684,10 @@ static int adi_axi_adc_probe(struct platform_device *pdev)
 	if (!st)
 		return -ENOMEM;
 
+	ret = devm_mutex_init(dev, &st->lock);
+	if (ret)
+		return ret;
+
 	base = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(base))
 		return PTR_ERR(base);

-- 
2.43.0

[PATCH v5 02/20] dt-bindings: iio: adc: Add AD7768

[Janani Sunil]

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

Signed-off-by: Janani Sunil <janani.sunil@analog.com>
---
 .../devicetree/bindings/iio/adc/adi,ad7768.yaml    | 270 +++++++++++++++++++++
 MAINTAINERS                                        |   7 +
 2 files changed, 277 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..d8e489fa1f6f
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/adc/adi,ad7768.yaml
@@ -0,0 +1,270 @@
+# 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 an 8-channel, 24-bit simultaneous sampling ADC with configurable
+  power and performance modes. The AD7768-4 is a 4-channel version.
+
+  This binding covers SPI mode only (register access via SPI). Pin control mode,
+  where configuration is set via hardware pins rather than SPI registers, is not
+  supported.
+
+  The io-backend represents the high-speed data output interface, consuming the
+  DOUTx data lines, DCLK (data clock), and DRDY (data ready) signals.
+
+  Datasheet at:
+    https://www.analog.com/media/en/technical-documentation/data-sheets/ad7768-ad7768-4.pdf
+
+  HDL reference design:
+    https://github.com/analogdevicesinc/hdl/tree/main/projects/ad7768evb
+
+properties:
+  compatible:
+    enum:
+      - adi,ad7768
+      - adi,ad7768-4
+
+  reg:
+    maxItems: 1
+
+  clocks:
+    maxItems: 1
+
+  clock-names:
+    description:
+      Describes the type of master clock (MCLK) attached to the XTAL1 and
+      XTAL2/MCLK pins. A CMOS clock is supplied on the XTAL2/MCLK pin, a
+      crystal oscillator is connected between the XTAL1 and XTAL2 pins, and an
+      LVDS differential clock is supplied on the XTAL1/XTAL2 pin pair. CMOS and
+      LVDS clocks must operate from 1.15 MHz to 34 MHz. Crystals must operate
+      from 8 MHz to 34 MHz.
+    enum:
+      - mclk
+      - xtal
+      - lvds
+
+  avdd1-supply:
+    description:
+      Analog supply. Its voltage is used to derive the supply-dependent VCM
+      output level, so it must be a regulator that can report its voltage.
+
+  avss-supply:
+    description:
+      Negative analog supply. If omitted, AVSS is assumed to be at system
+      ground.
+
+  avdd2-supply: true
+
+  iovdd-supply: true
+
+  ref1p-supply: true
+
+  ref1n-supply:
+    description:
+      Negative reference input supply for REF1. If omitted, REF1- is assumed
+      to be connected to ground.
+
+  ref2p-supply: true
+
+  ref2n-supply:
+    description:
+      Negative reference input supply for REF2. If omitted, REF2- is assumed
+      to be connected to ground.
+
+  reset-gpios:
+    maxItems: 1
+    description: GPIO connected to the active-low RESET pin
+
+  start-gpios:
+    maxItems: 1
+    description:
+      GPIO connected to the START pin. An active-low pulse on this pin
+      synchronizes the device to other AD7768 devices. When not used, this
+      pin must be tied to a logic high level through a pull-up resistor.
+      When used, SYNC_OUT must be wired back to SYNC_IN on all devices in
+      the synchronization chain.
+
+  sync-in-gpios:
+    maxItems: 1
+    description:
+      GPIO connected to the SYNC_IN pin. Receives the synchronization pulse
+      generated on SYNC_OUT in response to a START pulse. Must be synchronous
+      to the MCLK clock domain. In multi-device or daisy-chained systems,
+      two successive synchronization pulses must be applied to guarantee all
+      ADCs are synchronized.
+
+  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 DOUTx lines used for the high-speed data output interface
+      (distinct from the SPI control interface). AD7768 supports 1, 2, or 8
+      lines; AD7768-4 supports 1 or 4 lines. Defaults to the maximum number
+      of lines for the selected variant if omitted.
+
+  regulators:
+    type: object
+    description: Container for the on-chip VCM regulator.
+    additionalProperties: false
+
+    properties:
+      vcm-output:
+        type: object
+        description:
+          Buffered common-mode voltage output on the VCM pin. Use
+          regulator-always-on when no consumer node references this output.
+          Channel 0 must be present and enabled while VCM is used, since
+          putting channel 0 in standby disables the VCM output.
+        $ref: /schemas/regulator/regulator.yaml#
+        unevaluatedProperties: false
+
+  io-backends:
+    maxItems: 1
+
+  '#address-cells':
+    const: 1
+
+  '#size-cells':
+    const: 0
+
+patternProperties:
+  "^channel@[0-7]$":
+    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,prechargebuf-pos-enable:
+        type: boolean
+        description: Enable positive input precharge buffer
+
+      adi,prechargebuf-neg-enable:
+        type: boolean
+        description: Enable negative input precharge buffer
+
+      adi,refbuf-pos-enable:
+        type: boolean
+        description: Enable positive reference buffer
+
+      adi,refbuf-neg-enable:
+        type: boolean
+        description: Enable negative reference buffer
+
+    required:
+      - reg
+
+    additionalProperties: false
+
+required:
+  - compatible
+  - reg
+  - clocks
+  - clock-names
+  - avdd1-supply
+  - avdd2-supply
+  - iovdd-supply
+  - ref1p-supply
+  - ref2p-supply
+  - io-backends
+
+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>;
+
+            avdd1-supply = <&avdd1_regulator>;
+            avss-supply = <&avss_regulator>;
+            avdd2-supply = <&avdd2_regulator>;
+            iovdd-supply = <&iovdd_regulator>;
+            ref1p-supply = <&ref1p_regulator>;
+            ref1n-supply = <&ref1n_regulator>;
+            ref2p-supply = <&ref2p_regulator>;
+            ref2n-supply = <&ref2n_regulator>;
+            reset-gpios = <&gpio0 86 GPIO_ACTIVE_LOW>;
+
+            clocks = <&ad7768_mclk>;
+            clock-names = "mclk";
+
+            adi,data-lines-number = <8>;
+            gpio-controller;
+            #gpio-cells = <2>;
+
+            io-backends = <&iio_backend>;
+
+            #address-cells = <1>;
+            #size-cells = <0>;
+
+            channel@0 {
+                reg = <0>;
+                adi,prechargebuf-pos-enable;
+                adi,refbuf-pos-enable;
+            };
+
+            channel@1 {
+                reg = <1>;
+                adi,prechargebuf-pos-enable;
+                adi,prechargebuf-neg-enable;
+                adi,refbuf-pos-enable;
+                adi,refbuf-neg-enable;
+            };
+
+            channel@7 {
+                reg = <7>;
+                adi,prechargebuf-pos-enable;
+                adi,refbuf-pos-enable;
+            };
+        };
+    };
+
+...
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

[PATCH v5 03/20] iio: backend: Add support for CRC

[Janani Sunil]

Add a backend operation to enable or disable direction-specific CRC
handling. On input data paths, the backend handles CRC data generated by
the frontend. On output data paths, the backend generates CRC data for
the frontend to verify.

Reviewed-by: David Lechner <dlechner@baylibre.com>
Signed-off-by: Janani Sunil <janani.sunil@analog.com>
---
 drivers/iio/industrialio-backend.c | 33 +++++++++++++++++++++++++++++++++
 include/linux/iio/backend.h        |  6 ++++++
 2 files changed, 39 insertions(+)

diff --git a/drivers/iio/industrialio-backend.c b/drivers/iio/industrialio-backend.c
index f7a4be8ec320..fbf5c39d7655 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 CRC handling
+ * @back: Backend device
+ *
+ * On input data paths, enable backend handling of CRC data generated by the
+ * frontend. On output data paths, enable the backend to generate CRC data for
+ * the frontend to verify.
+ *
+ * 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 CRC handling
+ * @back: Backend device
+ *
+ * On input data paths, disable backend handling of CRC data generated by the
+ * frontend. On output data paths, disable CRC generation by the backend.
+ *
+ * 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..9c16b695a602 100644
--- a/include/linux/iio/backend.h
+++ b/include/linux/iio/backend.h
@@ -133,6 +133,8 @@ enum iio_backend_capabilities {
  * @filter_type_set: Set filter type.
  * @interface_data_align: Perform the data alignment process.
  * @num_lanes_set: Set the number of lanes enabled.
+ * @crc_enable: Enable direction-specific CRC handling.
+ * @crc_disable: Disable direction-specific CRC handling.
  * @ddr_enable: Enable interface DDR (Double Data Rate) mode.
  * @ddr_disable: Disable interface DDR (Double Data Rate) mode.
  * @data_stream_enable: Enable data stream.
@@ -189,6 +191,8 @@ 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 +241,8 @@ 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

[PATCH v5 04/20] 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.

Reviewed-by: David Lechner <dlechner@baylibre.com>
Signed-off-by: Janani Sunil <janani.sunil@analog.com>
---
 drivers/iio/adc/adi-axi-adc.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/drivers/iio/adc/adi-axi-adc.c b/drivers/iio/adc/adi-axi-adc.c
index b5e59b1871b6..e8f149e230e7 100644
--- a/drivers/iio/adc/adi-axi-adc.c
+++ b/drivers/iio/adc/adi-axi-adc.c
@@ -47,6 +47,9 @@
 #define    ADI_AXI_ADC_CTRL_DDR_EDGESEL_MASK	BIT(1)
 
 #define ADI_AXI_ADC_REG_CNTRL_3			0x004c
+/* Bit 8 is common to all AXI ADC cores; bits 7-0 are per-HDL-project. */
+#define    ADI_AXI_ADC_CNTRL_3_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 +570,22 @@ 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_CNTRL_3_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_CNTRL_3_CRC_EN_MASK);
+}
+
 static const struct regmap_config axi_adc_regmap_config = {
 	.val_bits = 32,
 	.reg_bits = 32,
@@ -615,6 +634,8 @@ 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

[PATCH v5 05/20] iio: adc: Add AD7768 and AD7768-4 core support

[Janani Sunil]

Add core support for the AD7768 and AD7768-4 simultaneous sampling ADCs.
Configure supplies, clock and reset, use a custom regmap bus for the SPI
protocol, and parse the enabled channels and input buffer settings from
devicetree.

Connect the converter to an IIO backend for buffered capture with CRC,
provide a fixed safe wideband sampling configuration and add runtime
power management.

