[PATCH RESEND v3 00/17] iio: adc: ad7768-1: Add features, improvements, and fixes

[PATCH RESEND v3 00/17] 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.

OBS: Resending patch series due to issues in the previous submission;
patches were generated without using the "--thread" option.
---
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 (13):
  iio: adc: ad7768-1: set MOSI idle state to prevent accidental reset
  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
  Documentation: ABI: add wideband filter type to  sysfs-bus-iio
  iio: adc: ad7768-1: remove unnecessary locking
  iio: adc: ad7768-1: convert driver to use regmap
  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 (4):
  iio: adc: ad7768-1: Fix conversion result sign
  iio: adc: ad7768-1: Add reset gpio
  iio: adc: ad7768-1: Move buffer allocation to a separate function
  iio: adc: ad7768-1: Add GPIO controller support

 Documentation/ABI/testing/sysfs-bus-iio       |    2 +
 .../bindings/iio/adc/adi,ad7768-1.yaml        |   59 +-
 drivers/iio/adc/ad7768-1.c                    | 1068 ++++++++++++++---
 3 files changed, 949 insertions(+), 180 deletions(-)


base-commit: 5de07b8a24cf44cdb78adeab790704bf577c2c1d
prerequisite-patch-id: 8b531bca46f7c7ea1c0f6d232d162fd05fda52f7
-- 
2.34.1

[PATCH RESEND v3 01/17] iio: adc: ad7768-1: Fix conversion result sign

[Jonathan Santos]

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

The ad7768-1 ADC output code is two's complement, meaning that the voltage
conversion result is a signed value. Since the value is a 24 bit one,
stored in a 32 bit variable, the sign should be extended in order to get
the correct representation.

Also the channel description has been updated to signed representation,
to match the ADC specifications.

Fixes: a5f8c7da3dbe ("iio: adc: Add AD7768-1 ADC basic support")
Reviewed-by: David Lechner <dlechner@baylibre.com>
Reviewed-by: Marcelo Schmitt <marcelo.schmitt@analog.com>
Signed-off-by: Sergiu Cuciurean <sergiu.cuciurean@analog.com>
Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com>
---
v3 Changes:
* Added missing SoB.

v2 Changes:
* Patch moved to the start of the patch series.
---
 drivers/iio/adc/ad7768-1.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/iio/adc/ad7768-1.c b/drivers/iio/adc/ad7768-1.c
index 113703fb7245..c3cf04311c40 100644
--- a/drivers/iio/adc/ad7768-1.c
+++ b/drivers/iio/adc/ad7768-1.c
@@ -142,7 +142,7 @@ static const struct iio_chan_spec ad7768_channels[] = {
 		.channel = 0,
 		.scan_index = 0,
 		.scan_type = {
-			.sign = 'u',
+			.sign = 's',
 			.realbits = 24,
 			.storagebits = 32,
 			.shift = 8,
@@ -371,7 +371,7 @@ static int ad7768_read_raw(struct iio_dev *indio_dev,
 
 		ret = ad7768_scan_direct(indio_dev);
 		if (ret >= 0)
-			*val = ret;
+			*val = sign_extend32(ret, chan->scan_type.realbits - 1);
 
 		iio_device_release_direct_mode(indio_dev);
 		if (ret < 0)
-- 
2.34.1

[PATCH RESEND v3 02/17] iio: adc: ad7768-1: set MOSI idle state to prevent accidental reset

[Jonathan Santos]

Datasheet recommends Setting the MOSI idle state to high in order to
prevent accidental reset of the device when SCLK is free running.
This happens when the controller clocks out a 1 followed by 63 zeros
while the CS is held low.

Check if SPI controller supports SPI_MOSI_IDLE_HIGH flag and set it.

Fixes: a5f8c7da3dbe ("iio: adc: Add AD7768-1 ADC basic support")
Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com>
---
v3 Changes:
* Patch moved closer to the start of the patch set.

v2 Changes:
* Only setup SPI_MOSI_IDLE_HIGH flag if the controller supports it, otherwise the driver
  continues the same. I realized that using bits_per_word does not avoid the problem that
  MOSI idle state is trying to solve. If the controller drives the MOSI low between bytes
  during a transfer, nothing happens.
---
 drivers/iio/adc/ad7768-1.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/drivers/iio/adc/ad7768-1.c b/drivers/iio/adc/ad7768-1.c
index c3cf04311c40..2e2d50ccb744 100644
--- a/drivers/iio/adc/ad7768-1.c
+++ b/drivers/iio/adc/ad7768-1.c
@@ -574,6 +574,21 @@ static int ad7768_probe(struct spi_device *spi)
 		return -ENOMEM;
 
 	st = iio_priv(indio_dev);
+	/*
+	 * Datasheet recommends SDI line to be kept high when data is not being
+	 * clocked out of the controller and the spi clock is free running,
+	 * to prevent accidental reset.
+	 * Since many controllers do not support the SPI_MOSI_IDLE_HIGH flag
+	 * yet, only request the MOSI idle state to enable if the controller
+	 * supports it.
+	 */
+	if (spi->controller->mode_bits & SPI_MOSI_IDLE_HIGH) {
+		spi->mode |= SPI_MOSI_IDLE_HIGH;
+		ret = spi_setup(spi);
+		if (ret < 0)
+			return ret;
+	}
+
 	st->spi = spi;
 
 	st->vref = devm_regulator_get(&spi->dev, "vref");
-- 
2.34.1

Re: [PATCH RESEND v3 02/17] iio: adc: ad7768-1: set MOSI idle state to prevent accidental reset

[Jonathan Cameron]

On Wed, 12 Feb 2025 15:16:07 -0300
Jonathan Santos <Jonathan.Santos@analog.com> wrote:

> Datasheet recommends Setting the MOSI idle state to high in order to
> prevent accidental reset of the device when SCLK is free running.
> This happens when the controller clocks out a 1 followed by 63 zeros
> while the CS is held low.
> 
> Check if SPI controller supports SPI_MOSI_IDLE_HIGH flag and set it.
> 
> Fixes: a5f8c7da3dbe ("iio: adc: Add AD7768-1 ADC basic support")
> Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com>
Just a quick note that I'm not picking these first two up on their
own (yet) as I don't want to create an upstream dependency issue that
might delay the main set.  If anyone would prefer these being rushed
in and potential delay to the new stuff in here, then let me know.

Jonathan

> ---
> v3 Changes:
> * Patch moved closer to the start of the patch set.
> 
> v2 Changes:
> * Only setup SPI_MOSI_IDLE_HIGH flag if the controller supports it, otherwise the driver
>   continues the same. I realized that using bits_per_word does not avoid the problem that
>   MOSI idle state is trying to solve. If the controller drives the MOSI low between bytes
>   during a transfer, nothing happens.
> ---
>  drivers/iio/adc/ad7768-1.c | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)
> 
> diff --git a/drivers/iio/adc/ad7768-1.c b/drivers/iio/adc/ad7768-1.c
> index c3cf04311c40..2e2d50ccb744 100644
> --- a/drivers/iio/adc/ad7768-1.c
> +++ b/drivers/iio/adc/ad7768-1.c
> @@ -574,6 +574,21 @@ static int ad7768_probe(struct spi_device *spi)
>  		return -ENOMEM;
>  
>  	st = iio_priv(indio_dev);
> +	/*
> +	 * Datasheet recommends SDI line to be kept high when data is not being
> +	 * clocked out of the controller and the spi clock is free running,
> +	 * to prevent accidental reset.
> +	 * Since many controllers do not support the SPI_MOSI_IDLE_HIGH flag
> +	 * yet, only request the MOSI idle state to enable if the controller
> +	 * supports it.
> +	 */
> +	if (spi->controller->mode_bits & SPI_MOSI_IDLE_HIGH) {
> +		spi->mode |= SPI_MOSI_IDLE_HIGH;
> +		ret = spi_setup(spi);
> +		if (ret < 0)
> +			return ret;
> +	}
> +
>  	st->spi = spi;
>  
>  	st->vref = devm_regulator_get(&spi->dev, "vref");

[PATCH RESEND v3 03/17] 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.

Add a new trigger-sources property to enable synchronization over SPI
and future multiple devices support. This property references the
main device (or trigger provider) responsible for generating the
SYNC_OUT pulse to drive the SYNC_IN of device.

While at it, add description to the interrupts property.

Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com>
---
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        | 28 +++++++++++++++++--
 1 file changed, 25 insertions(+), 3 deletions(-)

diff --git a/Documentation/devicetree/bindings/iio/adc/adi,ad7768-1.yaml b/Documentation/devicetree/bindings/iio/adc/adi,ad7768-1.yaml
index 3ce59d4d065f..4bcc9e20fab9 100644
--- a/Documentation/devicetree/bindings/iio/adc/adi,ad7768-1.yaml
+++ b/Documentation/devicetree/bindings/iio/adc/adi,ad7768-1.yaml
@@ -26,7 +26,19 @@ properties:
   clock-names:
     const: mclk
 
+  trigger-sources:
+    description:
+      Specifies the device responsible for driving the synchronization pin,
+      as an alternative to adi,sync-in-gpios. If the own device node is
+      referenced, The synchronization over SPI is enabled and the SYNC_OUT
+      output will drive the SYNC_IN pin.
+    maxItems: 2
+
   interrupts:
+    description:
+      Specifies the interrupt line associated with the ADC. This refers
+      to the DRDY (Data Ready) pin, which signals when conversion results are
+      available.
     maxItems: 1
 
   '#address-cells':
@@ -57,6 +69,9 @@ properties:
   "#io-channel-cells":
     const: 1
 
+  "#trigger-source-cells":
+    const: 0
+
 required:
   - compatible
   - reg
@@ -65,7 +80,6 @@ required:
   - vref-supply
   - spi-cpol
   - spi-cpha
-  - adi,sync-in-gpios
 
 patternProperties:
   "^channel@([0-9]|1[0-5])$":
@@ -89,6 +103,13 @@ patternProperties:
 allOf:
   - $ref: /schemas/spi/spi-peripheral-props.yaml#
 
+  - oneOf:
+      - required:
+          - trigger-sources
+          - "#trigger-source-cells"
+      - required:
+          - adi,sync-in-gpios
+
 unevaluatedProperties: false
 
 examples:
@@ -99,7 +120,7 @@ examples:
         #address-cells = <1>;
         #size-cells = <0>;
 
-        adc@0 {
+        adc0: adc@0 {
             compatible = "adi,ad7768-1";
             reg = <0>;
             spi-max-frequency = <2000000>;
@@ -108,7 +129,8 @@ examples:
             vref-supply = <&adc_vref>;
             interrupts = <25 IRQ_TYPE_EDGE_RISING>;
             interrupt-parent = <&gpio>;
-            adi,sync-in-gpios = <&gpio 22 GPIO_ACTIVE_LOW>;
+            trigger-sources = <&adc0 0>;
+            #trigger-source-cells = <0>;
             reset-gpios = <&gpio 27 GPIO_ACTIVE_LOW>;
             clocks = <&ad7768_mclk>;
             clock-names = "mclk";
-- 
2.34.1

Re: [PATCH RESEND v3 03/17] dt-bindings: iio: adc: ad7768-1: add trigger-sources property

[Conor Dooley]

[-- Attachment #1: Type: text/plain, Size: 4156 bytes --]

On Wed, Feb 12, 2025 at 03:16:16PM -0300, Jonathan Santos wrote:
> 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.
> 
> Add a new trigger-sources property to enable synchronization over SPI
> and future multiple devices support. This property references the
> main device (or trigger provider) responsible for generating the
> SYNC_OUT pulse to drive the SYNC_IN of device.
> 
> While at it, add description to the interrupts property.
> 
> Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com>
> ---
> 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        | 28 +++++++++++++++++--
>  1 file changed, 25 insertions(+), 3 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/iio/adc/adi,ad7768-1.yaml b/Documentation/devicetree/bindings/iio/adc/adi,ad7768-1.yaml
> index 3ce59d4d065f..4bcc9e20fab9 100644
> --- a/Documentation/devicetree/bindings/iio/adc/adi,ad7768-1.yaml
> +++ b/Documentation/devicetree/bindings/iio/adc/adi,ad7768-1.yaml
> @@ -26,7 +26,19 @@ properties:
>    clock-names:
>      const: mclk
>  
> +  trigger-sources:
> +    description:
> +      Specifies the device responsible for driving the synchronization pin,
> +      as an alternative to adi,sync-in-gpios. If the own device node is
> +      referenced, The synchronization over SPI is enabled and the SYNC_OUT
> +      output will drive the SYNC_IN pin.

Maybe a silly question, but why is self-reference needed here?
sync-in-gpios is a required property at present, so why can't you
operate under the assumption that neither the trigger-sources when
neither are present? Is it because only one of the sources could be
external and one internal, or there could be either one or two internal
sources? Self-referencing properties always feel like a bit of a
mistake.

