[PATCH v9 00/12] iio: adc: ad7768-1: Add features, improvements, and fixes

[PATCH v9 00/12] iio: adc: ad7768-1: Add features, improvements, and fixes

[Jonathan Santos]

This patch series introduces some new features, improvements,
and fixes for the AD7768-1 ADC driver. 

The goal is to support all key functionalities listed in the device
datasheet, including filter mode selection, common mode voltage output
configuration and GPIO support. Additionally, this includes fixes 
for SPI communication and for IIO interface, and also code improvements
to enhance maintainability and readability.

---
Changes in v9:
* added fwnode_find_reference_args() patch.
* Refactored ad7768_trigger_sources_get_sync() to avoid jumps and used 
  fwnode_find_reference_args() to get the trigger-sources property with
  proper cleanup.
* Fixed oversampling_ratio_available attribute. Previous ranges did not 
  follow a standard. Now we mix range (for sinc3) with list 
  (for sinc5 and wideband).
* Addressed review comments, see individual pacthes.
* Link to v8: https://lore.kernel.org/linux-iio/cover.1747175187.git.Jonathan.Santos@analog.com/T/#t

Changes in v8:
* Removed "reorganize driver headers patch", since Jonathan said he picked 
  it.
* refactored ad7768_trigger_sources_get_sync() function.
* Addressed review comments, see individual pacthes.
* Link to v7: https://lore.kernel.org/linux-iio/cover.1746662899.git.Jonathan.Santos@analog.com/T/#t


Changes in v7:
* Added a new patch to reorganize driver headers.
* Added the new files to MAINTAINERS.
* Added dependencies to constrain the use of trigger-sources and
  adi,sync-in-gpios properties at the same time.
* Self triggering is enabled only when the trigger-sources property is
  not defined. Added TODO to support other trigger sources when the subsystem
  is available.
* Refactor code to avoid forward declarations.
* Mentioned that sampling frequency changes is not allowed in
  buffered mode.
* Addressed review comments, see individual pacthes.
* Link to v6: https://lore.kernel.org/linux-iio/cover.1745605382.git.Jonathan.Santos@analog.com/T/#t

Changes in v6:
* Changed description and addressed other nits in the gpio-trigger patch.
* Rewrote the #trigger-sources-cells description and removed mentions 
  to offload engine.
* Added adi,ad7768-1.h header with macros for the trigger source cells.
* removed of_match_ptr() from regulator_desc.
* Replaced deprecated .set callback with .set_rv in the gpio controller
  patch.
* Use `trigger-sources` as an alternative to `adi,sync-in-gpios`
  (now optional), instead of replacing it.
* Check trigger source by the compatible string (and the dev node for the
  self triggering).
* Addressed review comments, see individual pacthes.
* Link to v5: https://lore.kernel.org/linux-iio/cover.1744325346.git.Jonathan.Santos@analog.com/T/#t

Changes in v5:
* Added gpio-trigger binding patch.
* Include START pin and DRDY in the trigger-sources description.
* increased trigger-source-cells to 1: this cell will define the trigger
  source type.
* Fixed the holes in the regmap ranges.
* replace old iio_device_claim_direct_mode() for the new 
  iio_device_claim/release_direct() functions.
* Changed some commit messages.
* Link to v4: https://lore.kernel.org/linux-iio/cover.1741268122.git.Jonathan.Santos@analog.com/T/#t

Changes in v4:
* Added missing `select REGMAP_SPI` and `select REGULATOR` to the device's Kconfig.
* VCM output regulator property renamed.
* Added direct mode conditional locks to regulator controller callbacks.
* Renamed regulator controller.
* Created helper function to precalculate the sampling frequency table and avoid
  race conditions.
* Link to v3: https://lore.kernel.org/linux-iio/cover.1739368121.git.Jonathan.Santos@analog.com/T/#t

Changes in v3:
* Fixed irregular or missing SoBs.
* Moved MOSI idle state patch to the start of the patch, as the other fix.
* fixed dt-binding errors.
* Trigger-sources is handled in a different way, as an alternative to sync-in-gpio.
  (this way we avoid breaking old applications).
* VCM output is controlled by the regulator framework.
* Added a second regmap for 24-bit register values.
* Add new preparatory patch replacing the manual attribute declarations for
  the read_avail from struct iio_info.
* included sinc3+rej60 filter type.
* Addressed review comments, see individual pacthes.
* Link to v2: https://lore.kernel.org/linux-iio/cover.1737985435.git.Jonathan.Santos@analog.com/T/#u

Changes in v2:
* Removed synchronization over SPI property and replaced it for trigger-sources.
* Added GPIO controller documentation.
* VCM output control changed from an IIO attribute to a devicetree property (static value).
* Converted driver to use regmap and dropped spi_read_reg and spi_write_reg pacthes.
* replaced decimation_rate attribute for oversampling_ratio and dropped device specific documentation patch.
* Added low pass -3dB cutoff attribute.
* Addressed review comments, see individual pacthes.
* Link to v1: https://lore.kernel.org/linux-iio/cover.1736201898.git.Jonathan.Santos@analog.com/T/#t

Jonathan Santos (11):
  device property: add fwnode_find_reference_args()
  dt-bindings: trigger-source: add generic GPIO trigger source
  dt-bindings: iio: adc: ad7768-1: add trigger-sources property
  dt-bindings: iio: adc: ad7768-1: Document GPIO controller
  dt-bindings: iio: adc: ad7768-1: document regulator provider property
  iio: adc: ad7768-1: add regulator to control VCM output
  iio: adc: ad7768-1: add multiple scan types to support 16-bits mode
  iio: adc: ad7768-1: add support for Synchronization over SPI
  iio: adc: ad7768-1: replace manual attribute declaration
  iio: adc: ad7768-1: add filter type and oversampling ratio attributes
  iio: adc: ad7768-1: add low pass -3dB cutoff attribute

Sergiu Cuciurean (1):
  iio: adc: ad7768-1: Add GPIO controller support

 .../bindings/iio/adc/adi,ad7768-1.yaml        |  68 +-
 .../bindings/trigger-source/gpio-trigger.yaml |  40 +
 MAINTAINERS                                   |   4 +-
 drivers/base/property.c                       |  32 +
 drivers/iio/adc/Kconfig                       |   1 +
 drivers/iio/adc/ad7768-1.c                    | 906 +++++++++++++++---
 include/dt-bindings/iio/adc/adi,ad7768-1.h    |  10 +
 include/linux/property.h                      |   6 +
 8 files changed, 952 insertions(+), 115 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/trigger-source/gpio-trigger.yaml
 create mode 100644 include/dt-bindings/iio/adc/adi,ad7768-1.h


base-commit: 9415c8b5b9b7ba927d98f80022a2890e8639e9e4
prerequisite-patch-id: fbb33747cd0293bacd5b6d801d6cfc087449a28e
-- 
2.34.1

[PATCH v9 01/12] device property: add fwnode_find_reference_args()

[Jonathan Santos]

Similarly to fwnode_find_reference(), find and return a named reference
to a fwnode handle, including its arguments. This wrapper facilitates
cleanup handling and improves readability.

Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com>
---
v9 Changes:
* New patch.
---
 drivers/base/property.c  | 32 ++++++++++++++++++++++++++++++++
 include/linux/property.h |  6 ++++++
 2 files changed, 38 insertions(+)

diff --git a/drivers/base/property.c b/drivers/base/property.c
index f42f32ff45fc..b5d82facd7c5 100644
--- a/drivers/base/property.c
+++ b/drivers/base/property.c
@@ -645,6 +645,38 @@ struct fwnode_handle *fwnode_find_reference(const struct fwnode_handle *fwnode,
 }
 EXPORT_SYMBOL_GPL(fwnode_find_reference);
 
+/**
+ * fwnode_find_reference_args - Find named reference to a fwnode_handle with arguments
+ * @fwnode:	Firmware node where to look for the reference
+ * @name:	The name of the reference
+ * @nargs_prop:	The name of the property telling the number of
+ *		arguments in the reference. NULL if @nargs is known,
+ *		otherwise @nargs is ignored. Only relevant on OF.
+ * @nargs:	Number of arguments. Ignored if @nargs_prop is non-NULL.
+ * @index:	Index of the reference
+ *
+ * @index can be used when the named reference holds a table of references.
+ *
+ * The caller is responsible for calling fwnode_handle_put() on the returned
+ * fwnode pointer.
+ *
+ * Return: a pointer to the reference fwnode, when found. Otherwise,
+ * returns an error pointer.
+ */
+struct fwnode_handle *
+fwnode_find_reference_args(const struct fwnode_handle *fwnode,
+			   const char *name, const char *nargs_prop,
+			   unsigned int nargs, unsigned int index,
+			   struct fwnode_reference_args *args)
+{
+	int ret;
+
+	ret = fwnode_property_get_reference_args(fwnode, name, nargs_prop,
+						 nargs, index, args);
+	return ret ? ERR_PTR(ret) : args->fwnode;
+}
+EXPORT_SYMBOL_GPL(fwnode_find_reference_args);
+
 /**
  * fwnode_get_name - Return the name of a node
  * @fwnode: The firmware node
diff --git a/include/linux/property.h b/include/linux/property.h
index 3e83babac0b0..f35ced8f50f7 100644
--- a/include/linux/property.h
+++ b/include/linux/property.h
@@ -144,6 +144,12 @@ struct fwnode_handle *fwnode_find_reference(const struct fwnode_handle *fwnode,
 					    const char *name,
 					    unsigned int index);
 
+struct fwnode_handle *
+fwnode_find_reference_args(const struct fwnode_handle *fwnode,
+			   const char *name, const char *nargs_prop,
+			   unsigned int nargs, unsigned int index,
+			   struct fwnode_reference_args *args);
+
 const char *fwnode_get_name(const struct fwnode_handle *fwnode);
 const char *fwnode_get_name_prefix(const struct fwnode_handle *fwnode);
 bool fwnode_name_eq(const struct fwnode_handle *fwnode, const char *name);
-- 
2.34.1

[PATCH v9 02/12] dt-bindings: trigger-source: add generic GPIO trigger source

[Jonathan Santos]

Inspired by pwm-trigger, create a new binding for using a GPIO
line as a trigger source.

Link: https://lore.kernel.org/linux-iio/20250207-dlech-mainline-spi-engine-offload-2-v8-3-e48a489be48c@baylibre.com/
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: David Lechner <dlechner@baylibre.com>
Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com>
---
v9 Changes:
* No changes.

v8 Changes:
* No changes.

v7 Changes:
* File added to MAINTAINERS and Made trigger source generic to include both pwm and gpio.

v6 Changes:
* Changed description.
* Fixed typos and replaced GPIO pin with GPIO line.
* Added link reference for pwm-trigger.

v5 Changes:
* New patch in v5.
---
 .../bindings/trigger-source/gpio-trigger.yaml | 40 +++++++++++++++++++
 MAINTAINERS                                   |  3 +-
 2 files changed, 42 insertions(+), 1 deletion(-)
 create mode 100644 Documentation/devicetree/bindings/trigger-source/gpio-trigger.yaml

diff --git a/Documentation/devicetree/bindings/trigger-source/gpio-trigger.yaml b/Documentation/devicetree/bindings/trigger-source/gpio-trigger.yaml
new file mode 100644
index 000000000000..1331d153ee82
--- /dev/null
+++ b/Documentation/devicetree/bindings/trigger-source/gpio-trigger.yaml
@@ -0,0 +1,40 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/trigger-source/gpio-trigger.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Generic trigger source using GPIO
+
+description: A GPIO used as a trigger source.
+
+maintainers:
+  - Jonathan Santos <Jonathan.Santos@analog.com>
+
+properties:
+  compatible:
+    const: gpio-trigger
+
+  '#trigger-source-cells':
+    const: 0
+
+  gpios:
+    maxItems: 1
+    description: GPIO to be used as a trigger source.
+
+required:
+  - compatible
+  - '#trigger-source-cells'
+  - gpios
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+
+    trigger {
+        compatible = "gpio-trigger";
+        #trigger-source-cells = <0>;
+        gpios = <&gpio1 15 GPIO_ACTIVE_HIGH>;
+    };
diff --git a/MAINTAINERS b/MAINTAINERS
index 01079a189c93..9b2e9a9dd8bc 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -24569,9 +24569,10 @@ W:	https://github.com/srcres258/linux-doc
 T:	git git://github.com/srcres258/linux-doc.git doc-zh-tw
 F:	Documentation/translations/zh_TW/
 
-TRIGGER SOURCE - PWM
+TRIGGER SOURCE
 M:	David Lechner <dlechner@baylibre.com>
 S:	Maintained
+F:	Documentation/devicetree/bindings/trigger-source/gpio-trigger.yaml
 F:	Documentation/devicetree/bindings/trigger-source/pwm-trigger.yaml
 
 TRUSTED SECURITY MODULE (TSM) ATTESTATION REPORTS
-- 
2.34.1

[PATCH v9 03/12] dt-bindings: iio: adc: ad7768-1: add trigger-sources property

[Jonathan Santos]

In addition to GPIO synchronization, The AD7768-1 also supports
synchronization over SPI, which use is recommended when the GPIO
cannot provide a pulse synchronous with the base MCLK signal. It
consists of looping back the SYNC_OUT to the SYNC_IN pin and send
a command via SPI to trigger the synchronization.

Introduce the 'trigger-sources' property to enable SPI-based
synchronization via SYNC_OUT pin, along with additional optional
entries for GPIO3 and DRDY pins.

Also create #trigger-source-cells property to differentiate the trigger
sources provided by the ADC. To improve readability, create a
adi,ad7768-1.h header with the macros for the cell values.

While at it, add description to the interrupts property.