Signed-off-by: Janani Sunil <janani.sunil@analog.com>
---
 MAINTAINERS              |   1 +
 drivers/iio/adc/Kconfig  |  14 +
 drivers/iio/adc/Makefile |   1 +
 drivers/iio/adc/ad7768.c | 974 +++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 990 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..48bb108382b5 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -429,6 +429,20 @@ 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 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..cb84bb344aef
--- /dev/null
+++ b/drivers/iio/adc/ad7768.c
@@ -0,0 +1,974 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Analog Devices AD7768 ADC driver
+ *
+ * Copyright 2018-2026 Analog Devices Inc.
+ */
+
+#include <linux/array_size.h>
+#include <linux/bitfield.h>
+#include <linux/bitops.h>
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/math.h>
+#include <linux/minmax.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/time.h>
+#include <linux/types.h>
+
+#include <linux/iio/backend.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/types.h>
+
+#define AD7768_REG_CH_STANDBY				0x00
+
+#define AD7768_REG_CH_MODE(x)				(0x01 + (x))
+#define   AD7768_CH_MODE_FILTER_TYPE_MSK		BIT(3)
+#define     AD7768_CH_MODE_FILTER_TYPE_WIDEBAND		0x0
+#define   AD7768_CH_MODE_DEC_RATE_MSK			GENMASK(2, 0)
+#define     AD7768_CH_MODE_DEC_RATE_64			0x1
+
+#define AD7768_REG_CH_MODE_SEL				0x03
+
+#define AD7768_REG_POWER_MODE				0x04
+#define   AD7768_SLEEP_MODE_MSK				BIT(7)
+#define   AD7768_POWER_MODE_POWER_MODE_MSK		GENMASK(5, 4)
+#define     AD7768_POWER_MODE_POWER_MODE_FAST		0x3
+#define   AD7768_POWER_MODE_LVDS_ENABLE			BIT(3)
+#define   AD7768_POWER_MODE_MCLK_DIV_MSK		GENMASK(1, 0)
+
+#define AD7768_REG_DATA_CONTROL				0x06
+#define   AD7768_DATA_CONTROL_SPI_RESET_1		0x03
+#define   AD7768_DATA_CONTROL_SPI_RESET_2		0x02
+#define   AD7768_DATA_CONTROL_SPI_SYNC			BIT(7)
+
+#define AD7768_REG_INTERFACE_CFG			0x07
+#define   AD7768_INTERFACE_CFG_CRC_SELECT_MSK		GENMASK(3, 2)
+#define     AD7768_INTERFACE_CFG_CRC_SELECT_4		0x1
+#define   AD7768_INTERFACE_CFG_DCLK_DIV_MSK		GENMASK(1, 0)
+#define     AD7768_INTERFACE_CFG_DCLK_DIV(x)		(4 - ffs(x))
+
+#define AD7768_REG_REV_ID				0x0A
+#define   AD7768_REV_ID_VAL				0x06
+
+#define AD7768_REG_GPIO_CONTROL				0x0E
+#define   AD7768_GPIO_UGPIO_ENABLE			BIT(7)
+#define   AD7768_GPIO4_OUTPUT_ENABLE			BIT(4)
+
+#define AD7768_REG_GPIO_WRITE				0x0F
+
+#define AD7768_REG_PRECHARGE_BUF1			0x11
+#define AD7768_REG_PRECHARGE_BUF2			0x12
+#define   AD7768_PREBUF_POS_EN(ch)			BIT((ch) * 2)
+#define   AD7768_PREBUF_NEG_EN(ch)			BIT(((ch) * 2) + 1)
+
+#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_CHOP_CTRL				0x59
+
+#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_MAX_CHANNEL				8
+
+enum ad7768_clock_source {
+	AD7768_CLOCK_SOURCE_MCLK,
+	AD7768_CLOCK_SOURCE_XTAL,
+	AD7768_CLOCK_SOURCE_LVDS,
+};
+
+struct ad7768_precharge_config {
+	bool prebufp_en;
+	bool prebufn_en;
+	bool refbufp;
+	bool refbufn;
+};
+
+struct ad7768_chip_info {
+	const char *name;
+	unsigned int num_channels;
+	const struct regmap_config *regmap_config;
+	const unsigned int *available_datalines;
+	unsigned int num_datalines;
+	const u8 *chan_map;
+	u8 prebuf_split;
+};
+
+struct ad7768_state {
+	struct regmap *regmap;
+	/* Protects device register access and configuration. */
+	struct mutex lock;
+	struct clk *mclk;
+	unsigned int datalines;
+	enum ad7768_clock_source clock_source;
+	const struct ad7768_chip_info *chip_info;
+	struct iio_backend *back;
+	unsigned int vref_uV[2];
+
+	__be16 d16 __aligned(IIO_DMA_MINALIGN);
+};
+
+static const unsigned int ad7768_available_datalines[] = {
+	1, 2, 8,
+};
+
+static const unsigned int ad7768_4_available_datalines[] = {
+	1, 4,
+};
+
+static const u8 ad7768_chan_map[] = {
+	0, 1, 2, 3, 4, 5, 6, 7,
+};
+
+static const u8 ad7768_4_chan_map[] = {
+	0, 1, 4, 5,
+};
+
+static const char * const ad7768_supply_names[] = {
+	"avdd2", "iovdd",
+};
+
+static const char * const ad7768_vref_supply_names[][2] = {
+	{ "ref1p", "ref1n" },
+	{ "ref2p", "ref2n" },
+};
+
+static const char * const ad7768_clock_names[] = {
+	[AD7768_CLOCK_SOURCE_MCLK] = "mclk",
+	[AD7768_CLOCK_SOURCE_XTAL] = "xtal",
+	[AD7768_CLOCK_SOURCE_LVDS] = "lvds",
+};
+
+static u8 ad7768_channel_mask(const struct ad7768_state *st, u8 ch)
+{
+	return BIT(st->chip_info->chan_map[ch]);
+}
+
+static u8 ad7768_all_standby_mask(const struct ad7768_state *st)
+{
+	return GENMASK(st->chip_info->num_channels - 1, 0);
+}
+
+static u8 ad7768_precharge_buf1_mask(const struct ad7768_state *st, u16 val)
+{
+	return val & GENMASK(st->chip_info->prebuf_split - 1, 0);
+}
+
+static u8 ad7768_precharge_buf2_mask(const struct ad7768_state *st, u16 val)
+{
+	return (val >> st->chip_info->prebuf_split) &
+	       GENMASK(st->chip_info->prebuf_split - 1, 0);
+}
+
+static int ad7768_regmap_read(void *context, const void *reg_buf,
+			      size_t reg_size, void *val_buf, size_t val_size)
+{
+	struct ad7768_state *st = spi_get_drvdata(context);
+	struct spi_device *spi = context;
+	struct spi_transfer t[] = {
+		{
+			.tx_buf = &st->d16,
+			.len = sizeof(st->d16),
+			.cs_change = 1,
+		}, {
+			/*
+			 * Register responses are delayed by one CS frame. While
+			 * receiving the response to this read, the device also
+			 * decodes another command on SDI. Repeat the read
+			 * command to avoid sending an unspecified dummy
+			 * command.
+			 */
+			.tx_buf = &st->d16,
+			.rx_buf = &st->d16,
+			.len = sizeof(st->d16),
+		},
+	};
+	u8 *data_val = val_buf;
+	unsigned int reg;
+	int ret;
+
+	reg = *(const u8 *)reg_buf;
+
+	st->d16 = be16_replace_bits(cpu_to_be16(AD7768_SPI_READ_CMD), reg,
+				    AD7768_SPI_REG_MASK);
+
+	ret = spi_sync_transfer(spi, t, ARRAY_SIZE(t));
+	if (ret)
+		return ret;
+
+	*data_val = be16_get_bits(st->d16, AD7768_SPI_DATA_MASK);
+
+	return 0;
+}
+
+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:
+	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:
+	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,
+	.use_single_read = true,
+	.use_single_write = true,
+	.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,
+	.use_single_read = true,
+	.use_single_write = true,
+	.readable_reg = ad7768_4_readable_reg,
+};
+
+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_AUTOSUSPEND(regmap_get_device(st->regmap), 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_clear_bits(st->regmap, AD7768_REG_DATA_CONTROL,
+				AD7768_DATA_CONTROL_SPI_SYNC);
+	if (ret)
+		return ret;
+
+	return regmap_set_bits(st->regmap, AD7768_REG_DATA_CONTROL,
+			       AD7768_DATA_CONTROL_SPI_SYNC);
+}
+
+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 long channel_mask;
+	unsigned long standby_mask;
+	int ret;
+
+	channel_mask = ad7768_all_standby_mask(st);
+	standby_mask = channel_mask & ~*scan_mask;
+
+	/*
+	 * Crystal excitation requires channel 4 on AD7768 or channel 2 on
+	 * AD7768-4 to remain active.
+	 */
+	if (st->clock_source == AD7768_CLOCK_SOURCE_XTAL)
+		standby_mask &= ~BIT(st->chip_info->num_channels / 2);
+
+	ret = regmap_update_bits(st->regmap, AD7768_REG_CH_STANDBY,
+				 channel_mask, standby_mask);
+	if (ret)
+		return ret;
+
+	for (unsigned int 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),
+	.chan_map = ad7768_chan_map,
+	.prebuf_split = 8,
+};
+
+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),
+	.chan_map = ad7768_4_chan_map,
+	.prebuf_split = 4,
+};
+
+static int ad7768_buffer_preenable(struct iio_dev *indio_dev)
+{
+	struct ad7768_state *st = iio_priv(indio_dev);
+
+	return pm_runtime_resume_and_get(regmap_get_device(st->regmap));
+}
+
+static int ad7768_buffer_postdisable(struct iio_dev *indio_dev)
+{
+	struct ad7768_state *st = iio_priv(indio_dev);
+
+	pm_runtime_put_autosuspend(regmap_get_device(st->regmap));
+	return 0;
+}
+
+static const struct iio_buffer_setup_ops ad7768_buffer_ops = {
+	.preenable = ad7768_buffer_preenable,
+	.postdisable = ad7768_buffer_postdisable,
+};
+
+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 vref_idx;
+
+	if (info != IIO_CHAN_INFO_SCALE)
+		return -EINVAL;
+
+	vref_idx = chan->channel >= st->chip_info->num_channels / 2;
+	*val = 2 * st->vref_uV[vref_idx] / 1000;
+	*val2 = chan->scan_type.realbits;
+
+	return IIO_VAL_FRACTIONAL_LOG2;
+}
+
+static const struct iio_info ad7768_info = {
+	.debugfs_reg_access = ad7768_reg_access,
+	.read_raw = ad7768_read_raw,
+	.update_scan_mode = ad7768_update_scan_mode,
+};
+
+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);
+	u8 prebuf1_val, prebuf2_val;
+	u16 prebuf_mask = 0;
+	u8 refbufp_val = 0;
+	u8 refbufn_val = 0;
+	int ret;
+
+	for (u8 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_channel_mask(st, channel);
+
+		if (precharge_cfg[channel].refbufn)
+			refbufn_val |= ad7768_channel_mask(st, channel);
+	}
+
+	prebuf1_val = ad7768_precharge_buf1_mask(st, ~prebuf_mask);
+	prebuf2_val = ad7768_precharge_buf2_mask(st, ~prebuf_mask);
+
+	ret = regmap_write(st->regmap, AD7768_REG_PRECHARGE_BUF1, prebuf1_val);
+	if (ret)
+		return ret;
+
+	ret = regmap_write(st->regmap, AD7768_REG_PRECHARGE_BUF2, prebuf2_val);
+	if (ret)
+		return ret;
+
+	ret = regmap_write(st->regmap, AD7768_REG_REFP_BUF, refbufp_val);
+	if (ret)
+		return ret;
+
+	return regmap_write(st->regmap, AD7768_REG_REFN_BUF, refbufn_val);
+}
+
+static int ad7768_configure_capture(struct ad7768_state *st)
+{
+	unsigned int dclk_div_reg;
+	unsigned int mode_config;
+	unsigned int dclk_div;
+	int ret;
+
+	ret = regmap_update_bits(st->regmap, AD7768_REG_POWER_MODE,
+				 AD7768_POWER_MODE_POWER_MODE_MSK |
+				 AD7768_POWER_MODE_MCLK_DIV_MSK,
+				 FIELD_PREP(AD7768_POWER_MODE_POWER_MODE_MSK,
+					    AD7768_POWER_MODE_POWER_MODE_FAST) |
+				 FIELD_PREP(AD7768_POWER_MODE_MCLK_DIV_MSK,
+					    AD7768_POWER_MODE_POWER_MODE_FAST));
+	if (ret)
+		return ret;
+
+	/*
+	 * Start with the wideband filter and a decimation rate of 64. This
+	 * supports every valid data-line configuration at the maximum MCLK.
+	 */
+	mode_config = FIELD_PREP(AD7768_CH_MODE_FILTER_TYPE_MSK,
+				 AD7768_CH_MODE_FILTER_TYPE_WIDEBAND);
+	mode_config |= FIELD_PREP(AD7768_CH_MODE_DEC_RATE_MSK,
+				  AD7768_CH_MODE_DEC_RATE_64);
+	ret = regmap_update_bits(st->regmap, AD7768_REG_CH_MODE(0),
+				 AD7768_CH_MODE_FILTER_TYPE_MSK |
+				 AD7768_CH_MODE_DEC_RATE_MSK,
+				 mode_config);
+	if (ret)
+		return ret;
+
+	ret = regmap_write(st->regmap, AD7768_REG_CH_MODE_SEL, 0);
+	if (ret)
+		return ret;
+
+	dclk_div = 8 * st->datalines / st->chip_info->num_channels;
+	dclk_div_reg = AD7768_INTERFACE_CFG_DCLK_DIV(dclk_div);
+	ret = regmap_update_bits(st->regmap, AD7768_REG_INTERFACE_CFG,
+				 AD7768_INTERFACE_CFG_DCLK_DIV_MSK,
+				 FIELD_PREP(AD7768_INTERFACE_CFG_DCLK_DIV_MSK,
+					    dclk_div_reg));
+	if (ret)
+		return ret;
+
+	return ad7768_sync(st);
+}
+
+static int ad7768_parse_config(struct iio_dev *indio_dev,
+			       struct device *dev)
+{
+	struct ad7768_precharge_config precharge_cfg[AD7768_MAX_CHANNEL] = { };
+	struct ad7768_state *st = iio_priv(indio_dev);
+	const unsigned int *available_datalines;
+	bool datalines_valid = false;
+	struct iio_chan_spec *chan;
+	unsigned int num_channels;
+	unsigned int standby_mask;
+	unsigned int len;
+	int chan_idx = 0;
+	int ret;
+
+	num_channels = 0;
+	device_for_each_named_child_node_scoped(dev, child, "channel")
+		num_channels++;
+
+	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;
+
+	standby_mask = ad7768_all_standby_mask(st);
+
+	/*
+	 * Crystal excitation requires channel 4 on AD7768 or channel 2 on
+	 * AD7768-4 to remain active.
+	 */
+	if (st->clock_source == AD7768_CLOCK_SOURCE_XTAL)
+		standby_mask &= ~BIT(st->chip_info->num_channels / 2);
+
+	ret = regmap_write(st->regmap, AD7768_REG_CH_STANDBY, standby_mask);
+	if (ret)
+		return ret;
+
+	device_for_each_named_child_node_scoped(dev, child, "channel") {
+		u32 channel;
+
+		ret = fwnode_property_read_u32(child, "reg", &channel);
+		if (ret)
+			return dev_err_probe(dev, ret,
+					     "Failed to parse reg of %pfwP\n",
+					     child);
+
+		if (channel >= st->chip_info->num_channels)
+			return dev_err_probe(dev, -EINVAL,
+					     "Invalid channel %u in firmware\n",
+					     channel);
+
+		ret = regmap_clear_bits(st->regmap, AD7768_REG_CH_STANDBY,
+					BIT(channel));
+		if (ret)
+			return ret;
+
+		precharge_cfg[channel].prebufp_en =
+			fwnode_property_read_bool(child,
+						  "adi,prechargebuf-pos-enable");
+		precharge_cfg[channel].prebufn_en =
+			fwnode_property_read_bool(child,
+						  "adi,prechargebuf-neg-enable");
+		precharge_cfg[channel].refbufp =
+			fwnode_property_read_bool(child,
+						  "adi,refbuf-pos-enable");
+		precharge_cfg[channel].refbufn =
+			fwnode_property_read_bool(child,
+						  "adi,refbuf-neg-enable");
+
+		chan[chan_idx] = (struct iio_chan_spec) {
+			.type = IIO_VOLTAGE,
+			.info_mask_separate = BIT(IIO_CHAN_INFO_SCALE),
+			.indexed = 1,
+			.channel = channel,
+			.scan_index = channel,
+			.scan_type = {
+				.sign = 's',
+				.realbits = 24,
+				.storagebits = 32,
+			},
+		};
+		chan_idx++;
+	}
+
+	ret = ad7768_configure_precharge_buffers(indio_dev, precharge_cfg);
+	if (ret)
+		return ret;
+
+	available_datalines = st->chip_info->available_datalines;
+	len = st->chip_info->num_datalines;
+	st->datalines = available_datalines[len - 1];
+	ret = device_property_read_u32(dev, "adi,data-lines-number",
+				       &st->datalines);
+	if (ret && ret != -EINVAL)
+		return dev_err_probe(dev, ret,
+				     "Invalid %s property\n",
+				     "adi,data-lines-number");
+
+	for (unsigned int i = 0; i < len; i++) {
+		if (available_datalines[i] == st->datalines) {
+			datalines_valid = true;
+			break;
+		}
+	}
+
+	if (!datalines_valid)
+		return dev_err_probe(dev, -EINVAL,
+				     "Invalid data-lines-number %d for %s\n",
+				     st->datalines, st->chip_info->name);
+
+	return ad7768_configure_capture(st);
+}
+
+static int ad7768_reset(struct ad7768_state *st)
+{
+	struct device *dev = regmap_get_device(st->regmap);
+	struct reset_control *reset_ctrl;
+	unsigned long reset_low_us;
+	unsigned long mclk;
+	int ret;
+
+	reset_ctrl = devm_reset_control_get_optional_exclusive(dev, NULL);
+	if (IS_ERR(reset_ctrl))
+		return PTR_ERR(reset_ctrl);
+
+	if (reset_ctrl) {
+		mclk = clk_get_rate(st->mclk);
+		if (!mclk)
+			return -EINVAL;
+
+		/*
+		 * Minimum RESET low pulse width: 2 x tMCLK
+		 * (datasheet Table 1).
+		 */
+		reset_low_us = DIV_ROUND_UP_ULL(2ULL * USEC_PER_SEC, mclk);
+
+		ret = reset_control_assert(reset_ctrl);
+		if (ret)
+			return ret;
+
+		fsleep(max(1UL, reset_low_us));
+
+		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(1660);
+
+	return 0;
+}
+
+static void ad7768_disable_clk(void *clk)
+{
+	clk_disable_unprepare(clk);
+}
+
+static int ad7768_configure_xtal_clock(struct ad7768_state *st)
+{
+	int ret;
+
+	ret = regmap_set_bits(st->regmap, AD7768_REG_GPIO_WRITE, BIT(4));
+	if (ret)
+		return ret;
+
+	return regmap_set_bits(st->regmap, AD7768_REG_GPIO_CONTROL,
+			       AD7768_GPIO_UGPIO_ENABLE |
+			       AD7768_GPIO4_OUTPUT_ENABLE);
+}
+
+static int ad7768_enable_lvds_clock(struct ad7768_state *st)
+{
+	struct device *dev = regmap_get_device(st->regmap);
+	int ret;
+
+	ret = regmap_clear_bits(st->regmap, AD7768_REG_GPIO_WRITE, BIT(4));
+	if (ret)
+		return ret;
+
+	ret = regmap_set_bits(st->regmap, AD7768_REG_GPIO_CONTROL,
+			      AD7768_GPIO_UGPIO_ENABLE |
+			      AD7768_GPIO4_OUTPUT_ENABLE);
+	if (ret)
+		return ret;
+
+	ret = regmap_set_bits(st->regmap, AD7768_REG_POWER_MODE,
+			      AD7768_POWER_MODE_LVDS_ENABLE);
+	if (ret)
+		return ret;
+
+	ret = clk_prepare_enable(st->mclk);
+	if (ret)
+		return ret;
+
+	return devm_add_action_or_reset(dev, ad7768_disable_clk, st->mclk);
+}
+
+static int ad7768_get_enable_vref(struct device *dev, unsigned int index)
+{
+	const char * const *supply = ad7768_vref_supply_names[index];
+	int refp_uV;
+	int refn_uV;
+
+	refp_uV = devm_regulator_get_enable_read_voltage(dev, supply[0]);
+	if (refp_uV < 0)
+		return dev_err_probe(dev, refp_uV,
+				     "Failed to get %s supply voltage\n", supply[0]);
+
+	refn_uV = devm_regulator_get_enable_read_voltage(dev, supply[1]);
+	if (refn_uV == -ENODEV)
+		refn_uV = 0;
+	else if (refn_uV < 0)
+		return dev_err_probe(dev, refn_uV,
+				     "Failed to get %s supply voltage\n", supply[1]);
+
+	if (refp_uV <= refn_uV)
+		return dev_err_probe(dev, -EINVAL,
+				     "Invalid reference %u voltage\n", index + 1);
+
+	return refp_uV - refn_uV;
+}
+
+static int ad7768_probe(struct spi_device *spi)
+{
+	unsigned int spi_readback, rev_id;
+	struct device *dev = &spi->dev;
+	struct iio_dev *indio_dev;
+	struct ad7768_state *st;
+	const char *clock_name;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*st));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	st = iio_priv(indio_dev);
+	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);
+	if (!st->chip_info)
+		return dev_err_probe(dev, -ENODEV,
+				     "Failed to get match data\n");
+
+	ret = devm_regulator_get_enable_optional(dev, "avss");
+	if (ret < 0 && ret != -ENODEV)
+		return dev_err_probe(dev, ret,
+				     "Failed to enable AVSS supply\n");
+
+	ret = devm_regulator_get_enable(dev, "avdd1");
+	if (ret)
+		return dev_err_probe(dev, ret,
+				     "Failed to enable AVDD1 supply\n");
+
+	ret = devm_regulator_bulk_get_enable(dev,
+					     ARRAY_SIZE(ad7768_supply_names),
+					     ad7768_supply_names);
+	if (ret)
+		return ret;
+
+	for (unsigned int i = 0;
+	     i < ARRAY_SIZE(ad7768_vref_supply_names); i++) {
+		ret = ad7768_get_enable_vref(dev, i);
+		if (ret < 0)
+			return ret;
+
+		st->vref_uV[i] = ret;
+	}
+
+	ret = device_property_match_property_string(dev, "clock-names",
+						    ad7768_clock_names,
+						    ARRAY_SIZE(ad7768_clock_names));
+	if (ret < 0)
+		return dev_err_probe(dev, ret, "Invalid clock source\n");
+
+	st->clock_source = ret;
+	clock_name = ad7768_clock_names[st->clock_source];
+
+	/*
+	 * The device must start on its internal clock. Keep the LVDS clock
+	 * disabled until GPIO4 is driven low and the LVDS input is enabled in
+	 * the power mode register.
+	 */
+	if (st->clock_source == AD7768_CLOCK_SOURCE_LVDS)
+		st->mclk = devm_clk_get(dev, clock_name);
+	else
+		st->mclk = devm_clk_get_enabled(dev, clock_name);
+
+	if (IS_ERR(st->mclk))
+		return dev_err_probe(dev, PTR_ERR(st->mclk),
+				     "Failed to get master clock\n");
+
+	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 = ad7768_reset(st);
+	if (ret)
+		return ret;
+
+	/* Discard the reset response with a dummy SPI register read. */
+	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_info(dev, "Unexpected revision ID 0x%02x\n", rev_id);
+
+	if (st->clock_source == AD7768_CLOCK_SOURCE_XTAL) {
+		ret = ad7768_configure_xtal_clock(st);
+		if (ret)
+			return dev_err_probe(dev, ret,
+					     "Failed to configure crystal clock\n");
+	} else if (st->clock_source == AD7768_CLOCK_SOURCE_LVDS) {
+		ret = ad7768_enable_lvds_clock(st);
+		if (ret)
+			return dev_err_probe(dev, ret,
+					     "Failed to enable LVDS clock\n");
+	}
+
+	ret = ad7768_parse_config(indio_dev, dev);
+	if (ret)
+		return ret;
+
+	/*
+	 * Hardware supports CRC every 4 or 16 samples; the backend supports only
+	 * 4-sample CRC.
+	 */
+	ret = regmap_update_bits(st->regmap, AD7768_REG_INTERFACE_CFG,
+				 AD7768_INTERFACE_CFG_CRC_SELECT_MSK,
+				 FIELD_PREP(AD7768_INTERFACE_CFG_CRC_SELECT_MSK,
+					    AD7768_INTERFACE_CFG_CRC_SELECT_4));
+	if (ret)
+		return ret;
+
+	indio_dev->name = st->chip_info->name;
+	indio_dev->info = &ad7768_info;
+	indio_dev->setup_ops = &ad7768_buffer_ops;
+
+	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);
+	ret = devm_pm_runtime_set_active_enabled(dev);
+	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_set_bits(st->regmap, AD7768_REG_POWER_MODE,
+			       AD7768_SLEEP_MODE_MSK);
+}
+
+static int ad7768_runtime_resume(struct device *dev)
+{
+	struct ad7768_state *st = dev_get_drvdata(dev);
+	int ret;
+
+	ret = regmap_clear_bits(st->regmap, AD7768_REG_POWER_MODE,
+				AD7768_SLEEP_MODE_MSK);
+	if (ret)
+		return ret;
+
+	/*
+	 * The datasheet does not specify a wake-up time. Allow 20 ms for the
+	 * ADC and digital clocks to restart.
+	 */
+	fsleep(20 * USEC_PER_MSEC);
+
+	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