> +    maxItems: 2
> +
>    interrupts:
> +    description:
> +      Specifies the interrupt line associated with the ADC. This refers
> +      to the DRDY (Data Ready) pin, which signals when conversion results are
> +      available.
>      maxItems: 1
>  
>    '#address-cells':
> @@ -57,6 +69,9 @@ properties:
>    "#io-channel-cells":
>      const: 1
>  
> +  "#trigger-source-cells":
> +    const: 0
> +
>  required:
>    - compatible
>    - reg
> @@ -65,7 +80,6 @@ required:
>    - vref-supply
>    - spi-cpol
>    - spi-cpha
> -  - adi,sync-in-gpios
>  
>  patternProperties:
>    "^channel@([0-9]|1[0-5])$":
> @@ -89,6 +103,13 @@ patternProperties:
>  allOf:
>    - $ref: /schemas/spi/spi-peripheral-props.yaml#
>  
> +  - oneOf:
> +      - required:
> +          - trigger-sources
> +          - "#trigger-source-cells"
> +      - required:
> +          - adi,sync-in-gpios
> +
>  unevaluatedProperties: false
>  
>  examples:
> @@ -99,7 +120,7 @@ examples:
>          #address-cells = <1>;
>          #size-cells = <0>;
>  
> -        adc@0 {
> +        adc0: adc@0 {
>              compatible = "adi,ad7768-1";
>              reg = <0>;
>              spi-max-frequency = <2000000>;
> @@ -108,7 +129,8 @@ examples:
>              vref-supply = <&adc_vref>;
>              interrupts = <25 IRQ_TYPE_EDGE_RISING>;
>              interrupt-parent = <&gpio>;
> -            adi,sync-in-gpios = <&gpio 22 GPIO_ACTIVE_LOW>;
> +            trigger-sources = <&adc0 0>;
> +            #trigger-source-cells = <0>;
>              reset-gpios = <&gpio 27 GPIO_ACTIVE_LOW>;
>              clocks = <&ad7768_mclk>;
>              clock-names = "mclk";
> -- 
> 2.34.1
> 

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Re: [PATCH RESEND v3 03/17] dt-bindings: iio: adc: ad7768-1: add trigger-sources property

[Jonathan Santos]

On 02/13, Conor Dooley wrote:
> On Wed, Feb 12, 2025 at 03:16:16PM -0300, Jonathan Santos wrote:
> > 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.
> > 
> > Add a new trigger-sources property to enable synchronization over SPI
> > and future multiple devices support. This property references the
> > main device (or trigger provider) responsible for generating the
> > SYNC_OUT pulse to drive the SYNC_IN of device.
> > 
> > While at it, add description to the interrupts property.
> > 
> > Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com>
> > ---
> > 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        | 28 +++++++++++++++++--
> >  1 file changed, 25 insertions(+), 3 deletions(-)
> > 
> > diff --git a/Documentation/devicetree/bindings/iio/adc/adi,ad7768-1.yaml b/Documentation/devicetree/bindings/iio/adc/adi,ad7768-1.yaml
> > index 3ce59d4d065f..4bcc9e20fab9 100644
> > --- a/Documentation/devicetree/bindings/iio/adc/adi,ad7768-1.yaml
> > +++ b/Documentation/devicetree/bindings/iio/adc/adi,ad7768-1.yaml
> > @@ -26,7 +26,19 @@ properties:
> >    clock-names:
> >      const: mclk
> >  
> > +  trigger-sources:
> > +    description:
> > +      Specifies the device responsible for driving the synchronization pin,
> > +      as an alternative to adi,sync-in-gpios. If the own device node is
> > +      referenced, The synchronization over SPI is enabled and the SYNC_OUT
> > +      output will drive the SYNC_IN pin.
> 
> Maybe a silly question, but why is self-reference needed here?
> sync-in-gpios is a required property at present, so why can't you
> operate under the assumption that neither the trigger-sources when
> neither are present? Is it because only one of the sources could be
> external and one internal, or there could be either one or two internal
> sources? Self-referencing properties always feel like a bit of a
> mistake.
> 
We have one internal synchronization source and two external ones.
The internal is when /SYNC_OUT drives /SYNC_IN (in this case with self
referencing). The external sources include using a GPIO to drive the 
/SYNC_IN (sync-in-gpio case) or using an external /SYNC_OUT, the last one
is described in the datasheet for multi-devices setup.

The trigger-sources property is inteded to indicate wheter the /SYNC_OUT
signal originates from within the device or from another source. currently
we are only handling the internal case. We are not sure yet how to handle
the external sources.

> > +    maxItems: 2
> > +
> >    interrupts:
> > +    description:
> > +      Specifies the interrupt line associated with the ADC. This refers
> > +      to the DRDY (Data Ready) pin, which signals when conversion results are
> > +      available.
> >      maxItems: 1
> >  
> >    '#address-cells':
> > @@ -57,6 +69,9 @@ properties:
> >    "#io-channel-cells":
> >      const: 1
> >  
> > +  "#trigger-source-cells":
> > +    const: 0
> > +
> >  required:
> >    - compatible
> >    - reg
> > @@ -65,7 +80,6 @@ required:
> >    - vref-supply
> >    - spi-cpol
> >    - spi-cpha
> > -  - adi,sync-in-gpios
> >  
> >  patternProperties:
> >    "^channel@([0-9]|1[0-5])$":
> > @@ -89,6 +103,13 @@ patternProperties:
> >  allOf:
> >    - $ref: /schemas/spi/spi-peripheral-props.yaml#
> >  
> > +  - oneOf:
> > +      - required:
> > +          - trigger-sources
> > +          - "#trigger-source-cells"
> > +      - required:
> > +          - adi,sync-in-gpios
> > +
> >  unevaluatedProperties: false
> >  
> >  examples:
> > @@ -99,7 +120,7 @@ examples:
> >          #address-cells = <1>;
> >          #size-cells = <0>;
> >  
> > -        adc@0 {
> > +        adc0: adc@0 {
> >              compatible = "adi,ad7768-1";
> >              reg = <0>;
> >              spi-max-frequency = <2000000>;
> > @@ -108,7 +129,8 @@ examples:
> >              vref-supply = <&adc_vref>;
> >              interrupts = <25 IRQ_TYPE_EDGE_RISING>;
> >              interrupt-parent = <&gpio>;
> > -            adi,sync-in-gpios = <&gpio 22 GPIO_ACTIVE_LOW>;
> > +            trigger-sources = <&adc0 0>;
> > +            #trigger-source-cells = <0>;
> >              reset-gpios = <&gpio 27 GPIO_ACTIVE_LOW>;
> >              clocks = <&ad7768_mclk>;
> >              clock-names = "mclk";
> > -- 
> > 2.34.1
> > 

Re: [PATCH RESEND v3 03/17] dt-bindings: iio: adc: ad7768-1: add trigger-sources property

[Rob Herring]

On Thu, Feb 27, 2025 at 06:30:04PM -0300, Jonathan Santos wrote:
> On 02/13, Conor Dooley wrote:
> > On Wed, Feb 12, 2025 at 03:16:16PM -0300, Jonathan Santos wrote:
> > > 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.
> > > 
> > > Add a new trigger-sources property to enable synchronization over SPI
> > > and future multiple devices support. This property references the
> > > main device (or trigger provider) responsible for generating the
> > > SYNC_OUT pulse to drive the SYNC_IN of device.
> > > 
> > > While at it, add description to the interrupts property.
> > > 
> > > Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com>
> > > ---
> > > 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        | 28 +++++++++++++++++--
> > >  1 file changed, 25 insertions(+), 3 deletions(-)
> > > 
> > > diff --git a/Documentation/devicetree/bindings/iio/adc/adi,ad7768-1.yaml b/Documentation/devicetree/bindings/iio/adc/adi,ad7768-1.yaml
> > > index 3ce59d4d065f..4bcc9e20fab9 100644
> > > --- a/Documentation/devicetree/bindings/iio/adc/adi,ad7768-1.yaml
> > > +++ b/Documentation/devicetree/bindings/iio/adc/adi,ad7768-1.yaml
> > > @@ -26,7 +26,19 @@ properties:
> > >    clock-names:
> > >      const: mclk
> > >  
> > > +  trigger-sources:
> > > +    description:
> > > +      Specifies the device responsible for driving the synchronization pin,
> > > +      as an alternative to adi,sync-in-gpios. If the own device node is
> > > +      referenced, The synchronization over SPI is enabled and the SYNC_OUT
> > > +      output will drive the SYNC_IN pin.
> > 
> > Maybe a silly question, but why is self-reference needed here?
> > sync-in-gpios is a required property at present, so why can't you
> > operate under the assumption that neither the trigger-sources when
> > neither are present? Is it because only one of the sources could be
> > external and one internal, or there could be either one or two internal
> > sources? Self-referencing properties always feel like a bit of a
> > mistake.
> > 
> We have one internal synchronization source and two external ones.
> The internal is when /SYNC_OUT drives /SYNC_IN (in this case with self
> referencing). The external sources include using a GPIO to drive the 
> /SYNC_IN (sync-in-gpio case) or using an external /SYNC_OUT, the last one
> is described in the datasheet for multi-devices setup.
> 
> The trigger-sources property is inteded to indicate wheter the /SYNC_OUT
> signal originates from within the device or from another source. currently
> we are only handling the internal case. We are not sure yet how to handle
> the external sources.
> 
> > > +    maxItems: 2

From the above, I don't follow how you have 2 entries. In any case, you 
need to define what each entry is in the schema.

I'm also wondering if adi,sync-in-gpios should be instead represented in 
trigger-sources. This would mean we need a 'gpio-trigger' binding. That 
would make the handling of trigger sources more uniform. But maybe not 
worth the complexity.

Rob

[PATCH RESEND v3 04/17] 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.

Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com>
---
v3 Changes:
* none.

v2 Changes:
* New patch in v2.
---
 .../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 4bcc9e20fab9..e2f9782b5fc8 100644
--- a/Documentation/devicetree/bindings/iio/adc/adi,ad7768-1.yaml
+++ b/Documentation/devicetree/bindings/iio/adc/adi,ad7768-1.yaml
@@ -72,6 +72,14 @@ properties:
   "#trigger-source-cells":
     const: 0
 
+  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
@@ -126,6 +134,8 @@ 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 RESEND v3 05/17] 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.

Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com>
---
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        | 21 +++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/Documentation/devicetree/bindings/iio/adc/adi,ad7768-1.yaml b/Documentation/devicetree/bindings/iio/adc/adi,ad7768-1.yaml
index e2f9782b5fc8..38f7bb0a0e20 100644
--- a/Documentation/devicetree/bindings/iio/adc/adi,ad7768-1.yaml
+++ b/Documentation/devicetree/bindings/iio/adc/adi,ad7768-1.yaml
@@ -59,6 +59,19 @@ 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
 
@@ -152,6 +165,14 @@ examples:
                 reg = <0>;
                 label = "channel_0";
             };
+
+            regulators {
+              vcm_reg: vcm_output {
+                regulator-name = "vcm_output";
+                regulator-min-microvolt = <900000>;
+                regulator-max-microvolt = <2500000>;
+              };
+            };
         };
     };
 ...
-- 
2.34.1

Re: [PATCH RESEND v3 05/17] dt-bindings: iio: adc: ad7768-1: document regulator provider property

[Conor Dooley]

[-- Attachment #1: Type: text/plain, Size: 439 bytes --]

On Wed, Feb 12, 2025 at 03:16:35PM -0300, Jonathan Santos wrote:
> 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.
> 
> Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com>

Acked-by: Conor Dooley <conor.dooley@microchip.com>

[-- Attachment #2: signature.asc --]
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Re: [PATCH RESEND v3 05/17] dt-bindings: iio: adc: ad7768-1: document regulator provider property

[David Lechner]

On 2/12/25 12:16 PM, Jonathan Santos wrote:
> 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.
> 
> Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com>
> ---
> 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        | 21 +++++++++++++++++++
>  1 file changed, 21 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/iio/adc/adi,ad7768-1.yaml b/Documentation/devicetree/bindings/iio/adc/adi,ad7768-1.yaml
> index e2f9782b5fc8..38f7bb0a0e20 100644
> --- a/Documentation/devicetree/bindings/iio/adc/adi,ad7768-1.yaml
> +++ b/Documentation/devicetree/bindings/iio/adc/adi,ad7768-1.yaml
> @@ -59,6 +59,19 @@ 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:

I think property names are supposed to use - and not _.

 +      vcm-output:

> +        $ref: /schemas/regulator/regulator.yaml#
> +        type: object
> +        unevaluatedProperties: false
> +
> +    additionalProperties: false
> +
>    reset-gpios:
>      maxItems: 1
>  
> @@ -152,6 +165,14 @@ examples:
>                  reg = <0>;
>                  label = "channel_0";
>              };
> +
> +            regulators {
> +              vcm_reg: vcm_output {
> +                regulator-name = "vcm_output";
> +                regulator-min-microvolt = <900000>;
> +                regulator-max-microvolt = <2500000>;
> +              };
> +            };
>          };
>      };
>  ...

[PATCH RESEND v3 06/17] Documentation: ABI: add wideband filter type to sysfs-bus-iio

[Jonathan Santos]

The Wideband Low Ripple filter is used for AD7768-1 Driver.
Document wideband filter option into filter_type_available
attribute.

Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com>
---
v3 Changes:
* None, since we still did not agree on a better name for this filter type.

v2 Changes:
* Removed FIR mentions.
---
 Documentation/ABI/testing/sysfs-bus-iio | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-bus-iio b/Documentation/ABI/testing/sysfs-bus-iio
index f83bd6829285..9b879e7732cd 100644
--- a/Documentation/ABI/testing/sysfs-bus-iio
+++ b/Documentation/ABI/testing/sysfs-bus-iio
@@ -2291,6 +2291,8 @@ Description:
 		* "sinc3+pf2" - Sinc3 + device specific Post Filter 2.
 		* "sinc3+pf3" - Sinc3 + device specific Post Filter 3.
 		* "sinc3+pf4" - Sinc3 + device specific Post Filter 4.
+		* "wideband" - filter with wideband low ripple passband
+		  and sharp transition band.
 
 What:		/sys/.../events/in_proximity_thresh_either_runningperiod
 KernelVersion:	6.6
-- 
2.34.1

Re: [PATCH RESEND v3 06/17] Documentation: ABI: add wideband filter type to sysfs-bus-iio

[David Lechner]

On 2/12/25 12:16 PM, Jonathan Santos wrote:
> The Wideband Low Ripple filter is used for AD7768-1 Driver.
> Document wideband filter option into filter_type_available
> attribute.
> 
> Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com>
> ---
> v3 Changes:
> * None, since we still did not agree on a better name for this filter type.
> 

I'm convinced at this point that "wideband" is fine.

> v2 Changes:
> * Removed FIR mentions.
> ---
>  Documentation/ABI/testing/sysfs-bus-iio | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/Documentation/ABI/testing/sysfs-bus-iio b/Documentation/ABI/testing/sysfs-bus-iio
> index f83bd6829285..9b879e7732cd 100644
> --- a/Documentation/ABI/testing/sysfs-bus-iio
> +++ b/Documentation/ABI/testing/sysfs-bus-iio
> @@ -2291,6 +2291,8 @@ Description:
>  		* "sinc3+pf2" - Sinc3 + device specific Post Filter 2.
>  		* "sinc3+pf3" - Sinc3 + device specific Post Filter 3.
>  		* "sinc3+pf4" - Sinc3 + device specific Post Filter 4.
> +		* "wideband" - filter with wideband low ripple passband
> +		  and sharp transition band.