Acked-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: David Lechner <dlechner@baylirbe.com>
Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com>
---
v9 Changes:
* No changes.

v8 Changes:
* No changes. I have decided to keep the 'dependencies' section header
  since Rob said it is ok for this case.

v7 Changes:
* added new file to the MAINTAINERS entry.
* Made interrupts description more concise.
* Added dependencies to constrain the use of trigger-sources and
  adi,sync-in-gpios properties at the same time.

v6 Changes:
* Removed references to offload.
* Changed trigger-sources-cells description. Each cell value indicates
  a gpio line from the ADC.
* Added adi,ad7768-1.h header with macros for the trigger source cells.
* Removed offload trigger entry from trigger-sources.

v5 Changes:
* Include START pin and DRDY in the trigger-sources description.
* Fixed "#trigger-source-cells" value and description.
* sync-in-gpios is represented in the trigger-sources property.

v4 Changes:
* none

v3 Changes:
* Fixed dt-bindings errors.
* Trigger-source is set as an alternative to sync-in-gpios, so we
  don't break the previous ABI.
* increased maxItems from trigger-sources to 2.

v2 Changes:
* Patch added as replacement for adi,sync-in-spi patch.
* addressed the request for a description to interrupts property.
---
 .../bindings/iio/adc/adi,ad7768-1.yaml        | 39 ++++++++++++++++++-
 MAINTAINERS                                   |  1 +
 include/dt-bindings/iio/adc/adi,ad7768-1.h    | 10 +++++
 3 files changed, 49 insertions(+), 1 deletion(-)
 create mode 100644 include/dt-bindings/iio/adc/adi,ad7768-1.h

diff --git a/Documentation/devicetree/bindings/iio/adc/adi,ad7768-1.yaml b/Documentation/devicetree/bindings/iio/adc/adi,ad7768-1.yaml
index 3ce59d4d065f..9a6df931edc3 100644
--- a/Documentation/devicetree/bindings/iio/adc/adi,ad7768-1.yaml
+++ b/Documentation/devicetree/bindings/iio/adc/adi,ad7768-1.yaml
@@ -26,7 +26,26 @@ properties:
   clock-names:
     const: mclk
 
+  trigger-sources:
+    $ref: /schemas/types.yaml#/definitions/phandle-array
+    minItems: 1
+    maxItems: 2
+    description: |
+      A list of phandles referencing trigger source providers. Each entry
+      represents a trigger source for the ADC:
+
+        - First entry specifies the device responsible for driving the
+          synchronization (SYNC_IN) pin, as an alternative to adi,sync-in-gpios.
+          This can be a `gpio-trigger` or another `ad7768-1` device. If the
+          device's own SYNC_OUT pin is internally connected to its SYNC_IN pin,
+          reference the device itself or omit this property.
+        - Second entry optionally defines a GPIO3 pin used as a START signal trigger.
+
+      Use the accompanying trigger source cell to identify the type of each entry.
+
   interrupts:
+    description:
+      DRDY (Data Ready) pin, which signals conversion results are available.
     maxItems: 1
 
   '#address-cells':
@@ -57,6 +76,15 @@ properties:
   "#io-channel-cells":
     const: 1
 
+  "#trigger-source-cells":
+    description: |
+      Cell indicates the trigger output signal: 0 = SYNC_OUT, 1 = GPIO3,
+      2 = DRDY.
+
+      For better readability, macros for these values are available in
+      dt-bindings/iio/adc/adi,ad7768-1.h.
+    const: 1
+
 required:
   - compatible
   - reg
@@ -65,7 +93,16 @@ required:
   - vref-supply
   - spi-cpol
   - spi-cpha
-  - adi,sync-in-gpios
+
+dependencies:
+  adi,sync-in-gpios:
+    not:
+      required:
+        - trigger-sources
+  trigger-sources:
+    not:
+      required:
+        - adi,sync-in-gpios
 
 patternProperties:
   "^channel@([0-9]|1[0-5])$":
diff --git a/MAINTAINERS b/MAINTAINERS
index 9b2e9a9dd8bc..be07926f6666 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1426,6 +1426,7 @@ S:	Supported
 W:	https://ez.analog.com/linux-software-drivers
 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 AD7780 DRIVER
 M:	Michael Hennerich <Michael.Hennerich@analog.com>
diff --git a/include/dt-bindings/iio/adc/adi,ad7768-1.h b/include/dt-bindings/iio/adc/adi,ad7768-1.h
new file mode 100644
index 000000000000..34d92856a50b
--- /dev/null
+++ b/include/dt-bindings/iio/adc/adi,ad7768-1.h
@@ -0,0 +1,10 @@
+/* SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) */
+
+#ifndef _DT_BINDINGS_ADI_AD7768_1_H
+#define _DT_BINDINGS_ADI_AD7768_1_H
+
+#define AD7768_TRIGGER_SOURCE_SYNC_OUT  0
+#define AD7768_TRIGGER_SOURCE_GPIO3     1
+#define AD7768_TRIGGER_SOURCE_DRDY      2
+
+#endif /* _DT_BINDINGS_ADI_AD7768_1_H */
-- 
2.34.1

[PATCH v9 04/12] dt-bindings: iio: adc: ad7768-1: Document GPIO controller

[Jonathan Santos]

The AD7768-1 ADC exports four bidirectional GPIOs accessible
via register map.

Document GPIO properties necessary to enable GPIO controller for this
device.

Acked-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com>
---
v9 Changes:
* none.

v8 Changes:
* none.

v7 Changes:
* none.

v6 Changes:
* none.

v5 Changes:
* none.

v4 Changes:
* none.

v3 Changes:
* none.

v2 Changes:
* New
---
 .../devicetree/bindings/iio/adc/adi,ad7768-1.yaml      | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/Documentation/devicetree/bindings/iio/adc/adi,ad7768-1.yaml b/Documentation/devicetree/bindings/iio/adc/adi,ad7768-1.yaml
index 9a6df931edc3..18f93586fcdf 100644
--- a/Documentation/devicetree/bindings/iio/adc/adi,ad7768-1.yaml
+++ b/Documentation/devicetree/bindings/iio/adc/adi,ad7768-1.yaml
@@ -85,6 +85,14 @@ properties:
       dt-bindings/iio/adc/adi,ad7768-1.h.
     const: 1
 
+  gpio-controller: true
+
+  "#gpio-cells":
+    const: 2
+    description: |
+      The first cell is for the GPIO number: 0 to 3.
+      The second cell takes standard GPIO flags.
+
 required:
   - compatible
   - reg
@@ -142,6 +150,8 @@ examples:
             spi-max-frequency = <2000000>;
             spi-cpol;
             spi-cpha;
+            gpio-controller;
+            #gpio-cells = <2>;
             vref-supply = <&adc_vref>;
             interrupts = <25 IRQ_TYPE_EDGE_RISING>;
             interrupt-parent = <&gpio>;
-- 
2.34.1

[PATCH v9 05/12] dt-bindings: iio: adc: ad7768-1: document regulator provider property

[Jonathan Santos]

The AD7768-1 provides a buffered common-mode voltage output
on the VCM pin that can be used to bias analog input signals.

Add regulators property to enable the use of the VCM output,
referenced here as vcm-output, by any other device.

Acked-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com>
---
v9 Changes:
* none.

v8 Changes:
* none.

v7 Changes:
* none.

v6 Changes:
* None.

v5 Changes:
* removed `regulator-min-microvolt` and `regulator-max-microvolt`. 

v4 Changes:
* replace "vcm_output" property name for "vcm-output". 

v3 Changes:
* VCM is now provided as a regulator within the device, instead of a 
  custom property.

v2 Changes:
* New patch in v2.
---
 .../bindings/iio/adc/adi,ad7768-1.yaml        | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/Documentation/devicetree/bindings/iio/adc/adi,ad7768-1.yaml b/Documentation/devicetree/bindings/iio/adc/adi,ad7768-1.yaml
index 18f93586fcdf..c06d0fc791d3 100644
--- a/Documentation/devicetree/bindings/iio/adc/adi,ad7768-1.yaml
+++ b/Documentation/devicetree/bindings/iio/adc/adi,ad7768-1.yaml
@@ -66,6 +66,19 @@ properties:
       in any way, for example if the filter decimation rate changes.
       As the line is active low, it should be marked GPIO_ACTIVE_LOW.
 
+  regulators:
+    type: object
+    description:
+      list of regulators provided by this controller.
+
+    properties:
+      vcm-output:
+        $ref: /schemas/regulator/regulator.yaml#
+        type: object
+        unevaluatedProperties: false
+
+    additionalProperties: false
+
   reset-gpios:
     maxItems: 1
 
@@ -167,6 +180,12 @@ examples:
                 reg = <0>;
                 label = "channel_0";
             };
+
+            regulators {
+              vcm_reg: vcm-output {
+                regulator-name = "ad7768-1-vcm";
+              };
+            };
         };
     };
 ...
-- 
2.34.1

[PATCH v9 06/12] iio: adc: ad7768-1: add regulator to control VCM output

[Jonathan Santos]

The VCM output voltage can be used as a common-mode voltage within the
amplifier preconditioning circuits external to the AD7768-1.

This change allows the user to configure VCM output using the regulator
framework.

Acked-by: Marcelo Schmitt <marcelo.schmitt@analog.com>
Reviewed-by: David Lechner <dlechner@baylibre.com>
Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com>
---
v9 Changes:
* None.

v8 Changes:
* None.

v7 Changes:
* removed dead code.
* removed of.h header.
* removed explicit casting in the clamp function.

v6 Changes:
* Rearranged iio_device_release_direct() calls to avoid
 some gotos.
* removed of_match_ptr() from regulator_desc.
* Addressed other nits.

v5 Changes:
* enforce AD7768_REG_ANALOG2_VCM macro argument evaluation.
* switched to the new iio_device_claim/release_direct() functions.

v4 Changes:
* Added iio_device_claim_direct_mode() to regulator callbacks to avoid register access
  while in buffered mode.
* Changed regulator name to "ad7768-1-vcm".
* When regulator enable is called, it will set the last voltage selector configured.
* Disabled regulator before configuring it.
* Addressed other nits.

v3 Changes:
* Register VCM output via the regulator framework for improved flexibility
  and external integration.

v2 Changes:
* VCM output support is now defined by a devicetree property, instead of 
  and IIO attribute.
---
 drivers/iio/adc/Kconfig    |   1 +
 drivers/iio/adc/ad7768-1.c | 159 +++++++++++++++++++++++++++++++++++++
 2 files changed, 160 insertions(+)

diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index ad06cf556785..8dc4cc4c25af 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -329,6 +329,7 @@ config AD7766
 config AD7768_1
 	tristate "Analog Devices AD7768-1 ADC driver"
 	depends on SPI
+	select REGULATOR
 	select REGMAP_SPI
 	select IIO_BUFFER
 	select IIO_TRIGGER
diff --git a/drivers/iio/adc/ad7768-1.c b/drivers/iio/adc/ad7768-1.c
index e90bb5d50076..cd5ce774df72 100644
--- a/drivers/iio/adc/ad7768-1.c
+++ b/drivers/iio/adc/ad7768-1.c
@@ -13,9 +13,11 @@
 #include <linux/err.h>
 #include <linux/gpio/consumer.h>
 #include <linux/interrupt.h>
+#include <linux/minmax.h>
 #include <linux/module.h>
 #include <linux/regmap.h>
 #include <linux/regulator/consumer.h>
+#include <linux/regulator/driver.h>
 #include <linux/sysfs.h>
 #include <linux/spi/spi.h>
 
@@ -82,6 +84,12 @@
 #define AD7768_CONV_MODE_MSK		GENMASK(2, 0)
 #define AD7768_CONV_MODE(x)		FIELD_PREP(AD7768_CONV_MODE_MSK, x)
 
+/* AD7768_REG_ANALOG2 */
+#define AD7768_REG_ANALOG2_VCM_MSK	GENMASK(2, 0)
+#define AD7768_REG_ANALOG2_VCM(x)	FIELD_PREP(AD7768_REG_ANALOG2_VCM_MSK, (x))
+
+#define AD7768_VCM_OFF			0x07
+
 enum ad7768_conv_mode {
 	AD7768_CONTINUOUS,
 	AD7768_ONE_SHOT,
@@ -159,6 +167,8 @@ struct ad7768_state {
 	struct regmap *regmap;
 	struct regmap *regmap24;
 	struct regulator *vref;
+	struct regulator_dev *vcm_rdev;
+	unsigned int vcm_output_sel;
 	struct clk *mclk;
 	unsigned int mclk_freq;
 	unsigned int samp_freq;
@@ -646,6 +656,150 @@ static int ad7768_triggered_buffer_alloc(struct iio_dev *indio_dev)
 					       &ad7768_buffer_ops);
 }
 
+static int ad7768_vcm_enable(struct regulator_dev *rdev)
+{
+	struct iio_dev *indio_dev = rdev_get_drvdata(rdev);
+	struct ad7768_state *st = iio_priv(indio_dev);
+	int ret, regval;
+
+	if (!iio_device_claim_direct(indio_dev))
+		return -EBUSY;
+
+	/* To enable, set the last selected output */
+	regval = AD7768_REG_ANALOG2_VCM(st->vcm_output_sel + 1);
+	ret = regmap_update_bits(st->regmap, AD7768_REG_ANALOG2,
+				 AD7768_REG_ANALOG2_VCM_MSK, regval);
+	iio_device_release_direct(indio_dev);
+
+	return ret;
+}
+
+static int ad7768_vcm_disable(struct regulator_dev *rdev)
+{
+	struct iio_dev *indio_dev = rdev_get_drvdata(rdev);
+	struct ad7768_state *st = iio_priv(indio_dev);
+	int ret;
+
+	if (!iio_device_claim_direct(indio_dev))
+		return -EBUSY;
+
+	ret = regmap_update_bits(st->regmap, AD7768_REG_ANALOG2,
+				 AD7768_REG_ANALOG2_VCM_MSK, AD7768_VCM_OFF);
+	iio_device_release_direct(indio_dev);
+
+	return ret;
+}
+
+static int ad7768_vcm_is_enabled(struct regulator_dev *rdev)
+{
+	struct iio_dev *indio_dev = rdev_get_drvdata(rdev);
+	struct ad7768_state *st = iio_priv(indio_dev);
+	int ret, val;
+
+	if (!iio_device_claim_direct(indio_dev))
+		return -EBUSY;
+
+	ret = regmap_read(st->regmap, AD7768_REG_ANALOG2, &val);
+	iio_device_release_direct(indio_dev);
+	if (ret)
+		return ret;
+
+	return FIELD_GET(AD7768_REG_ANALOG2_VCM_MSK, val) != AD7768_VCM_OFF;
+}
+
+static int ad7768_set_voltage_sel(struct regulator_dev *rdev,
+				  unsigned int selector)
+{
+	unsigned int regval = AD7768_REG_ANALOG2_VCM(selector + 1);
+	struct iio_dev *indio_dev = rdev_get_drvdata(rdev);
+	struct ad7768_state *st = iio_priv(indio_dev);
+	int ret;
+
+	if (!iio_device_claim_direct(indio_dev))
+		return -EBUSY;
+
+	ret = regmap_update_bits(st->regmap, AD7768_REG_ANALOG2,
+				 AD7768_REG_ANALOG2_VCM_MSK, regval);
+	iio_device_release_direct(indio_dev);
+	if (ret)
+		return ret;
+
+	st->vcm_output_sel = selector;
+
+	return 0;
+}
+
+static int ad7768_get_voltage_sel(struct regulator_dev *rdev)
+{
+	struct iio_dev *indio_dev = rdev_get_drvdata(rdev);
+	struct ad7768_state *st = iio_priv(indio_dev);
+	int ret, val;
+
+	if (!iio_device_claim_direct(indio_dev))
+		return -EBUSY;
+
+	ret = regmap_read(st->regmap, AD7768_REG_ANALOG2, &val);
+	iio_device_release_direct(indio_dev);
+	if (ret)
+		return ret;
+
+	val = FIELD_GET(AD7768_REG_ANALOG2_VCM_MSK, val);
+
+	return clamp(val, 1, rdev->desc->n_voltages) - 1;
+}
+
+static const struct regulator_ops vcm_regulator_ops = {
+	.enable = ad7768_vcm_enable,
+	.disable = ad7768_vcm_disable,
+	.is_enabled = ad7768_vcm_is_enabled,
+	.list_voltage = regulator_list_voltage_table,
+	.set_voltage_sel = ad7768_set_voltage_sel,
+	.get_voltage_sel = ad7768_get_voltage_sel,
+};
+
+static const unsigned int vcm_voltage_table[] = {
+	2500000,
+	2050000,
+	1650000,
+	1900000,
+	1100000,
+	900000,
+};
+
+static const struct regulator_desc vcm_desc = {
+	.name = "ad7768-1-vcm",
+	.of_match = "vcm-output",
+	.regulators_node = "regulators",
+	.n_voltages = ARRAY_SIZE(vcm_voltage_table),
+	.volt_table = vcm_voltage_table,
+	.ops = &vcm_regulator_ops,
+	.type = REGULATOR_VOLTAGE,
+	.owner = THIS_MODULE,
+};
+
+static int ad7768_register_regulators(struct device *dev, struct ad7768_state *st,
+				      struct iio_dev *indio_dev)
+{
+	struct regulator_config config = {
+		.dev = dev,
+		.driver_data = indio_dev,
+	};
+	int ret;
+
+	/* Disable the regulator before registering it */
+	ret = regmap_update_bits(st->regmap, AD7768_REG_ANALOG2,
+				 AD7768_REG_ANALOG2_VCM_MSK, AD7768_VCM_OFF);
+	if (ret)
+		return ret;
+
+	st->vcm_rdev = devm_regulator_register(dev, &vcm_desc, &config);
+	if (IS_ERR(st->vcm_rdev))
+		return dev_err_probe(dev, PTR_ERR(st->vcm_rdev),
+				     "failed to register VCM regulator\n");
+
+	return 0;
+}
+
 static int ad7768_probe(struct spi_device *spi)
 {
 	struct ad7768_state *st;
@@ -710,6 +864,11 @@ static int ad7768_probe(struct spi_device *spi)
 	indio_dev->info = &ad7768_info;
 	indio_dev->modes = INDIO_DIRECT_MODE;
 