[PATCH v5 06/20] iio: adc: ad7768: Validate master clock rate

[Janani Sunil]

Reject master clock rates outside the limits specified by the device.
External CMOS and LVDS clocks support 1.15 MHz to 34 MHz, while a
crystal requires 8 MHz to 34 MHz.

Signed-off-by: Janani Sunil <janani.sunil@analog.com>
---
 drivers/iio/adc/ad7768.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/drivers/iio/adc/ad7768.c b/drivers/iio/adc/ad7768.c
index cb84bb344aef..ccd457c75224 100644
--- a/drivers/iio/adc/ad7768.c
+++ b/drivers/iio/adc/ad7768.c
@@ -24,6 +24,7 @@
 #include <linux/spi/spi.h>
 #include <linux/time.h>
 #include <linux/types.h>
+#include <linux/units.h>
 
 #include <linux/iio/backend.h>
 #include <linux/iio/iio.h>
@@ -100,6 +101,9 @@
 #define AD7768_SPI_REG_MASK				GENMASK(14, 8)
 #define AD7768_SPI_DATA_MASK				GENMASK(7, 0)
 
+#define AD7768_MIN_MCLK_FREQ_HZ				(1150 * HZ_PER_KHZ)
+#define AD7768_MIN_XTAL_FREQ_HZ				(8 * HZ_PER_MHZ)
+#define AD7768_MAX_MCLK_FREQ_HZ				(34 * HZ_PER_MHZ)
 #define AD7768_MAX_CHANNEL				8
 
 enum ad7768_clock_source {
@@ -758,6 +762,23 @@ static int ad7768_get_enable_vref(struct device *dev, unsigned int index)
 	return refp_uV - refn_uV;
 }
 
+static int ad7768_validate_mclk_rate(struct device *dev,
+				     const struct ad7768_state *st)
+{
+	unsigned long min_rate = AD7768_MIN_MCLK_FREQ_HZ;
+	unsigned long rate = clk_get_rate(st->mclk);
+
+	if (st->clock_source == AD7768_CLOCK_SOURCE_XTAL)
+		min_rate = AD7768_MIN_XTAL_FREQ_HZ;
+
+	if (rate < min_rate || rate > AD7768_MAX_MCLK_FREQ_HZ)
+		return dev_err_probe(dev, -EINVAL,
+				     "MCLK rate %lu Hz outside %lu-%lu Hz\n",
+				     rate, min_rate, AD7768_MAX_MCLK_FREQ_HZ);
+
+	return 0;
+}
+
 static int ad7768_probe(struct spi_device *spi)
 {
 	unsigned int spi_readback, rev_id;
@@ -831,6 +852,10 @@ static int ad7768_probe(struct spi_device *spi)
 		return dev_err_probe(dev, PTR_ERR(st->mclk),
 				     "Failed to get master clock\n");
 
+	ret = ad7768_validate_mclk_rate(dev, st);
+	if (ret)
+		return ret;
+
 	st->regmap = devm_regmap_init(dev, &ad7768_regmap_bus, spi,
 				      st->chip_info->regmap_config);
 	if (IS_ERR(st->regmap))

-- 
2.43.0

[PATCH v5 07/20] iio: adc: ad7768: Add power mode helper

[Janani Sunil]

Describe each power mode and its internal master-clock divisor in a
table. Replace the open-coded fast-mode setup with a helper that records
the active mode, preparing for dynamic mode selection.

Signed-off-by: Janani Sunil <janani.sunil@analog.com>
---
 drivers/iio/adc/ad7768.c | 52 +++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 45 insertions(+), 7 deletions(-)

diff --git a/drivers/iio/adc/ad7768.c b/drivers/iio/adc/ad7768.c
index ccd457c75224..67db6f4971a2 100644
--- a/drivers/iio/adc/ad7768.c
+++ b/drivers/iio/adc/ad7768.c
@@ -43,6 +43,8 @@
 #define AD7768_REG_POWER_MODE				0x04
 #define   AD7768_SLEEP_MODE_MSK				BIT(7)
 #define   AD7768_POWER_MODE_POWER_MODE_MSK		GENMASK(5, 4)
+#define     AD7768_POWER_MODE_POWER_MODE_LOW		0x0
+#define     AD7768_POWER_MODE_POWER_MODE_MEDIAN		0x2
 #define     AD7768_POWER_MODE_POWER_MODE_FAST		0x3
 #define   AD7768_POWER_MODE_LVDS_ENABLE			BIT(3)
 #define   AD7768_POWER_MODE_MCLK_DIV_MSK		GENMASK(1, 0)
@@ -112,6 +114,17 @@ enum ad7768_clock_source {
 	AD7768_CLOCK_SOURCE_LVDS,
 };
 
+struct ad7768_power_mode_info {
+	unsigned int mode;
+	unsigned int mclk_div;
+};
+
+static const struct ad7768_power_mode_info ad7768_power_modes[] = {
+	{ .mode = AD7768_POWER_MODE_POWER_MODE_LOW, .mclk_div = 32 },
+	{ .mode = AD7768_POWER_MODE_POWER_MODE_MEDIAN, .mclk_div = 8 },
+	{ .mode = AD7768_POWER_MODE_POWER_MODE_FAST, .mclk_div = 4 },
+};
+
 struct ad7768_precharge_config {
 	bool prebufp_en;
 	bool prebufn_en;
@@ -136,6 +149,7 @@ struct ad7768_state {
 	struct clk *mclk;
 	unsigned int datalines;
 	enum ad7768_clock_source clock_source;
+	unsigned int power_mode_idx;
 	const struct ad7768_chip_info *chip_info;
 	struct iio_backend *back;
 	unsigned int vref_uV[2];
@@ -333,6 +347,36 @@ static int ad7768_sync(struct ad7768_state *st)
 			       AD7768_DATA_CONTROL_SPI_SYNC);
 }
 
+static int ad7768_set_power_mode(struct ad7768_state *st,
+				 unsigned int mode_idx)
+{
+	const struct ad7768_power_mode_info *mode_info;
+	int ret;
+
+	mode_info = &ad7768_power_modes[mode_idx];
+	ret = regmap_update_bits(st->regmap, AD7768_REG_POWER_MODE,
+				 AD7768_POWER_MODE_POWER_MODE_MSK,
+				 FIELD_PREP(AD7768_POWER_MODE_POWER_MODE_MSK,
+					    mode_info->mode));
+	if (ret)
+		return ret;
+
+	ret = regmap_update_bits(st->regmap, AD7768_REG_POWER_MODE,
+				 AD7768_POWER_MODE_MCLK_DIV_MSK,
+				 FIELD_PREP(AD7768_POWER_MODE_MCLK_DIV_MSK,
+					    mode_info->mode));
+	if (ret)
+		return ret;
+
+	ret = ad7768_sync(st);
+	if (ret)
+		return ret;
+
+	st->power_mode_idx = mode_idx;
+
+	return 0;
+}
+
 static int ad7768_update_scan_mode(struct iio_dev *indio_dev,
 				   const unsigned long *scan_mask)
 {
@@ -482,13 +526,7 @@ static int ad7768_configure_capture(struct ad7768_state *st)
 	unsigned int dclk_div;
 	int ret;
 
-	ret = regmap_update_bits(st->regmap, AD7768_REG_POWER_MODE,
-				 AD7768_POWER_MODE_POWER_MODE_MSK |
-				 AD7768_POWER_MODE_MCLK_DIV_MSK,
-				 FIELD_PREP(AD7768_POWER_MODE_POWER_MODE_MSK,
-					    AD7768_POWER_MODE_POWER_MODE_FAST) |
-				 FIELD_PREP(AD7768_POWER_MODE_MCLK_DIV_MSK,
-					    AD7768_POWER_MODE_POWER_MODE_FAST));
+	ret = ad7768_set_power_mode(st, ARRAY_SIZE(ad7768_power_modes) - 1);
 	if (ret)
 		return ret;
 

-- 
2.43.0

[PATCH v5 08/20] iio: adc: ad7768: Derive output data rates

[Janani Sunil]

Derive valid output data rates from the master clock, power mode and
decimation ratio.

Replace the fixed x64 decimation and open-coded DCLK divider in
ad7768_configure_capture() with the derived default output rate and the
new decimation and clock-divider helpers. Select the maximum rate
supported by the configured data interface for the initial capture
configuration.

Signed-off-by: Janani Sunil <janani.sunil@analog.com>
---
 drivers/iio/adc/ad7768.c | 144 +++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 127 insertions(+), 17 deletions(-)

diff --git a/drivers/iio/adc/ad7768.c b/drivers/iio/adc/ad7768.c
index 67db6f4971a2..09b4e2f32304 100644
--- a/drivers/iio/adc/ad7768.c
+++ b/drivers/iio/adc/ad7768.c
@@ -12,6 +12,7 @@
 #include <linux/delay.h>
 #include <linux/device.h>
 #include <linux/err.h>
+#include <linux/log2.h>
 #include <linux/math.h>
 #include <linux/minmax.h>
 #include <linux/module.h>
@@ -36,7 +37,6 @@
 #define   AD7768_CH_MODE_FILTER_TYPE_MSK		BIT(3)
 #define     AD7768_CH_MODE_FILTER_TYPE_WIDEBAND		0x0
 #define   AD7768_CH_MODE_DEC_RATE_MSK			GENMASK(2, 0)
-#define     AD7768_CH_MODE_DEC_RATE_64			0x1
 
 #define AD7768_REG_CH_MODE_SEL				0x03
 
@@ -103,9 +103,12 @@
 #define AD7768_SPI_REG_MASK				GENMASK(14, 8)
 #define AD7768_SPI_DATA_MASK				GENMASK(7, 0)
 
+#define AD7768_SAMPLE_SIZE				32
+#define AD7768_MAX_DCLK_DIV				8
 #define AD7768_MIN_MCLK_FREQ_HZ				(1150 * HZ_PER_KHZ)
 #define AD7768_MIN_XTAL_FREQ_HZ				(8 * HZ_PER_MHZ)
 #define AD7768_MAX_MCLK_FREQ_HZ				(34 * HZ_PER_MHZ)
+#define AD7768_MAX_FREQ_PER_MODE			6
 #define AD7768_MAX_CHANNEL				8
 
 enum ad7768_clock_source {
@@ -132,6 +135,16 @@ struct ad7768_precharge_config {
 	bool refbufn;
 };
 
+struct ad7768_freq_config {
+	unsigned int freq_hz;
+	unsigned int dec_rate;
+};
+
+struct ad7768_avail_freq {
+	unsigned int n_freqs;
+	struct ad7768_freq_config freq_cfg[AD7768_MAX_FREQ_PER_MODE];
+};
+
 struct ad7768_chip_info {
 	const char *name;
 	unsigned int num_channels;
@@ -151,12 +164,18 @@ struct ad7768_state {
 	enum ad7768_clock_source clock_source;
 	unsigned int power_mode_idx;
 	const struct ad7768_chip_info *chip_info;
+	struct ad7768_avail_freq avail_freq[ARRAY_SIZE(ad7768_power_modes)];
+	unsigned int ch_freq[AD7768_MAX_CHANNEL];
 	struct iio_backend *back;
 	unsigned int vref_uV[2];
 
 	__be16 d16 __aligned(IIO_DMA_MINALIGN);
 };
 
+static const unsigned int ad7768_dec_rate[AD7768_MAX_FREQ_PER_MODE] = {
+	32, 64, 128, 256, 512, 1024,
+};
+
 static const unsigned int ad7768_available_datalines[] = {
 	1, 2, 8,
 };
@@ -377,6 +396,70 @@ static int ad7768_set_power_mode(struct ad7768_state *st,
 	return 0;
 }
 