The description could perhaps be made a bit more generic though
instead of using specifics from the AD7768-1 datasheet. Something
along the lines of Jonathan's 'flattish to a wide range of frequencies'
description.

>  
>  What:		/sys/.../events/in_proximity_thresh_either_runningperiod
>  KernelVersion:	6.6

Re: [PATCH RESEND v3 06/17] Documentation: ABI: add wideband filter type to sysfs-bus-iio

[Jonathan Cameron]

On Thu, 20 Feb 2025 15:28:09 -0600
David Lechner <dlechner@baylibre.com> wrote:

> On 2/12/25 12:16 PM, Jonathan Santos wrote:
> > The Wideband Low Ripple filter is used for AD7768-1 Driver.
> > Document wideband filter option into filter_type_available
> > attribute.
> > 
> > Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com>
> > ---
> > v3 Changes:
> > * None, since we still did not agree on a better name for this filter type.
> >   
> 
> I'm convinced at this point that "wideband" is fine.
> 
> > v2 Changes:
> > * Removed FIR mentions.
> > ---
> >  Documentation/ABI/testing/sysfs-bus-iio | 2 ++
> >  1 file changed, 2 insertions(+)
> > 
> > diff --git a/Documentation/ABI/testing/sysfs-bus-iio b/Documentation/ABI/testing/sysfs-bus-iio
> > index f83bd6829285..9b879e7732cd 100644
> > --- a/Documentation/ABI/testing/sysfs-bus-iio
> > +++ b/Documentation/ABI/testing/sysfs-bus-iio
> > @@ -2291,6 +2291,8 @@ Description:
> >  		* "sinc3+pf2" - Sinc3 + device specific Post Filter 2.
> >  		* "sinc3+pf3" - Sinc3 + device specific Post Filter 3.
> >  		* "sinc3+pf4" - Sinc3 + device specific Post Filter 4.
> > +		* "wideband" - filter with wideband low ripple passband
> > +		  and sharp transition band.  
> 
> The description could perhaps be made a bit more generic though
> instead of using specifics from the AD7768-1 datasheet. Something
> along the lines of Jonathan's 'flattish to a wide range of frequencies'
> description.

That is sort of what what low ripple passband and sharp transition band means
but with technical (sounding :) terms.  The only missing bit is it isn't
a narrow pass filter.


> 
> >  
> >  What:		/sys/.../events/in_proximity_thresh_either_runningperiod
> >  KernelVersion:	6.6  
> 

[PATCH RESEND v3 07/17] iio: adc: ad7768-1: remove unnecessary locking

[Jonathan Santos]

The current locking is only preventing a triggered buffer Transfer and a
debugfs register access from happening at the same time. If a register
access happens during a buffered read, the action is doomed to fail anyway,
since we need to write a magic value to exit continuous read mode.

Remove locking from the trigger handler and use
iio_device_claim_direct_mode() instead in the register access function.

Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com>
---
v3 Changes:
* Also removed the mutex_init and lock variable.

v2 Changes:
* New patch in v2. It replaces the guard(mutex) patch. 
---
 drivers/iio/adc/ad7768-1.c | 21 +++++++++------------
 1 file changed, 9 insertions(+), 12 deletions(-)

diff --git a/drivers/iio/adc/ad7768-1.c b/drivers/iio/adc/ad7768-1.c
index 2e2d50ccb744..f5509a0a36ab 100644
--- a/drivers/iio/adc/ad7768-1.c
+++ b/drivers/iio/adc/ad7768-1.c
@@ -154,7 +154,6 @@ static const struct iio_chan_spec ad7768_channels[] = {
 struct ad7768_state {
 	struct spi_device *spi;
 	struct regulator *vref;
-	struct mutex lock;
 	struct clk *mclk;
 	unsigned int mclk_freq;
 	unsigned int samp_freq;
@@ -256,18 +255,21 @@ static int ad7768_reg_access(struct iio_dev *indio_dev,
 	struct ad7768_state *st = iio_priv(indio_dev);
 	int ret;
 
-	mutex_lock(&st->lock);
+	ret = iio_device_claim_direct_mode(indio_dev);
+	if (ret)
+		return ret;
+
 	if (readval) {
 		ret = ad7768_spi_reg_read(st, reg, 1);
 		if (ret < 0)
-			goto err_unlock;
+			goto err_release;
 		*readval = ret;
 		ret = 0;
 	} else {
 		ret = ad7768_spi_reg_write(st, reg, writeval);
 	}
-err_unlock:
-	mutex_unlock(&st->lock);
+err_release:
+	iio_device_release_direct_mode(indio_dev);
 
 	return ret;
 }
@@ -471,18 +473,15 @@ static irqreturn_t ad7768_trigger_handler(int irq, void *p)
 	struct ad7768_state *st = iio_priv(indio_dev);
 	int ret;
 
-	mutex_lock(&st->lock);
-
 	ret = spi_read(st->spi, &st->data.scan.chan, 3);
 	if (ret < 0)
-		goto err_unlock;
+		goto out;
 
 	iio_push_to_buffers_with_timestamp(indio_dev, &st->data.scan,
 					   iio_get_time_ns(indio_dev));
 
-err_unlock:
+out:
 	iio_trigger_notify_done(indio_dev->trig);
-	mutex_unlock(&st->lock);
 
 	return IRQ_HANDLED;
 }
@@ -611,8 +610,6 @@ static int ad7768_probe(struct spi_device *spi)
 
 	st->mclk_freq = clk_get_rate(st->mclk);
 
-	mutex_init(&st->lock);
-
 	indio_dev->channels = ad7768_channels;
 	indio_dev->num_channels = ARRAY_SIZE(ad7768_channels);
 	indio_dev->name = spi_get_device_id(spi)->name;
-- 
2.34.1

Re: [PATCH RESEND v3 07/17] iio: adc: ad7768-1: remove unnecessary locking

[David Lechner]

On 2/12/25 12:17 PM, Jonathan Santos wrote:
> The current locking is only preventing a triggered buffer Transfer and a
> debugfs register access from happening at the same time. If a register
> access happens during a buffered read, the action is doomed to fail anyway,
> since we need to write a magic value to exit continuous read mode.
> 
> Remove locking from the trigger handler and use
> iio_device_claim_direct_mode() instead in the register access function.
> 
> Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com>
> ---
Reviewed-by: David Lechner <dlechner@baylibre.com>

[PATCH RESEND v3 08/17] iio: adc: ad7768-1: convert driver to use regmap

[Jonathan Santos]

Convert the AD7768-1 driver to use the regmap API for register
access. This change simplifies and standardizes register interactions,
reducing code duplication and improving maintainability.

Create two regmap configurations, one for 8-bit register values and
other for 24-bit register values.

Since we are using regmap now, define the remaining registers from 0x32
to 0x34.

Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com>
---
v3 Changes:
* Included a second register map for the 24-bit register values.
* Added register tables to separate the 24-bit from the 8-bit values.

v2 Changes:
* New patch in v2.
---
 drivers/iio/adc/ad7768-1.c | 148 +++++++++++++++++++++++++------------
 1 file changed, 101 insertions(+), 47 deletions(-)

diff --git a/drivers/iio/adc/ad7768-1.c b/drivers/iio/adc/ad7768-1.c
index f5509a0a36ab..64d123b52b02 100644
--- a/drivers/iio/adc/ad7768-1.c
+++ b/drivers/iio/adc/ad7768-1.c
@@ -12,6 +12,7 @@
 #include <linux/gpio/consumer.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
+#include <linux/regmap.h>
 #include <linux/regulator/consumer.h>
 #include <linux/sysfs.h>
 #include <linux/spi/spi.h>
@@ -59,6 +60,9 @@
 #define AD7768_REG_ADC_DIAG_STATUS	0x2F
 #define AD7768_REG_DIG_DIAG_STATUS	0x30
 #define AD7768_REG_MCLK_COUNTER		0x31
+#define AD7768_REG_COEFF_CONTROL	0x32
+#define AD7768_REG_COEFF_DATA		0x33
+#define AD7768_REG_ACCESS_KEY		0x34
 
 /* AD7768_REG_POWER_CLOCK */
 #define AD7768_PWR_MCLK_DIV_MSK		GENMASK(5, 4)
@@ -153,6 +157,8 @@ static const struct iio_chan_spec ad7768_channels[] = {
 
 struct ad7768_state {
 	struct spi_device *spi;
+	struct regmap *regmap;
+	struct regmap *regmap24;
 	struct regulator *vref;
 	struct clk *mclk;
 	unsigned int mclk_freq;
@@ -175,46 +181,76 @@ struct ad7768_state {
 	} data __aligned(IIO_DMA_MINALIGN);
 };
 
-static int ad7768_spi_reg_read(struct ad7768_state *st, unsigned int addr,
-			       unsigned int len)
-{
-	unsigned int shift;
-	int ret;
+static const struct regmap_range ad7768_regmap_rd_ranges[] = {
+	regmap_reg_range(AD7768_REG_CHIP_TYPE, AD7768_REG_DIG_DIAG_ENABLE),
+	regmap_reg_range(AD7768_REG_MASTER_STATUS, AD7768_REG_COEFF_CONTROL),
+	regmap_reg_range(AD7768_REG_ACCESS_KEY, AD7768_REG_ACCESS_KEY),
+};
 
-	shift = 32 - (8 * len);
-	st->data.d8[0] = AD7768_RD_FLAG_MSK(addr);
+static const struct regmap_access_table ad7768_regmap_rd_table = {
+	.yes_ranges = ad7768_regmap_rd_ranges,
+	.n_yes_ranges = ARRAY_SIZE(ad7768_regmap_rd_ranges),
+};
 
-	ret = spi_write_then_read(st->spi, st->data.d8, 1,
-				  &st->data.d32, len);
-	if (ret < 0)
-		return ret;
+static const struct regmap_range ad7768_regmap_wr_ranges[] = {
+	regmap_reg_range(AD7768_REG_SCRATCH_PAD, AD7768_REG_SCRATCH_PAD),
+	regmap_reg_range(AD7768_REG_INTERFACE_FORMAT, AD7768_REG_GPIO_WRITE),
+	regmap_reg_range(AD7768_REG_OFFSET_HI, AD7768_REG_DIG_DIAG_ENABLE),
+	regmap_reg_range(AD7768_REG_SPI_DIAG_STATUS, AD7768_REG_SPI_DIAG_STATUS),
+	regmap_reg_range(AD7768_REG_COEFF_CONTROL, AD7768_REG_COEFF_CONTROL),
+};
 
-	return (be32_to_cpu(st->data.d32) >> shift);
-}
+static const struct regmap_access_table ad7768_regmap_wr_table = {
+	.yes_ranges = ad7768_regmap_wr_ranges,
+	.n_yes_ranges = ARRAY_SIZE(ad7768_regmap_wr_ranges),
+};
 
-static int ad7768_spi_reg_write(struct ad7768_state *st,
-				unsigned int addr,
-				unsigned int val)
-{
-	st->data.d8[0] = AD7768_WR_FLAG_MSK(addr);
-	st->data.d8[1] = val & 0xFF;
+static const struct regmap_config ad7768_regmap_config = {
+	.name = "ad7768-1-8",
+	.reg_bits = 8,
+	.val_bits = 8,
+	.read_flag_mask = BIT(6),
+	.rd_table = &ad7768_regmap_rd_table,
+	.wr_table = &ad7768_regmap_wr_table,
+	.max_register = AD7768_REG_ACCESS_KEY,
+	.use_single_write = true,
+	.use_single_read = true,
+};
 
-	return spi_write(st->spi, st->data.d8, 2);
-}
+static const struct regmap_range ad7768_regmap24_rd_ranges[] = {
+	regmap_reg_range(AD7768_REG_ADC_DATA, AD7768_REG_ADC_DATA),
+	regmap_reg_range(AD7768_REG_COEFF_DATA, AD7768_REG_COEFF_DATA),
+};
 
-static int ad7768_set_mode(struct ad7768_state *st,
-			   enum ad7768_conv_mode mode)
-{
-	int regval;
+static const struct regmap_access_table ad7768_regmap24_rd_table = {
+	.yes_ranges = ad7768_regmap24_rd_ranges,
+	.n_yes_ranges = ARRAY_SIZE(ad7768_regmap24_rd_ranges),
+};
 
-	regval = ad7768_spi_reg_read(st, AD7768_REG_CONVERSION, 1);
-	if (regval < 0)
-		return regval;
+static const struct regmap_range ad7768_regmap24_wr_ranges[] = {
+	regmap_reg_range(AD7768_REG_COEFF_DATA, AD7768_REG_COEFF_DATA),
+};
 
-	regval &= ~AD7768_CONV_MODE_MSK;
-	regval |= AD7768_CONV_MODE(mode);
+static const struct regmap_access_table ad7768_regmap24_wr_table = {
+	.yes_ranges = ad7768_regmap24_wr_ranges,
+	.n_yes_ranges = ARRAY_SIZE(ad7768_regmap24_wr_ranges),
+};
+
+static const struct regmap_config ad7768_regmap24_config = {
+	.name = "ad7768-1-24",
+	.reg_bits = 8,
+	.val_bits = 24,
+	.read_flag_mask = BIT(6),
+	.rd_table = &ad7768_regmap24_rd_table,
+	.wr_table = &ad7768_regmap24_wr_table,
+	.max_register = AD7768_REG_COEFF_DATA,
+};
 
-	return ad7768_spi_reg_write(st, AD7768_REG_CONVERSION, regval);
+static int ad7768_set_mode(struct ad7768_state *st,
+			   enum ad7768_conv_mode mode)
+{
+	return regmap_update_bits(st->regmap, AD7768_REG_CONVERSION,
+				 AD7768_CONV_MODE_MSK, AD7768_CONV_MODE(mode));
 }
 
 static int ad7768_scan_direct(struct iio_dev *indio_dev)
@@ -233,9 +269,10 @@ static int ad7768_scan_direct(struct iio_dev *indio_dev)
 	if (!ret)
 		return -ETIMEDOUT;
 