+	/* Register VCM output regulator */
+	ret = ad7768_register_regulators(&spi->dev, st, indio_dev);
+	if (ret)
+		return ret;
+
 	ret = ad7768_setup(st);
 	if (ret < 0) {
 		dev_err(&spi->dev, "AD7768 setup failed\n");
-- 
2.34.1

[PATCH v9 07/12] iio: adc: ad7768-1: Add GPIO controller support

[Jonathan Santos]

From: Sergiu Cuciurean <sergiu.cuciurean@analog.com>

The AD7768-1 has the ability to control other local hardware (such as gain
stages),to power down other blocks in the signal chain, or read local
status signals over the SPI interface.

Add direct mode conditional locks in the gpio callbacks to prevent register
access when the device is in buffered mode.

This change exports the AD7768-1's four gpios and makes them accessible
at an upper layer.

Reviewed-by: Marcelo Schmitt <marcelo.schmitt@analog.com>
Acked-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Sergiu Cuciurean <sergiu.cuciurean@analog.com>
Co-developed-by: Jonathan Santos <Jonathan.Santos@analog.com>
Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com>
---
v9 Changes:
* None.

v8 Changes:
* None.

v7 Changes:
* moved gpiochip field in the ad7768_state struct.
* replaced regmap_update_bits() for regmap_assign_bits() in the gpio_set() function.
* other nits.
* removed gpio.h header.

v6 Changes:
* Replaced deprecated .set callback with .set_rv.

v5 Changes:
* Use the new new iio_device_claim/release_direct() functions.
* replaced gpiochip_add_data() for devm_gpiochip_add_data().

v4 Changes:
* Mentioned in the commit message that we cannot tweak the GPIO controller
  when the device is not in direct mode.

v3 Changes:
* Fixed SoB order.
* Added missing iio_device_release_direct_mode().
* Simplified some regmap writes.
* Removed ad7768_gpio_request() callback.
* Fixed line wrapping.

v2 Changes:
* Replaced mutex for iio_device_claim_direct_mode().
* Use gpio-controller property to conditionally enable the
  GPIO support.
* OBS: when the GPIO is configured as output, we should read 
  the current state value from AD7768_REG_GPIO_WRITE.
---
 drivers/iio/adc/ad7768-1.c | 140 ++++++++++++++++++++++++++++++++++++-
 1 file changed, 138 insertions(+), 2 deletions(-)

diff --git a/drivers/iio/adc/ad7768-1.c b/drivers/iio/adc/ad7768-1.c
index cd5ce774df72..d0366d570c14 100644
--- a/drivers/iio/adc/ad7768-1.c
+++ b/drivers/iio/adc/ad7768-1.c
@@ -11,6 +11,7 @@
 #include <linux/delay.h>
 #include <linux/device.h>
 #include <linux/err.h>
+#include <linux/gpio/driver.h>
 #include <linux/gpio/consumer.h>
 #include <linux/interrupt.h>
 #include <linux/minmax.h>
@@ -88,6 +89,16 @@
 #define AD7768_REG_ANALOG2_VCM_MSK	GENMASK(2, 0)
 #define AD7768_REG_ANALOG2_VCM(x)	FIELD_PREP(AD7768_REG_ANALOG2_VCM_MSK, (x))
 
+/* AD7768_REG_GPIO_CONTROL */
+#define AD7768_GPIO_UNIVERSAL_EN	BIT(7)
+#define AD7768_GPIO_CONTROL_MSK		GENMASK(3, 0)
+
+/* AD7768_REG_GPIO_WRITE */
+#define AD7768_GPIO_WRITE_MSK		GENMASK(3, 0)
+
+/* AD7768_REG_GPIO_READ */
+#define AD7768_GPIO_READ_MSK		GENMASK(3, 0)
+
 #define AD7768_VCM_OFF			0x07
 
 enum ad7768_conv_mode {
@@ -177,6 +188,7 @@ struct ad7768_state {
 	struct gpio_desc *gpio_sync_in;
 	struct gpio_desc *gpio_reset;
 	const char *labels[ARRAY_SIZE(ad7768_channels)];
+	struct gpio_chip gpiochip;
 	/*
 	 * DMA (thus cache coherency maintenance) may require the
 	 * transfer buffers to live in their own cache lines.
@@ -355,6 +367,122 @@ static int ad7768_set_dig_fil(struct ad7768_state *st,
 	return 0;
 }
 
+static int ad7768_gpio_direction_input(struct gpio_chip *chip, unsigned int offset)
+{
+	struct iio_dev *indio_dev = gpiochip_get_data(chip);
+	struct ad7768_state *st = iio_priv(indio_dev);
+	int ret;
+
+	if (!iio_device_claim_direct(indio_dev))
+		return -EBUSY;
+
+	ret = regmap_clear_bits(st->regmap, AD7768_REG_GPIO_CONTROL,
+				BIT(offset));
+	iio_device_release_direct(indio_dev);
+
+	return ret;
+}
+
+static int ad7768_gpio_direction_output(struct gpio_chip *chip,
+					unsigned int offset, int value)
+{
+	struct iio_dev *indio_dev = gpiochip_get_data(chip);
+	struct ad7768_state *st = iio_priv(indio_dev);
+	int ret;
+
+	if (!iio_device_claim_direct(indio_dev))
+		return -EBUSY;
+
+	ret = regmap_set_bits(st->regmap, AD7768_REG_GPIO_CONTROL,
+			      BIT(offset));
+	iio_device_release_direct(indio_dev);
+
+	return ret;
+}
+
+static int ad7768_gpio_get(struct gpio_chip *chip, unsigned int offset)
+{
+	struct iio_dev *indio_dev = gpiochip_get_data(chip);
+	struct ad7768_state *st = iio_priv(indio_dev);
+	unsigned int val;
+	int ret;
+
+	if (!iio_device_claim_direct(indio_dev))
+		return -EBUSY;
+
+	ret = regmap_read(st->regmap, AD7768_REG_GPIO_CONTROL, &val);
+	if (ret)
+		goto err_release;
+
+	/*
+	 * If the GPIO is configured as an output, read the current value from
+	 * AD7768_REG_GPIO_WRITE. Otherwise, read the input value from
+	 * AD7768_REG_GPIO_READ.
+	 */
+	if (val & BIT(offset))
+		ret = regmap_read(st->regmap, AD7768_REG_GPIO_WRITE, &val);
+	else
+		ret = regmap_read(st->regmap, AD7768_REG_GPIO_READ, &val);
+	if (ret)
+		goto err_release;
+
+	ret = !!(val & BIT(offset));
+err_release:
+	iio_device_release_direct(indio_dev);
+
+	return ret;
+}
+
+static int ad7768_gpio_set(struct gpio_chip *chip, unsigned int offset, int value)
+{
+	struct iio_dev *indio_dev = gpiochip_get_data(chip);
+	struct ad7768_state *st = iio_priv(indio_dev);
+	unsigned int val;
+	int ret;
+
+	if (!iio_device_claim_direct(indio_dev))
+		return -EBUSY;
+
+	ret = regmap_read(st->regmap, AD7768_REG_GPIO_CONTROL, &val);
+	if (ret)
+		goto err_release;
+
+	if (val & BIT(offset))
+		ret = regmap_assign_bits(st->regmap, AD7768_REG_GPIO_WRITE,
+					 BIT(offset), value);
+
+err_release:
+	iio_device_release_direct(indio_dev);
+
+	return ret;
+}
+
+static int ad7768_gpio_init(struct iio_dev *indio_dev)
+{
+	struct ad7768_state *st = iio_priv(indio_dev);
+	int ret;
+
+	ret = regmap_write(st->regmap, AD7768_REG_GPIO_CONTROL,
+			   AD7768_GPIO_UNIVERSAL_EN);
+	if (ret)
+		return ret;
+
+	st->gpiochip = (struct gpio_chip) {
+		.label = "ad7768_1_gpios",
+		.base = -1,
+		.ngpio = 4,
+		.parent = &st->spi->dev,
+		.can_sleep = true,
+		.direction_input = ad7768_gpio_direction_input,
+		.direction_output = ad7768_gpio_direction_output,
+		.get = ad7768_gpio_get,
+		.set_rv = ad7768_gpio_set,
+		.owner = THIS_MODULE,
+	};
+
+	return devm_gpiochip_add_data(&st->spi->dev, &st->gpiochip, indio_dev);
+}
+
 static int ad7768_set_freq(struct ad7768_state *st,
 			   unsigned int freq)
 {
@@ -496,8 +624,9 @@ static const struct iio_info ad7768_info = {
 	.debugfs_reg_access = &ad7768_reg_access,
 };
 
-static int ad7768_setup(struct ad7768_state *st)
+static int ad7768_setup(struct iio_dev *indio_dev)
 {
+	struct ad7768_state *st = iio_priv(indio_dev);
 	int ret;
 
 	st->gpio_reset = devm_gpiod_get_optional(&st->spi->dev, "reset",
@@ -530,6 +659,13 @@ static int ad7768_setup(struct ad7768_state *st)
 	if (IS_ERR(st->gpio_sync_in))
 		return PTR_ERR(st->gpio_sync_in);
 
+	/* Only create a Chip GPIO if flagged for it */
+	if (device_property_read_bool(&st->spi->dev, "gpio-controller")) {
+		ret = ad7768_gpio_init(indio_dev);
+		if (ret)
+			return ret;
+	}
+
 	/* Set the default sampling frequency to 32000 kSPS */
 	return ad7768_set_freq(st, 32000);
 }
@@ -869,7 +1005,7 @@ static int ad7768_probe(struct spi_device *spi)
 	if (ret)
 		return ret;
 
-	ret = ad7768_setup(st);
+	ret = ad7768_setup(indio_dev);
 	if (ret < 0) {
 		dev_err(&spi->dev, "AD7768 setup failed\n");
 		return ret;
-- 
2.34.1

[PATCH v9 08/12] iio: adc: ad7768-1: add multiple scan types to support 16-bits mode

[Jonathan Santos]

When the device is configured to decimation x8, only possible in the
sinc5 filter, output data is reduced to 16-bits in order to support
1 MHz of sampling frequency due to clock limitation.

Use multiple scan types feature to enable the driver to switch
scan type at runtime, making it possible to support both 24-bit and
16-bit resolution.