+static const struct ad7768_freq_config *
+ad7768_find_freq_config(const struct ad7768_state *st,
+			unsigned int mode_idx, unsigned int freq)
+{
+	const struct ad7768_avail_freq *avail_freq = &st->avail_freq[mode_idx];
+
+	for (unsigned int i = 0; i < avail_freq->n_freqs; i++) {
+		if (freq == avail_freq->freq_cfg[i].freq_hz)
+			return &avail_freq->freq_cfg[i];
+	}
+
+	return NULL;
+}
+
+static int ad7768_set_clk_divs(struct ad7768_state *st, unsigned int freq)
+{
+	const struct ad7768_freq_config *freq_cfg;
+	unsigned int mclk, dclk, dclk_div;
+	unsigned int chan_per_doutx;
+	unsigned int dclk_div_reg;
+
+	freq_cfg = ad7768_find_freq_config(st, st->power_mode_idx, freq);
+	if (!freq_cfg)
+		return -EINVAL;
+
+	mclk = clk_get_rate(st->mclk);
+	chan_per_doutx = st->chip_info->num_channels / st->datalines;
+	if (!chan_per_doutx)
+		return -EINVAL;
+
+	dclk = freq_cfg->freq_hz * AD7768_SAMPLE_SIZE * chan_per_doutx;
+	if (!dclk || dclk > mclk)
+		return -EINVAL;
+
+	/* Set the divider to the next-lowest supported power of two. */
+	dclk_div = DIV_ROUND_CLOSEST(mclk, dclk);
+	if (dclk_div > AD7768_MAX_DCLK_DIV)
+		dclk_div = AD7768_MAX_DCLK_DIV;
+	else
+		dclk_div = rounddown_pow_of_two(dclk_div);
+
+	dclk_div_reg = AD7768_INTERFACE_CFG_DCLK_DIV(dclk_div);
+
+	return regmap_update_bits(st->regmap, AD7768_REG_INTERFACE_CFG,
+				  AD7768_INTERFACE_CFG_DCLK_DIV_MSK,
+				  FIELD_PREP(AD7768_INTERFACE_CFG_DCLK_DIV_MSK,
+					     dclk_div_reg));
+}
+
+static int ad7768_set_mode_decimation(struct ad7768_state *st,
+				      unsigned int freq, unsigned int mode)
+{
+	const struct ad7768_freq_config *freq_cfg;
+
+	freq_cfg = ad7768_find_freq_config(st, st->power_mode_idx, freq);
+	if (!freq_cfg)
+		return -EINVAL;
+
+	return regmap_update_bits(st->regmap, AD7768_REG_CH_MODE(mode),
+				  AD7768_CH_MODE_DEC_RATE_MSK,
+				  FIELD_PREP(AD7768_CH_MODE_DEC_RATE_MSK,
+					     freq_cfg->dec_rate));
+}
+
 static int ad7768_update_scan_mode(struct iio_dev *indio_dev,
 				   const unsigned long *scan_mask)
 {
@@ -519,28 +602,58 @@ static int ad7768_configure_precharge_buffers(struct iio_dev *indio_dev,
 	return regmap_write(st->regmap, AD7768_REG_REFN_BUF, refbufn_val);
 }
 
+static void ad7768_set_available_sampling_freqs(struct ad7768_state *st)
+{
+	unsigned int mclk = clk_get_rate(st->mclk);
+
+	for (unsigned int mode_idx = 0;
+	     mode_idx < ARRAY_SIZE(ad7768_power_modes); mode_idx++) {
+		struct ad7768_avail_freq *avail_freq;
+
+		avail_freq = &st->avail_freq[mode_idx];
+		for (unsigned int dec = ARRAY_SIZE(ad7768_dec_rate); dec > 0;
+		     dec--) {
+			struct ad7768_freq_config *freq_cfg;
+
+			freq_cfg = &avail_freq->freq_cfg[avail_freq->n_freqs++];
+			freq_cfg->dec_rate = dec - 1;
+			freq_cfg->freq_hz = mclk /
+				(ad7768_dec_rate[dec - 1] *
+				 ad7768_power_modes[mode_idx].mclk_div);
+		}
+	}
+
+	/* One DOUT line cannot carry the AD7768 fast-mode x32 output rate. */
+	if (st->datalines == 1 &&
+	    st->chip_info->num_channels == AD7768_MAX_CHANNEL)
+		st->avail_freq[ARRAY_SIZE(ad7768_power_modes) - 1].n_freqs--;
+}
+
 static int ad7768_configure_capture(struct ad7768_state *st)
 {
-	unsigned int dclk_div_reg;
+	const struct ad7768_avail_freq *avail_freq;
+	unsigned int default_freq;
 	unsigned int mode_config;
-	unsigned int dclk_div;
 	int ret;
 
 	ret = ad7768_set_power_mode(st, ARRAY_SIZE(ad7768_power_modes) - 1);
 	if (ret)
 		return ret;
 
-	/*
-	 * Start with the wideband filter and a decimation rate of 64. This
-	 * supports every valid data-line configuration at the maximum MCLK.
-	 */
+	avail_freq = &st->avail_freq[st->power_mode_idx];
+	default_freq = avail_freq->freq_cfg[avail_freq->n_freqs - 1].freq_hz;
+	for (unsigned int channel = 0;
+	     channel < st->chip_info->num_channels; channel++)
+		st->ch_freq[channel] = default_freq;
+
+	ret = ad7768_set_mode_decimation(st, default_freq, 0);
+	if (ret)
+		return ret;
+
 	mode_config = FIELD_PREP(AD7768_CH_MODE_FILTER_TYPE_MSK,
 				 AD7768_CH_MODE_FILTER_TYPE_WIDEBAND);
-	mode_config |= FIELD_PREP(AD7768_CH_MODE_DEC_RATE_MSK,
-				  AD7768_CH_MODE_DEC_RATE_64);
 	ret = regmap_update_bits(st->regmap, AD7768_REG_CH_MODE(0),
-				 AD7768_CH_MODE_FILTER_TYPE_MSK |
-				 AD7768_CH_MODE_DEC_RATE_MSK,
+				 AD7768_CH_MODE_FILTER_TYPE_MSK,
 				 mode_config);
 	if (ret)
 		return ret;
@@ -549,12 +662,7 @@ static int ad7768_configure_capture(struct ad7768_state *st)
 	if (ret)
 		return ret;
 
-	dclk_div = 8 * st->datalines / st->chip_info->num_channels;
-	dclk_div_reg = AD7768_INTERFACE_CFG_DCLK_DIV(dclk_div);
-	ret = regmap_update_bits(st->regmap, AD7768_REG_INTERFACE_CFG,
-				 AD7768_INTERFACE_CFG_DCLK_DIV_MSK,
-				 FIELD_PREP(AD7768_INTERFACE_CFG_DCLK_DIV_MSK,
-					    dclk_div_reg));
+	ret = ad7768_set_clk_divs(st, default_freq);
 	if (ret)
 		return ret;
 
@@ -677,6 +785,8 @@ static int ad7768_parse_config(struct iio_dev *indio_dev,
 				     "Invalid data-lines-number %d for %s\n",
 				     st->datalines, st->chip_info->name);
 
+	ad7768_set_available_sampling_freqs(st);
+
 	return ad7768_configure_capture(st);
 }
 

-- 
2.43.0

[PATCH v5 09/20] iio: adc: ad7768: Configure channel sampling profiles

[Janani Sunil]

At buffered capture setup, select the fastest compatible power mode for
the enabled channel rates. Group channels into the two hardware mode
profiles and program their decimation, mode selection, and data clock.

Signed-off-by: Janani Sunil <janani.sunil@analog.com>
---
 drivers/iio/adc/ad7768.c | 153 ++++++++++++++++++++++++++++++++++++++---------
 1 file changed, 126 insertions(+), 27 deletions(-)

diff --git a/drivers/iio/adc/ad7768.c b/drivers/iio/adc/ad7768.c
index 09b4e2f32304..00d6f1dce591 100644
--- a/drivers/iio/adc/ad7768.c
+++ b/drivers/iio/adc/ad7768.c
@@ -7,7 +7,9 @@
 
 #include <linux/array_size.h>
 #include <linux/bitfield.h>
+#include <linux/bitmap.h>
 #include <linux/bitops.h>
+#include <linux/cleanup.h>
 #include <linux/clk.h>
 #include <linux/delay.h>
 #include <linux/device.h>
@@ -35,7 +37,6 @@
 
 #define AD7768_REG_CH_MODE(x)				(0x01 + (x))
 #define   AD7768_CH_MODE_FILTER_TYPE_MSK		BIT(3)
-#define     AD7768_CH_MODE_FILTER_TYPE_WIDEBAND		0x0
 #define   AD7768_CH_MODE_DEC_RATE_MSK			GENMASK(2, 0)
 
 #define AD7768_REG_CH_MODE_SEL				0x03
@@ -110,6 +111,7 @@
 #define AD7768_MAX_MCLK_FREQ_HZ				(34 * HZ_PER_MHZ)
 #define AD7768_MAX_FREQ_PER_MODE			6
 #define AD7768_MAX_CHANNEL				8
+#define AD7768_NUM_CHANNEL_MODES			2
 
 enum ad7768_clock_source {
 	AD7768_CLOCK_SOURCE_MCLK,
@@ -212,6 +214,11 @@ static u8 ad7768_channel_mask(const struct ad7768_state *st, u8 ch)
 	return BIT(st->chip_info->chan_map[ch]);
 }
 
+static u8 ad7768_channel_mode_mask(const struct ad7768_state *st, u8 ch)
+{
+	return BIT(ch) | ad7768_channel_mask(st, ch);
+}
+
 static u8 ad7768_all_standby_mask(const struct ad7768_state *st)
 {
 	return GENMASK(st->chip_info->num_channels - 1, 0);
@@ -460,14 +467,69 @@ static int ad7768_set_mode_decimation(struct ad7768_state *st,
 					     freq_cfg->dec_rate));
 }
 
-static int ad7768_update_scan_mode(struct iio_dev *indio_dev,
-				   const unsigned long *scan_mask)
+static int ad7768_set_lowest_noise_mode(struct ad7768_state *st,
+					const unsigned long *scan_mask)
+{
+	/*
+	 * The output data rate ranges overlap between the power modes. At a
+	 * common ODR, the faster mode has lower noise, so prefer the fastest
+	 * mode that supports every enabled channel.
+	 */
+	for (unsigned int mode_idx = ARRAY_SIZE(ad7768_power_modes);
+	     mode_idx-- > 0;) {
+		bool supported = true;
+		unsigned int channel;
+
+		for_each_set_bit(channel, scan_mask,
+				 st->chip_info->num_channels) {
+			if (!ad7768_find_freq_config(st, mode_idx,
+						     st->ch_freq[channel])) {
+				supported = false;
+				break;
+			}
+		}
+
+		if (supported)
+			return ad7768_set_power_mode(st, mode_idx);
+	}
+
+	return -EINVAL;
+}
+
+static int ad7768_find_matching_mode(const bool *mode_used,
+				     const unsigned int *mode_freq,
+				     unsigned int freq)
+{
+	for (unsigned int mode = 0; mode < AD7768_NUM_CHANNEL_MODES; mode++) {
+		if (!mode_used[mode] || mode_freq[mode] == freq)
+			return mode;
+	}
+
+	return -EINVAL;
+}
+
+static int ad7768_apply_channel_modes(struct iio_dev *indio_dev,
+				      const unsigned long *scan_mask)
 {
+	unsigned int mode_freq[AD7768_NUM_CHANNEL_MODES] = { };
+	bool mode_used[AD7768_NUM_CHANNEL_MODES] = { };
 	struct ad7768_state *st = iio_priv(indio_dev);
+	struct device *dev = indio_dev->dev.parent;
 	unsigned long channel_mask;
 	unsigned long standby_mask;
+	unsigned int max_freq = 0;
+	unsigned int c;
 	int ret;
 
+	guard(mutex)(&st->lock);
+
+	ret = ad7768_set_lowest_noise_mode(st, scan_mask);
+	if (ret == -EINVAL)
+		return dev_err_probe(dev, ret,
+				     "No power mode supports all ODRs\n");
+	if (ret)
+		return ret;
+
 	channel_mask = ad7768_all_standby_mask(st);
 	standby_mask = channel_mask & ~*scan_mask;
 
@@ -478,11 +540,65 @@ static int ad7768_update_scan_mode(struct iio_dev *indio_dev,
 	if (st->clock_source == AD7768_CLOCK_SOURCE_XTAL)
 		standby_mask &= ~BIT(st->chip_info->num_channels / 2);
 
+	for_each_set_bit(c, scan_mask, st->chip_info->num_channels) {
+		unsigned int mask;
+		int mode;
+
+		mode = ad7768_find_matching_mode(mode_used, mode_freq,
+						 st->ch_freq[c]);
+		if (mode < 0)
+			return dev_err_probe(dev, -EINVAL,
+					     "Over %d channel modes required\n",
+					     AD7768_NUM_CHANNEL_MODES);
+
+		mode_freq[mode] = st->ch_freq[c];
+		mode_used[mode] = true;
+
+		mask = ad7768_channel_mode_mask(st, c);
+		ret = regmap_assign_bits(st->regmap, AD7768_REG_CH_MODE_SEL,
+					 mask, mode);
+		if (ret)
+			return ret;
+	}
+
 	ret = regmap_update_bits(st->regmap, AD7768_REG_CH_STANDBY,
 				 channel_mask, standby_mask);
 	if (ret)
 		return ret;
 
+	for (unsigned int mode = 0; mode < AD7768_NUM_CHANNEL_MODES; mode++) {
+		if (!mode_used[mode])
+			continue;
+
+		ret = ad7768_set_mode_decimation(st, mode_freq[mode], mode);
+		if (ret)
+			return ret;
+
+		ret = regmap_clear_bits(st->regmap, AD7768_REG_CH_MODE(mode),
+					AD7768_CH_MODE_FILTER_TYPE_MSK);
+		if (ret)
+			return ret;
+
+		max_freq = max(max_freq, mode_freq[mode]);
+	}
+
+	ret = ad7768_set_clk_divs(st, max_freq);
+	if (ret)
+		return ret;
+
+	return ad7768_sync(st);
+}
+
+static int ad7768_update_scan_mode(struct iio_dev *indio_dev,
+				   const unsigned long *scan_mask)
+{
+	struct ad7768_state *st = iio_priv(indio_dev);
+	int ret;
+
+	ret = ad7768_apply_channel_modes(indio_dev, scan_mask);
+	if (ret)
+		return ret;
+
 	for (unsigned int c = 0; c < st->chip_info->num_channels; c++) {
 		if (test_bit(c, scan_mask))
 			ret = iio_backend_chan_enable(st->back, c);
@@ -629,11 +745,10 @@ static void ad7768_set_available_sampling_freqs(struct ad7768_state *st)
 		st->avail_freq[ARRAY_SIZE(ad7768_power_modes) - 1].n_freqs--;
 }
 
-static int ad7768_configure_capture(struct ad7768_state *st)
+static int ad7768_init_sampling_freqs(struct ad7768_state *st)
 {
 	const struct ad7768_avail_freq *avail_freq;
 	unsigned int default_freq;
-	unsigned int mode_config;
 	int ret;
 
 	ret = ad7768_set_power_mode(st, ARRAY_SIZE(ad7768_power_modes) - 1);
@@ -646,27 +761,7 @@ static int ad7768_configure_capture(struct ad7768_state *st)
 	     channel < st->chip_info->num_channels; channel++)
 		st->ch_freq[channel] = default_freq;
 
-	ret = ad7768_set_mode_decimation(st, default_freq, 0);
-	if (ret)
-		return ret;
-
-	mode_config = FIELD_PREP(AD7768_CH_MODE_FILTER_TYPE_MSK,
-				 AD7768_CH_MODE_FILTER_TYPE_WIDEBAND);
-	ret = regmap_update_bits(st->regmap, AD7768_REG_CH_MODE(0),
-				 AD7768_CH_MODE_FILTER_TYPE_MSK,
-				 mode_config);
-	if (ret)
-		return ret;
-
-	ret = regmap_write(st->regmap, AD7768_REG_CH_MODE_SEL, 0);
-	if (ret)
-		return ret;
-
-	ret = ad7768_set_clk_divs(st, default_freq);
-	if (ret)
-		return ret;
-
-	return ad7768_sync(st);
+	return 0;
 }
 
 static int ad7768_parse_config(struct iio_dev *indio_dev,
@@ -787,7 +882,11 @@ static int ad7768_parse_config(struct iio_dev *indio_dev,
 
 	ad7768_set_available_sampling_freqs(st);
 
-	return ad7768_configure_capture(st);
+	ret = ad7768_init_sampling_freqs(st);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to set power mode\n");
+
+	return 0;
 }
 
 static int ad7768_reset(struct ad7768_state *st)

-- 
2.43.0

[PATCH v5 10/20] iio: adc: ad7768: Add sampling frequency controls

[Janani Sunil]

Expose the requested sampling frequency and available rates for each
channel. Validate requests against the rates supported by the power mode
tables and apply them when buffered capture starts.