-	readval = ad7768_spi_reg_read(st, AD7768_REG_ADC_DATA, 3);
-	if (readval < 0)
-		return readval;
+	ret = regmap_read(st->regmap24, AD7768_REG_ADC_DATA, &readval);
+	if (ret)
+		return ret;
+
 	/*
 	 * Any SPI configuration of the AD7768-1 can only be
 	 * performed in continuous conversion mode.
@@ -260,15 +297,21 @@ static int ad7768_reg_access(struct iio_dev *indio_dev,
 		return ret;
 
 	if (readval) {
-		ret = ad7768_spi_reg_read(st, reg, 1);
-		if (ret < 0)
-			goto err_release;
-		*readval = ret;
-		ret = 0;
+		if (regmap_check_range_table(st->regmap, reg, &ad7768_regmap_rd_table))
+			ret = regmap_read(st->regmap, reg, readval);
+
+		if (regmap_check_range_table(st->regmap24, reg, &ad7768_regmap24_rd_table))
+			ret = regmap_read(st->regmap24, reg, readval);
+
 	} else {
-		ret = ad7768_spi_reg_write(st, reg, writeval);
+		if (regmap_check_range_table(st->regmap, reg, &ad7768_regmap_wr_table))
+			ret = regmap_write(st->regmap, reg, writeval);
+
+		if (regmap_check_range_table(st->regmap24, reg, &ad7768_regmap24_wr_table))
+			ret = regmap_write(st->regmap24, reg, writeval);
+
 	}
-err_release:
+
 	iio_device_release_direct_mode(indio_dev);
 
 	return ret;
@@ -285,7 +328,7 @@ static int ad7768_set_dig_fil(struct ad7768_state *st,
 	else
 		mode = AD7768_DIG_FIL_DEC_RATE(dec_rate);
 
-	ret = ad7768_spi_reg_write(st, AD7768_REG_DIGITAL_FILTER, mode);
+	ret = regmap_write(st->regmap, AD7768_REG_DIGITAL_FILTER, mode);
 	if (ret < 0)
 		return ret;
 
@@ -322,7 +365,7 @@ static int ad7768_set_freq(struct ad7768_state *st,
 	 */
 	pwr_mode = AD7768_PWR_MCLK_DIV(ad7768_clk_config[idx].mclk_div) |
 		   AD7768_PWR_PWRMODE(ad7768_clk_config[idx].pwrmode);
-	ret = ad7768_spi_reg_write(st, AD7768_REG_POWER_CLOCK, pwr_mode);
+	ret = regmap_write(st->regmap, AD7768_REG_POWER_CLOCK, pwr_mode);
 	if (ret < 0)
 		return ret;
 
@@ -449,11 +492,11 @@ static int ad7768_setup(struct ad7768_state *st)
 	 * to 10. When the sequence is detected, the reset occurs.
 	 * See the datasheet, page 70.
 	 */
-	ret = ad7768_spi_reg_write(st, AD7768_REG_SYNC_RESET, 0x3);
+	ret = regmap_write(st->regmap, AD7768_REG_SYNC_RESET, 0x3);
 	if (ret)
 		return ret;
 
-	ret = ad7768_spi_reg_write(st, AD7768_REG_SYNC_RESET, 0x2);
+	ret = regmap_write(st->regmap, AD7768_REG_SYNC_RESET, 0x2);
 	if (ret)
 		return ret;
 
@@ -508,18 +551,19 @@ static int ad7768_buffer_postenable(struct iio_dev *indio_dev)
 	 * continuous read mode. Subsequent data reads do not require an
 	 * initial 8-bit write to query the ADC_DATA register.
 	 */
-	return ad7768_spi_reg_write(st, AD7768_REG_INTERFACE_FORMAT, 0x01);
+	return regmap_write(st->regmap, AD7768_REG_INTERFACE_FORMAT, 0x01);
 }
 
 static int ad7768_buffer_predisable(struct iio_dev *indio_dev)
 {
 	struct ad7768_state *st = iio_priv(indio_dev);
+	unsigned int unused;
 
 	/*
 	 * To exit continuous read mode, perform a single read of the ADC_DATA
 	 * reg (0x2C), which allows further configuration of the device.
 	 */
-	return ad7768_spi_reg_read(st, AD7768_REG_ADC_DATA, 3);
+	return regmap_read(st->regmap, AD7768_REG_ADC_DATA, &unused);
 }
 
 static const struct iio_buffer_setup_ops ad7768_buffer_ops = {
@@ -590,6 +634,16 @@ static int ad7768_probe(struct spi_device *spi)
 
 	st->spi = spi;
 
+	st->regmap = devm_regmap_init_spi(spi, &ad7768_regmap_config);
+	if (IS_ERR(st->regmap))
+		return dev_err_probe(&spi->dev, PTR_ERR(st->regmap),
+				     "Failed to initialize regmap");
+
+	st->regmap24 = devm_regmap_init_spi(spi, &ad7768_regmap24_config);
+	if (IS_ERR(st->regmap24))
+		return dev_err_probe(&spi->dev, PTR_ERR(st->regmap24),
+				     "Failed to initialize regmap24");
+
 	st->vref = devm_regulator_get(&spi->dev, "vref");
 	if (IS_ERR(st->vref))
 		return PTR_ERR(st->vref);
-- 
2.34.1

Re: [PATCH RESEND v3 08/17] iio: adc: ad7768-1: convert driver to use regmap

[Jonathan Cameron]

On Wed, 12 Feb 2025 15:17:16 -0300
Jonathan Santos <Jonathan.Santos@analog.com> wrote:

> Convert the AD7768-1 driver to use the regmap API for register
> access. This change simplifies and standardizes register interactions,
> reducing code duplication and improving maintainability.
> 
> Create two regmap configurations, one for 8-bit register values and
> other for 24-bit register values.
> 
> Since we are using regmap now, define the remaining registers from 0x32
> to 0x34.
> 
> Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com>
Looks good.  Just one passing suggestion that might reduce chance of
future bugs a tiny bit.  Any bug that uses the wrong regmap should show
up quickly in testing but none the less, maybe naming can help too.

Not an important comment though so don't respin the series just for this.

Jonathan


>  
>  static int ad7768_scan_direct(struct iio_dev *indio_dev)
> @@ -233,9 +269,10 @@ static int ad7768_scan_direct(struct iio_dev *indio_dev)
>  	if (!ret)
>  		return -ETIMEDOUT;
>  
> -	readval = ad7768_spi_reg_read(st, AD7768_REG_ADC_DATA, 3);
> -	if (readval < 0)
> -		return readval;
> +	ret = regmap_read(st->regmap24, AD7768_REG_ADC_DATA, &readval);
I wonder if it is worth reducing the possibility of reading the register
via the wrong regmap by changing the defintion to
AD7768_REG24_ADC_DATA or something along those lines?

> +	if (ret)
> +		return ret;
> +

Re: [PATCH RESEND v3 08/17] iio: adc: ad7768-1: convert driver to use regmap

[David Lechner]

On 2/12/25 12:17 PM, Jonathan Santos wrote:
> Convert the AD7768-1 driver to use the regmap API for register
> access. This change simplifies and standardizes register interactions,
> reducing code duplication and improving maintainability.
> 
> Create two regmap configurations, one for 8-bit register values and
> other for 24-bit register values.
> 
> Since we are using regmap now, define the remaining registers from 0x32
> to 0x34.
> 
> Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com>
> ---
> v3 Changes:
> * Included a second register map for the 24-bit register values.
> * Added register tables to separate the 24-bit from the 8-bit values.
> 
> v2 Changes:
> * New patch in v2.
> ---

Should also add a `select REGMAP_SPI` line to the Kconfig
for this driver to avoid compile errors for random configs.

>  drivers/iio/adc/ad7768-1.c | 148 +++++++++++++++++++++++++------------
>  1 file changed, 101 insertions(+), 47 deletions(-)
> 


...

> @@ -260,15 +297,21 @@ static int ad7768_reg_access(struct iio_dev *indio_dev,
>  		return ret;
>  


I think we should set ret = -EINVAL; here, otherwise the ret from above
can survive and we return 0 even though no read or write was done if
the requested register was not valid.

>  	if (readval) {
> -		ret = ad7768_spi_reg_read(st, reg, 1);
> -		if (ret < 0)
> -			goto err_release;
> -		*readval = ret;
> -		ret = 0;
> +		if (regmap_check_range_table(st->regmap, reg, &ad7768_regmap_rd_table))
> +			ret = regmap_read(st->regmap, reg, readval);
> +
> +		if (regmap_check_range_table(st->regmap24, reg, &ad7768_regmap24_rd_table))
> +			ret = regmap_read(st->regmap24, reg, readval);
> +
>  	} else {
> -		ret = ad7768_spi_reg_write(st, reg, writeval);
> +		if (regmap_check_range_table(st->regmap, reg, &ad7768_regmap_wr_table))
> +			ret = regmap_write(st->regmap, reg, writeval);
> +
> +		if (regmap_check_range_table(st->regmap24, reg, &ad7768_regmap24_wr_table))
> +			ret = regmap_write(st->regmap24, reg, writeval);
> +
>  	}
> -err_release:
> +
>  	iio_device_release_direct_mode(indio_dev);
>  
>  	return ret;

[PATCH RESEND v3 09/17] iio: adc: ad7768-1: Add reset gpio

[Jonathan Santos]

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

Depending on the controller, the default state of a gpio can vary. This
change excludes the probability that the dafult state of the ADC reset
gpio will be HIGH if it will be passed as reference in the devicetree.

Reviewed-by: David Lechner <dlechner@baylibre.com>
Reviewed-by: Marcelo Schmitt <marcelo.schmitt@analog.com>
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>
---
v3 Changes:
* fixed SoB order.
* increased delay after finishing the reset action to 200us, as the
  datasheet recommends.

v2 Changes:
* Replaced usleep_range() for fsleep() and gpiod_direction_output() for 
  gpiod_set_value_cansleep().
* Reset via SPI register is performed if the Reset GPIO is not defined. 
---
 drivers/iio/adc/ad7768-1.c | 36 ++++++++++++++++++++++++------------
 1 file changed, 24 insertions(+), 12 deletions(-)

diff --git a/drivers/iio/adc/ad7768-1.c b/drivers/iio/adc/ad7768-1.c
index 64d123b52b02..5ee29f9813ce 100644
--- a/drivers/iio/adc/ad7768-1.c
+++ b/drivers/iio/adc/ad7768-1.c
@@ -166,6 +166,7 @@ struct ad7768_state {
 	struct completion completion;
 	struct iio_trigger *trig;
 	struct gpio_desc *gpio_sync_in;
+	struct gpio_desc *gpio_reset;
 	const char *labels[ARRAY_SIZE(ad7768_channels)];
 	/*
 	 * DMA (thus cache coherency maintenance) may require the
@@ -486,19 +487,30 @@ static int ad7768_setup(struct ad7768_state *st)
 {
 	int ret;
 
-	/*
-	 * Two writes to the SPI_RESET[1:0] bits are required to initiate
-	 * a software reset. The bits must first be set to 11, and then
-	 * to 10. When the sequence is detected, the reset occurs.
-	 * See the datasheet, page 70.
-	 */
-	ret = regmap_write(st->regmap, AD7768_REG_SYNC_RESET, 0x3);
-	if (ret)
-		return ret;
+	st->gpio_reset = devm_gpiod_get_optional(&st->spi->dev, "reset",
+						 GPIOD_OUT_HIGH);
+	if (IS_ERR(st->gpio_reset))
+		return PTR_ERR(st->gpio_reset);
 
-	ret = regmap_write(st->regmap, AD7768_REG_SYNC_RESET, 0x2);
-	if (ret)
-		return ret;
+	if (st->gpio_reset) {
+		fsleep(10);
+		gpiod_set_value_cansleep(st->gpio_reset, 0);
+		fsleep(200);
+	} else {
+		/*
+		 * Two writes to the SPI_RESET[1:0] bits are required to initiate
+		 * a software reset. The bits must first be set to 11, and then
+		 * to 10. When the sequence is detected, the reset occurs.
+		 * See the datasheet, page 70.
+		 */
+		ret = regmap_write(st->regmap, AD7768_REG_SYNC_RESET, 0x3);
+		if (ret)
+			return ret;
+
+		ret = regmap_write(st->regmap, AD7768_REG_SYNC_RESET, 0x2);
+		if (ret)
+			return ret;
+	}
 
 	st->gpio_sync_in = devm_gpiod_get(&st->spi->dev, "adi,sync-in",
 					  GPIOD_OUT_LOW);
-- 
2.34.1

[PATCH RESEND v3 10/17] iio: adc: ad7768-1: Move buffer allocation to a separate function

[Jonathan Santos]

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

This change moves the buffer allocation in a separate function, making
space for adding another type of iio buffer if needed.