Reviewed-by: Marcelo Schmitt <marcelo.schmitt@analog.com>
Reviewed-by: David Lechner <dlechner@baylibre.com>
Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com>
---
v9 Changes:
* Addressed indentation issue.

v8 Changes:
* Fixed typo in David's Email.
* Removed TODO comment related to the spi_bpw_to_bytes() function.

v7 Changes:
* Added TODO comment to use spi_bpw_to_bytes() helper function.
* Minor commit description changes.

v6 Changes:
* None.

v5 Changes:
* None.

v4 Changes:
* None.

v3 Changes:
* Decreased storagebits to 16 for AD7768_SCAN_TYPE_HIGH_SPEED
  scan type.

v2 Changes:
* Included the ".shift" value back to scan_type.
* Changed the number of bytes from regmap_read instead of shifting the 
  ADC sample value when the word size is lower (16-bits).
---
 drivers/iio/adc/ad7768-1.c | 74 ++++++++++++++++++++++++++++++++------
 1 file changed, 64 insertions(+), 10 deletions(-)

diff --git a/drivers/iio/adc/ad7768-1.c b/drivers/iio/adc/ad7768-1.c
index d0366d570c14..6a409a46773c 100644
--- a/drivers/iio/adc/ad7768-1.c
+++ b/drivers/iio/adc/ad7768-1.c
@@ -140,6 +140,15 @@ struct ad7768_clk_configuration {
 	enum ad7768_pwrmode pwrmode;
 };
 
+enum ad7768_scan_type {
+	AD7768_SCAN_TYPE_NORMAL,
+	AD7768_SCAN_TYPE_HIGH_SPEED,
+};
+
+static const int ad7768_mclk_div_rates[] = {
+	16, 8, 4, 2,
+};
+
 static const struct ad7768_clk_configuration ad7768_clk_config[] = {
 	{ AD7768_MCLK_DIV_2, AD7768_DEC_RATE_8, 16,  AD7768_FAST_MODE },
 	{ AD7768_MCLK_DIV_2, AD7768_DEC_RATE_16, 32,  AD7768_FAST_MODE },
@@ -154,6 +163,22 @@ static const struct ad7768_clk_configuration ad7768_clk_config[] = {
 	{ AD7768_MCLK_DIV_16, AD7768_DEC_RATE_1024, 16384, AD7768_ECO_MODE },
 };
 
+static const struct iio_scan_type ad7768_scan_type[] = {
+	[AD7768_SCAN_TYPE_NORMAL] = {
+		.sign = 's',
+		.realbits = 24,
+		.storagebits = 32,
+		.shift = 8,
+		.endianness = IIO_BE,
+	},
+	[AD7768_SCAN_TYPE_HIGH_SPEED] = {
+		.sign = 's',
+		.realbits = 16,
+		.storagebits = 16,
+		.endianness = IIO_BE,
+	},
+};
+
 static const struct iio_chan_spec ad7768_channels[] = {
 	{
 		.type = IIO_VOLTAGE,
@@ -163,13 +188,9 @@ static const struct iio_chan_spec ad7768_channels[] = {
 		.indexed = 1,
 		.channel = 0,
 		.scan_index = 0,
-		.scan_type = {
-			.sign = 's',
-			.realbits = 24,
-			.storagebits = 32,
-			.shift = 8,
-			.endianness = IIO_BE,
-		},
+		.has_ext_scan_type = 1,
+		.ext_scan_type = ad7768_scan_type,
+		.num_ext_scan_type = ARRAY_SIZE(ad7768_scan_type),
 	},
 };
 
@@ -182,6 +203,7 @@ struct ad7768_state {
 	unsigned int vcm_output_sel;
 	struct clk *mclk;
 	unsigned int mclk_freq;
+	unsigned int dec_rate;
 	unsigned int samp_freq;
 	struct completion completion;
 	struct iio_trigger *trig;
@@ -301,6 +323,15 @@ static int ad7768_scan_direct(struct iio_dev *indio_dev)
 	if (ret)
 		return ret;
 
+	/*
+	 * When the decimation rate is set to x8, the ADC data precision is
+	 * reduced from 24 bits to 16 bits. Since the AD7768_REG_ADC_DATA
+	 * register provides 24-bit data, the precision is reduced by
+	 * right-shifting the read value by 8 bits.
+	 */
+	if (st->dec_rate == 8)
+		readval >>= 8;
+
 	/*
 	 * Any SPI configuration of the AD7768-1 can only be
 	 * performed in continuous conversion mode.
@@ -517,6 +548,8 @@ static int ad7768_set_freq(struct ad7768_state *st,
 	if (ret < 0)
 		return ret;
 
+	st->dec_rate = ad7768_clk_config[idx].clk_div /
+		       ad7768_mclk_div_rates[ad7768_clk_config[idx].mclk_div];
 	st->samp_freq = DIV_ROUND_CLOSEST(st->mclk_freq,
 					  ad7768_clk_config[idx].clk_div);
 
@@ -550,8 +583,13 @@ static int ad7768_read_raw(struct iio_dev *indio_dev,
 			   int *val, int *val2, long info)
 {
 	struct ad7768_state *st = iio_priv(indio_dev);
+	const struct iio_scan_type *scan_type;
 	int scale_uv, ret;
 
+	scan_type = iio_get_current_scan_type(indio_dev, chan);
+	if (IS_ERR(scan_type))
+		return PTR_ERR(scan_type);
+
 	switch (info) {
 	case IIO_CHAN_INFO_RAW:
 		if (!iio_device_claim_direct(indio_dev))
@@ -562,7 +600,7 @@ static int ad7768_read_raw(struct iio_dev *indio_dev,
 		iio_device_release_direct(indio_dev);
 		if (ret < 0)
 			return ret;
-		*val = sign_extend32(ret, chan->scan_type.realbits - 1);
+		*val = sign_extend32(ret, scan_type->realbits - 1);
 
 		return IIO_VAL_INT;
 
@@ -572,7 +610,7 @@ static int ad7768_read_raw(struct iio_dev *indio_dev,
 			return scale_uv;
 
 		*val = (scale_uv * 2) / 1000;
-		*val2 = chan->scan_type.realbits;
+		*val2 = scan_type->realbits;
 
 		return IIO_VAL_FRACTIONAL_LOG2;
 
@@ -616,11 +654,21 @@ static const struct attribute_group ad7768_group = {
 	.attrs = ad7768_attributes,
 };
 
+static int ad7768_get_current_scan_type(const struct iio_dev *indio_dev,
+					const struct iio_chan_spec *chan)
+{
+	struct ad7768_state *st = iio_priv(indio_dev);
+
+	return st->dec_rate == 8 ?
+	       AD7768_SCAN_TYPE_HIGH_SPEED : AD7768_SCAN_TYPE_NORMAL;
+}
+
 static const struct iio_info ad7768_info = {
 	.attrs = &ad7768_group,
 	.read_raw = &ad7768_read_raw,
 	.write_raw = &ad7768_write_raw,
 	.read_label = ad7768_read_label,
+	.get_current_scan_type = &ad7768_get_current_scan_type,
 	.debugfs_reg_access = &ad7768_reg_access,
 };
 
@@ -675,9 +723,15 @@ static irqreturn_t ad7768_trigger_handler(int irq, void *p)
 	struct iio_poll_func *pf = p;
 	struct iio_dev *indio_dev = pf->indio_dev;
 	struct ad7768_state *st = iio_priv(indio_dev);
+	const struct iio_scan_type *scan_type;
 	int ret;
 
-	ret = spi_read(st->spi, &st->data.scan.chan, 3);
+	scan_type = iio_get_current_scan_type(indio_dev, &indio_dev->channels[0]);
+	if (IS_ERR(scan_type))
+		goto out;
+
+	ret = spi_read(st->spi, &st->data.scan.chan,
+		       BITS_TO_BYTES(scan_type->realbits));
 	if (ret < 0)
 		goto out;
 
-- 
2.34.1

[PATCH v9 09/12] iio: adc: ad7768-1: add support for Synchronization over SPI

[Jonathan Santos]

The synchronization method using GPIO requires the generated pulse to be
truly synchronous with the base MCLK signal. When it is not possible to
do that in hardware, the datasheet recommends using synchronization over
SPI, where the generated pulse is already synchronous with MCLK. This
requires the SYNC_OUT pin to be connected to the SYNC_IN pin.

Use trigger-sources property to enable device synchronization over SPI
and multi-device synchronization while replacing sync-in-gpios property.

Reviewed-by: David Lechner <dlechner@baylibre.com>
Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com>
---
v9 Changes:
* Refactored ad7768_trigger_sources_get_sync() again to split the
  trigger-sources setup and to remove the labels/jumps.
* used new fwnode_find_reference_args() to get the trigger-sources
  property with proper cleanup, as recommended.

v8 Changes:
* Putted ad7768_trigger_source_get_gpio() code inline to fix the compatible
  issue.

v7 Changes:
* Added delay in the synchronization pulse via GPIO.
* replaced device_property_present() for fwnode_property_present().
* Refactored ad7768_trigger_sources_get_sync() to avoid excessive jumps.
* Self triggering is enabled only when the trigger-sources property is
  not defined. Added TODO to support other trigger sources when the subsystem
  is available.

v6 Changes:
* Created macro for the SYNC index from trigger-sources.
* Check trigger source by the compatible string (and the dev node for the
  self triggering).
* Check nargs before accessing the args array.
* Use `trigger-sources` as an alternative to `adi,sync-in-gpios`
  (now optional), instead of replacing it. 

v5 Changes:
* Allow omitting trigger-sources property.
* include gpio-trigger to trigger-sources to replace adi,sync-in-gpios
  property.
* Read trigger-sources cell value to differentiate the trigger type.

v4 Changes:
* None.

v3 Changes:
* Fixed args.fwnode leakage in the trigger-sources parsing.
* Synchronization over spi is enabled when the trigger-sources
  references the own device.
* Synchronization is kept within the device, and return error if the
  gpio is not defined and the trigger-sources reference does not match
  the current device. 

v2 Changes:
* Synchronization via SPI is enabled when the Sync GPIO is not defined.
* now trigger-sources property indicates the synchronization provider or
  main device. The main device will be used to drive the SYNC_IN when
  requested (via GPIO or SPI).
---
 drivers/iio/adc/ad7768-1.c | 102 ++++++++++++++++++++++++++++++++++---
 1 file changed, 96 insertions(+), 6 deletions(-)

diff --git a/drivers/iio/adc/ad7768-1.c b/drivers/iio/adc/ad7768-1.c
index 6a409a46773c..01da1c2a138c 100644
--- a/drivers/iio/adc/ad7768-1.c
+++ b/drivers/iio/adc/ad7768-1.c
@@ -29,6 +29,8 @@
 #include <linux/iio/triggered_buffer.h>
 #include <linux/iio/trigger_consumer.h>
 
+#include <dt-bindings/iio/adc/adi,ad7768-1.h>
+
 /* AD7768 registers definition */
 #define AD7768_REG_CHIP_TYPE		0x3
 #define AD7768_REG_PROD_ID_L		0x4
@@ -101,6 +103,8 @@
 
 #define AD7768_VCM_OFF			0x07
 
+#define AD7768_TRIGGER_SOURCE_SYNC_IDX 0
+
 enum ad7768_conv_mode {
 	AD7768_CONTINUOUS,
 	AD7768_ONE_SHOT,
@@ -209,6 +213,7 @@ struct ad7768_state {
 	struct iio_trigger *trig;
 	struct gpio_desc *gpio_sync_in;
 	struct gpio_desc *gpio_reset;
+	bool en_spi_sync;
 	const char *labels[ARRAY_SIZE(ad7768_channels)];
 	struct gpio_chip gpiochip;
 	/*
@@ -296,6 +301,27 @@ static const struct regmap_config ad7768_regmap24_config = {
 	.max_register = AD7768_REG24_COEFF_DATA,
 };
 
+static int ad7768_send_sync_pulse(struct ad7768_state *st)
+{
+	if (st->en_spi_sync)
+		return regmap_write(st->regmap, AD7768_REG_SYNC_RESET, 0x00);
+
+	/*
+	 * The datasheet specifies a minimum SYNC_IN pulse width of 1.5 × Tmclk,
+	 * where Tmclk is the MCLK period. The supported MCLK frequencies range
+	 * from 0.6 MHz to 17 MHz, which corresponds to a minimum SYNC_IN pulse
+	 * width of approximately 2.5 µs in the worst-case scenario (0.6 MHz).
+	 *
+	 * Add a delay to ensure the pulse width is always sufficient to
+	 * trigger synchronization.
+	 */
+	gpiod_set_value_cansleep(st->gpio_sync_in, 1);
+	fsleep(3);
+	gpiod_set_value_cansleep(st->gpio_sync_in, 0);
+
+	return 0;
+}
+
 static int ad7768_set_mode(struct ad7768_state *st,
 			   enum ad7768_conv_mode mode)
 {
@@ -392,10 +418,7 @@ static int ad7768_set_dig_fil(struct ad7768_state *st,
 		return ret;
 
 	/* A sync-in pulse is required every time the filter dec rate changes */
-	gpiod_set_value(st->gpio_sync_in, 1);
-	gpiod_set_value(st->gpio_sync_in, 0);
-
-	return 0;
+	return ad7768_send_sync_pulse(st);
 }
 
 static int ad7768_gpio_direction_input(struct gpio_chip *chip, unsigned int offset)
@@ -672,6 +695,62 @@ static const struct iio_info ad7768_info = {
 	.debugfs_reg_access = &ad7768_reg_access,
 };
 
+static int ad7768_trigger_sources_sync_setup(struct device *dev,
+					     struct fwnode_handle *dev_fwnode,
+					     struct ad7768_state *st)
+{
+	struct fwnode_reference_args args;
+
+	struct fwnode_handle *fwnode __free(fwnode_handle) =
+		fwnode_find_reference_args(dev_fwnode, "trigger-sources",
+					   "#trigger-source-cells", 0,
+					   AD7768_TRIGGER_SOURCE_SYNC_IDX, &args);
+	if (IS_ERR(fwnode))
+		return PTR_ERR(fwnode);
+
+	/* First, try getting the GPIO trigger source */
+	if (fwnode_device_is_compatible(fwnode, "gpio-trigger")) {
+		st->gpio_sync_in = devm_fwnode_gpiod_get_index(dev, fwnode,
+							       NULL,
+							       0,
+							       GPIOD_OUT_LOW,
+							       "sync-in");
+		return PTR_ERR_OR_ZERO(st->gpio_sync_in);
+	}
+
+	/*
+	 * TODO: Support the other cases when we have a trigger subsystem
+	 * to reliably handle other types of devices as trigger sources.
+	 *
+	 * For now, return an error message. For self triggering, omit the
+	 * trigger-sources property.
+	 */
+	return dev_err_probe(dev, -EOPNOTSUPP, "Invalid synchronization trigger source\n");
+}
+
+static int ad7768_trigger_sources_get_sync(struct device *dev,
+					   struct ad7768_state *st)
+{
+	struct fwnode_handle *dev_fwnode = dev_fwnode(dev);
+
+	/*
+	 * The AD7768-1 allows two primary methods for driving the SYNC_IN pin
+	 * to synchronize one or more devices:
+	 * 1. Using an external GPIO.
+	 * 2. Using a SPI command, where the SYNC_OUT pin generates a
+	 *    synchronization pulse that drives the SYNC_IN pin.
+	 */
+	if (fwnode_property_present(dev_fwnode, "trigger-sources"))
+		return ad7768_trigger_sources_sync_setup(dev, dev_fwnode, st);
+
+	/*
+	 * In the absence of trigger-sources property, enable self
+	 * synchronization over SPI (SYNC_OUT).
+	 */
+	st->en_spi_sync = true;
+	return 0;
+}
+
 static int ad7768_setup(struct iio_dev *indio_dev)
 {
 	struct ad7768_state *st = iio_priv(indio_dev);
@@ -702,11 +781,22 @@ static int ad7768_setup(struct iio_dev *indio_dev)
 			return ret;
 	}
 
-	st->gpio_sync_in = devm_gpiod_get(&st->spi->dev, "adi,sync-in",
-					  GPIOD_OUT_LOW);
+	/* For backwards compatibility, try the adi,sync-in-gpios property */
+	st->gpio_sync_in = devm_gpiod_get_optional(&st->spi->dev, "adi,sync-in",
+						   GPIOD_OUT_LOW);
 	if (IS_ERR(st->gpio_sync_in))
 		return PTR_ERR(st->gpio_sync_in);
 
+	/*
+	 * If the synchronization is not defined by adi,sync-in-gpios, try the
+	 * trigger-sources.
+	 */
+	if (!st->gpio_sync_in) {
+		ret = ad7768_trigger_sources_get_sync(&st->spi->dev, st);
+		if (ret)
+			return ret;
+	}
+
 	/* Only create a Chip GPIO if flagged for it */
 	if (device_property_read_bool(&st->spi->dev, "gpio-controller")) {
 		ret = ad7768_gpio_init(indio_dev);
-- 
2.34.1

[PATCH v9 10/12] iio: adc: ad7768-1: replace manual attribute declaration

[Jonathan Santos]

Use read_avail callback from struct iio_info to replace the manual
declaration of sampling_frequency_available attribute.