Signed-off-by: Janani Sunil <janani.sunil@analog.com>
---
 drivers/iio/adc/ad7768.c | 116 ++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 109 insertions(+), 7 deletions(-)

diff --git a/drivers/iio/adc/ad7768.c b/drivers/iio/adc/ad7768.c
index 00d6f1dce591..1245ec94b637 100644
--- a/drivers/iio/adc/ad7768.c
+++ b/drivers/iio/adc/ad7768.c
@@ -130,6 +130,9 @@ static const struct ad7768_power_mode_info ad7768_power_modes[] = {
 	{ .mode = AD7768_POWER_MODE_POWER_MODE_FAST, .mclk_div = 4 },
 };
 
+#define AD7768_MAX_FREQS \
+	(AD7768_MAX_FREQ_PER_MODE + ARRAY_SIZE(ad7768_power_modes))
+
 struct ad7768_precharge_config {
 	bool prebufp_en;
 	bool prebufn_en;
@@ -167,6 +170,8 @@ struct ad7768_state {
 	unsigned int power_mode_idx;
 	const struct ad7768_chip_info *chip_info;
 	struct ad7768_avail_freq avail_freq[ARRAY_SIZE(ad7768_power_modes)];
+	unsigned int n_freqs;
+	int freqs[AD7768_MAX_FREQS];
 	unsigned int ch_freq[AD7768_MAX_CHANNEL];
 	struct iio_backend *back;
 	unsigned int vref_uV[2];
@@ -496,6 +501,32 @@ static int ad7768_set_lowest_noise_mode(struct ad7768_state *st,
 	return -EINVAL;
 }
 
+static bool ad7768_freq_supported_in_any_mode(const struct ad7768_state *st,
+					      unsigned int freq)
+{
+	for (unsigned int mode_idx = 0;
+	     mode_idx < ARRAY_SIZE(ad7768_power_modes); mode_idx++) {
+		if (ad7768_find_freq_config(st, mode_idx, freq))
+			return true;
+	}
+
+	return false;
+}
+
+static int ad7768_set_sampling_freq(struct iio_dev *indio_dev,
+				    unsigned int freq, unsigned int channel)
+{
+	struct ad7768_state *st = iio_priv(indio_dev);
+
+	if (!freq || !ad7768_freq_supported_in_any_mode(st, freq))
+		return -EINVAL;
+
+	guard(mutex)(&st->lock);
+	st->ch_freq[channel] = freq;
+
+	return 0;
+}
+
 static int ad7768_find_matching_mode(const bool *mode_used,
 				     const unsigned int *mode_freq,
 				     unsigned int freq)
@@ -656,21 +687,74 @@ static int ad7768_read_raw(struct iio_dev *indio_dev,
 			   int *val, int *val2, long info)
 {
 	struct ad7768_state *st = iio_priv(indio_dev);
-	unsigned int vref_idx;
 
-	if (info != IIO_CHAN_INFO_SCALE)
+	switch (info) {
+	case IIO_CHAN_INFO_SCALE: {
+		unsigned int vref_idx;
+
+		vref_idx = chan->channel >= st->chip_info->num_channels / 2;
+		*val = 2 * st->vref_uV[vref_idx] / 1000;
+		*val2 = chan->scan_type.realbits;
+
+		return IIO_VAL_FRACTIONAL_LOG2;
+	}
+	case IIO_CHAN_INFO_SAMP_FREQ: {
+		guard(mutex)(&st->lock);
+		*val = st->ch_freq[chan->channel];
+
+		return IIO_VAL_INT;
+	}
+	default:
+		return -EINVAL;
+	}
+}
+
+static int ad7768_write_raw_get_fmt(struct iio_dev *indio_dev,
+				    struct iio_chan_spec const *chan, long info)
+{
+	if (info == IIO_CHAN_INFO_SAMP_FREQ)
+		return IIO_VAL_INT;
+
+	return -EINVAL;
+}
+
+static int ad7768_write_raw(struct iio_dev *indio_dev,
+			    struct iio_chan_spec const *chan,
+			    int val, int val2, long info)
+{
+	IIO_DEV_ACQUIRE_DIRECT_MODE(indio_dev, claim);
+	if (IIO_DEV_ACQUIRE_FAILED(claim))
+		return -EBUSY;
+
+	if (info == IIO_CHAN_INFO_SAMP_FREQ)
+		return ad7768_set_sampling_freq(indio_dev, val, chan->channel);
+
+	return -EINVAL;
+}
+
+static int ad7768_read_avail(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan,
+			     const int **vals, int *type, int *length,
+			     long info)
+{
+	struct ad7768_state *st = iio_priv(indio_dev);
+
+	if (info != IIO_CHAN_INFO_SAMP_FREQ)
 		return -EINVAL;
 
-	vref_idx = chan->channel >= st->chip_info->num_channels / 2;
-	*val = 2 * st->vref_uV[vref_idx] / 1000;
-	*val2 = chan->scan_type.realbits;
+	*vals = st->freqs;
+	*type = IIO_VAL_INT;
+	*length = st->n_freqs;
 
-	return IIO_VAL_FRACTIONAL_LOG2;
+	return IIO_AVAIL_LIST;
 }
 
 static const struct iio_info ad7768_info = {
 	.debugfs_reg_access = ad7768_reg_access,
 	.read_raw = ad7768_read_raw,
+	.write_raw_get_fmt = ad7768_write_raw_get_fmt,
+	.write_raw = ad7768_write_raw,
+	.read_avail = ad7768_read_avail,
 	.update_scan_mode = ad7768_update_scan_mode,
 };
 
@@ -743,6 +827,21 @@ static void ad7768_set_available_sampling_freqs(struct ad7768_state *st)
 	if (st->datalines == 1 &&
 	    st->chip_info->num_channels == AD7768_MAX_CHANNEL)
 		st->avail_freq[ARRAY_SIZE(ad7768_power_modes) - 1].n_freqs--;
+
+	for (unsigned int mode_idx = 0;
+	     mode_idx < ARRAY_SIZE(ad7768_power_modes); mode_idx++) {
+		const struct ad7768_avail_freq *avail_freq;
+
+		avail_freq = &st->avail_freq[mode_idx];
+		for (unsigned int i = 0; i < avail_freq->n_freqs; i++) {
+			unsigned int freq = avail_freq->freq_cfg[i].freq_hz;
+
+			if (st->n_freqs && st->freqs[st->n_freqs - 1] >= freq)
+				continue;
+
+			st->freqs[st->n_freqs++] = freq;
+		}
+	}
 }
 
 static int ad7768_init_sampling_freqs(struct ad7768_state *st)
@@ -841,7 +940,10 @@ static int ad7768_parse_config(struct iio_dev *indio_dev,
 
 		chan[chan_idx] = (struct iio_chan_spec) {
 			.type = IIO_VOLTAGE,
-			.info_mask_separate = BIT(IIO_CHAN_INFO_SCALE),
+			.info_mask_separate = BIT(IIO_CHAN_INFO_SCALE) |
+					      BIT(IIO_CHAN_INFO_SAMP_FREQ),
+			.info_mask_separate_available =
+				BIT(IIO_CHAN_INFO_SAMP_FREQ),
 			.indexed = 1,
 			.channel = channel,
 			.scan_index = channel,

-- 
2.43.0

[PATCH v5 11/20] iio: adc: ad7768: Add per-channel filter controls

[Janani Sunil]

Expose wideband and sinc5 filter selection for each channel. Group
enabled channels by their requested sampling frequency and filter pairs
and program each pair into one of the two hardware mode profiles.

Signed-off-by: Janani Sunil <janani.sunil@analog.com>
---
 drivers/iio/adc/ad7768.c | 72 ++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 66 insertions(+), 6 deletions(-)

diff --git a/drivers/iio/adc/ad7768.c b/drivers/iio/adc/ad7768.c
index 1245ec94b637..4c67f692861e 100644
--- a/drivers/iio/adc/ad7768.c
+++ b/drivers/iio/adc/ad7768.c
@@ -113,6 +113,11 @@
 #define AD7768_MAX_CHANNEL				8
 #define AD7768_NUM_CHANNEL_MODES			2
 
+enum ad7768_filter_type {
+	AD7768_FILTER_TYPE_WIDEBAND,
+	AD7768_FILTER_TYPE_SINC5,
+};
+
 enum ad7768_clock_source {
 	AD7768_CLOCK_SOURCE_MCLK,
 	AD7768_CLOCK_SOURCE_XTAL,
@@ -173,6 +178,7 @@ struct ad7768_state {
 	unsigned int n_freqs;
 	int freqs[AD7768_MAX_FREQS];
 	unsigned int ch_freq[AD7768_MAX_CHANNEL];
+	enum ad7768_filter_type ch_filter[AD7768_MAX_CHANNEL];
 	struct iio_backend *back;
 	unsigned int vref_uV[2];
 
@@ -527,12 +533,59 @@ static int ad7768_set_sampling_freq(struct iio_dev *indio_dev,
 	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);
+
+	IIO_DEV_ACQUIRE_DIRECT_MODE(indio_dev, claim);
+	if (IIO_DEV_ACQUIRE_FAILED(claim))
+		return -EBUSY;
+
+	guard(mutex)(&st->lock);
+	st->ch_filter[chan->channel] = mode;
+
+	return 0;
+}
+
+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);
+
+	guard(mutex)(&st->lock);
+
+	return st->ch_filter[chan->channel];
+}
+
+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 int ad7768_find_matching_mode(const bool *mode_used,
 				     const unsigned int *mode_freq,
-				     unsigned int freq)
+				     const enum ad7768_filter_type *mode_filter,
+				     unsigned int freq,
+				     enum ad7768_filter_type filter)
 {
 	for (unsigned int mode = 0; mode < AD7768_NUM_CHANNEL_MODES; mode++) {
-		if (!mode_used[mode] || mode_freq[mode] == freq)
+		if (!mode_used[mode] ||
+		    (mode_freq[mode] == freq && mode_filter[mode] == filter))
 			return mode;
 	}
 
@@ -542,6 +595,7 @@ static int ad7768_find_matching_mode(const bool *mode_used,
 static int ad7768_apply_channel_modes(struct iio_dev *indio_dev,
 				      const unsigned long *scan_mask)
 {
+	enum ad7768_filter_type mode_filter[AD7768_NUM_CHANNEL_MODES] = { };
 	unsigned int mode_freq[AD7768_NUM_CHANNEL_MODES] = { };
 	bool mode_used[AD7768_NUM_CHANNEL_MODES] = { };
 	struct ad7768_state *st = iio_priv(indio_dev);
@@ -576,13 +630,15 @@ static int ad7768_apply_channel_modes(struct iio_dev *indio_dev,
 		int mode;
 
 		mode = ad7768_find_matching_mode(mode_used, mode_freq,
-						 st->ch_freq[c]);
+						 mode_filter, st->ch_freq[c],
+						 st->ch_filter[c]);
 		if (mode < 0)
 			return dev_err_probe(dev, -EINVAL,
 					     "Over %d channel modes required\n",
 					     AD7768_NUM_CHANNEL_MODES);
 
 		mode_freq[mode] = st->ch_freq[c];
+		mode_filter[mode] = st->ch_filter[c];
 		mode_used[mode] = true;
 
 		mask = ad7768_channel_mode_mask(st, c);
@@ -605,8 +661,9 @@ static int ad7768_apply_channel_modes(struct iio_dev *indio_dev,
 		if (ret)
 			return ret;
 
-		ret = regmap_clear_bits(st->regmap, AD7768_REG_CH_MODE(mode),
-					AD7768_CH_MODE_FILTER_TYPE_MSK);
+		ret = regmap_assign_bits(st->regmap, AD7768_REG_CH_MODE(mode),
+					 AD7768_CH_MODE_FILTER_TYPE_MSK,
+					 mode_filter[mode]);
 		if (ret)
 			return ret;
 
@@ -857,8 +914,10 @@ static int ad7768_init_sampling_freqs(struct ad7768_state *st)
 	avail_freq = &st->avail_freq[st->power_mode_idx];
 	default_freq = avail_freq->freq_cfg[avail_freq->n_freqs - 1].freq_hz;
 	for (unsigned int channel = 0;
-	     channel < st->chip_info->num_channels; channel++)
+	     channel < st->chip_info->num_channels; channel++) {
 		st->ch_freq[channel] = default_freq;
+		st->ch_filter[channel] = AD7768_FILTER_TYPE_WIDEBAND;
+	}
 
 	return 0;
 }
@@ -952,6 +1011,7 @@ static int ad7768_parse_config(struct iio_dev *indio_dev,
 				.realbits = 24,
 				.storagebits = 32,
 			},
+			.ext_info = ad7768_ext_info,
 		};
 		chan_idx++;
 	}

-- 
2.43.0

[PATCH v5 12/20] iio: adc: ad7768: Wait for digital filters to settle

[Janani Sunil]

After synchronizing the channel mode configuration, wait for the longest
settling period required by the active profiles. Derive the delay from
the selected output data rate and the datasheet filter-settling limits.

Signed-off-by: Janani Sunil <janani.sunil@analog.com>
---
 drivers/iio/adc/ad7768.c | 38 +++++++++++++++++++++++++++++++++++++-
 1 file changed, 37 insertions(+), 1 deletion(-)

diff --git a/drivers/iio/adc/ad7768.c b/drivers/iio/adc/ad7768.c
index 4c67f692861e..84b96b1fab09 100644
--- a/drivers/iio/adc/ad7768.c
+++ b/drivers/iio/adc/ad7768.c
@@ -112,6 +112,8 @@
 #define AD7768_MAX_FREQ_PER_MODE			6
 #define AD7768_MAX_CHANNEL				8
 #define AD7768_NUM_CHANNEL_MODES			2
+#define AD7768_WIDEBAND_SETTLING_SAMPLES		68
+#define AD7768_SINC5_SETTLING_SAMPLES			7
 
 enum ad7768_filter_type {
 	AD7768_FILTER_TYPE_WIDEBAND,
@@ -592,6 +594,33 @@ static int ad7768_find_matching_mode(const bool *mode_used,
 	return -EINVAL;
 }
 
+static void ad7768_filter_wait(const unsigned int *mode_freq,
+			       const enum ad7768_filter_type *mode_filter,
+			       const bool *mode_used)
+{
+	unsigned int t_settle_us = 0;
+
+	for (unsigned int mode = 0; mode < AD7768_NUM_CHANNEL_MODES; mode++) {
+		unsigned int settling_samples;
+		unsigned int t_mode_us;
+
+		if (!mode_used[mode] || !mode_freq[mode])
+			continue;
+
+		if (mode_filter[mode] == AD7768_FILTER_TYPE_SINC5)
+			settling_samples = AD7768_SINC5_SETTLING_SAMPLES;
+		else
+			settling_samples = AD7768_WIDEBAND_SETTLING_SAMPLES;
+
+		t_mode_us = DIV_ROUND_UP(settling_samples * USEC_PER_SEC,
+					 mode_freq[mode]);
+		t_settle_us = max(t_settle_us, t_mode_us);
+	}
+
+	if (t_settle_us)
+		fsleep(t_settle_us);
+}
+
 static int ad7768_apply_channel_modes(struct iio_dev *indio_dev,
 				      const unsigned long *scan_mask)
 {
@@ -674,7 +703,14 @@ static int ad7768_apply_channel_modes(struct iio_dev *indio_dev,
 	if (ret)
 		return ret;
 
-	return ad7768_sync(st);
+	ret = ad7768_sync(st);
+	if (ret)
+		return ret;
+
+	/* Apply a filter settling time (datasheet Tables 28 and 29). */
+	ad7768_filter_wait(mode_freq, mode_filter, mode_used);
+
+	return 0;
 }
 
 static int ad7768_update_scan_mode(struct iio_dev *indio_dev,

-- 
2.43.0

[PATCH v5 13/20] iio: adc: ad7768: Add calibration controls

[Janani Sunil]

Expose the per-channel offset and gain calibration registers through the
IIO calibbias and calibscale attributes.