Signed-off-by: Sergiu Cuciurean <sergiu.cuciurean@analog.com>
Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com>
---
v3 Changes:
* Added missing SoB.

v2 Changes:
* Interrupt and completion moved out from ad7768_triggered_buffer_alloc(). 
---
 drivers/iio/adc/ad7768-1.c | 44 ++++++++++++++++++++++----------------
 1 file changed, 26 insertions(+), 18 deletions(-)

diff --git a/drivers/iio/adc/ad7768-1.c b/drivers/iio/adc/ad7768-1.c
index 5ee29f9813ce..378245bce199 100644
--- a/drivers/iio/adc/ad7768-1.c
+++ b/drivers/iio/adc/ad7768-1.c
@@ -618,6 +618,31 @@ static int ad7768_set_channel_label(struct iio_dev *indio_dev,
 	return 0;
 }
 
+static int ad7768_triggered_buffer_alloc(struct iio_dev *indio_dev)
+{
+	struct ad7768_state *st = iio_priv(indio_dev);
+	int ret;
+
+	st->trig = devm_iio_trigger_alloc(indio_dev->dev.parent, "%s-dev%d",
+					  indio_dev->name,
+					  iio_device_id(indio_dev));
+	if (!st->trig)
+		return -ENOMEM;
+
+	st->trig->ops = &ad7768_trigger_ops;
+	iio_trigger_set_drvdata(st->trig, indio_dev);
+	ret = devm_iio_trigger_register(indio_dev->dev.parent, st->trig);
+	if (ret)
+		return ret;
+
+	indio_dev->trig = iio_trigger_get(st->trig);
+
+	return devm_iio_triggered_buffer_setup(indio_dev->dev.parent, indio_dev,
+					       &iio_pollfunc_store_time,
+					       &ad7768_trigger_handler,
+					       &ad7768_buffer_ops);
+}
+
 static int ad7768_probe(struct spi_device *spi)
 {
 	struct ad7768_state *st;
@@ -688,20 +713,6 @@ static int ad7768_probe(struct spi_device *spi)
 		return ret;
 	}
 
-	st->trig = devm_iio_trigger_alloc(&spi->dev, "%s-dev%d",
-					  indio_dev->name,
-					  iio_device_id(indio_dev));
-	if (!st->trig)
-		return -ENOMEM;
-
-	st->trig->ops = &ad7768_trigger_ops;
-	iio_trigger_set_drvdata(st->trig, indio_dev);
-	ret = devm_iio_trigger_register(&spi->dev, st->trig);
-	if (ret)
-		return ret;
-
-	indio_dev->trig = iio_trigger_get(st->trig);
-
 	init_completion(&st->completion);
 
 	ret = ad7768_set_channel_label(indio_dev, ARRAY_SIZE(ad7768_channels));
@@ -715,10 +726,7 @@ static int ad7768_probe(struct spi_device *spi)
 	if (ret)
 		return ret;
 
-	ret = devm_iio_triggered_buffer_setup(&spi->dev, indio_dev,
-					      &iio_pollfunc_store_time,
-					      &ad7768_trigger_handler,
-					      &ad7768_buffer_ops);
+	ret = ad7768_triggered_buffer_alloc(indio_dev);
 	if (ret)
 		return ret;
 
-- 
2.34.1

Re: [PATCH RESEND v3 10/17] iio: adc: ad7768-1: Move buffer allocation to a separate function

[David Lechner]

On 2/12/25 12:17 PM, Jonathan Santos wrote:
> From: Sergiu Cuciurean <sergiu.cuciurean@analog.com>
> 
> This change moves the buffer allocation in a separate function, making
> space for adding another type of iio buffer if needed.
> 
> Signed-off-by: Sergiu Cuciurean <sergiu.cuciurean@analog.com>
> Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com>
> ---
Reviewed-by: David Lechner <dlechner@baylibre.com>

[PATCH RESEND v3 11/17] 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.

Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com>
---
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/ad7768-1.c | 138 +++++++++++++++++++++++++++++++++++++
 1 file changed, 138 insertions(+)

diff --git a/drivers/iio/adc/ad7768-1.c b/drivers/iio/adc/ad7768-1.c
index 378245bce199..a359cd8fceca 100644
--- a/drivers/iio/adc/ad7768-1.c
+++ b/drivers/iio/adc/ad7768-1.c
@@ -12,8 +12,10 @@
 #include <linux/gpio/consumer.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
+#include <linux/of.h>
 #include <linux/regmap.h>
 #include <linux/regulator/consumer.h>
+#include <linux/regulator/driver.h>
 #include <linux/sysfs.h>
 #include <linux/spi/spi.h>
 
@@ -80,9 +82,15 @@
 #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_RD_FLAG_MSK(x)		(BIT(6) | ((x) & 0x3F))
 #define AD7768_WR_FLAG_MSK(x)		((x) & 0x3F)
 
+#define AD7768_VCM_OFF			0x08
+
 enum ad7768_conv_mode {
 	AD7768_CONTINUOUS,
 	AD7768_ONE_SHOT,
@@ -160,6 +168,7 @@ struct ad7768_state {
 	struct regmap *regmap;
 	struct regmap *regmap24;
 	struct regulator *vref;
+	struct regulator_dev *vcm_rdev;
 	struct clk *mclk;
 	unsigned int mclk_freq;
 	unsigned int samp_freq;
@@ -643,6 +652,130 @@ static int ad7768_triggered_buffer_alloc(struct iio_dev *indio_dev)
 					       &ad7768_buffer_ops);
 }
 
+static int ad7768_vcm_enable(struct regulator_dev *rdev)
+{
+	struct ad7768_state *st = rdev_get_drvdata(rdev);
+	int ret, val;
+
+	if (!st)
+		return -EINVAL;
+
+	ret = regmap_read(st->regmap, AD7768_REG_ANALOG2, &val);
+	if (ret)
+		return ret;
+
+	/* if regulator is off, turn it on */
+	if (FIELD_GET(AD7768_REG_ANALOG2_VCM_MSK, val) == AD7768_VCM_OFF)
+		return regmap_update_bits(st->regmap, AD7768_REG_ANALOG2,
+					  AD7768_REG_ANALOG2_VCM_MSK, 0x00);
+
+	return 0;
+}
+
+static int ad7768_vcm_disable(struct regulator_dev *rdev)
+{
+	struct ad7768_state *st = rdev_get_drvdata(rdev);
+
+	if (!st)
+		return -EINVAL;
+
+	return regmap_update_bits(st->regmap, AD7768_REG_ANALOG2,
+				  AD7768_REG_ANALOG2_VCM_MSK, AD7768_VCM_OFF);
+}
+
+static int ad7768_vcm_is_enabled(struct regulator_dev *rdev)
+{
+	struct ad7768_state *st = rdev_get_drvdata(rdev);
+	int ret, val;
+
+	if (!st)
+		return -EINVAL;
+
+	ret = regmap_read(st->regmap, AD7768_REG_ANALOG2, &val);
+	if (ret)
+		return ret;
+
+	if (FIELD_GET(AD7768_REG_ANALOG2_VCM_MSK, val) == AD7768_VCM_OFF)
+		return 0;
+
+	return 1;
+}
+
+static int ad7768_set_voltage_sel(struct regulator_dev *rdev,
+				  unsigned int selector)
+{
+	unsigned int regval = AD7768_REG_ANALOG2_VCM(selector + 1);
+	struct ad7768_state *st = rdev_get_drvdata(rdev);
+
+	if (!st)
+		return -EINVAL;
+
+	return regmap_update_bits(st->regmap, AD7768_REG_ANALOG2,
+				  AD7768_REG_ANALOG2_VCM_MSK, regval);
+}
+
+static int ad7768_get_voltage_sel(struct regulator_dev *rdev)
+{
+	struct ad7768_state *st = rdev_get_drvdata(rdev);
+	int ret, val;
+
+	if (!st)
+		return -EINVAL;
+
+	ret = regmap_read(st->regmap, AD7768_REG_ANALOG2, &val);
+	if (ret)
+		return ret;
+
+	val = FIELD_GET(AD7768_REG_ANALOG2_VCM_MSK, val) - 1;
+	val = clamp(val, 0, 8);
+
+	return val;
+}
+
+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 = "vcm_output",
+	.of_match = of_match_ptr("vcm_output"),
+	.regulators_node = of_match_ptr("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 regulator_config config = {
+		.dev = dev,
+		.driver_data = st,
+	};
+
+	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;
@@ -707,6 +840,11 @@ 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);
+	if (ret)
+		return ret;
+
 	ret = ad7768_setup(st);
 	if (ret < 0) {
 		dev_err(&spi->dev, "AD7768 setup failed\n");
-- 
2.34.1

Re: [PATCH RESEND v3 11/17] iio: adc: ad7768-1: add regulator to control VCM output

[kernel test robot]

Hi Jonathan,

kernel test robot noticed the following build errors:

[auto build test ERROR on 5de07b8a24cf44cdb78adeab790704bf577c2c1d]

url:    https://github.com/intel-lab-lkp/linux/commits/Jonathan-Santos/iio-adc-ad7768-1-Fix-conversion-result-sign/20250213-022329
base:   5de07b8a24cf44cdb78adeab790704bf577c2c1d
patch link:    https://lore.kernel.org/r/3552833157f252f3b6813f0042059e858c90d53a.1739368121.git.Jonathan.Santos%40analog.com
patch subject: [PATCH RESEND v3 11/17] iio: adc: ad7768-1: add regulator to control VCM output
config: loongarch-randconfig-002-20250214 (https://download.01.org/0day-ci/archive/20250214/202502140626.PzhgxFMq-lkp@intel.com/config)
compiler: loongarch64-linux-gcc (GCC) 14.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250214/202502140626.PzhgxFMq-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202502140626.PzhgxFMq-lkp@intel.com/

All errors (new ones prefixed by >>, old ones prefixed by <<):

>> ERROR: modpost: "rdev_get_drvdata" [drivers/iio/adc/ad7768-1.ko] undefined!
>> ERROR: modpost: "devm_regulator_register" [drivers/iio/adc/ad7768-1.ko] undefined!
>> ERROR: modpost: "regulator_list_voltage_table" [drivers/iio/adc/ad7768-1.ko] undefined!

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

Re: [PATCH RESEND v3 11/17] iio: adc: ad7768-1: add regulator to control VCM output

[Jonathan Cameron]

On Wed, 12 Feb 2025 15:17:54 -0300
Jonathan Santos <Jonathan.Santos@analog.com> wrote:

> 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.
> 
> Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com>

Whilst this is a pretty simple regulator driver, I would still +CC
the maintainers for regulators in same way you would for
a standalone regulator driver.

+CC Liam and Mark


> ---
> 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/ad7768-1.c | 138 +++++++++++++++++++++++++++++++++++++
>  1 file changed, 138 insertions(+)
> 
> diff --git a/drivers/iio/adc/ad7768-1.c b/drivers/iio/adc/ad7768-1.c
> index 378245bce199..a359cd8fceca 100644
> --- a/drivers/iio/adc/ad7768-1.c
> +++ b/drivers/iio/adc/ad7768-1.c
> @@ -12,8 +12,10 @@
>  #include <linux/gpio/consumer.h>
>  #include <linux/kernel.h>
>  #include <linux/module.h>
> +#include <linux/of.h>
>  #include <linux/regmap.h>
>  #include <linux/regulator/consumer.h>
> +#include <linux/regulator/driver.h>
>  #include <linux/sysfs.h>
>  #include <linux/spi/spi.h>
>  
> @@ -80,9 +82,15 @@
>  #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_RD_FLAG_MSK(x)		(BIT(6) | ((x) & 0x3F))
>  #define AD7768_WR_FLAG_MSK(x)		((x) & 0x3F)
>  
> +#define AD7768_VCM_OFF			0x08
> +
>  enum ad7768_conv_mode {
>  	AD7768_CONTINUOUS,
>  	AD7768_ONE_SHOT,
> @@ -160,6 +168,7 @@ struct ad7768_state {
>  	struct regmap *regmap;
>  	struct regmap *regmap24;
>  	struct regulator *vref;
> +	struct regulator_dev *vcm_rdev;
>  	struct clk *mclk;
>  	unsigned int mclk_freq;
>  	unsigned int samp_freq;
> @@ -643,6 +652,130 @@ static int ad7768_triggered_buffer_alloc(struct iio_dev *indio_dev)
>  					       &ad7768_buffer_ops);
>  }
>  
> +static int ad7768_vcm_enable(struct regulator_dev *rdev)
> +{
> +	struct ad7768_state *st = rdev_get_drvdata(rdev);
> +	int ret, val;
> +
> +	if (!st)
> +		return -EINVAL;
> +
> +	ret = regmap_read(st->regmap, AD7768_REG_ANALOG2, &val);
> +	if (ret)
> +		return ret;
> +
> +	/* if regulator is off, turn it on */
> +	if (FIELD_GET(AD7768_REG_ANALOG2_VCM_MSK, val) == AD7768_VCM_OFF)
> +		return regmap_update_bits(st->regmap, AD7768_REG_ANALOG2,
> +					  AD7768_REG_ANALOG2_VCM_MSK, 0x00);
> +
> +	return 0;
> +}
> +
> +static int ad7768_vcm_disable(struct regulator_dev *rdev)
> +{
> +	struct ad7768_state *st = rdev_get_drvdata(rdev);
> +
> +	if (!st)
> +		return -EINVAL;
> +
> +	return regmap_update_bits(st->regmap, AD7768_REG_ANALOG2,
> +				  AD7768_REG_ANALOG2_VCM_MSK, AD7768_VCM_OFF);
> +}
> +
> +static int ad7768_vcm_is_enabled(struct regulator_dev *rdev)
> +{
> +	struct ad7768_state *st = rdev_get_drvdata(rdev);
> +	int ret, val;
> +
> +	if (!st)
> +		return -EINVAL;
> +
> +	ret = regmap_read(st->regmap, AD7768_REG_ANALOG2, &val);
> +	if (ret)
> +		return ret;
> +
> +	if (FIELD_GET(AD7768_REG_ANALOG2_VCM_MSK, val) == AD7768_VCM_OFF)
> +		return 0;
> +
> +	return 1;
> +}
> +
> +static int ad7768_set_voltage_sel(struct regulator_dev *rdev,
> +				  unsigned int selector)
> +{
> +	unsigned int regval = AD7768_REG_ANALOG2_VCM(selector + 1);
> +	struct ad7768_state *st = rdev_get_drvdata(rdev);
> +
> +	if (!st)
> +		return -EINVAL;
> +
> +	return regmap_update_bits(st->regmap, AD7768_REG_ANALOG2,
> +				  AD7768_REG_ANALOG2_VCM_MSK, regval);
> +}
> +
> +static int ad7768_get_voltage_sel(struct regulator_dev *rdev)
> +{
> +	struct ad7768_state *st = rdev_get_drvdata(rdev);
> +	int ret, val;
> +
> +	if (!st)
> +		return -EINVAL;
> +
> +	ret = regmap_read(st->regmap, AD7768_REG_ANALOG2, &val);
> +	if (ret)
> +		return ret;
> +
> +	val = FIELD_GET(AD7768_REG_ANALOG2_VCM_MSK, val) - 1;
> +	val = clamp(val, 0, 8);
> +
> +	return val;
> +}
> +
> +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 = "vcm_output",
> +	.of_match = of_match_ptr("vcm_output"),
> +	.regulators_node = of_match_ptr("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 regulator_config config = {
> +		.dev = dev,
> +		.driver_data = st,
> +	};
> +
> +	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;
> @@ -707,6 +840,11 @@ 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);
> +	if (ret)
> +		return ret;
> +
>  	ret = ad7768_setup(st);
>  	if (ret < 0) {
>  		dev_err(&spi->dev, "AD7768 setup failed\n");