Reviewed-by: David Lechner <dlechner@baylibre.com>
Reviewed-by: Marcelo Schmitt <marcelo.schmitt@analog.com>
Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com>
---
v9 Changes:
* None.

v8 Changes:
* Addressed formatting issue.

v7 Changes:
* Iteractor changed to unsigned in the ad7768_fill_samp_freq_tbl()
  function.

v6 Changes:
* none.

v5 Changes:
* none.

v4 Changes:
* Added ad7768_fill_samp_freq_tbl() helper function.
* Sampling frequency table is precomputed at probe.

v3 Changes:
* New patch in v3.
---
 drivers/iio/adc/ad7768-1.c | 63 +++++++++++++++++++-------------------
 1 file changed, 31 insertions(+), 32 deletions(-)

diff --git a/drivers/iio/adc/ad7768-1.c b/drivers/iio/adc/ad7768-1.c
index 01da1c2a138c..4c8152624c33 100644
--- a/drivers/iio/adc/ad7768-1.c
+++ b/drivers/iio/adc/ad7768-1.c
@@ -189,6 +189,7 @@ static const struct iio_chan_spec ad7768_channels[] = {
 		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
 		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
 		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ),
+		.info_mask_shared_by_all_available = BIT(IIO_CHAN_INFO_SAMP_FREQ),
 		.indexed = 1,
 		.channel = 0,
 		.scan_index = 0,
@@ -209,6 +210,7 @@ struct ad7768_state {
 	unsigned int mclk_freq;
 	unsigned int dec_rate;
 	unsigned int samp_freq;
+	unsigned int samp_freq_avail[ARRAY_SIZE(ad7768_clk_config)];
 	struct completion completion;
 	struct iio_trigger *trig;
 	struct gpio_desc *gpio_sync_in;
@@ -322,6 +324,15 @@ static int ad7768_send_sync_pulse(struct ad7768_state *st)
 	return 0;
 }
 
+static void ad7768_fill_samp_freq_tbl(struct ad7768_state *st)
+{
+	unsigned int i;
+
+	for (i = 0; i < ARRAY_SIZE(ad7768_clk_config); i++)
+		st->samp_freq_avail[i] =
+			DIV_ROUND_CLOSEST(st->mclk_freq, ad7768_clk_config[i].clk_div);
+}
+
 static int ad7768_set_mode(struct ad7768_state *st,
 			   enum ad7768_conv_mode mode)
 {
@@ -579,28 +590,6 @@ static int ad7768_set_freq(struct ad7768_state *st,
 	return 0;
 }
 
-static ssize_t ad7768_sampling_freq_avail(struct device *dev,
-					  struct device_attribute *attr,
-					  char *buf)
-{
-	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
-	struct ad7768_state *st = iio_priv(indio_dev);
-	unsigned int freq;
-	int i, len = 0;
-
-	for (i = 0; i < ARRAY_SIZE(ad7768_clk_config); i++) {
-		freq = DIV_ROUND_CLOSEST(st->mclk_freq,
-					 ad7768_clk_config[i].clk_div);
-		len += scnprintf(buf + len, PAGE_SIZE - len, "%d ", freq);
-	}
-
-	buf[len - 1] = '\n';
-
-	return len;
-}
-
-static IIO_DEV_ATTR_SAMP_FREQ_AVAIL(ad7768_sampling_freq_avail);
-
 static int ad7768_read_raw(struct iio_dev *indio_dev,
 			   struct iio_chan_spec const *chan,
 			   int *val, int *val2, long info)
@@ -646,6 +635,24 @@ static int ad7768_read_raw(struct iio_dev *indio_dev,
 	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);
+
+	switch (info) {
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		*vals = (int *)st->samp_freq_avail;
+		*length = ARRAY_SIZE(ad7768_clk_config);
+		*type = IIO_VAL_INT;
+		return IIO_AVAIL_LIST;
+	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)
@@ -668,15 +675,6 @@ static int ad7768_read_label(struct iio_dev *indio_dev,
 	return sprintf(label, "%s\n", st->labels[chan->channel]);
 }
 
-static struct attribute *ad7768_attributes[] = {
-	&iio_dev_attr_sampling_frequency_available.dev_attr.attr,
-	NULL
-};
-
-static const struct attribute_group ad7768_group = {
-	.attrs = ad7768_attributes,
-};
-
 static int ad7768_get_current_scan_type(const struct iio_dev *indio_dev,
 					const struct iio_chan_spec *chan)
 {
@@ -687,8 +685,8 @@ static int ad7768_get_current_scan_type(const struct iio_dev *indio_dev,
 }
 
 static const struct iio_info ad7768_info = {
-	.attrs = &ad7768_group,
 	.read_raw = &ad7768_read_raw,
+	.read_avail = &ad7768_read_avail,
 	.write_raw = &ad7768_write_raw,
 	.read_label = ad7768_read_label,
 	.get_current_scan_type = &ad7768_get_current_scan_type,
@@ -1137,6 +1135,7 @@ static int ad7768_probe(struct spi_device *spi)
 		return PTR_ERR(st->mclk);
 
 	st->mclk_freq = clk_get_rate(st->mclk);
+	ad7768_fill_samp_freq_tbl(st);
 
 	indio_dev->channels = ad7768_channels;
 	indio_dev->num_channels = ARRAY_SIZE(ad7768_channels);
-- 
2.34.1

[PATCH v9 11/12] iio: adc: ad7768-1: add filter type and oversampling ratio attributes

[Jonathan Santos]

Separate filter type and decimation rate from the sampling frequency
attribute. The new filter type attribute enables sinc3, sinc3+rej60
and wideband filters, which were previously unavailable.

Previously, combining decimation and MCLK divider in the sampling
frequency obscured performance trade-offs. Lower MCLK divider
settings increase power usage, while lower decimation rates reduce
precision by decreasing averaging. By creating an oversampling
attribute, which controls the decimation, users gain finer control
over performance.

The addition of those attributes allows a wider range of sampling
frequencies and more access to the device features. Sampling frequency
table is updated after every digital filter parameter change.

Changes in the sampling frequency are not allowed anymore while in
buffered mode.

Reviewed-by: David Lechner <dlechner@baylibre.com>
Co-developed-by: Pop Paul <paul.pop@analog.com>
Signed-off-by: Pop Paul <paul.pop@analog.com>
Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com>
---
v9 Changes:
* Addressed some nits.
* Fixed oversampling_ratio_available attribute. Now we mix range 
  (for sinc3) with list (for sinc5 and wideband).

v8 Changes:
* Addressed formatting issue.
* used find_closest_descending() implementation to find the closest mclk
  divider.
* Reorganized ad7768_fill_samp_freq_tbl() function to improve the
  samp_freq_avail assignment. 

v7 Changes:
* Refactor code to avoid forward declarations.
* replaced clamp_t() for clamp();
* Mentioned that sampling frequency changes is not allowed in
  buffered mode.
* removed 60Hz rejection enable from the filter mask and create
  AD7768_DIG_FIL_EN_60HZ_REJ for it.
* addressed other nits.

v6 Changes:
* Made sinc3 decimation rate calculation clearer as requested.
* Renamed some filter functions to clarify the purpose.
* Other nits.

v5 Changes:
* Addressed some nits.
* Use the new new iio_device_claim/release_direct() functions.

v4 Changes:
* Sampling frequency table is dynamically updated after every
  filter configuration.

v3 Changes:
* removed unused variables.
* included sinc3+rej60 filter type.
* oversampling_ratio moved to info_mask_shared_by_type.
* reordered functions to avoid forward declaration.
* simplified regmap writes.
* Removed locking.
* replaced some helper functions for direct regmap_update_bits
  calls.
* Addressed other nits.

v2 Changes:
* Decimation_rate attribute replaced for oversampling_ratio.
---
 drivers/iio/adc/ad7768-1.c | 414 ++++++++++++++++++++++++++++---------
 1 file changed, 319 insertions(+), 95 deletions(-)

diff --git a/drivers/iio/adc/ad7768-1.c b/drivers/iio/adc/ad7768-1.c
index 4c8152624c33..c86afb0fc4c1 100644
--- a/drivers/iio/adc/ad7768-1.c
+++ b/drivers/iio/adc/ad7768-1.c
@@ -21,6 +21,8 @@
 #include <linux/regulator/driver.h>
 #include <linux/sysfs.h>
 #include <linux/spi/spi.h>
+#include <linux/unaligned.h>
+#include <linux/util_macros.h>
 
 #include <linux/iio/buffer.h>
 #include <linux/iio/iio.h>
@@ -78,6 +80,7 @@
 #define AD7768_PWR_PWRMODE(x)		FIELD_PREP(AD7768_PWR_PWRMODE_MSK, x)
 
 /* AD7768_REG_DIGITAL_FILTER */
+#define AD7768_DIG_FIL_EN_60HZ_REJ	BIT(7)
 #define AD7768_DIG_FIL_FIL_MSK		GENMASK(6, 4)
 #define AD7768_DIG_FIL_FIL(x)		FIELD_PREP(AD7768_DIG_FIL_FIL_MSK, x)
 #define AD7768_DIG_FIL_DEC_MSK		GENMASK(2, 0)
@@ -105,6 +108,8 @@
 
 #define AD7768_TRIGGER_SOURCE_SYNC_IDX 0
 
+#define AD7768_MAX_CHANNELS 1
+
 enum ad7768_conv_mode {
 	AD7768_CONTINUOUS,
 	AD7768_ONE_SHOT,
@@ -126,22 +131,20 @@ enum ad7768_mclk_div {
 	AD7768_MCLK_DIV_2
 };
 
-enum ad7768_dec_rate {
-	AD7768_DEC_RATE_32 = 0,
-	AD7768_DEC_RATE_64 = 1,
-	AD7768_DEC_RATE_128 = 2,
-	AD7768_DEC_RATE_256 = 3,
-	AD7768_DEC_RATE_512 = 4,
-	AD7768_DEC_RATE_1024 = 5,
-	AD7768_DEC_RATE_8 = 9,
-	AD7768_DEC_RATE_16 = 10
+enum ad7768_filter_type {
+	AD7768_FILTER_SINC5,
+	AD7768_FILTER_SINC3,
+	AD7768_FILTER_WIDEBAND,
+	AD7768_FILTER_SINC3_REJ60,
 };
 
-struct ad7768_clk_configuration {
-	enum ad7768_mclk_div mclk_div;
-	enum ad7768_dec_rate dec_rate;
-	unsigned int clk_div;
-	enum ad7768_pwrmode pwrmode;
+enum ad7768_filter_regval {
+	AD7768_FILTER_REGVAL_SINC5 = 0,
+	AD7768_FILTER_REGVAL_SINC5_X8 = 1,
+	AD7768_FILTER_REGVAL_SINC5_X16 = 2,
+	AD7768_FILTER_REGVAL_SINC3 = 3,
+	AD7768_FILTER_REGVAL_WIDEBAND = 4,
+	AD7768_FILTER_REGVAL_SINC3_REJ60 = 11,
 };
 
 enum ad7768_scan_type {
@@ -153,18 +156,36 @@ static const int ad7768_mclk_div_rates[] = {
 	16, 8, 4, 2,
 };
 
-static const struct ad7768_clk_configuration ad7768_clk_config[] = {
-	{ AD7768_MCLK_DIV_2, AD7768_DEC_RATE_8, 16,  AD7768_FAST_MODE },
-	{ AD7768_MCLK_DIV_2, AD7768_DEC_RATE_16, 32,  AD7768_FAST_MODE },
-	{ AD7768_MCLK_DIV_2, AD7768_DEC_RATE_32, 64, AD7768_FAST_MODE },
-	{ AD7768_MCLK_DIV_2, AD7768_DEC_RATE_64, 128, AD7768_FAST_MODE },
-	{ AD7768_MCLK_DIV_2, AD7768_DEC_RATE_128, 256, AD7768_FAST_MODE },
-	{ AD7768_MCLK_DIV_4, AD7768_DEC_RATE_128, 512, AD7768_MED_MODE },
-	{ AD7768_MCLK_DIV_4, AD7768_DEC_RATE_256, 1024, AD7768_MED_MODE },
-	{ AD7768_MCLK_DIV_4, AD7768_DEC_RATE_512, 2048, AD7768_MED_MODE },
-	{ AD7768_MCLK_DIV_4, AD7768_DEC_RATE_1024, 4096, AD7768_MED_MODE },
-	{ AD7768_MCLK_DIV_8, AD7768_DEC_RATE_1024, 8192, AD7768_MED_MODE },
-	{ AD7768_MCLK_DIV_16, AD7768_DEC_RATE_1024, 16384, AD7768_ECO_MODE },
+static const int ad7768_dec_rate_values[8] = {
+	8, 16, 32, 64, 128, 256, 512, 1024,
+};
+
+/* Decimation rate range for sinc3 filter */
+static const int ad7768_sinc3_dec_rate_range[3] = {
+	32, 32, 163840
+};
+
+/*
+ * The AD7768-1 supports three primary filter types:
+ * Sinc5, Sinc3, and Wideband.
+ * However, the filter register values can also encode additional parameters
+ * such as decimation rates and 60Hz rejection. This utility array separates
+ * the filter type from these parameters.
+ */
+static const int ad7768_filter_regval_to_type[] = {
+	[AD7768_FILTER_REGVAL_SINC5] = AD7768_FILTER_SINC5,
+	[AD7768_FILTER_REGVAL_SINC5_X8] = AD7768_FILTER_SINC5,
+	[AD7768_FILTER_REGVAL_SINC5_X16] = AD7768_FILTER_SINC5,
+	[AD7768_FILTER_REGVAL_SINC3] = AD7768_FILTER_SINC3,
+	[AD7768_FILTER_REGVAL_WIDEBAND] = AD7768_FILTER_WIDEBAND,
+	[AD7768_FILTER_REGVAL_SINC3_REJ60] = AD7768_FILTER_SINC3_REJ60,
+};
+
+static const char * const ad7768_filter_enum[] = {
+	[AD7768_FILTER_SINC5] = "sinc5",
+	[AD7768_FILTER_SINC3] = "sinc3",
+	[AD7768_FILTER_WIDEBAND] = "wideband",
+	[AD7768_FILTER_SINC3_REJ60] = "sinc3+rej60"
 };
 
 static const struct iio_scan_type ad7768_scan_type[] = {
@@ -183,22 +204,6 @@ static const struct iio_scan_type ad7768_scan_type[] = {
 	},
 };
 