Signed-off-by: Janani Sunil <janani.sunil@analog.com>
---
 drivers/iio/adc/ad7768.c | 118 ++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 112 insertions(+), 6 deletions(-)

diff --git a/drivers/iio/adc/ad7768.c b/drivers/iio/adc/ad7768.c
index 84b96b1fab09..f2f318ebf964 100644
--- a/drivers/iio/adc/ad7768.c
+++ b/drivers/iio/adc/ad7768.c
@@ -27,6 +27,7 @@
 #include <linux/spi/spi.h>
 #include <linux/time.h>
 #include <linux/types.h>
+#include <linux/unaligned.h>
 #include <linux/units.h>
 
 #include <linux/iio/backend.h>
@@ -112,6 +113,7 @@
 #define AD7768_MAX_FREQ_PER_MODE			6
 #define AD7768_MAX_CHANNEL				8
 #define AD7768_NUM_CHANNEL_MODES			2
+#define AD7768_CALIB_REG_MSK				GENMASK(23, 0)
 #define AD7768_WIDEBAND_SETTLING_SAMPLES		68
 #define AD7768_SINC5_SETTLING_SAMPLES			7
 
@@ -237,6 +239,18 @@ static u8 ad7768_all_standby_mask(const struct ad7768_state *st)
 	return GENMASK(st->chip_info->num_channels - 1, 0);
 }
 
+static unsigned int ad7768_offset_reg(const struct ad7768_state *st,
+				      unsigned int ch)
+{
+	return AD7768_REG_OFFSET(st->chip_info->chan_map[ch]);
+}
+
+static unsigned int ad7768_gain_reg(const struct ad7768_state *st,
+				    unsigned int ch)
+{
+	return AD7768_REG_GAIN(st->chip_info->chan_map[ch]);
+}
+
 static u8 ad7768_precharge_buf1_mask(const struct ad7768_state *st, u16 val)
 {
 	return val & GENMASK(st->chip_info->prebuf_split - 1, 0);
@@ -354,6 +368,59 @@ static const struct regmap_config ad7768_4_regmap_config = {
 	.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)
+		return ad7768_gain_reg(st, chan->channel);
+
+	return ad7768_offset_reg(st, chan->channel);
+}
+
+static int ad7768_read_calib_value(struct ad7768_state *st,
+				   unsigned int base_reg, unsigned int *val)
+{
+	u8 data[3];
+	int ret;
+
+	PM_RUNTIME_ACQUIRE_AUTOSUSPEND(regmap_get_device(st->regmap), pm);
+	ret = PM_RUNTIME_ACQUIRE_ERR(&pm);
+	if (ret)
+		return ret;
+
+	guard(mutex)(&st->lock);
+
+	ret = regmap_bulk_read(st->regmap, base_reg, data, sizeof(data));
+	if (ret)
+		return ret;
+
+	*val = get_unaligned_be24(data);
+
+	return 0;
+}
+
+static int ad7768_write_calib_value(struct ad7768_state *st,
+				    unsigned int base_reg, unsigned int val)
+{
+	u8 data[3];
+	int ret;
+
+	if (val > AD7768_CALIB_REG_MSK)
+		return -EINVAL;
+
+	put_unaligned_be24(val, data);
+
+	PM_RUNTIME_ACQUIRE_AUTOSUSPEND(regmap_get_device(st->regmap), pm);
+	ret = PM_RUNTIME_ACQUIRE_ERR(&pm);
+	if (ret)
+		return ret;
+
+	guard(mutex)(&st->lock);
+
+	return regmap_bulk_write(st->regmap, base_reg, data, sizeof(data));
+}
+
 static int ad7768_reg_access(struct iio_dev *indio_dev,
 			     unsigned int reg,
 			     unsigned int writeval,
@@ -780,6 +847,7 @@ static int ad7768_read_raw(struct iio_dev *indio_dev,
 			   int *val, int *val2, long info)
 {
 	struct ad7768_state *st = iio_priv(indio_dev);
+	int ret;
 
 	switch (info) {
 	case IIO_CHAN_INFO_SCALE: {
@@ -797,6 +865,21 @@ static int ad7768_read_raw(struct iio_dev *indio_dev,
 
 		return IIO_VAL_INT;
 	}
+
+	case IIO_CHAN_INFO_CALIBBIAS:
+	case IIO_CHAN_INFO_CALIBSCALE: {
+		bool is_gain = info == IIO_CHAN_INFO_CALIBSCALE;
+		unsigned int base_reg;
+		unsigned int calib;
+
+		base_reg = ad7768_get_calib_reg_base(st, chan, is_gain);
+		ret = ad7768_read_calib_value(st, base_reg, &calib);
+		if (ret)
+			return ret;
+
+		*val = calib;
+		return IIO_VAL_INT;
+	}
 	default:
 		return -EINVAL;
 	}
@@ -805,24 +888,45 @@ static int ad7768_read_raw(struct iio_dev *indio_dev,
 static int ad7768_write_raw_get_fmt(struct iio_dev *indio_dev,
 				    struct iio_chan_spec const *chan, long info)
 {
-	if (info == IIO_CHAN_INFO_SAMP_FREQ)
+	switch (info) {
+	case IIO_CHAN_INFO_SAMP_FREQ:
+	case IIO_CHAN_INFO_CALIBBIAS:
+	case IIO_CHAN_INFO_CALIBSCALE:
 		return IIO_VAL_INT;
-
-	return -EINVAL;
+	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;
+
 	IIO_DEV_ACQUIRE_DIRECT_MODE(indio_dev, claim);
 	if (IIO_DEV_ACQUIRE_FAILED(claim))
 		return -EBUSY;
 
-	if (info == IIO_CHAN_INFO_SAMP_FREQ)
+	switch (info) {
+	case IIO_CHAN_INFO_SAMP_FREQ:
 		return ad7768_set_sampling_freq(indio_dev, val, chan->channel);
+	case IIO_CHAN_INFO_CALIBBIAS:
+		if (val < 0 || val > AD7768_CALIB_REG_MSK)
+			return -EINVAL;
 
-	return -EINVAL;
+		base_reg = ad7768_get_calib_reg_base(st, chan, false);
+		return ad7768_write_calib_value(st, base_reg, val);
+	case IIO_CHAN_INFO_CALIBSCALE:
+		if (val < 0 || val > AD7768_CALIB_REG_MSK)
+			return -EINVAL;
+
+		base_reg = ad7768_get_calib_reg_base(st, chan, true);
+		return ad7768_write_calib_value(st, base_reg, val);
+	default:
+		return -EINVAL;
+	}
 }
 
 static int ad7768_read_avail(struct iio_dev *indio_dev,
@@ -1035,7 +1139,9 @@ static int ad7768_parse_config(struct iio_dev *indio_dev,
 
 		chan[chan_idx] = (struct iio_chan_spec) {
 			.type = IIO_VOLTAGE,
-			.info_mask_separate = BIT(IIO_CHAN_INFO_SCALE) |
+			.info_mask_separate = BIT(IIO_CHAN_INFO_CALIBBIAS) |
+					      BIT(IIO_CHAN_INFO_CALIBSCALE) |
+					      BIT(IIO_CHAN_INFO_SCALE) |
 					      BIT(IIO_CHAN_INFO_SAMP_FREQ),
 			.info_mask_separate_available =
 				BIT(IIO_CHAN_INFO_SAMP_FREQ),

-- 
2.43.0

[PATCH v5 14/20] iio: adc: ad7768: Add per-channel conversion delay

[Janani Sunil]

Expose the per-channel synchronization phase offset through the IIO
conversion-delay attribute.

Derive the delay resolution from MCLK, power mode and decimation rate.
Validate the requested delay and program the corresponding phase
register when applying the active channel configuration.

Signed-off-by: Janani Sunil <janani.sunil@analog.com>
---
 drivers/iio/adc/ad7768.c | 129 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 129 insertions(+)

diff --git a/drivers/iio/adc/ad7768.c b/drivers/iio/adc/ad7768.c
index f2f318ebf964..4133e3a033b4 100644
--- a/drivers/iio/adc/ad7768.c
+++ b/drivers/iio/adc/ad7768.c
@@ -154,6 +154,12 @@ struct ad7768_freq_config {
 	unsigned int dec_rate;
 };
 
+struct ad7768_convdelay_params {
+	unsigned int shift;
+	unsigned int max_raw;
+	u64 step_ps;
+};
+
 struct ad7768_avail_freq {
 	unsigned int n_freqs;
 	struct ad7768_freq_config freq_cfg[AD7768_MAX_FREQ_PER_MODE];
@@ -182,6 +188,7 @@ struct ad7768_state {
 	unsigned int n_freqs;
 	int freqs[AD7768_MAX_FREQS];
 	unsigned int ch_freq[AD7768_MAX_CHANNEL];
+	u64 ch_convdelay_ps[AD7768_MAX_CHANNEL];
 	enum ad7768_filter_type ch_filter[AD7768_MAX_CHANNEL];
 	struct iio_backend *back;
 	unsigned int vref_uV[2];
@@ -251,6 +258,12 @@ static unsigned int ad7768_gain_reg(const struct ad7768_state *st,
 	return AD7768_REG_GAIN(st->chip_info->chan_map[ch]);
 }
 
+static unsigned int ad7768_phase_reg(const struct ad7768_state *st,
+				     unsigned int ch)
+{
+	return AD7768_REG_PHASE(st->chip_info->chan_map[ch]);
+}
+
 static u8 ad7768_precharge_buf1_mask(const struct ad7768_state *st, u16 val)
 {
 	return val & GENMASK(st->chip_info->prebuf_split - 1, 0);
@@ -661,6 +674,92 @@ static int ad7768_find_matching_mode(const bool *mode_used,
 	return -EINVAL;
 }
 
+static int ad7768_get_convdelay_params(struct ad7768_state *st, unsigned int ch,
+				       struct ad7768_convdelay_params *params)
+{
+	const struct ad7768_freq_config *freq_cfg;
+	unsigned int dec_rate;
+	unsigned int mclk_div;
+	unsigned int mult;
+	u64 mclk;
+
+	freq_cfg = ad7768_find_freq_config(st, st->power_mode_idx,
+					   st->ch_freq[ch]);
+	if (!freq_cfg)
+		return -EINVAL;
+
+	dec_rate = ad7768_dec_rate[freq_cfg->dec_rate];
+	switch (dec_rate) {
+	case 32:
+		params->shift = 3;
+		params->max_raw = 31;
+		mult = 1;
+		break;
+	case 64:
+		params->shift = 2;
+		params->max_raw = 63;
+		mult = 1;
+		break;
+	case 128:
+		params->shift = 1;
+		params->max_raw = 127;
+		mult = 1;
+		break;
+	case 256:
+		params->shift = 0;
+		params->max_raw = 255;
+		mult = 1;
+		break;
+	case 512:
+		params->shift = 0;
+		params->max_raw = 255;
+		mult = 2;
+		break;
+	case 1024:
+		params->shift = 0;
+		params->max_raw = 255;
+		mult = 4;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	mclk = clk_get_rate(st->mclk);
+	if (!mclk)
+		return -EINVAL;
+
+	mclk_div = ad7768_power_modes[st->power_mode_idx].mclk_div;
+	params->step_ps = DIV_ROUND_CLOSEST_ULL((u64)mult * PSEC_PER_SEC *
+						mclk_div, mclk);
+
+	return 0;
+}
+
+static int ad7768_set_channel_convdelay(struct ad7768_state *st,
+					unsigned int ch)
+{
+	u64 delay_ps = st->ch_convdelay_ps[ch];
+	struct ad7768_convdelay_params params;
+	u64 max_delay_ps;
+	u64 raw;
+	int ret;
+
+	ret = ad7768_get_convdelay_params(st, ch, &params);
+	if (ret)
+		return ret;
+
+	max_delay_ps = (u64)params.max_raw * params.step_ps;
+	if (delay_ps > max_delay_ps)
+		return -EINVAL;
+
+	raw = DIV_ROUND_CLOSEST_ULL(delay_ps, params.step_ps);
+	if (raw > params.max_raw)
+		return -EINVAL;
+
+	return regmap_write(st->regmap, ad7768_phase_reg(st, ch),
+			    raw << params.shift);
+}
+
 static void ad7768_filter_wait(const unsigned int *mode_freq,
 			       const enum ad7768_filter_type *mode_filter,
 			       const bool *mode_used)
@@ -766,6 +865,16 @@ static int ad7768_apply_channel_modes(struct iio_dev *indio_dev,
 		max_freq = max(max_freq, mode_freq[mode]);
 	}
 
+	for_each_set_bit(c, scan_mask, st->chip_info->num_channels) {
+		ret = ad7768_set_channel_convdelay(st, c);
+		if (ret == -EINVAL)
+			return dev_err_probe(regmap_get_device(st->regmap), ret,
+					     "Invalid conversion delay for channel %u\n",
+					     c);
+		if (ret)
+			return ret;
+	}
+
 	ret = ad7768_set_clk_divs(st, max_freq);
 	if (ret)
 		return ret;
@@ -880,6 +989,13 @@ static int ad7768_read_raw(struct iio_dev *indio_dev,
 		*val = calib;
 		return IIO_VAL_INT;
 	}
+	case IIO_CHAN_INFO_CONVDELAY: {
+		guard(mutex)(&st->lock);
+		iio_val_s64_decompose(st->ch_convdelay_ps[chan->channel],
+				      val, val2);
+
+		return IIO_VAL_DECIMAL64_PICO;
+	}
 	default:
 		return -EINVAL;
 	}
@@ -893,6 +1009,8 @@ static int ad7768_write_raw_get_fmt(struct iio_dev *indio_dev,
 	case IIO_CHAN_INFO_CALIBBIAS:
 	case IIO_CHAN_INFO_CALIBSCALE:
 		return IIO_VAL_INT;
+	case IIO_CHAN_INFO_CONVDELAY:
+		return IIO_VAL_DECIMAL64_PICO;
 	default:
 		return -EINVAL;
 	}
@@ -904,6 +1022,7 @@ static int ad7768_write_raw(struct iio_dev *indio_dev,
 {
 	struct ad7768_state *st = iio_priv(indio_dev);
 	unsigned int base_reg;
+	s64 delay_ps;
 
 	IIO_DEV_ACQUIRE_DIRECT_MODE(indio_dev, claim);
 	if (IIO_DEV_ACQUIRE_FAILED(claim))
@@ -924,6 +1043,15 @@ static int ad7768_write_raw(struct iio_dev *indio_dev,
 
 		base_reg = ad7768_get_calib_reg_base(st, chan, true);
 		return ad7768_write_calib_value(st, base_reg, val);
+	case IIO_CHAN_INFO_CONVDELAY: {
+		delay_ps = iio_val_s64_compose(val, val2);
+		if (delay_ps < 0)
+			return -EINVAL;
+
+		guard(mutex)(&st->lock);
+		st->ch_convdelay_ps[chan->channel] = delay_ps;
+		return 0;
+	}
 	default:
 		return -EINVAL;
 	}
@@ -1141,6 +1269,7 @@ static int ad7768_parse_config(struct iio_dev *indio_dev,
 			.type = IIO_VOLTAGE,
 			.info_mask_separate = BIT(IIO_CHAN_INFO_CALIBBIAS) |
 					      BIT(IIO_CHAN_INFO_CALIBSCALE) |
+					      BIT(IIO_CHAN_INFO_CONVDELAY) |
 					      BIT(IIO_CHAN_INFO_SCALE) |
 					      BIT(IIO_CHAN_INFO_SAMP_FREQ),
 			.info_mask_separate_available =

-- 
2.43.0

[PATCH v5 15/20] iio: adc: ad7768: Add VCM regulator support

[Janani Sunil]

Expose the on-chip common mode voltage output through the regulator
framework. Support the three fixed output levels and the
supply-dependent AVDD1/2 setting.

Keep the ADC runtime active while VCM is enabled and release the runtime
PM reference when the output is disabled.