Re: [PATCH RESEND v3 11/17] iio: adc: ad7768-1: add regulator to control VCM output

[David Lechner]

On 2/12/25 12:17 PM, Jonathan Santos wrote:
> 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.
> 
> Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com>
> ---
> 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/ad7768-1.c | 138 +++++++++++++++++++++++++++++++++++++
>  1 file changed, 138 insertions(+)
> 
> diff --git a/drivers/iio/adc/ad7768-1.c b/drivers/iio/adc/ad7768-1.c
> index 378245bce199..a359cd8fceca 100644
> --- a/drivers/iio/adc/ad7768-1.c
> +++ b/drivers/iio/adc/ad7768-1.c
> @@ -12,8 +12,10 @@
>  #include <linux/gpio/consumer.h>
>  #include <linux/kernel.h>
>  #include <linux/module.h>
> +#include <linux/of.h>
>  #include <linux/regmap.h>
>  #include <linux/regulator/consumer.h>
> +#include <linux/regulator/driver.h>
>  #include <linux/sysfs.h>
>  #include <linux/spi/spi.h>
>  
> @@ -80,9 +82,15 @@
>  #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_RD_FLAG_MSK(x)		(BIT(6) | ((x) & 0x3F))
>  #define AD7768_WR_FLAG_MSK(x)		((x) & 0x3F)
>  
> +#define AD7768_VCM_OFF			0x08
> +
>  enum ad7768_conv_mode {
>  	AD7768_CONTINUOUS,
>  	AD7768_ONE_SHOT,
> @@ -160,6 +168,7 @@ struct ad7768_state {
>  	struct regmap *regmap;
>  	struct regmap *regmap24;
>  	struct regulator *vref;
> +	struct regulator_dev *vcm_rdev;
>  	struct clk *mclk;
>  	unsigned int mclk_freq;
>  	unsigned int samp_freq;
> @@ -643,6 +652,130 @@ static int ad7768_triggered_buffer_alloc(struct iio_dev *indio_dev)
>  					       &ad7768_buffer_ops);
>  }
>  
> +static int ad7768_vcm_enable(struct regulator_dev *rdev)
> +{
> +	struct ad7768_state *st = rdev_get_drvdata(rdev);
> +	int ret, val;
> +
> +	if (!st)
> +		return -EINVAL;

Do we need iio_device_claim_direct_mode() here to prevent accessing
registers on the ADC during a buffered read?

Same applies to other functions too.

> +
> +	ret = regmap_read(st->regmap, AD7768_REG_ANALOG2, &val);
> +	if (ret)
> +		return ret;
> +
> +	/* if regulator is off, turn it on */
> +	if (FIELD_GET(AD7768_REG_ANALOG2_VCM_MSK, val) == AD7768_VCM_OFF)

regmap_update_bits() already does this sort of check internally, so
open-coding it here is redundant.

> +		return regmap_update_bits(st->regmap, AD7768_REG_ANALOG2,
> +					  AD7768_REG_ANALOG2_VCM_MSK, 0x00);

Can be simplified with regmap_clear_bits().

> +
> +	return 0;
> +}
> +
> +static int ad7768_vcm_disable(struct regulator_dev *rdev)
> +{
> +	struct ad7768_state *st = rdev_get_drvdata(rdev);
> +
> +	if (!st)
> +		return -EINVAL;
> +
> +	return regmap_update_bits(st->regmap, AD7768_REG_ANALOG2,
> +				  AD7768_REG_ANALOG2_VCM_MSK, AD7768_VCM_OFF);
> +}
> +
> +static int ad7768_vcm_is_enabled(struct regulator_dev *rdev)
> +{
> +	struct ad7768_state *st = rdev_get_drvdata(rdev);
> +	int ret, val;
> +
> +	if (!st)
> +		return -EINVAL;
> +
> +	ret = regmap_read(st->regmap, AD7768_REG_ANALOG2, &val);
> +	if (ret)
> +		return ret;
> +
> +	if (FIELD_GET(AD7768_REG_ANALOG2_VCM_MSK, val) == AD7768_VCM_OFF)
> +		return 0;

Could skip the if and just return directly.

> +
> +	return 1;
> +}
> +
> +static int ad7768_set_voltage_sel(struct regulator_dev *rdev,
> +				  unsigned int selector)
> +{
> +	unsigned int regval = AD7768_REG_ANALOG2_VCM(selector + 1);
> +	struct ad7768_state *st = rdev_get_drvdata(rdev);
> +
> +	if (!st)
> +		return -EINVAL;
> +
> +	return regmap_update_bits(st->regmap, AD7768_REG_ANALOG2,
> +				  AD7768_REG_ANALOG2_VCM_MSK, regval);
> +}
> +
> +static int ad7768_get_voltage_sel(struct regulator_dev *rdev)
> +{
> +	struct ad7768_state *st = rdev_get_drvdata(rdev);
> +	int ret, val;
> +
> +	if (!st)
> +		return -EINVAL;
> +
> +	ret = regmap_read(st->regmap, AD7768_REG_ANALOG2, &val);
> +	if (ret)
> +		return ret;
> +
> +	val = FIELD_GET(AD7768_REG_ANALOG2_VCM_MSK, val) - 1;
> +	val = clamp(val, 0, 8);
> +
> +	return val;
> +}
> +
> +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 = "vcm_output",

It looks like this is typically a datasheet name, like

"AD7768-1 VCM"

> +	.of_match = of_match_ptr("vcm_output"),

"vcm-output" as in DT bindings review.

> +	.regulators_node = of_match_ptr("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 regulator_config config = {
> +		.dev = dev,
> +		.driver_data = st,
> +	};
> +
> +	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;
> @@ -707,6 +840,11 @@ 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);
> +	if (ret)
> +		return ret;
> +
>  	ret = ad7768_setup(st);
>  	if (ret < 0) {
>  		dev_err(&spi->dev, "AD7768 setup failed\n");

[PATCH RESEND v3 12/17] 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.

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

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>
---
v3 Changes:
* Fixed SoB order.
* Added mising 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 | 143 ++++++++++++++++++++++++++++++++++++-
 1 file changed, 141 insertions(+), 2 deletions(-)

diff --git a/drivers/iio/adc/ad7768-1.c b/drivers/iio/adc/ad7768-1.c
index a359cd8fceca..afcc8678cf83 100644
--- a/drivers/iio/adc/ad7768-1.c
+++ b/drivers/iio/adc/ad7768-1.c
@@ -9,6 +9,8 @@
 #include <linux/delay.h>
 #include <linux/device.h>
 #include <linux/err.h>
+#include <linux/gpio.h>
+#include <linux/gpio/driver.h>
 #include <linux/gpio/consumer.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
@@ -86,6 +88,16 @@
 #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_RD_FLAG_MSK(x)		(BIT(6) | ((x) & 0x3F))
 #define AD7768_WR_FLAG_MSK(x)		((x) & 0x3F)
 
@@ -170,6 +182,7 @@ struct ad7768_state {
 	struct regulator *vref;
 	struct regulator_dev *vcm_rdev;
 	struct clk *mclk;
+	struct gpio_chip gpiochip;
 	unsigned int mclk_freq;
 	unsigned int samp_freq;
 	struct completion completion;
@@ -349,6 +362,124 @@ 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;
+
+	ret = iio_device_claim_direct_mode(indio_dev);
+	if (ret)
+		return ret;
+
+	ret = regmap_clear_bits(st->regmap, AD7768_REG_GPIO_CONTROL,
+				BIT(offset));
+	iio_device_release_direct_mode(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;
+
+	ret = iio_device_claim_direct_mode(indio_dev);
+	if (ret)
+		return ret;
+
+	ret = regmap_set_bits(st->regmap, AD7768_REG_GPIO_CONTROL,
+			      BIT(offset));
+	iio_device_release_direct_mode(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;
+
+	ret = iio_device_claim_direct_mode(indio_dev);
+	if (ret)
+		return ret;
+
+	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_mode(indio_dev);
+
+	return ret;
+}
+
+static void 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;
+
+	ret = iio_device_claim_direct_mode(indio_dev);
+	if (ret)
+		return;
+
+	ret = regmap_read(st->regmap, AD7768_REG_GPIO_CONTROL, &val);
+	if (ret)
+		goto err_release;
+
+	if (val & BIT(offset))
+		regmap_update_bits(st->regmap, AD7768_REG_GPIO_WRITE,
+				   BIT(offset), value << offset);
+
+err_release:
+	iio_device_release_direct_mode(indio_dev);
+}
+
+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 = ad7768_gpio_set,
+		.owner = THIS_MODULE,
+	};
+
+	return gpiochip_add_data(&st->gpiochip, indio_dev);
+}
+
 static int ad7768_set_freq(struct ad7768_state *st,
 			   unsigned int freq)
 {
@@ -492,8 +623,9 @@ 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",
@@ -526,6 +658,13 @@ 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 < 0)
+			return ret;
+	}
+
 	/* Set the default sampling frequency to 32000 kSPS */
 	return ad7768_set_freq(st, 32000);
 }
@@ -845,7 +984,7 @@ 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

Re: [PATCH RESEND v3 12/17] iio: adc: ad7768-1: Add GPIO controller support

[Jonathan Cameron]

On Wed, 12 Feb 2025 15:18:04 -0300
Jonathan Santos <Jonathan.Santos@analog.com> wrote:

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

Similar to previous.  +CC the gpio driver maintainers.
Whilst small part of this much larger driver, good to make sure
they have visibility and can choose whether to review or not.

+CC Linus, Bartosz and the linux-gpio list.
Probably also worth calling out in this patch description the reason we can't set
the GPIO state when in buffered mode as that won't be obvious to
anyone just reviewing the GPIO part of the driver.

> ---
> v3 Changes:
> * Fixed SoB order.
> * Added mising 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 | 143 ++++++++++++++++++++++++++++++++++++-
>  1 file changed, 141 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iio/adc/ad7768-1.c b/drivers/iio/adc/ad7768-1.c
> index a359cd8fceca..afcc8678cf83 100644
> --- a/drivers/iio/adc/ad7768-1.c
> +++ b/drivers/iio/adc/ad7768-1.c
> @@ -9,6 +9,8 @@
>  #include <linux/delay.h>
>  #include <linux/device.h>
>  #include <linux/err.h>
> +#include <linux/gpio.h>
> +#include <linux/gpio/driver.h>
>  #include <linux/gpio/consumer.h>
>  #include <linux/kernel.h>
>  #include <linux/module.h>
> @@ -86,6 +88,16 @@
>  #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_RD_FLAG_MSK(x)		(BIT(6) | ((x) & 0x3F))
>  #define AD7768_WR_FLAG_MSK(x)		((x) & 0x3F)
>  
> @@ -170,6 +182,7 @@ struct ad7768_state {
>  	struct regulator *vref;
>  	struct regulator_dev *vcm_rdev;
>  	struct clk *mclk;
> +	struct gpio_chip gpiochip;
>  	unsigned int mclk_freq;
>  	unsigned int samp_freq;
>  	struct completion completion;
> @@ -349,6 +362,124 @@ 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;
> +
> +	ret = iio_device_claim_direct_mode(indio_dev);
> +	if (ret)
> +		return ret;
> +
> +	ret = regmap_clear_bits(st->regmap, AD7768_REG_GPIO_CONTROL,
> +				BIT(offset));
> +	iio_device_release_direct_mode(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;
> +
> +	ret = iio_device_claim_direct_mode(indio_dev);
> +	if (ret)
> +		return ret;
> +
> +	ret = regmap_set_bits(st->regmap, AD7768_REG_GPIO_CONTROL,
> +			      BIT(offset));
> +	iio_device_release_direct_mode(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;
> +
> +	ret = iio_device_claim_direct_mode(indio_dev);
> +	if (ret)
> +		return ret;
> +
> +	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_mode(indio_dev);
> +
> +	return ret;
> +}
> +
> +static void 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;
> +
> +	ret = iio_device_claim_direct_mode(indio_dev);
> +	if (ret)
> +		return;
> +
> +	ret = regmap_read(st->regmap, AD7768_REG_GPIO_CONTROL, &val);
> +	if (ret)
> +		goto err_release;
> +
> +	if (val & BIT(offset))
> +		regmap_update_bits(st->regmap, AD7768_REG_GPIO_WRITE,
> +				   BIT(offset), value << offset);
> +
> +err_release:
> +	iio_device_release_direct_mode(indio_dev);
> +}
> +
> +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 = ad7768_gpio_set,
> +		.owner = THIS_MODULE,
> +	};
> +
> +	return gpiochip_add_data(&st->gpiochip, indio_dev);
> +}
> +
>  static int ad7768_set_freq(struct ad7768_state *st,
>  			   unsigned int freq)
>  {
> @@ -492,8 +623,9 @@ 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",
> @@ -526,6 +658,13 @@ 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 < 0)
> +			return ret;
> +	}
> +
>  	/* Set the default sampling frequency to 32000 kSPS */
>  	return ad7768_set_freq(st, 32000);
>  }
> @@ -845,7 +984,7 @@ 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;

Re: [PATCH RESEND v3 12/17] iio: adc: ad7768-1: Add GPIO controller support

[Linus Walleij]

Hi Jonathan/Sergiu,

thanks for your patch!

On Wed, Feb 12, 2025 at 7:20 PM Jonathan Santos
<Jonathan.Santos@analog.com> wrote:

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

Is it not possible to use the gpio regmap library in this driver
like we do in drivers/iio/addac/stx104.c?

It cuts down the code size of simple GPIO chips on random
chips quite a lot.