-static const struct iio_chan_spec ad7768_channels[] = {
-	{
-		.type = IIO_VOLTAGE,
-		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
-		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
-		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ),
-		.info_mask_shared_by_all_available = BIT(IIO_CHAN_INFO_SAMP_FREQ),
-		.indexed = 1,
-		.channel = 0,
-		.scan_index = 0,
-		.has_ext_scan_type = 1,
-		.ext_scan_type = ad7768_scan_type,
-		.num_ext_scan_type = ARRAY_SIZE(ad7768_scan_type),
-	},
-};
-
 struct ad7768_state {
 	struct spi_device *spi;
 	struct regmap *regmap;
@@ -208,15 +213,18 @@ struct ad7768_state {
 	unsigned int vcm_output_sel;
 	struct clk *mclk;
 	unsigned int mclk_freq;
-	unsigned int dec_rate;
+	unsigned int mclk_div;
+	unsigned int oversampling_ratio;
+	enum ad7768_filter_type filter_type;
 	unsigned int samp_freq;
-	unsigned int samp_freq_avail[ARRAY_SIZE(ad7768_clk_config)];
+	unsigned int samp_freq_avail[ARRAY_SIZE(ad7768_mclk_div_rates)];
+	unsigned int samp_freq_avail_len;
 	struct completion completion;
 	struct iio_trigger *trig;
 	struct gpio_desc *gpio_sync_in;
 	struct gpio_desc *gpio_reset;
 	bool en_spi_sync;
-	const char *labels[ARRAY_SIZE(ad7768_channels)];
+	const char *labels[AD7768_MAX_CHANNELS];
 	struct gpio_chip gpiochip;
 	/*
 	 * DMA (thus cache coherency maintenance) may require the
@@ -326,11 +334,38 @@ static int ad7768_send_sync_pulse(struct ad7768_state *st)
 
 static void ad7768_fill_samp_freq_tbl(struct ad7768_state *st)
 {
-	unsigned int i;
+	unsigned int i, samp_freq_avail, freq_filtered;
+	unsigned int len = 0;
+
+	freq_filtered = DIV_ROUND_CLOSEST(st->mclk_freq, st->oversampling_ratio);
+	for (i = 0; i < ARRAY_SIZE(ad7768_mclk_div_rates); i++) {
+		samp_freq_avail = DIV_ROUND_CLOSEST(freq_filtered, ad7768_mclk_div_rates[i]);
+		/* Sampling frequency cannot be lower than the minimum of 50 SPS */
+		if (samp_freq_avail < 50)
+			continue;
 
-	for (i = 0; i < ARRAY_SIZE(ad7768_clk_config); i++)
-		st->samp_freq_avail[i] =
-			DIV_ROUND_CLOSEST(st->mclk_freq, ad7768_clk_config[i].clk_div);
+		st->samp_freq_avail[len++] = samp_freq_avail;
+	}
+
+	st->samp_freq_avail_len = len;
+}
+
+static int ad7768_set_mclk_div(struct ad7768_state *st, unsigned int mclk_div)
+{
+	unsigned int mclk_div_value;
+
+	mclk_div_value = AD7768_PWR_MCLK_DIV(mclk_div);
+	/*
+	 * Set power mode based on mclk_div value.
+	 * ECO_MODE is only recommended for MCLK_DIV 16
+	 */
+	mclk_div_value |= mclk_div > AD7768_MCLK_DIV_16 ?
+			  AD7768_PWR_PWRMODE(AD7768_FAST_MODE) :
+			  AD7768_PWR_PWRMODE(AD7768_ECO_MODE);
+
+	return regmap_update_bits(st->regmap, AD7768_REG_POWER_CLOCK,
+				  AD7768_PWR_MCLK_DIV_MSK | AD7768_PWR_PWRMODE_MSK,
+				  mclk_div_value);
 }
 
 static int ad7768_set_mode(struct ad7768_state *st,
@@ -366,7 +401,7 @@ static int ad7768_scan_direct(struct iio_dev *indio_dev)
 	 * register provides 24-bit data, the precision is reduced by
 	 * right-shifting the read value by 8 bits.
 	 */
-	if (st->dec_rate == 8)
+	if (st->oversampling_ratio == 8)
 		readval >>= 8;
 
 	/*
@@ -413,22 +448,110 @@ static int ad7768_reg_access(struct iio_dev *indio_dev,
 	return ret;
 }
 
-static int ad7768_set_dig_fil(struct ad7768_state *st,
-			      enum ad7768_dec_rate dec_rate)
+static int ad7768_set_sinc3_dec_rate(struct ad7768_state *st,
+				     unsigned int dec_rate)
 {
-	unsigned int mode;
+	unsigned int max_dec_rate;
+	u8 dec_rate_reg[2];
+	u16 regval;
 	int ret;
 
-	if (dec_rate == AD7768_DEC_RATE_8 || dec_rate == AD7768_DEC_RATE_16)
-		mode = AD7768_DIG_FIL_FIL(dec_rate);
-	else
-		mode = AD7768_DIG_FIL_DEC_RATE(dec_rate);
+	/*
+	 * Maximum dec_rate is limited by the MCLK_DIV value and by the ODR.
+	 * The edge case is for MCLK_DIV = 2, ODR = 50 SPS.
+	 * max_dec_rate <= MCLK / (2 * 50)
+	 */
+	max_dec_rate = st->mclk_freq / 100;
+	dec_rate = clamp(dec_rate, 32, max_dec_rate);
+	/*
+	 * Calculate the equivalent value to sinc3 decimation ratio
+	 * to be written on the SINC3_DEC_RATE register:
+	 *  Value = (DEC_RATE / 32) - 1
+	 */
+	dec_rate = DIV_ROUND_UP(dec_rate, 32) - 1;
 
-	ret = regmap_write(st->regmap, AD7768_REG_DIGITAL_FILTER, mode);
-	if (ret < 0)
+	/*
+	 * The SINC3_DEC_RATE value is a 13-bit value split across two
+	 * registers: MSB [12:8] and LSB [7:0]. Prepare the 13-bit value using
+	 * FIELD_PREP and store it with the right endianness in dec_rate_reg.
+	 */
+	regval = FIELD_PREP(GENMASK(12, 0), dec_rate);
+	put_unaligned_be16(regval, dec_rate_reg);
+	ret = regmap_bulk_write(st->regmap, AD7768_REG_SINC3_DEC_RATE_MSB,
+				dec_rate_reg, 2);
+	if (ret)
+		return ret;
+
+	st->oversampling_ratio = (dec_rate + 1) * 32;
+
+	return 0;
+}
+
+static int ad7768_configure_dig_fil(struct iio_dev *dev,
+				    enum ad7768_filter_type filter_type,
+				    unsigned int dec_rate)
+{
+	struct ad7768_state *st = iio_priv(dev);
+	unsigned int dec_rate_idx, dig_filter_regval;
+	int ret;
+
+	switch (filter_type) {
+	case AD7768_FILTER_SINC3:
+		dig_filter_regval = AD7768_DIG_FIL_FIL(AD7768_FILTER_REGVAL_SINC3);
+		break;
+	case AD7768_FILTER_SINC3_REJ60:
+		dig_filter_regval = AD7768_DIG_FIL_FIL(AD7768_FILTER_REGVAL_SINC3) |
+				    AD7768_DIG_FIL_EN_60HZ_REJ;
+		break;
+	case AD7768_FILTER_WIDEBAND:
+		/* Skip decimations 8 and 16, not supported by the wideband filter */
+		dec_rate_idx = find_closest(dec_rate, &ad7768_dec_rate_values[2],
+					    ARRAY_SIZE(ad7768_dec_rate_values) - 2);
+		dig_filter_regval = AD7768_DIG_FIL_FIL(AD7768_FILTER_REGVAL_WIDEBAND) |
+				    AD7768_DIG_FIL_DEC_RATE(dec_rate_idx);
+		/* Correct the index offset */
+		dec_rate_idx += 2;
+		break;
+	case AD7768_FILTER_SINC5:
+		dec_rate_idx = find_closest(dec_rate, ad7768_dec_rate_values,
+					    ARRAY_SIZE(ad7768_dec_rate_values));
+
+		/*
+		 * Decimations 8 (idx 0) and 16 (idx 1) are set in the
+		 * FILTER[6:4] field. The other decimations are set in the
+		 * DEC_RATE[2:0] field, and the idx needs to be offsetted by two.
+		 */
+		if (dec_rate_idx == 0)
+			dig_filter_regval = AD7768_DIG_FIL_FIL(AD7768_FILTER_REGVAL_SINC5_X8);
+		else if (dec_rate_idx == 1)
+			dig_filter_regval = AD7768_DIG_FIL_FIL(AD7768_FILTER_REGVAL_SINC5_X16);
+		else
+			dig_filter_regval = AD7768_DIG_FIL_FIL(AD7768_FILTER_REGVAL_SINC5) |
+					    AD7768_DIG_FIL_DEC_RATE(dec_rate_idx - 2);
+		break;
+	}
+
+	ret = regmap_write(st->regmap, AD7768_REG_DIGITAL_FILTER, dig_filter_regval);
+	if (ret)
 		return ret;
 
-	/* A sync-in pulse is required every time the filter dec rate changes */
+	st->filter_type = filter_type;
+	/*
+	 * The decimation for SINC3 filters are configured in different
+	 * registers.
+	 */
+	if (filter_type == AD7768_FILTER_SINC3 ||
+	    filter_type == AD7768_FILTER_SINC3_REJ60) {
+		ret = ad7768_set_sinc3_dec_rate(st, dec_rate);
+		if (ret)
+			return ret;
+	} else {
+		st->oversampling_ratio = ad7768_dec_rate_values[dec_rate_idx];
+	}
+
+	ad7768_fill_samp_freq_tbl(st);
+
+	/* A sync-in pulse is required after every configuration change */
 	return ad7768_send_sync_pulse(st);
 }
 
@@ -551,45 +674,92 @@ static int ad7768_gpio_init(struct iio_dev *indio_dev)
 static int ad7768_set_freq(struct ad7768_state *st,
 			   unsigned int freq)
 {
-	unsigned int diff_new, diff_old, pwr_mode, i, idx;
-	int res, ret;
-
-	diff_old = U32_MAX;
-	idx = 0;
+	unsigned int idx, mclk_div;
+	int ret;
 
-	res = DIV_ROUND_CLOSEST(st->mclk_freq, freq);
+	freq = clamp(freq, 50, 1024000);
+	if (freq == 0)
+		return -EINVAL;
 
+	mclk_div = DIV_ROUND_CLOSEST(st->mclk_freq, freq * st->oversampling_ratio);
 	/* Find the closest match for the desired sampling frequency */
-	for (i = 0; i < ARRAY_SIZE(ad7768_clk_config); i++) {
-		diff_new = abs(res - ad7768_clk_config[i].clk_div);
-		if (diff_new < diff_old) {
-			diff_old = diff_new;
-			idx = i;
-		}
-	}
-
-	/*
-	 * Set both the mclk_div and pwrmode with a single write to the
-	 * POWER_CLOCK register
-	 */
-	pwr_mode = AD7768_PWR_MCLK_DIV(ad7768_clk_config[idx].mclk_div) |
-		   AD7768_PWR_PWRMODE(ad7768_clk_config[idx].pwrmode);
-	ret = regmap_write(st->regmap, AD7768_REG_POWER_CLOCK, pwr_mode);
-	if (ret < 0)
+	idx = find_closest_descending(mclk_div, ad7768_mclk_div_rates,
+				      ARRAY_SIZE(ad7768_mclk_div_rates));
+	/* Set both the mclk_div and pwrmode */
+	ret = ad7768_set_mclk_div(st, idx);
+	if (ret)
 		return ret;
 
-	ret =  ad7768_set_dig_fil(st, ad7768_clk_config[idx].dec_rate);
-	if (ret < 0)
+	st->samp_freq = DIV_ROUND_CLOSEST(st->mclk_freq,
+					  ad7768_mclk_div_rates[idx] * st->oversampling_ratio);
+
+	/* A sync-in pulse is required after every configuration change */
+	return ad7768_send_sync_pulse(st);
+}
+
+static int ad7768_set_filter_type_attr(struct iio_dev *dev,
+				       const struct iio_chan_spec *chan,
+				       unsigned int filter)
+{
+	struct ad7768_state *st = iio_priv(dev);
+	int ret;
+
+	ret = ad7768_configure_dig_fil(dev, filter, st->oversampling_ratio);
+	if (ret)
 		return ret;
 
-	st->dec_rate = ad7768_clk_config[idx].clk_div /
-		       ad7768_mclk_div_rates[ad7768_clk_config[idx].mclk_div];
-	st->samp_freq = DIV_ROUND_CLOSEST(st->mclk_freq,
-					  ad7768_clk_config[idx].clk_div);
+	/* Update sampling frequency */
+	return ad7768_set_freq(st, st->samp_freq);
+}
 
-	return 0;
+static int ad7768_get_filter_type_attr(struct iio_dev *dev,
+				       const struct iio_chan_spec *chan)
+{
+	struct ad7768_state *st = iio_priv(dev);
+	int ret;
+	unsigned int mode, mask;
+
+	ret = regmap_read(st->regmap, AD7768_REG_DIGITAL_FILTER, &mode);
+	if (ret)
+		return ret;
+
+	mask = AD7768_DIG_FIL_EN_60HZ_REJ | AD7768_DIG_FIL_FIL_MSK;
+	/* From the register value, get the corresponding filter type */
+	return ad7768_filter_regval_to_type[FIELD_GET(mask, mode)];
 }
 