Signed-off-by: Janani Sunil <janani.sunil@analog.com>
---
 drivers/iio/adc/Kconfig  |   2 +-
 drivers/iio/adc/ad7768.c | 162 ++++++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 161 insertions(+), 3 deletions(-)

diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 48bb108382b5..a16f36f9502c 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -432,7 +432,7 @@ config AD7766
 config AD7768
 	tristate "Analog Devices AD7768/AD7768-4 ADC driver"
 	depends on SPI
-	depends on REGULATOR || COMPILE_TEST
+	select REGULATOR
 	select IIO_BUFFER
 	select IIO_BACKEND
 	select REGMAP
diff --git a/drivers/iio/adc/ad7768.c b/drivers/iio/adc/ad7768.c
index 4133e3a033b4..5e93d4632f17 100644
--- a/drivers/iio/adc/ad7768.c
+++ b/drivers/iio/adc/ad7768.c
@@ -23,6 +23,7 @@
 #include <linux/property.h>
 #include <linux/regmap.h>
 #include <linux/regulator/consumer.h>
+#include <linux/regulator/driver.h>
 #include <linux/reset.h>
 #include <linux/spi/spi.h>
 #include <linux/time.h>
@@ -51,6 +52,10 @@
 #define   AD7768_POWER_MODE_LVDS_ENABLE			BIT(3)
 #define   AD7768_POWER_MODE_MCLK_DIV_MSK		GENMASK(1, 0)
 
+#define AD7768_REG_GENERAL_CONFIG			0x05
+#define   AD7768_GEN_CONFIG_VCM_SEL_MSK			GENMASK(1, 0)
+#define   AD7768_GEN_CONFIG_VCM_PD			BIT(4)
+
 #define AD7768_REG_DATA_CONTROL				0x06
 #define   AD7768_DATA_CONTROL_SPI_RESET_1		0x03
 #define   AD7768_DATA_CONTROL_SPI_RESET_2		0x02
@@ -191,11 +196,157 @@ struct ad7768_state {
 	u64 ch_convdelay_ps[AD7768_MAX_CHANNEL];
 	enum ad7768_filter_type ch_filter[AD7768_MAX_CHANNEL];
 	struct iio_backend *back;
+	struct regulator_dev *vcm_rdev;
+	unsigned int avdd1_uV;
 	unsigned int vref_uV[2];
 
 	__be16 d16 __aligned(IIO_DMA_MINALIGN);
 };
 
+static const unsigned int ad7768_vcm_voltage_table[] = {
+	0, 1650000, 2500000, 2140000,
+};
+
+static int ad7768_vcm_list_voltage(struct regulator_dev *rdev,
+				   unsigned int selector)
+{
+	struct ad7768_state *st = rdev_get_drvdata(rdev);
+
+	if (selector >= ARRAY_SIZE(ad7768_vcm_voltage_table))
+		return -EINVAL;
+
+	if (!selector)
+		return DIV_ROUND_CLOSEST(st->avdd1_uV, 2);
+
+	return ad7768_vcm_voltage_table[selector];
+}
+
+static int ad7768_vcm_enable(struct regulator_dev *rdev)
+{
+	struct ad7768_state *st = rdev_get_drvdata(rdev);
+	int ret;
+
+	ret = pm_runtime_resume_and_get(regmap_get_device(st->regmap));
+	if (ret < 0)
+		return ret;
+
+	ret = regmap_clear_bits(st->regmap, AD7768_REG_GENERAL_CONFIG,
+				AD7768_GEN_CONFIG_VCM_PD);
+	if (ret)
+		pm_runtime_put_autosuspend(regmap_get_device(st->regmap));
+
+	return ret;
+}
+
+static int ad7768_vcm_disable(struct regulator_dev *rdev)
+{
+	struct ad7768_state *st = rdev_get_drvdata(rdev);
+	int ret;
+
+	ret = regmap_set_bits(st->regmap, AD7768_REG_GENERAL_CONFIG,
+			      AD7768_GEN_CONFIG_VCM_PD);
+	if (ret)
+		return ret;
+
+	pm_runtime_put_autosuspend(regmap_get_device(st->regmap));
+
+	return 0;
+}
+
+static int ad7768_vcm_is_enabled(struct regulator_dev *rdev)
+{
+	struct ad7768_state *st = rdev_get_drvdata(rdev);
+	int ret;
+
+	PM_RUNTIME_ACQUIRE_AUTOSUSPEND(regmap_get_device(st->regmap), pm);
+	ret = PM_RUNTIME_ACQUIRE_ERR(&pm);
+	if (ret)
+		return ret;
+
+	ret = regmap_test_bits(st->regmap, AD7768_REG_GENERAL_CONFIG,
+			       AD7768_GEN_CONFIG_VCM_PD);
+	if (ret < 0)
+		return ret;
+
+	return !ret;
+}
+
+static int ad7768_vcm_set_voltage_sel(struct regulator_dev *rdev,
+				      unsigned int selector)
+{
+	struct ad7768_state *st = rdev_get_drvdata(rdev);
+	int ret;
+
+	PM_RUNTIME_ACQUIRE_AUTOSUSPEND(regmap_get_device(st->regmap), pm);
+	ret = PM_RUNTIME_ACQUIRE_ERR(&pm);
+	if (ret)
+		return ret;
+
+	return regmap_update_bits(st->regmap, AD7768_REG_GENERAL_CONFIG,
+				  AD7768_GEN_CONFIG_VCM_SEL_MSK,
+				  FIELD_PREP(AD7768_GEN_CONFIG_VCM_SEL_MSK,
+					     selector));
+}
+
+static int ad7768_vcm_get_voltage_sel(struct regulator_dev *rdev)
+{
+	struct ad7768_state *st = rdev_get_drvdata(rdev);
+	unsigned int val;
+	int ret;
+
+	PM_RUNTIME_ACQUIRE_AUTOSUSPEND(regmap_get_device(st->regmap), pm);
+	ret = PM_RUNTIME_ACQUIRE_ERR(&pm);
+	if (ret)
+		return ret;
+
+	ret = regmap_read(st->regmap, AD7768_REG_GENERAL_CONFIG, &val);
+	if (ret)
+		return ret;
+
+	return FIELD_GET(AD7768_GEN_CONFIG_VCM_SEL_MSK, val);
+}
+
+static const struct regulator_ops ad7768_vcm_ops = {
+	.enable = ad7768_vcm_enable,
+	.disable = ad7768_vcm_disable,
+	.is_enabled = ad7768_vcm_is_enabled,
+	.list_voltage = ad7768_vcm_list_voltage,
+	.set_voltage_sel = ad7768_vcm_set_voltage_sel,
+	.get_voltage_sel = ad7768_vcm_get_voltage_sel,
+};
+
+static const struct regulator_desc ad7768_vcm_desc = {
+	.name = "vcm",
+	.of_match = "vcm-output",
+	.regulators_node = "regulators",
+	.n_voltages = ARRAY_SIZE(ad7768_vcm_voltage_table),
+	.ops = &ad7768_vcm_ops,
+	.type = REGULATOR_VOLTAGE,
+	.owner = THIS_MODULE,
+};
+
+static int ad7768_register_vcm_regulator(struct device *dev,
+					 struct ad7768_state *st)
+{
+	struct regulator_config config = {
+		.dev = dev,
+		.driver_data = st,
+	};
+	int ret;
+
+	/*
+	 * Start with VCM disabled so each enabled state is paired with the
+	 * runtime PM reference acquired by ad7768_vcm_enable().
+	 */
+	ret = regmap_set_bits(st->regmap, AD7768_REG_GENERAL_CONFIG,
+			      AD7768_GEN_CONFIG_VCM_PD);
+	if (ret)
+		return ret;
+
+	st->vcm_rdev = devm_regulator_register(dev, &ad7768_vcm_desc, &config);
+	return PTR_ERR_OR_ZERO(st->vcm_rdev);
+}
+
 static const unsigned int ad7768_dec_rate[AD7768_MAX_FREQ_PER_MODE] = {
 	32, 64, 128, 256, 512, 1024,
 };
@@ -1489,11 +1640,13 @@ static int ad7768_probe(struct spi_device *spi)
 		return dev_err_probe(dev, ret,
 				     "Failed to enable AVSS supply\n");
 
-	ret = devm_regulator_get_enable(dev, "avdd1");
-	if (ret)
+	ret = devm_regulator_get_enable_read_voltage(dev, "avdd1");
+	if (ret < 0)
 		return dev_err_probe(dev, ret,
 				     "Failed to enable AVDD1 supply\n");
 
+	st->avdd1_uV = ret;
+
 	ret = devm_regulator_bulk_get_enable(dev,
 					     ARRAY_SIZE(ad7768_supply_names),
 					     ad7768_supply_names);
@@ -1614,6 +1767,11 @@ static int ad7768_probe(struct spi_device *spi)
 	if (ret)
 		return ret;
 
+	ret = ad7768_register_vcm_regulator(dev, st);
+	if (ret)
+		return dev_err_probe(dev, ret,
+				     "Failed to register VCM regulator\n");
+
 	return devm_iio_device_register(dev, indio_dev);
 }
 

-- 
2.43.0

[PATCH v5 16/20] iio: adc: ad7768: Register GPIO auxiliary device

[Janani Sunil]

Register an auxiliary device when the AD7768 is described as a GPIO
controller. This allows the GPIO driver to share the parent regmap and
runtime power-management state.

Signed-off-by: Janani Sunil <janani.sunil@analog.com>
---
 drivers/iio/adc/Kconfig  |  1 +
 drivers/iio/adc/ad7768.c | 35 +++++++++++++++++++++++++++++++++++
 2 files changed, 36 insertions(+)

diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index a16f36f9502c..68334793c9ba 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -433,6 +433,7 @@ config AD7768
 	tristate "Analog Devices AD7768/AD7768-4 ADC driver"
 	depends on SPI
 	select REGULATOR
+	select AUXILIARY_BUS
 	select IIO_BUFFER
 	select IIO_BACKEND
 	select REGMAP
diff --git a/drivers/iio/adc/ad7768.c b/drivers/iio/adc/ad7768.c
index 5e93d4632f17..71d91ac6eec5 100644
--- a/drivers/iio/adc/ad7768.c
+++ b/drivers/iio/adc/ad7768.c
@@ -6,6 +6,7 @@
  */
 
 #include <linux/array_size.h>
+#include <linux/auxiliary_bus.h>
 #include <linux/bitfield.h>
 #include <linux/bitmap.h>
 #include <linux/bitops.h>
@@ -117,6 +118,7 @@
 #define AD7768_MAX_MCLK_FREQ_HZ				(34 * HZ_PER_MHZ)
 #define AD7768_MAX_FREQ_PER_MODE			6
 #define AD7768_MAX_CHANNEL				8
+#define AD7768_NUM_GPIOS				5
 #define AD7768_NUM_CHANNEL_MODES			2
 #define AD7768_CALIB_REG_MSK				GENMASK(23, 0)
 #define AD7768_WIDEBAND_SETTLING_SAMPLES		68
@@ -186,6 +188,7 @@ struct ad7768_state {
 	struct mutex lock;
 	struct clk *mclk;
 	unsigned int datalines;
+	unsigned long gpio_valid_mask;
 	enum ad7768_clock_source clock_source;
 	unsigned int power_mode_idx;
 	const struct ad7768_chip_info *chip_info;
@@ -1234,6 +1237,34 @@ static const struct iio_info ad7768_info = {
 	.update_scan_mode = ad7768_update_scan_mode,
 };
 
+static int ad7768_gpio_adev_init(struct ad7768_state *st)
+{
+	struct device *dev = regmap_get_device(st->regmap);
+	struct spi_device *spi = to_spi_device(dev);
+	struct auxiliary_device *adev;
+	int id;
+
+	if (!device_property_read_bool(dev, "gpio-controller"))
+		return 0;
+
+	st->gpio_valid_mask = GENMASK(AD7768_NUM_GPIOS - 1, 0);
+	if (st->clock_source != AD7768_CLOCK_SOURCE_MCLK)
+		st->gpio_valid_mask &= ~BIT(4);
+
+	/*
+	 * Use the SPI bus number and chip select to derive a stable per-device
+	 * ID.
+	 */
+	id = (spi->controller->bus_num << 8) | spi_get_chipselect(spi, 0);
+	adev = __devm_auxiliary_device_create(dev, KBUILD_MODNAME, "gpio",
+					      &st->gpio_valid_mask, id);
+	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)
 {
@@ -1772,6 +1803,10 @@ static int ad7768_probe(struct spi_device *spi)
 		return dev_err_probe(dev, ret,
 				     "Failed to register VCM regulator\n");
 
+	ret = ad7768_gpio_adev_init(st);
+	if (ret)
+		return ret;
+
 	return devm_iio_device_register(dev, indio_dev);
 }
 

-- 
2.43.0

[PATCH v5 17/20] gpio: regmap: Use regmap_test_bits() for single bit reads

[Janani Sunil]

Use regmap_test_bits() when reading a single GPIO value from a normal
register and when reading the direction bit.

Reviewed-by: Linus Walleij <linusw@kernel.org>
Reviewed-by: Michael Walle <mwalle@kernel.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Signed-off-by: Janani Sunil <janani.sunil@analog.com>
---
 drivers/gpio/gpio-regmap.c | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/drivers/gpio/gpio-regmap.c b/drivers/gpio/gpio-regmap.c
index 51b4d69b8740..0012e03d0d4e 100644
--- a/drivers/gpio/gpio-regmap.c
+++ b/drivers/gpio/gpio-regmap.c
@@ -83,11 +83,11 @@ static int gpio_regmap_get(struct gpio_chip *chip, unsigned int offset)
 	if (ret)
 		return ret;
 
+	if (gpio->reg_dat_base != gpio->reg_set_base)
+		return regmap_test_bits(gpio->regmap, reg, mask);
+
 	/* ensure we don't spoil any register cache with pin input values */
-	if (gpio->reg_dat_base == gpio->reg_set_base)
-		ret = regmap_read_bypassed(gpio->regmap, reg, &val);
-	else
-		ret = regmap_read(gpio->regmap, reg, &val);
+	ret = regmap_read_bypassed(gpio->regmap, reg, &val);
 	if (ret)
 		return ret;
 
@@ -157,7 +157,7 @@ static int gpio_regmap_get_direction(struct gpio_chip *chip,
 				     unsigned int offset)
 {
 	struct gpio_regmap *gpio = gpiochip_get_data(chip);
-	unsigned int base, val, reg, mask;
+	unsigned int base, reg, mask;
 	int invert, ret;
 
 	if (gpio_regmap_fixed_direction(gpio, offset)) {
@@ -186,14 +186,14 @@ static int gpio_regmap_get_direction(struct gpio_chip *chip,
 	if (ret)
 		return ret;
 
-	ret = regmap_read(gpio->regmap, reg, &val);
-	if (ret)
+	ret = regmap_test_bits(gpio->regmap, reg, mask);
+	if (ret < 0)
 		return ret;
 
-	if (!!(val & mask) ^ invert)
+	if (ret ^ invert)
 		return GPIO_LINE_DIRECTION_OUT;
-	else
-		return GPIO_LINE_DIRECTION_IN;
+
+	return GPIO_LINE_DIRECTION_IN;
 }
 
 static int gpio_regmap_try_direction_fixed(struct gpio_regmap *gpio,

-- 
2.43.0

[PATCH v5 18/20] gpio: regmap: Add optional runtime PM support

[Janani Sunil]

Some gpio-regmap consumers share their regmap with a parent device that
may be runtime suspended. GPIO register accesses must resume that device
first.

Add an optional pm_dev field and acquire it before register translation
or access. Release it using runtime autosuspend after each operation.
Keep the device active across the complete direction-output sequence and
propagate failure when setting the initial output value.

Signed-off-by: Janani Sunil <janani.sunil@analog.com>
---
 drivers/gpio/gpio-regmap.c  | 67 +++++++++++++++++++++++++++++++++++++++++++--
 include/linux/gpio/regmap.h |  2 ++
 2 files changed, 67 insertions(+), 2 deletions(-)

diff --git a/drivers/gpio/gpio-regmap.c b/drivers/gpio/gpio-regmap.c
index 0012e03d0d4e..154916050ac5 100644
--- a/drivers/gpio/gpio-regmap.c
+++ b/drivers/gpio/gpio-regmap.c
@@ -6,10 +6,12 @@
  */
 
 #include <linux/bits.h>
+#include <linux/cleanup.h>
 #include <linux/device.h>
 #include <linux/err.h>
 #include <linux/io.h>
 #include <linux/module.h>
+#include <linux/pm_runtime.h>
 #include <linux/regmap.h>
 #include <linux/slab.h>
 #include <linux/types.h>
@@ -23,6 +25,7 @@ struct gpio_regmap {
 	struct device *parent;
 	struct regmap *regmap;
 	struct gpio_chip gpio_chip;
+	struct device *pm_dev;
 
 	int reg_stride;
 	int ngpio_per_reg;
@@ -67,6 +70,33 @@ static int gpio_regmap_simple_xlate(struct gpio_regmap *gpio,
 	return 0;
 }
 
+static int gpio_regmap_runtime_get(struct gpio_regmap *gpio)
+{
+	if (!gpio->pm_dev)
+		return 0;
+
+	return pm_runtime_get_active(gpio->pm_dev, RPM_TRANSPARENT);
+}
+
+static void gpio_regmap_runtime_put(struct gpio_regmap *gpio)
+{
+	if (!gpio->pm_dev)
+		return;
+
+	pm_runtime_put_autosuspend(gpio->pm_dev);
+}
+
+DEFINE_GUARD(gpio_regmap_runtime, struct gpio_regmap *,
+	     gpio_regmap_runtime_get(_T), gpio_regmap_runtime_put(_T))
+DEFINE_GUARD_COND(gpio_regmap_runtime, _try,
+		  gpio_regmap_runtime_get(_T), _RET == 0)
+
+#define GPIO_REGMAP_RUNTIME_ACQUIRE(_gpio, _var) \
+	ACQUIRE(gpio_regmap_runtime_try, _var)(_gpio)
+
+#define GPIO_REGMAP_RUNTIME_ACQUIRE_ERR(_var_ptr) \
+	ACQUIRE_ERR(gpio_regmap_runtime, _var_ptr)
+
 static int gpio_regmap_get(struct gpio_chip *chip, unsigned int offset)
 {
 	struct gpio_regmap *gpio = gpiochip_get_data(chip);
@@ -79,6 +109,11 @@ static int gpio_regmap_get(struct gpio_chip *chip, unsigned int offset)
 	else
 		base = gpio_regmap_addr(gpio->reg_set_base);
 