Yours,
Linus Walleij

Re: [PATCH RESEND v3 12/17] iio: adc: ad7768-1: Add GPIO controller support

[David Lechner]

On 2/19/25 2:34 PM, Linus Walleij wrote:
> Hi Jonathan/Sergiu,
> 
> thanks for your patch!
> 
> On Wed, Feb 12, 2025 at 7:20 PM Jonathan Santos
> <Jonathan.Santos@analog.com> wrote:
> 
>> 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.
>>
>> This change exports the AD7768-1's four gpios and makes them accessible
>> at an upper layer.
>>
>> 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>
> 
> Is it not possible to use the gpio regmap library in this driver
> like we do in drivers/iio/addac/stx104.c?
> 
> It cuts down the code size of simple GPIO chips on random
> chips quite a lot.
> 
> Yours,
> Linus Walleij

I think the answer is "no" since we need to hold a conditional lock
while accessing registers. Namely: iio_device_claim_direct_mode()/
iio_device_release_direct_mode().

Unless we add some extra stuff to the gpio regmap implementation to
add optional callbacks to call these. Which could be worth it given
that quite a few ADCs provide GPIOs like this.

Re: [PATCH RESEND v3 12/17] iio: adc: ad7768-1: Add GPIO controller support

[Jonathan Santos]

On 02/20, David Lechner wrote:
> On 2/19/25 2:34 PM, Linus Walleij wrote:
> > Hi Jonathan/Sergiu,
> > 
> > thanks for your patch!
> > 
> > On Wed, Feb 12, 2025 at 7:20 PM Jonathan Santos
> > <Jonathan.Santos@analog.com> wrote:
> > 
> >> 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.
> >>
> >> This change exports the AD7768-1's four gpios and makes them accessible
> >> at an upper layer.
> >>
> >> 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>
> > 
> > Is it not possible to use the gpio regmap library in this driver
> > like we do in drivers/iio/addac/stx104.c?
> > 
> > It cuts down the code size of simple GPIO chips on random
> > chips quite a lot.
> > 
> > Yours,
> > Linus Walleij
> 
> I think the answer is "no" since we need to hold a conditional lock
> while accessing registers. Namely: iio_device_claim_direct_mode()/
> iio_device_release_direct_mode().
> 
> Unless we add some extra stuff to the gpio regmap implementation to
> add optional callbacks to call these. Which could be worth it given
> that quite a few ADCs provide GPIOs like this.

Since this patch set is quite large already, is it worth to do this
here? if you say it is necessary, i can try this.

> 

Re: [PATCH RESEND v3 12/17] iio: adc: ad7768-1: Add GPIO controller support

[David Lechner]

On 2/27/25 3:36 PM, Jonathan Santos wrote:
> On 02/20, David Lechner wrote:
>> On 2/19/25 2:34 PM, Linus Walleij wrote:
>>> Hi Jonathan/Sergiu,
>>>
>>> thanks for your patch!
>>>
>>> On Wed, Feb 12, 2025 at 7:20 PM Jonathan Santos
>>> <Jonathan.Santos@analog.com> wrote:
>>>
>>>> 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.
>>>>
>>>> This change exports the AD7768-1's four gpios and makes them accessible
>>>> at an upper layer.
>>>>
>>>> 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>
>>>
>>> Is it not possible to use the gpio regmap library in this driver
>>> like we do in drivers/iio/addac/stx104.c?
>>>
>>> It cuts down the code size of simple GPIO chips on random
>>> chips quite a lot.
>>>
>>> Yours,
>>> Linus Walleij
>>
>> I think the answer is "no" since we need to hold a conditional lock
>> while accessing registers. Namely: iio_device_claim_direct_mode()/
>> iio_device_release_direct_mode().
>>
>> Unless we add some extra stuff to the gpio regmap implementation to
>> add optional callbacks to call these. Which could be worth it given
>> that quite a few ADCs provide GPIOs like this.
> 
> Since this patch set is quite large already, is it worth to do this
> here? if you say it is necessary, i can try this.
> 
>>

I'm a big fan of not trying to implement every single possible
feature in one big patch series, but rather splitting it up.

Re: [PATCH RESEND v3 12/17] iio: adc: ad7768-1: Add GPIO controller support

[Linus Walleij]

On Thu, Feb 20, 2025 at 11:27 PM David Lechner <dlechner@baylibre.com> wrote:
> On 2/19/25 2:34 PM, Linus Walleij wrote:

> > Is it not possible to use the gpio regmap library in this driver
> > like we do in drivers/iio/addac/stx104.c?
> >
> > It cuts down the code size of simple GPIO chips on random
> > chips quite a lot.
>
> I think the answer is "no" since we need to hold a conditional lock
> while accessing registers. Namely: iio_device_claim_direct_mode()/
> iio_device_release_direct_mode().

Sorry for potentially dumb question, but if this is required to access
the registers, why is it not done in the regmap abstraction itself?
It's kind of that stuff regmap is supposed to hide.

Yours,
Linus Walleij

Re: [PATCH RESEND v3 12/17] iio: adc: ad7768-1: Add GPIO controller support

[David Lechner]

On 2/28/25 2:52 AM, Linus Walleij wrote:
> On Thu, Feb 20, 2025 at 11:27 PM David Lechner <dlechner@baylibre.com> wrote:
>> On 2/19/25 2:34 PM, Linus Walleij wrote:
> 
>>> Is it not possible to use the gpio regmap library in this driver
>>> like we do in drivers/iio/addac/stx104.c?
>>>
>>> It cuts down the code size of simple GPIO chips on random
>>> chips quite a lot.
>>
>> I think the answer is "no" since we need to hold a conditional lock
>> while accessing registers. Namely: iio_device_claim_direct_mode()/
>> iio_device_release_direct_mode().
> 
> Sorry for potentially dumb question, but if this is required to access
> the registers, why is it not done in the regmap abstraction itself?
> It's kind of that stuff regmap is supposed to hide.
> 
> Yours,
> Linus Walleij

In some cases, we need to do multiple regmap operations while
holding the lock. Moving it to the regmap abstraction would only
allow the lock to be held for each individual regmap_x() call.
That would leave us vulnerable to race conditions.

regmap_multi_reg_write() couldn't be used for this currently
either because regmap_lock does not allow for a conditional
lock.

Re: [PATCH RESEND v3 12/17] iio: adc: ad7768-1: Add GPIO controller support

[Linus Walleij]

On Wed, Feb 12, 2025 at 7:20 PM Jonathan Santos
<Jonathan.Santos@analog.com> wrote:

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

I'm convinced!
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>

Yours,
Linus Walleij

[PATCH RESEND v3 13/17] iio: adc: ad7768-1: add multiple scan types to support 16-bits mode

[Jonathan Santos]

When the device is configured to Sinc5 filter and decimation x8,
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 in runtime, making possible to support both 24-bit and
16-bit resolution.

Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com>
---
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 afcc8678cf83..c16149b395af 100644
--- a/drivers/iio/adc/ad7768-1.c
+++ b/drivers/iio/adc/ad7768-1.c
@@ -142,6 +142,15 @@ 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[4] = {
+	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 },
@@ -156,6 +165,22 @@ 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,
@@ -165,13 +190,9 @@ 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),
 	},
 };
 
@@ -184,6 +205,7 @@ struct ad7768_state {
 	struct clk *mclk;
 	struct gpio_chip gpiochip;
 	unsigned int mclk_freq;
+	unsigned int dec_rate;
 	unsigned int samp_freq;
 	struct completion completion;
 	struct iio_trigger *trig;
@@ -296,6 +318,15 @@ 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.
@@ -514,6 +545,8 @@ 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);
 
@@ -547,8 +580,13 @@ 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:
 		ret = iio_device_claim_direct_mode(indio_dev);
@@ -557,7 +595,7 @@ static int ad7768_read_raw(struct iio_dev *indio_dev,
 
 		ret = ad7768_scan_direct(indio_dev);
 		if (ret >= 0)
-			*val = sign_extend32(ret, chan->scan_type.realbits - 1);
+			*val = sign_extend32(ret, scan_type->realbits - 1);
 
 		iio_device_release_direct_mode(indio_dev);
 		if (ret < 0)
@@ -571,7 +609,7 @@ 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;
 
@@ -615,11 +653,21 @@ 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,
 };
 
@@ -674,9 +722,15 @@ 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))
+		return PTR_ERR(scan_type);
+
+	ret = spi_read(st->spi, &st->data.scan.chan,
+		       BITS_TO_BYTES(scan_type->realbits));
 	if (ret < 0)
 		goto out;
 
-- 
2.34.1

Re: [PATCH RESEND v3 13/17] iio: adc: ad7768-1: add multiple scan types to support 16-bits mode

[David Lechner]

On 2/12/25 12:18 PM, Jonathan Santos wrote:
> When the device is configured to Sinc5 filter and decimation x8,
> output data is reduced to 16-bits in order to support 1 MHz of
> sampling frequency due to clock limitation.

It would be a bit more clear if this said that x8 is only possible
with sinc5, so we don't have to check the filter type in the code.
At first, I thought the code was missing that part of the check.

> 
> Use multiple scan types feature to enable the driver to switch
> scan type in runtime, making possible to support both 24-bit and
> 16-bit resolution.
> 
> Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com>
> ---

Reviewed-by: David Lechner <dlechner@baylire.com>

[PATCH RESEND v3 14/17] 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 SYNC_IN pin.

Use trigger-sources property to enable device synchronization over SPI.

Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com>
---
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 | 80 ++++++++++++++++++++++++++++++++++----
 1 file changed, 72 insertions(+), 8 deletions(-)

diff --git a/drivers/iio/adc/ad7768-1.c b/drivers/iio/adc/ad7768-1.c
index c16149b395af..716cf3582577 100644
--- a/drivers/iio/adc/ad7768-1.c
+++ b/drivers/iio/adc/ad7768-1.c
@@ -211,6 +211,7 @@ 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)];
 	/*
 	 * DMA (thus cache coherency maintenance) may require the
@@ -291,6 +292,19 @@ static const struct regmap_config ad7768_regmap24_config = {
 	.max_register = AD7768_REG_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);
+
+	if (st->gpio_sync_in) {
+		gpiod_set_value_cansleep(st->gpio_sync_in, 1);
+		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)
 {
@@ -387,10 +401,7 @@ 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)
@@ -671,6 +682,60 @@ static const struct iio_info ad7768_info = {
 	.debugfs_reg_access = &ad7768_reg_access,
 };
 
+static int ad7768_setup_spi_sync(struct device *dev, struct ad7768_state *st)
+{
+	struct fwnode_reference_args args;
+	int ret;
+
+	ret = fwnode_property_get_reference_args(dev_fwnode(dev),
+						 "trigger-sources",
+						 "#trigger-source-cells",
+						 0, 0, &args);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to get trigger-sources reference\n");
+
+	/*
+	 * Currently, the driver supports SPI-based synchronization only for
+	 * single-device setups, where the device's own SYNC_OUT is looped back
+	 * to its SYNC_IN. Only enable this feature if the trigger-sources
+	 * references the current device.
+	 */
+	st->en_spi_sync = args.fwnode->dev == dev;
+	fwnode_handle_put(args.fwnode);
+
+	return st->en_spi_sync ? 0 : -EOPNOTSUPP;
+}
+
+static int ad7768_set_sync_source(struct device *dev, struct ad7768_state *st)
+{
+	int ret;
+
+	/*
+	 * The AD7768-1 allows two primary methods for driving the SYNC_IN pin
+	 * to synchronize one or more devices:
+	 * 1. Using a GPIO to directly drive the SYNC_IN pin.
+	 * 2. Using a SPI command, where the SYNC_OUT pin generates a
+	 *    synchronization pulse that loops back to the SYNC_IN pin.
+	 */
+	st->gpio_sync_in = devm_gpiod_get_optional(dev, "adi,sync-in",
+						   GPIOD_OUT_LOW);
+	if (IS_ERR(st->gpio_sync_in))
+		return PTR_ERR(st->gpio_sync_in);
+
+	/*
+	 * If the SYNC_IN GPIO is not defined, fall back to synchronization
+	 * over SPI.
+	 */
+	if (!st->gpio_sync_in) {
+		ret = ad7768_setup_spi_sync(dev, st);
+		if (ret)
+			return dev_err_probe(dev, ret,
+					      "No valid synchronization source provided\n");
+	}
+
+	return 0;
+}
+
 static int ad7768_setup(struct iio_dev *indio_dev)
 {
 	struct ad7768_state *st = iio_priv(indio_dev);
@@ -701,10 +766,9 @@ 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);
-	if (IS_ERR(st->gpio_sync_in))
-		return PTR_ERR(st->gpio_sync_in);
+	ret = ad7768_set_sync_source(&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")) {
-- 
2.34.1

[PATCH RESEND v3 15/17] 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.

Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com>
---
v3 Changes:
* New patch in v3.
---
 drivers/iio/adc/ad7768-1.c | 58 +++++++++++++++++---------------------
 1 file changed, 26 insertions(+), 32 deletions(-)

diff --git a/drivers/iio/adc/ad7768-1.c b/drivers/iio/adc/ad7768-1.c
index 716cf3582577..8aea38c154fe 100644
--- a/drivers/iio/adc/ad7768-1.c
+++ b/drivers/iio/adc/ad7768-1.c
@@ -187,6 +187,7 @@ 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,
@@ -207,6 +208,7 @@ 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;
@@ -564,28 +566,6 @@ 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)
@@ -633,6 +613,29 @@ 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);
+	int i;
+
+	switch (info) {
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		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);
+
+		*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)
@@ -655,15 +658,6 @@ 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)
 {
@@ -674,8 +668,8 @@ 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,
-- 
2.34.1

Re: [PATCH RESEND v3 15/17] iio: adc: ad7768-1: replace manual attribute declaration

[Jonathan Cameron]

On Wed, 12 Feb 2025 15:18:48 -0300
Jonathan Santos <Jonathan.Santos@analog.com> wrote:

> Use read_avail callback from struct iio_info to replace the manual
> declaration of sampling_frequency_available attribute.
> 
> Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com>
> ---
> v3 Changes:
> * New patch in v3.
> ---
>  drivers/iio/adc/ad7768-1.c | 58 +++++++++++++++++---------------------
>  1 file changed, 26 insertions(+), 32 deletions(-)
> 
> diff --git a/drivers/iio/adc/ad7768-1.c b/drivers/iio/adc/ad7768-1.c
> index 716cf3582577..8aea38c154fe 100644
> --- a/drivers/iio/adc/ad7768-1.c
> +++ b/drivers/iio/adc/ad7768-1.c
> @@ -187,6 +187,7 @@ 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,
> @@ -207,6 +208,7 @@ 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;
> @@ -564,28 +566,6 @@ 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)
> @@ -633,6 +613,29 @@ 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);
> +	int i;
> +
> +	switch (info) {
> +	case IIO_CHAN_INFO_SAMP_FREQ:
> +		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);
There are some complex race conditions around these available arrays, so in
general it is better to make it obvious when they are static after
init vs actually dynamic.  In this case I think we can fill this
in the moment we know mclk_freq?  If so please move the calculation into
probe() and just reference it here.