+static const struct iio_enum ad7768_filter_type_iio_enum = {
+	.items = ad7768_filter_enum,
+	.num_items = ARRAY_SIZE(ad7768_filter_enum),
+	.set = ad7768_set_filter_type_attr,
+	.get = ad7768_get_filter_type_attr,
+};
+
+static const struct iio_chan_spec_ext_info ad7768_ext_info[] = {
+	IIO_ENUM("filter_type", IIO_SHARED_BY_ALL, &ad7768_filter_type_iio_enum),
+	IIO_ENUM_AVAILABLE("filter_type", IIO_SHARED_BY_ALL, &ad7768_filter_type_iio_enum),
+	{ }
+};
+
+static const struct iio_chan_spec ad7768_channels[] = {
+	{
+		.type = IIO_VOLTAGE,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) |
+					    BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
+		.info_mask_shared_by_type_available = BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
+		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ),
+		.info_mask_shared_by_all_available = BIT(IIO_CHAN_INFO_SAMP_FREQ),
+		.ext_info = ad7768_ext_info,
+		.indexed = 1,
+		.channel = 0,
+		.scan_index = 0,
+		.has_ext_scan_type = 1,
+		.ext_scan_type = ad7768_scan_type,
+		.num_ext_scan_type = ARRAY_SIZE(ad7768_scan_type),
+	},
+};
+
 static int ad7768_read_raw(struct iio_dev *indio_dev,
 			   struct iio_chan_spec const *chan,
 			   int *val, int *val2, long info)
@@ -629,6 +799,11 @@ static int ad7768_read_raw(struct iio_dev *indio_dev,
 	case IIO_CHAN_INFO_SAMP_FREQ:
 		*val = st->samp_freq;
 
+		return IIO_VAL_INT;
+
+	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
+		*val = st->oversampling_ratio;
+
 		return IIO_VAL_INT;
 	}
 
@@ -641,11 +816,29 @@ static int ad7768_read_avail(struct iio_dev *indio_dev,
 			     long info)
 {
 	struct ad7768_state *st = iio_priv(indio_dev);
+	unsigned int shift;
 
 	switch (info) {
+	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
+		/*
+		 * Sinc3 filter allows a wider range of OSR values, so show
+		 * the available values in range format.
+		 */
+		if (st->filter_type == AD7768_FILTER_SINC3 ||
+		    st->filter_type == AD7768_FILTER_SINC3_REJ60) {
+			*vals = (int *)ad7768_sinc3_dec_rate_range;
+			*type = IIO_VAL_INT;
+			return IIO_AVAIL_RANGE;
+		}
+
+		shift = st->filter_type == AD7768_FILTER_SINC5 ? 0 : 2;
+		*vals = (int *)&ad7768_dec_rate_values[shift];
+		*length = ARRAY_SIZE(ad7768_dec_rate_values) - shift;
+		*type = IIO_VAL_INT;
+		return IIO_AVAIL_LIST;
 	case IIO_CHAN_INFO_SAMP_FREQ:
 		*vals = (int *)st->samp_freq_avail;
-		*length = ARRAY_SIZE(ad7768_clk_config);
+		*length = st->samp_freq_avail_len;
 		*type = IIO_VAL_INT;
 		return IIO_AVAIL_LIST;
 	default:
@@ -653,20 +846,44 @@ static int ad7768_read_avail(struct iio_dev *indio_dev,
 	}
 }
 
-static int ad7768_write_raw(struct iio_dev *indio_dev,
-			    struct iio_chan_spec const *chan,
-			    int val, int val2, long info)
+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);
+	int ret;
 
 	switch (info) {
 	case IIO_CHAN_INFO_SAMP_FREQ:
 		return ad7768_set_freq(st, val);
+
+	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
+		ret = ad7768_configure_dig_fil(indio_dev, st->filter_type, val);
+		if (ret)
+			return ret;
+
+		/* Update sampling frequency */
+		return ad7768_set_freq(st, st->samp_freq);
 	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)
+{
+	int ret;
+
+	if (!iio_device_claim_direct(indio_dev))
+		return -EBUSY;
+
+	ret = __ad7768_write_raw(indio_dev, chan, val, val2, info);
+	iio_device_release_direct(indio_dev);
+
+	return ret;
+}
+
 static int ad7768_read_label(struct iio_dev *indio_dev,
 	const struct iio_chan_spec *chan, char *label)
 {
@@ -680,7 +897,7 @@ static int ad7768_get_current_scan_type(const struct iio_dev *indio_dev,
 {
 	struct ad7768_state *st = iio_priv(indio_dev);
 
-	return st->dec_rate == 8 ?
+	return st->oversampling_ratio == 8 ?
 	       AD7768_SCAN_TYPE_HIGH_SPEED : AD7768_SCAN_TYPE_NORMAL;
 }
 
@@ -802,6 +1019,14 @@ static int ad7768_setup(struct iio_dev *indio_dev)
 			return ret;
 	}
 
+	/*
+	 * Set Default Digital Filter configuration:
+	 * SINC5 filter with x32 Decimation rate
+	 */
+	ret = ad7768_configure_dig_fil(indio_dev, AD7768_FILTER_SINC5, 32);
+	if (ret)
+		return ret;
+
 	/* Set the default sampling frequency to 32000 kSPS */
 	return ad7768_set_freq(st, 32000);
 }
@@ -1135,7 +1360,6 @@ static int ad7768_probe(struct spi_device *spi)
 		return PTR_ERR(st->mclk);
 
 	st->mclk_freq = clk_get_rate(st->mclk);
-	ad7768_fill_samp_freq_tbl(st);
 
 	indio_dev->channels = ad7768_channels;
 	indio_dev->num_channels = ARRAY_SIZE(ad7768_channels);
-- 
2.34.1

[PATCH v9 12/12] iio: adc: ad7768-1: add low pass -3dB cutoff attribute

[Jonathan Santos]

Ad7768-1 has a different -3db frequency multiplier depending on
the filter type configured. The cutoff frequency also varies according
to the current ODR.

Add a readonly low pass -3dB frequency cutoff attribute to clarify to
the user which bandwidth is being allowed depending on the filter
configurations.

Reviewed-by: Marcelo Schmitt <marcelo.schmitt@analog.com>
Reviewed-by: David Lechner <dlechner@baylibre.com>
Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com>
---
v9 Changes:
* Rearraged new BIT(IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY) to 
  make the diff look cleaner.

v8 Changes:
* None

v7 Changes:
* None

v6 Changes:
* None

v5 Changes:
* None

v4 Changes:
* None

v3 Changes:
* None

v2 Changes:
* New patch in v2.
---
 drivers/iio/adc/ad7768-1.c | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/drivers/iio/adc/ad7768-1.c b/drivers/iio/adc/ad7768-1.c
index c86afb0fc4c1..dfc1f49d4b81 100644
--- a/drivers/iio/adc/ad7768-1.c
+++ b/drivers/iio/adc/ad7768-1.c
@@ -152,6 +152,17 @@ enum ad7768_scan_type {
 	AD7768_SCAN_TYPE_HIGH_SPEED,
 };
 
+/*
+ * -3dB cutoff frequency multipliers (relative to ODR) for
+ * each filter type. Values are multiplied by 1000.
+ */
+static const int ad7768_filter_3db_odr_multiplier[] = {
+	[AD7768_FILTER_SINC5] = 204,
+	[AD7768_FILTER_SINC3] = 262,
+	[AD7768_FILTER_SINC3_REJ60] = 262,
+	[AD7768_FILTER_WIDEBAND] = 433,
+};
+
 static const int ad7768_mclk_div_rates[] = {
 	16, 8, 4, 2,
 };
@@ -746,6 +757,7 @@ static const struct iio_chan_spec ad7768_channels[] = {
 		.type = IIO_VOLTAGE,
 		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
 		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) |
+					    BIT(IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY) |
 					    BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
 		.info_mask_shared_by_type_available = BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
 		.info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ),
@@ -766,7 +778,7 @@ static int ad7768_read_raw(struct iio_dev *indio_dev,
 {
 	struct ad7768_state *st = iio_priv(indio_dev);
 	const struct iio_scan_type *scan_type;
-	int scale_uv, ret;
+	int scale_uv, ret, temp;
 
 	scan_type = iio_get_current_scan_type(indio_dev, chan);
 	if (IS_ERR(scan_type))
@@ -804,6 +816,12 @@ static int ad7768_read_raw(struct iio_dev *indio_dev,
 	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
 		*val = st->oversampling_ratio;
 
+		return IIO_VAL_INT;
+
+	case IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY:
+		temp = st->samp_freq * ad7768_filter_3db_odr_multiplier[st->filter_type];
+		*val = DIV_ROUND_CLOSEST(temp, 1000);
+
 		return IIO_VAL_INT;
 	}
 
-- 
2.34.1

Re: [PATCH v9 09/12] iio: adc: ad7768-1: add support for Synchronization over SPI

[Jonathan Cameron]

On Thu, 29 May 2025 19:50:29 -0300
Jonathan Santos <Jonathan.Santos@analog.com> wrote:

> The synchronization method using GPIO requires the generated pulse to be
> truly synchronous with the base MCLK signal. When it is not possible to
> do that in hardware, the datasheet recommends using synchronization over
> SPI, where the generated pulse is already synchronous with MCLK. This
> requires the SYNC_OUT pin to be connected to the SYNC_IN pin.
> 
> Use trigger-sources property to enable device synchronization over SPI
> and multi-device synchronization while replacing sync-in-gpios property.
> 
> Reviewed-by: David Lechner <dlechner@baylibre.com>
> Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com>

A couple of trivial comments.  Not enough to respin unless something else comes
up.


> @@ -296,6 +301,27 @@ static const struct regmap_config ad7768_regmap24_config = {
>  	.max_register = AD7768_REG24_COEFF_DATA,
>  };
>  
> +static int ad7768_send_sync_pulse(struct ad7768_state *st)
> +{
> +	if (st->en_spi_sync)
> +		return regmap_write(st->regmap, AD7768_REG_SYNC_RESET, 0x00);
> +
> +	/*
> +	 * The datasheet specifies a minimum SYNC_IN pulse width of 1.5 × Tmclk,
> +	 * where Tmclk is the MCLK period. The supported MCLK frequencies range
> +	 * from 0.6 MHz to 17 MHz, which corresponds to a minimum SYNC_IN pulse
> +	 * width of approximately 2.5 µs in the worst-case scenario (0.6 MHz).
> +	 *
> +	 * Add a delay to ensure the pulse width is always sufficient to
> +	 * trigger synchronization.
> +	 */
> +	gpiod_set_value_cansleep(st->gpio_sync_in, 1);
> +	fsleep(3);
> +	gpiod_set_value_cansleep(st->gpio_sync_in, 0);

This change + comment should really have been in a separate patch
as there is always the potential someone might want to backport it.

> +
> +	return 0;
> +}
> +
>  static int ad7768_set_mode(struct ad7768_state *st,
>  			   enum ad7768_conv_mode mode)
>  {
> @@ -392,10 +418,7 @@ static int ad7768_set_dig_fil(struct ad7768_state *st,
>  		return ret;
>  
>  	/* A sync-in pulse is required every time the filter dec rate changes */
> -	gpiod_set_value(st->gpio_sync_in, 1);
> -	gpiod_set_value(st->gpio_sync_in, 0);
> -
> -	return 0;
> +	return ad7768_send_sync_pulse(st);
>  }

> +
> +static int ad7768_trigger_sources_get_sync(struct device *dev,
> +					   struct ad7768_state *st)
> +{
> +	struct fwnode_handle *dev_fwnode = dev_fwnode(dev);
> +
> +	/*
> +	 * The AD7768-1 allows two primary methods for driving the SYNC_IN pin
> +	 * to synchronize one or more devices:
> +	 * 1. Using an external GPIO.
> +	 * 2. Using a SPI command, where the SYNC_OUT pin generates a
> +	 *    synchronization pulse that drives the SYNC_IN pin.
> +	 */
> +	if (fwnode_property_present(dev_fwnode, "trigger-sources"))
> +		return ad7768_trigger_sources_sync_setup(dev, dev_fwnode, st);
> +
> +	/*
> +	 * In the absence of trigger-sources property, enable self
> +	 * synchronization over SPI (SYNC_OUT).
> +	 */
> +	st->en_spi_sync = true;

Really trivial but if you respin for some reason blank line here.

> +	return 0;
> +}

Re: [PATCH v9 00/12] iio: adc: ad7768-1: Add features, improvements, and fixes

[Jonathan Cameron]

On Thu, 29 May 2025 19:47:57 -0300
Jonathan Santos <Jonathan.Santos@analog.com> wrote:

> This patch series introduces some new features, improvements,
> and fixes for the AD7768-1 ADC driver. 
> 
> The goal is to support all key functionalities listed in the device
> datasheet, including filter mode selection, common mode voltage output
> configuration and GPIO support. Additionally, this includes fixes 
> for SPI communication and for IIO interface, and also code improvements
> to enhance maintainability and readability.

Looks good to me.  I'll be waiting on at least some tags on patch 1 though
before applying this.

Thanks,

Jonathan

Re: [PATCH v9 09/12] iio: adc: ad7768-1: add support for Synchronization over SPI

[Andy Shevchenko]

On Thu, May 29, 2025 at 07:50:29PM -0300, Jonathan Santos wrote:
> The synchronization method using GPIO requires the generated pulse to be
> truly synchronous with the base MCLK signal. When it is not possible to
> do that in hardware, the datasheet recommends using synchronization over
> SPI, where the generated pulse is already synchronous with MCLK. This
> requires the SYNC_OUT pin to be connected to the SYNC_IN pin.
> 
> Use trigger-sources property to enable device synchronization over SPI
> and multi-device synchronization while replacing sync-in-gpios property.

...

> struct ad7768_state {

>  	struct iio_trigger *trig;
>  	struct gpio_desc *gpio_sync_in;
>  	struct gpio_desc *gpio_reset;

> +	bool en_spi_sync;

I'm wondering if moving this...

>  	const char *labels[ARRAY_SIZE(ad7768_channels)];
>  	struct gpio_chip gpiochip;

...to here saves a few bytes in accordance to `pahole`.

>  };

...

> +static int ad7768_trigger_sources_sync_setup(struct device *dev,
> +					     struct fwnode_handle *dev_fwnode,
> +					     struct ad7768_state *st)
> +{
> +	struct fwnode_reference_args args;
> +
> +	struct fwnode_handle *fwnode __free(fwnode_handle) =
> +		fwnode_find_reference_args(dev_fwnode, "trigger-sources",
> +					   "#trigger-source-cells", 0,
> +					   AD7768_TRIGGER_SOURCE_SYNC_IDX, &args);

I don't see how args are being used. This puts in doubt the need of the first
patch.

> +	if (IS_ERR(fwnode))
> +		return PTR_ERR(fwnode);
> +
> +	/* First, try getting the GPIO trigger source */
> +	if (fwnode_device_is_compatible(fwnode, "gpio-trigger")) {
> +		st->gpio_sync_in = devm_fwnode_gpiod_get_index(dev, fwnode,
> +							       NULL,
> +							       0,
> +							       GPIOD_OUT_LOW,
> +							       "sync-in");
> +		return PTR_ERR_OR_ZERO(st->gpio_sync_in);
> +	}
> +
> +	/*
> +	 * TODO: Support the other cases when we have a trigger subsystem
> +	 * to reliably handle other types of devices as trigger sources.
> +	 *
> +	 * For now, return an error message. For self triggering, omit the
> +	 * trigger-sources property.
> +	 */
> +	return dev_err_probe(dev, -EOPNOTSUPP, "Invalid synchronization trigger source\n");
> +}

...