+	GPIO_REGMAP_RUNTIME_ACQUIRE(gpio, pm);
+	ret = GPIO_REGMAP_RUNTIME_ACQUIRE_ERR(&pm);
+	if (ret)
+		return ret;
+
 	ret = gpio->reg_mask_xlate(gpio, base, offset, &reg, &mask);
 	if (ret)
 		return ret;
@@ -102,6 +137,11 @@ static int gpio_regmap_set(struct gpio_chip *chip, unsigned int offset,
 	unsigned int reg, mask, mask_val;
 	int ret;
 
+	GPIO_REGMAP_RUNTIME_ACQUIRE(gpio, pm);
+	ret = GPIO_REGMAP_RUNTIME_ACQUIRE_ERR(&pm);
+	if (ret)
+		return ret;
+
 	ret = gpio->reg_mask_xlate(gpio, base, offset, &reg, &mask);
 	if (ret)
 		return ret;
@@ -127,6 +167,11 @@ static int gpio_regmap_set_with_clear(struct gpio_chip *chip,
 	unsigned int base, reg, mask;
 	int ret;
 
+	GPIO_REGMAP_RUNTIME_ACQUIRE(gpio, pm);
+	ret = GPIO_REGMAP_RUNTIME_ACQUIRE_ERR(&pm);
+	if (ret)
+		return ret;
+
 	if (val)
 		base = gpio_regmap_addr(gpio->reg_set_base);
 	else
@@ -182,6 +227,11 @@ static int gpio_regmap_get_direction(struct gpio_chip *chip,
 		return -ENOTSUPP;
 	}
 
+	GPIO_REGMAP_RUNTIME_ACQUIRE(gpio, pm);
+	ret = GPIO_REGMAP_RUNTIME_ACQUIRE_ERR(&pm);
+	if (ret)
+		return ret;
+
 	ret = gpio->reg_mask_xlate(gpio, base, offset, &reg, &mask);
 	if (ret)
 		return ret;
@@ -236,6 +286,11 @@ static int gpio_regmap_set_direction(struct gpio_chip *chip,
 		return -ENOTSUPP;
 	}
 
+	GPIO_REGMAP_RUNTIME_ACQUIRE(gpio, pm);
+	ret = GPIO_REGMAP_RUNTIME_ACQUIRE_ERR(&pm);
+	if (ret)
+		return ret;
+
 	ret = gpio->reg_mask_xlate(gpio, base, offset, &reg, &mask);
 	if (ret)
 		return ret;
@@ -260,6 +315,11 @@ static int gpio_regmap_direction_output(struct gpio_chip *chip,
 	struct gpio_regmap *gpio = gpiochip_get_data(chip);
 	int ret;
 
+	GPIO_REGMAP_RUNTIME_ACQUIRE(gpio, pm);
+	ret = GPIO_REGMAP_RUNTIME_ACQUIRE_ERR(&pm);
+	if (ret)
+		return ret;
+
 	/*
 	 * First check if this is gonna work on a fixed direction line,
 	 * if it doesn't (i.e. this is a fixed input line), then do not
@@ -271,7 +331,9 @@ static int gpio_regmap_direction_output(struct gpio_chip *chip,
 			return ret;
 	}
 
-	gpio_regmap_set(chip, offset, value);
+	ret = gpio_regmap_set(chip, offset, value);
+	if (ret)
+		return ret;
 
 	return gpio_regmap_set_direction(chip, offset, true);
 }
@@ -323,6 +385,7 @@ struct gpio_regmap *gpio_regmap_register(const struct gpio_regmap_config *config
 	gpio->reg_clr_base = config->reg_clr_base;
 	gpio->reg_dir_in_base = config->reg_dir_in_base;
 	gpio->reg_dir_out_base = config->reg_dir_out_base;
+	gpio->pm_dev = config->pm_dev;
 
 	chip = &gpio->gpio_chip;
 	chip->parent = config->parent;
@@ -330,7 +393,7 @@ struct gpio_regmap *gpio_regmap_register(const struct gpio_regmap_config *config
 	chip->base = -1;
 	chip->names = config->names;
 	chip->label = config->label ?: dev_name(config->parent);
-	chip->can_sleep = regmap_might_sleep(config->regmap);
+	chip->can_sleep = config->pm_dev || regmap_might_sleep(config->regmap);
 	chip->init_valid_mask = config->init_valid_mask;
 
 	chip->request = gpiochip_generic_request;
diff --git a/include/linux/gpio/regmap.h b/include/linux/gpio/regmap.h
index 06255756710d..ba68d8cbd38d 100644
--- a/include/linux/gpio/regmap.h
+++ b/include/linux/gpio/regmap.h
@@ -18,6 +18,7 @@ struct regmap;
  * @parent:		The parent device
  * @regmap:		The regmap used to access the registers
  *			given, the name of the device is used
+ * @pm_dev:		(Optional) Device to use for runtime power management.
  * @fwnode:		(Optional) The firmware node.
  *			If not given, the fwnode of the parent is used.
  * @label:		(Optional) Descriptive name for GPIO controller.
@@ -81,6 +82,7 @@ struct regmap;
 struct gpio_regmap_config {
 	struct device *parent;
 	struct regmap *regmap;
+	struct device *pm_dev;
 	struct fwnode_handle *fwnode;
 
 	const char *label;

-- 
2.43.0

[PATCH v5 19/20] gpio: ad7768: Add AD7768 GPIO auxiliary driver

[Janani Sunil]

The AD7768 provides five GPIOs controlled through registers shared
with the parent IIO device. Register an auxiliary gpio-regmap driver
and use the parent device for runtime PM.

The device has separate input-state and output-latch registers. Add a
reg_mask_xlate() callback that checks the line direction and reads the
programmed output latch for output lines while retaining input-state
reads for input lines.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Reviewed-by: Linus Walleij <linusw@kernel.org>
Signed-off-by: Janani Sunil <janani.sunil@analog.com>
---
 drivers/gpio/Kconfig       |  12 +++++
 drivers/gpio/Makefile      |   1 +
 drivers/gpio/gpio-ad7768.c | 118 +++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 131 insertions(+)

diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 28cf6d2e83c2..85cb0c82a823 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -1796,6 +1796,18 @@ endmenu
 menu "Auxiliary Bus GPIO drivers"
 	depends on AUXILIARY_BUS
 
+config GPIO_AD7768
+	tristate "Analog Devices AD7768 GPIO support"
+	depends on AD7768
+	depends on GPIOLIB
+	select GPIO_REGMAP
+	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..587ac8b291b4
--- /dev/null
+++ b/drivers/gpio/gpio-ad7768.c
@@ -0,0 +1,118 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Analog Devices AD7768 GPIO auxiliary driver
+ *
+ * Copyright 2026 Analog Devices Inc.
+ */
+
+#include <linux/auxiliary_bus.h>
+#include <linux/bitmap.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/gpio/driver.h>
+#include <linux/gpio/regmap.h>
+#include <linux/module.h>
+#include <linux/pm_runtime.h>
+#include <linux/regmap.h>
+
+#define AD7768_REG_GPIO_CONTROL		0x0E
+#define   AD7768_GPIO_UGPIO_ENABLE	BIT(7)
+
+#define AD7768_REG_GPIO_WRITE		0x0F
+#define AD7768_REG_GPIO_READ		0x10
+
+#define AD7768_NUM_GPIOS		5
+
+static int ad7768_gpio_init_valid_mask(struct gpio_chip *gc,
+				       unsigned long *valid_mask,
+				       unsigned int ngpios)
+{
+	unsigned long *mask = dev_get_platdata(gc->parent);
+
+	bitmap_copy(valid_mask, mask, ngpios);
+
+	return 0;
+}
+
+static int ad7768_gpio_reg_mask_xlate(struct gpio_regmap *gpio,
+				      unsigned int base, unsigned int offset,
+				      unsigned int *reg, unsigned int *mask)
+{
+	struct regmap *regmap = gpio_regmap_get_drvdata(gpio);
+	int ret;
+
+	*reg = base;
+	*mask = BIT(offset);
+
+	if (base != AD7768_REG_GPIO_READ)
+		return 0;
+
+	/*
+	 * AD7768 has separate input-state and output-latch registers. For an
+	 * output line, report the programmed value from the output latch;
+	 * input lines continue to use the input-state register.
+	 */
+	ret = regmap_test_bits(regmap, AD7768_REG_GPIO_CONTROL, *mask);
+	if (ret < 0)
+		return ret;
+	if (ret)
+		*reg = AD7768_REG_GPIO_WRITE;
+
+	return 0;
+}
+
+static int ad7768_gpio_probe(struct auxiliary_device *adev,
+			     const struct auxiliary_device_id *id)
+{
+	struct gpio_regmap_config config;
+	struct device *dev = &adev->dev;
+	struct device *parent;
+	struct regmap *map;
+	int ret;
+
+	parent = dev->parent;
+	map = dev_get_regmap(parent, NULL);
+	if (!map)
+		return -ENODEV;
+
+	PM_RUNTIME_ACQUIRE_AUTOSUSPEND(parent, pm);
+	ret = PM_RUNTIME_ACQUIRE_ERR(&pm);
+	if (ret)
+		return ret;
+
+	ret = regmap_set_bits(map, AD7768_REG_GPIO_CONTROL, AD7768_GPIO_UGPIO_ENABLE);
+	if (ret)
+		return ret;
+
+	config = (struct gpio_regmap_config) {
+		.parent = dev,
+		.regmap = map,
+		.label = dev_name(parent),
+		.ngpio = AD7768_NUM_GPIOS,
+		.reg_dat_base = AD7768_REG_GPIO_READ,
+		.reg_set_base = AD7768_REG_GPIO_WRITE,
+		.reg_dir_out_base = AD7768_REG_GPIO_CONTROL,
+		.pm_dev = parent,
+		.reg_mask_xlate = ad7768_gpio_reg_mask_xlate,
+		.init_valid_mask = ad7768_gpio_init_valid_mask,
+		.drvdata = map,
+	};
+
+	return PTR_ERR_OR_ZERO(devm_gpio_regmap_register(dev, &config));
+}
+
+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

[PATCH v5 20/20] 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 | 273 +++++++++++++++++++++++++++++++++++++++++++
 Documentation/iio/index.rst  |   1 +
 MAINTAINERS                  |   1 +
 3 files changed, 275 insertions(+)

diff --git a/Documentation/iio/ad7768.rst b/Documentation/iio/ad7768.rst
new file mode 100644
index 000000000000..49aeff27b00a
--- /dev/null
+++ b/Documentation/iio/ad7768.rst
@@ -0,0 +1,273 @@
+.. 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
+==================
+
+Clock sources
+-------------
+
+The master clock source is selected using the ``clock-names`` device tree
+property:
+
+* ``mclk`` selects a CMOS clock on XTAL2/MCLK. CLK_SEL must be low and XTAL1
+  must be connected to DGND.
+* ``xtal`` selects a crystal connected between XTAL1 and XTAL2. CLK_SEL must
+  be high. The driver drives FILTER/GPIO4 high and keeps channel 4 on the
+  AD7768 or channel 2 on the AD7768-4 enabled to maintain crystal excitation.
+* ``lvds`` selects a differential clock on XTAL1 and XTAL2. CLK_SEL must be
+  high. The driver drives FILTER/GPIO4 low before enabling the LVDS input.
+
+GPIO4 is reserved when ``xtal`` or ``lvds`` is selected.
+
+Power modes
+-----------
+
+The AD7768 family supports three 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 driver initializes the device in fast mode and uses the maximum fast-mode
+output data rate as the default sampling frequency.
+
+When buffered capture starts, the driver selects the lowest-noise mode that can
+produce the requested output data rates for all enabled channels. Where output
+data rates overlap, fast mode is preferred over median mode, and median mode is
+preferred over low power mode. This prioritizes the lower RMS noise and higher
+dynamic range offered by a faster mode at the same output data rate.
+
+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 can be configured via the ``adi,data-lines-number``
+device tree property. If omitted, the driver uses the maximum supported by the
+selected variant: eight lines for AD7768 and four lines for AD7768-4.
+
+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
+
+The hardware provides two mode profiles (A and B), each holding one
+(frequency, filter) combination. When buffered capture is started,
+enabled channels are grouped by their configured (frequency, filter)
+pair. Up to two distinct groups are supported; the driver automatically
+assigns each group to a mode slot and programs the hardware accordingly.
+
+Precharge and reference buffers
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Per-channel buffer control for optimal signal integrity:
+
+* Positive input precharge buffer (``adi,prechargebuf-pos-enable``)
+* Negative input precharge buffer (``adi,prechargebuf-neg-enable``)
+* Positive reference buffer (``adi,refbuf-pos-enable``)
+* Negative reference buffer (``adi,refbuf-neg-enable``)
+
+Common mode voltage
+-------------------
+
+The VCM pin provides a buffered common-mode voltage output used to bias
+the analog inputs. The driver exposes this as a standard voltage regulator
+provider under a ``regulators`` subnode in the device tree. Supported
+output voltage levels are:
+
+* (AVDD1 - AVSS) / 2 - Mid-supply (hardware default), reported as half the
+  voltage provided by ``avdd1-supply``
+* 1,650,000 µV - 1.65V
+* 2,500,000 µV - 2.5V
+* 2,140,000 µV - 2.14V
+
+The regulator can be enabled and disabled at runtime using the standard
+regulator framework interfaces.
+
+The VCM circuitry is associated with channel 0. When VCM is used externally,
+``channel@0`` must be present in the device tree and channel 0 must remain
+enabled in the active scan mask. Placing channel 0 in standby disables the VCM
+output.
+
+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.
+
+GPIO4 is reserved when a crystal or LVDS master clock is used. GPIO0 through
+GPIO3 remain available in these configurations.
+
+Device attributes
+=================
+
+The following IIO attributes are available for each enabled channel:
+
+Voltage scale
+-------------
+
+.. list-table::
+   :header-rows: 1
+   :widths: 40 60
+
+   * - Attribute
+     - Description
+   * - ``in_voltage<N>_scale``
+     - Scale in millivolts per least significant bit for signed 24-bit data,
+       calculated as twice the differential reference voltage used by channel
+       N divided by 2\ :sup:`24`.
+
+Sampling frequency
+------------------
+
+.. list-table::
+   :header-rows: 1
+   :widths: 40 60
+
+   * - Attribute
+     - Description
+   * - ``in_voltage<N>_sampling_frequency``
+     - Requested sampling frequency in Hz for channel N. Enabled channels are
+       grouped into up to two profiles at capture time.
+   * - ``in_voltage<N>_sampling_frequency_available``
+     - Available sampling frequencies in Hz for channel N across all power
+       modes, based on the master clock frequency. Buffer setup fails if no
+       single power mode supports the frequencies requested by all enabled
+       channels.
+
+Filter configuration
+---------------------
+
+.. list-table::
+   :header-rows: 1
+   :widths: 40 60
+
+   * - Attribute
+     - Description
+   * - ``in_voltage<N>_filter_type``
+     - Requested filter type for channel N: "wideband" or "sinc5". It is
+       grouped with sampling frequency at capture time.
+   * - ``in_voltage<N>_filter_type_available``
+     - Available filter types for channel N: "wideband sinc5".
+
+Per-channel calibration
+-----------------------
+
+.. list-table::
+   :header-rows: 1
+   :widths: 40 60
+
+   * - Attribute
+     - Description
+   * - ``in_voltage<N>_calibbias``
+     - Raw unsigned 24-bit channel offset register value.
+   * - ``in_voltage<N>_calibscale``
+     - Raw unsigned 24-bit channel gain register value.
+   * - ``in_voltage<N>_convdelay``
+     - Per-channel conversion delay. The driver exposes the sync phase offset
+       value in seconds with picosecond precision. Resolution and valid range
+       depend on the decimation ratio in use (see datasheet
+       Table 32).
+
+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-driven 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
+
+	# Buffer setup fails if enabled channels request more than two distinct
+	# (sampling frequency, filter type) combinations.
+
+	# Read calibration scale for channel 0
+	cat /sys/bus/iio/devices/iio:device0/in_voltage0_calibscale
+
+	# Read conversion delay for channel 0
+	cat /sys/bus/iio/devices/iio:device0/in_voltage0_convdelay
+
+
+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 dc94e7803a7c..229f49730138 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/iio/adc/ad7768.c
 
 ANALOG DEVICES INC AD7780 DRIVER

-- 
2.43.0