> +static int ad7768_trigger_sources_get_sync(struct device *dev,
> +					   struct ad7768_state *st)
> +{
> +	struct fwnode_handle *dev_fwnode = dev_fwnode(dev);

Call it just fwnode.

> +	/*
> +	 * The AD7768-1 allows two primary methods for driving the SYNC_IN pin
> +	 * to synchronize one or more devices:
> +	 * 1. Using an external GPIO.
> +	 * 2. Using a SPI command, where the SYNC_OUT pin generates a
> +	 *    synchronization pulse that drives the SYNC_IN pin.
> +	 */
> +	if (fwnode_property_present(dev_fwnode, "trigger-sources"))
> +		return ad7768_trigger_sources_sync_setup(dev, dev_fwnode, st);
> +
> +	/*
> +	 * In the absence of trigger-sources property, enable self
> +	 * synchronization over SPI (SYNC_OUT).
> +	 */
> +	st->en_spi_sync = true;
> +	return 0;
> +}

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v9 01/12] device property: add fwnode_find_reference_args()

[Andy Shevchenko]

On Thu, May 29, 2025 at 07:48:17PM -0300, Jonathan Santos wrote:
> Similarly to fwnode_find_reference(), find and return a named reference
> to a fwnode handle, including its arguments. This wrapper facilitates
> cleanup handling and improves readability.

In principle I'm okay with the code, but I probably missed how this new API is
being used (in terms of a need of those arguments to be retrieved).

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v9 00/12] iio: adc: ad7768-1: Add features, improvements, and fixes

[Andy Shevchenko]

On Thu, May 29, 2025 at 07:47:57PM -0300, Jonathan Santos wrote:
> This patch series introduces some new features, improvements,
> and fixes for the AD7768-1 ADC driver. 
> 
> The goal is to support all key functionalities listed in the device
> datasheet, including filter mode selection, common mode voltage output
> configuration and GPIO support. Additionally, this includes fixes 
> for SPI communication and for IIO interface, and also code improvements
> to enhance maintainability and readability.

If you haven't run `make W=1 ...` build against this driver, do it with
GCC and clang and fix all respective compilation warnings / errors,
if any.

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v9 09/12] iio: adc: ad7768-1: add support for Synchronization over SPI

[Jonathan Cameron]

On Fri, 30 May 2025 20:45:32 +0300
Andy Shevchenko <andy@kernel.org> wrote:

> On Thu, May 29, 2025 at 07:50:29PM -0300, Jonathan Santos wrote:
> > The synchronization method using GPIO requires the generated pulse to be
> > truly synchronous with the base MCLK signal. When it is not possible to
> > do that in hardware, the datasheet recommends using synchronization over
> > SPI, where the generated pulse is already synchronous with MCLK. This
> > requires the SYNC_OUT pin to be connected to the SYNC_IN pin.
> > 
> > Use trigger-sources property to enable device synchronization over SPI
> > and multi-device synchronization while replacing sync-in-gpios property.  
> 
> ...
> 
> > struct ad7768_state {  
> 
> >  	struct iio_trigger *trig;
> >  	struct gpio_desc *gpio_sync_in;
> >  	struct gpio_desc *gpio_reset;  
> 
> > +	bool en_spi_sync;  
> 
> I'm wondering if moving this...
> 
> >  	const char *labels[ARRAY_SIZE(ad7768_channels)];
> >  	struct gpio_chip gpiochip;  
> 
> ...to here saves a few bytes in accordance to `pahole`.
> 
> >  };  
> 
> ...
> 
> > +static int ad7768_trigger_sources_sync_setup(struct device *dev,
> > +					     struct fwnode_handle *dev_fwnode,
> > +					     struct ad7768_state *st)
> > +{
> > +	struct fwnode_reference_args args;
> > +
> > +	struct fwnode_handle *fwnode __free(fwnode_handle) =
> > +		fwnode_find_reference_args(dev_fwnode, "trigger-sources",
> > +					   "#trigger-source-cells", 0,
> > +					   AD7768_TRIGGER_SOURCE_SYNC_IDX, &args);  
> 
> I don't see how args are being used. This puts in doubt the need of the first
> patch.

That did get discussed (more context needed in the commit message for patch 1).
I wasn't happy with ignoring #trigger-source-cells which is required in the
binding but here is known to be 0.

If it was larger than 0 but we didn't care about the arguments I believe
we'd still need to use this call to take the right stride through the
data array that this is coming from.
Ultimately I think that is this bit of code establishing the end of the phandle.
https://elixir.bootlin.com/linux/v6.15/source/drivers/of/base.c#L1300

I might have gotten it wrong how this all works though!

J

Re: [PATCH v9 01/12] device property: add fwnode_find_reference_args()

[Jonathan Cameron]

On Fri, 30 May 2025 20:48:14 +0300
Andy Shevchenko <andy@kernel.org> wrote:

> On Thu, May 29, 2025 at 07:48:17PM -0300, Jonathan Santos wrote:
> > Similarly to fwnode_find_reference(), find and return a named reference
> > to a fwnode handle, including its arguments. This wrapper facilitates
> > cleanup handling and improves readability.  
> 
> In principle I'm okay with the code, but I probably missed how this new API is
> being used (in terms of a need of those arguments to be retrieved).
> 

Good point - this needs a little more justification, particularly with respect
to why we are using it in this driver.

J

Re: [PATCH v9 09/12] iio: adc: ad7768-1: add support for Synchronization over SPI

[Jonathan Santos]

On 05/30, Andy Shevchenko wrote:
> On Thu, May 29, 2025 at 07:50:29PM -0300, Jonathan Santos wrote:
 
> > +static int ad7768_trigger_sources_sync_setup(struct device *dev,
> > +					     struct fwnode_handle *dev_fwnode,
> > +					     struct ad7768_state *st)
> > +{
> > +	struct fwnode_reference_args args;
> > +
> > +	struct fwnode_handle *fwnode __free(fwnode_handle) =
> > +		fwnode_find_reference_args(dev_fwnode, "trigger-sources",
> > +					   "#trigger-source-cells", 0,
> > +					   AD7768_TRIGGER_SOURCE_SYNC_IDX, &args);
> 
> I don't see how args are being used. This puts in doubt the need of the first
> patch.
> 

If the wrapper is the issue, maybe it is better doing this instead?

static int ad7768_trigger_sources_sync_setup(struct device *dev,
					     struct fwnode_handle *dev_fwnode,
					     struct ad7768_state *st)
{
	struct fwnode_reference_args args;
	struct fwnode_handle *fwnode __free(fwnode_handle) = NULL;
	int ret;

	ret = fwnode_property_get_reference_args(dev_fwnode, "trigger-sources",
						 "#trigger-source-cells", 0,
						 AD7768_TRIGGER_SOURCE_SYNC_IDX, &args);
	if (ret)
		return ret;

	fwnode = args.fwnode;
> > +	/* First, try getting the GPIO trigger source */
> > +	if (fwnode_device_is_compatible(fwnode, "gpio-trigger")) {
> > +		st->gpio_sync_in = devm_fwnode_gpiod_get_index(dev, fwnode,
> > +							       NULL,
> > +							       0,
> > +							       GPIOD_OUT_LOW,
> > +							       "sync-in");
> > +		return PTR_ERR_OR_ZERO(st->gpio_sync_in);
> > +	}
> > +
> > +	/*
> > +	 * TODO: Support the other cases when we have a trigger subsystem
> > +	 * to reliably handle other types of devices as trigger sources.
> > +	 *
> > +	 * For now, return an error message. For self triggering, omit the
> > +	 * trigger-sources property.
> > +	 */
> > +	return dev_err_probe(dev, -EOPNOTSUPP, "Invalid synchronization trigger source\n");
> > +}

Then we can get rid of the first patch.

Regards,
Jonathan S.

Re: [PATCH v9 09/12] iio: adc: ad7768-1: add support for Synchronization over SPI

[Andy Shevchenko]

Mon, Jun 02, 2025 at 02:15:23PM -0300, Jonathan Santos kirjoitti:
> On 05/30, Andy Shevchenko wrote:
> > On Thu, May 29, 2025 at 07:50:29PM -0300, Jonathan Santos wrote:

...

> > > +static int ad7768_trigger_sources_sync_setup(struct device *dev,
> > > +					     struct fwnode_handle *dev_fwnode,
> > > +					     struct ad7768_state *st)
> > > +{
> > > +	struct fwnode_reference_args args;
> > > +
> > > +	struct fwnode_handle *fwnode __free(fwnode_handle) =
> > > +		fwnode_find_reference_args(dev_fwnode, "trigger-sources",
> > > +					   "#trigger-source-cells", 0,
> > > +					   AD7768_TRIGGER_SOURCE_SYNC_IDX, &args);
> > 
> > I don't see how args are being used. This puts in doubt the need of the first
> > patch.
> 
> If the wrapper is the issue, maybe it is better doing this instead?
> 
> static int ad7768_trigger_sources_sync_setup(struct device *dev,
> 					     struct fwnode_handle *dev_fwnode,

Name it fwnode...

> 					     struct ad7768_state *st)
> {
> 	struct fwnode_reference_args args;
> 	struct fwnode_handle *fwnode __free(fwnode_handle) = NULL;

...and this one something like 'ref'. Also I'm not sure the __free() will do
what you expect from it.

> 	int ret;
> 
> 	ret = fwnode_property_get_reference_args(dev_fwnode, "trigger-sources",
> 						 "#trigger-source-cells", 0,
> 						 AD7768_TRIGGER_SOURCE_SYNC_IDX, &args);
> 	if (ret)
> 		return ret;
> 
> 	fwnode = args.fwnode;

Yes, please. This looks better.

> > > +	/* First, try getting the GPIO trigger source */
> > > +	if (fwnode_device_is_compatible(fwnode, "gpio-trigger")) {
> > > +		st->gpio_sync_in = devm_fwnode_gpiod_get_index(dev, fwnode,
> > > +							       NULL,
> > > +							       0,
> > > +							       GPIOD_OUT_LOW,
> > > +							       "sync-in");
> > > +		return PTR_ERR_OR_ZERO(st->gpio_sync_in);
> > > +	}
> > > +
> > > +	/*
> > > +	 * TODO: Support the other cases when we have a trigger subsystem
> > > +	 * to reliably handle other types of devices as trigger sources.
> > > +	 *
> > > +	 * For now, return an error message. For self triggering, omit the
> > > +	 * trigger-sources property.
> > > +	 */
> > > +	return dev_err_probe(dev, -EOPNOTSUPP, "Invalid synchronization trigger source\n");
> > > +}
> 
> Then we can get rid of the first patch.

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v9 09/12] iio: adc: ad7768-1: add support for Synchronization over SPI

[Jonathan Cameron]

On Tue, 3 Jun 2025 00:25:40 +0300
Andy Shevchenko <andy.shevchenko@gmail.com> wrote:

> Mon, Jun 02, 2025 at 02:15:23PM -0300, Jonathan Santos kirjoitti:
> > On 05/30, Andy Shevchenko wrote:  
> > > On Thu, May 29, 2025 at 07:50:29PM -0300, Jonathan Santos wrote:  
> 
> ...
> 
> > > > +static int ad7768_trigger_sources_sync_setup(struct device *dev,
> > > > +					     struct fwnode_handle *dev_fwnode,
> > > > +					     struct ad7768_state *st)
> > > > +{
> > > > +	struct fwnode_reference_args args;
> > > > +
> > > > +	struct fwnode_handle *fwnode __free(fwnode_handle) =
> > > > +		fwnode_find_reference_args(dev_fwnode, "trigger-sources",
> > > > +					   "#trigger-source-cells", 0,
> > > > +					   AD7768_TRIGGER_SOURCE_SYNC_IDX, &args);  
> > > 
> > > I don't see how args are being used. This puts in doubt the need of the first
> > > patch.  
> > 
> > If the wrapper is the issue, maybe it is better doing this instead?
> > 
> > static int ad7768_trigger_sources_sync_setup(struct device *dev,
> > 					     struct fwnode_handle *dev_fwnode,  
> 
> Name it fwnode...
> 
> > 					     struct ad7768_state *st)
> > {
> > 	struct fwnode_reference_args args;
> > 	struct fwnode_handle *fwnode __free(fwnode_handle) = NULL;  
> 
> ...and this one something like 'ref'. Also I'm not sure the __free() will do
> what you expect from it.
> 
> > 	int ret;
> > 
> > 	ret = fwnode_property_get_reference_args(dev_fwnode, "trigger-sources",
> > 						 "#trigger-source-cells", 0,
> > 						 AD7768_TRIGGER_SOURCE_SYNC_IDX, &args);
> > 	if (ret)
> > 		return ret;
> > 
> > 	fwnode = args.fwnode;  
> 
> Yes, please. This looks better.

Take a look at the guidance in cleanup.h first.  Linus made it very clear
that the = NULL then set it later pattern was not the way to go. That was
one of the things buried deep in a discussion thread soon after the cleanup.h
stuff was proposed and the lack of general knowledge of that preference lead
to Dan adding that documentation to cleanup.h.

If __free is used Linus always wants to see the constructor and destructor in the same line. 

That is why I suggested the approach in patch 1.

If that isn't acceptable (yet), wrap this up in a local function doing the equivalent
of patch 1 and we can wait and see how common this ends up being.

Jonathan


> 
> > > > +	/* First, try getting the GPIO trigger source */
> > > > +	if (fwnode_device_is_compatible(fwnode, "gpio-trigger")) {
> > > > +		st->gpio_sync_in = devm_fwnode_gpiod_get_index(dev, fwnode,
> > > > +							       NULL,
> > > > +							       0,
> > > > +							       GPIOD_OUT_LOW,
> > > > +							       "sync-in");
> > > > +		return PTR_ERR_OR_ZERO(st->gpio_sync_in);
> > > > +	}
> > > > +
> > > > +	/*
> > > > +	 * TODO: Support the other cases when we have a trigger subsystem
> > > > +	 * to reliably handle other types of devices as trigger sources.
> > > > +	 *
> > > > +	 * For now, return an error message. For self triggering, omit the
> > > > +	 * trigger-sources property.
> > > > +	 */
> > > > +	return dev_err_probe(dev, -EOPNOTSUPP, "Invalid synchronization trigger source\n");
> > > > +}  
> > 
> > Then we can get rid of the first patch.  
>