How to close the race condition is an ongoing topic but I don't think
that problem applies here anyway!

Jonathan

> +
> +		*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)
> @@ -655,15 +658,6 @@ 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)
>  {
> @@ -674,8 +668,8 @@ 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,

[PATCH RESEND v3 16/17] 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.

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>
---
v3 Changes:
* removed unsed variables.
* included sinc3+rej60 filter type.
* oversampling_ratio moved to info_mask_shared_by_type.
* reordered functions to avoid foward 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 | 359 ++++++++++++++++++++++++++++++-------
 1 file changed, 290 insertions(+), 69 deletions(-)

diff --git a/drivers/iio/adc/ad7768-1.c b/drivers/iio/adc/ad7768-1.c
index 8aea38c154fe..18f1ea0bf66d 100644
--- a/drivers/iio/adc/ad7768-1.c
+++ b/drivers/iio/adc/ad7768-1.c
@@ -20,6 +20,7 @@
 #include <linux/regulator/driver.h>
 #include <linux/sysfs.h>
 #include <linux/spi/spi.h>
+#include <linux/util_macros.h>
 
 #include <linux/iio/buffer.h>
 #include <linux/iio/iio.h>
@@ -75,11 +76,15 @@
 #define AD7768_PWR_PWRMODE(x)		FIELD_PREP(AD7768_PWR_PWRMODE_MSK, x)
 
 /* AD7768_REG_DIGITAL_FILTER */
-#define AD7768_DIG_FIL_FIL_MSK		GENMASK(6, 4)
+#define AD7768_DIG_FIL_FIL_MSK		GENMASK(7, 4)
 #define AD7768_DIG_FIL_FIL(x)		FIELD_PREP(AD7768_DIG_FIL_FIL_MSK, x)
 #define AD7768_DIG_FIL_DEC_MSK		GENMASK(2, 0)
 #define AD7768_DIG_FIL_DEC_RATE(x)	FIELD_PREP(AD7768_DIG_FIL_DEC_MSK, x)
 
+/* AD7768_SINC3_DEC_RATE */
+#define AD7768_SINC3_DEC_RATE_MSB_MSK	GENMASK(12, 8)
+#define AD7768_SINC3_DEC_RATE_LSB_MSK	GENMASK(7, 0)
+
 /* AD7768_REG_CONVERSION */
 #define AD7768_CONV_MODE_MSK		GENMASK(2, 0)
 #define AD7768_CONV_MODE(x)		FIELD_PREP(AD7768_CONV_MODE_MSK, x)
@@ -124,22 +129,20 @@ 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 {
@@ -151,18 +154,40 @@ static const int ad7768_mclk_div_rates[4] = {
 	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 each filter type */
+static const int ad7768_dec_rate_range[][3] = {
+	[AD7768_FILTER_SINC5] = { 8, 8, 1024 },
+	[AD7768_FILTER_SINC3] = { 32, 32, 163840 },
+	[AD7768_FILTER_WIDEBAND] = { 32, 32, 1024 },
+	[AD7768_FILTER_SINC3_REJ60] = { 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 function 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[] = {
@@ -181,13 +206,34 @@ static const struct iio_scan_type ad7768_scan_type[] = {
 	},
 };
 
+static int ad7768_get_fil_type_attr(struct iio_dev *dev,
+				    const struct iio_chan_spec *chan);
+static int ad7768_set_fil_type_attr(struct iio_dev *dev,
+				    const struct iio_chan_spec *chan, unsigned int filter);
+
+static const struct iio_enum ad7768_flt_type_iio_enum = {
+	.items = ad7768_filter_enum,
+	.num_items = ARRAY_SIZE(ad7768_filter_enum),
+	.set = ad7768_set_fil_type_attr,
+	.get = ad7768_get_fil_type_attr,
+};
+
+static struct iio_chan_spec_ext_info ad7768_ext_info[] = {
+	IIO_ENUM("filter_type", IIO_SHARED_BY_ALL, &ad7768_flt_type_iio_enum),
+	IIO_ENUM_AVAILABLE("filter_type", IIO_SHARED_BY_ALL, &ad7768_flt_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),
+		.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,
@@ -206,9 +252,11 @@ struct ad7768_state {
 	struct clk *mclk;
 	struct gpio_chip gpiochip;
 	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)];
 	struct completion completion;
 	struct iio_trigger *trig;
 	struct gpio_desc *gpio_sync_in;
@@ -307,6 +355,24 @@ static int ad7768_send_sync_pulse(struct ad7768_state *st)
 	return 0;
 }
 
+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,
 			   enum ad7768_conv_mode mode)
 {
@@ -340,7 +406,7 @@ 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;
 
 	/*
@@ -387,22 +453,101 @@ 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];
 	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_t(unsigned int, dec_rate, 32, max_dec_rate);
+	/*
+	 * Calculate the equivalent value to sinc3 decimation ratio
+	 * to be written on the SINC3_DECIMATION_RATE register:
+	 *  Value = (DEC_RATE / 32) -1
+	 */
+	dec_rate = DIV_ROUND_UP(dec_rate, 32) - 1;
+	dec_rate_reg[0] = FIELD_GET(AD7768_SINC3_DEC_RATE_MSB_MSK, dec_rate);
+	dec_rate_reg[1] = FIELD_GET(AD7768_SINC3_DEC_RATE_LSB_MSK, dec_rate);
+	ret = regmap_bulk_write(st->regmap, AD7768_REG_SINC3_DEC_RATE_MSB,
+				dec_rate_reg, 2);
+	if (ret)
+		return ret;
 
-	ret = regmap_write(st->regmap, AD7768_REG_DIGITAL_FILTER, mode);
-	if (ret < 0)
+	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_REJ60);
+		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 need 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];
+	}
+
+	/* A sync-in pulse is required after every configuration change */
 	return ad7768_send_sync_pulse(st);
 }
 
@@ -527,43 +672,72 @@ 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;
+	unsigned int diff_new, diff_old, i, idx;
 	int res, ret;
 
+	freq = clamp_t(unsigned int, freq, 50, 1024000);
 	diff_old = U32_MAX;
 	idx = 0;
 
-	res = DIV_ROUND_CLOSEST(st->mclk_freq, freq);
+	if (freq == 0)
+		return -EINVAL;
+
+	res = 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);
+	for (i = 0; i < ARRAY_SIZE(ad7768_mclk_div_rates); i++) {
+		diff_new = abs(res - ad7768_mclk_div_rates[i]);
 		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)
+	/* 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_fil_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_fil_type_attr(struct iio_dev *dev,
+				    const struct iio_chan_spec *chan)
+{
+	struct ad7768_state *st = iio_priv(dev);
+	int ret;
+	unsigned int mode;
+
+	ret = regmap_read(st->regmap, AD7768_REG_DIGITAL_FILTER, &mode);
+	if (ret)
+		return ret;
+
+	mode = FIELD_GET(AD7768_DIG_FIL_FIL_MSK, mode);
+
+	/*
+	 * From the register value, get the corresponding
+	 * filter type.
+	 */
+	return ad7768_filter_regval_to_type[mode];
 }
 
 static int ad7768_read_raw(struct iio_dev *indio_dev,
@@ -607,6 +781,11 @@ 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;
 	}
 
@@ -619,16 +798,25 @@ static int ad7768_read_avail(struct iio_dev *indio_dev,
 			     long info)
 {
 	struct ad7768_state *st = iio_priv(indio_dev);
-	int i;
+	int i, freq_filtered, len = 0;
 
 	switch (info) {
+	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
+		*vals = (int *)ad7768_dec_rate_range[st->filter_type];
+		*type = IIO_VAL_INT;
+		return IIO_AVAIL_RANGE;
 	case IIO_CHAN_INFO_SAMP_FREQ:
-		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);
+		freq_filtered = DIV_ROUND_CLOSEST(st->mclk_freq, st->oversampling_ratio);
+		for (i = 0; i < ARRAY_SIZE(ad7768_mclk_div_rates); i++) {
+			st->samp_freq_avail[len] = DIV_ROUND_CLOSEST(freq_filtered,
+								     ad7768_mclk_div_rates[i]);
+			/* Sampling frequency cannot be lower than the minimum of 50 SPS */
+			if (st->samp_freq_avail[len] >= 50)
+				len++;
+		}
 
 		*vals = (int *)st->samp_freq_avail;
-		*length = ARRAY_SIZE(ad7768_clk_config);
+		*length = len;
 		*type = IIO_VAL_INT;
 		return IIO_AVAIL_LIST;
 	default:
@@ -636,20 +824,45 @@ 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;
+
+	ret = iio_device_claim_direct_mode(indio_dev);
+	if (ret)
+		return ret;
+
+	ret = __ad7768_write_raw(indio_dev, chan, val, val2, info);
+	iio_device_release_direct_mode(indio_dev);
+
+	return ret;
+}
+
 static int ad7768_read_label(struct iio_dev *indio_dev,
 	const struct iio_chan_spec *chan, char *label)
 {
@@ -663,7 +876,7 @@ 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 ? AD7768_SCAN_TYPE_HIGH_SPEED :
+	return st->oversampling_ratio == 8 ? AD7768_SCAN_TYPE_HIGH_SPEED :
 		AD7768_SCAN_TYPE_NORMAL;
 }
 
@@ -771,6 +984,14 @@ 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);
 }
-- 
2.34.1

Re: [PATCH RESEND v3 16/17] iio: adc: ad7768-1: add filter type and oversampling ratio attributes

[Jonathan Cameron]

On Wed, 12 Feb 2025 15:18:59 -0300
Jonathan Santos <Jonathan.Santos@analog.com> wrote:

> 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.
> 
> 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>
As below. We should aim to 'pre bake' the value arrays for
get_available() to avoid the potential race conditions of a consumer
seeing a partly updated set a parameters change.

Better to see a consistent but stale one.

Jonathan

> ---
> v3 Changes:
> * removed unsed variables.
> * included sinc3+rej60 filter type.
> * oversampling_ratio moved to info_mask_shared_by_type.
> * reordered functions to avoid foward 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 | 359 ++++++++++++++++++++++++++++++-------
>  1 file changed, 290 insertions(+), 69 deletions(-)
> 
> diff --git a/drivers/iio/adc/ad7768-1.c b/drivers/iio/adc/ad7768-1.c
> index 8aea38c154fe..18f1ea0bf66d 100644
> --- a/drivers/iio/adc/ad7768-1.c
> +++ b/drivers/iio/adc/ad7768-1.c

> +
> +/* Decimation Rate range for each filter type */
> +static const int ad7768_dec_rate_range[][3] = {
> +	[AD7768_FILTER_SINC5] = { 8, 8, 1024 },
> +	[AD7768_FILTER_SINC3] = { 32, 32, 163840 },
> +	[AD7768_FILTER_WIDEBAND] = { 32, 32, 1024 },
> +	[AD7768_FILTER_SINC3_REJ60] = { 32, 32, 163840 },
> +};
> +
> +/*
> + * The AD7768-1 supports three primary filter types:
> + * Sinc5, Sinc3, and Wideband.
> + * However, the filter register values can also encode
wrap at 80 chars.
> + * additional parameters such as decimation rates and
> + * 60Hz rejection. This utility function separates the
> + * filter type from these parameters.
> + */

>  
> -	return 0;
> +static int ad7768_get_fil_type_attr(struct iio_dev *dev,
> +				    const struct iio_chan_spec *chan)
> +{
> +	struct ad7768_state *st = iio_priv(dev);
> +	int ret;
> +	unsigned int mode;
> +
> +	ret = regmap_read(st->regmap, AD7768_REG_DIGITAL_FILTER, &mode);
> +	if (ret)
> +		return ret;
> +
> +	mode = FIELD_GET(AD7768_DIG_FIL_FIL_MSK, mode);
> +
> +	/*
> +	 * From the register value, get the corresponding
> +	 * filter type.

Very short line wrap.  Stick to 80 chars.

> +	 */
> +	return ad7768_filter_regval_to_type[mode];
>  }

>  
> @@ -619,16 +798,25 @@ static int ad7768_read_avail(struct iio_dev *indio_dev,
>  			     long info)
>  {
>  	struct ad7768_state *st = iio_priv(indio_dev);
> -	int i;
> +	int i, freq_filtered, len = 0;
>  
>  	switch (info) {
> +	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
> +		*vals = (int *)ad7768_dec_rate_range[st->filter_type];
> +		*type = IIO_VAL_INT;
> +		return IIO_AVAIL_RANGE;
>  	case IIO_CHAN_INFO_SAMP_FREQ:
> -		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);
> +		freq_filtered = DIV_ROUND_CLOSEST(st->mclk_freq, st->oversampling_ratio);

Ah. So now it is dynamic.  This hits the previously mentioned race.
A consumer can be holding a copy of this and acting on it whilst holding no
locks on this device - thus it can see a mixture of values as this update
occurs. To avoid that you need to precompute the combinations +
store the lot in arrays.  Then this code should simply be selecting the arrays.
A consumer holding a stale one will get a consistent (if wrong) set.

The < 50 check makes this more complex than normal but they are still static
choices I think as long as the input clock doesn't change.

> +		for (i = 0; i < ARRAY_SIZE(ad7768_mclk_div_rates); i++) {
> +			st->samp_freq_avail[len] = DIV_ROUND_CLOSEST(freq_filtered,
> +								     ad7768_mclk_div_rates[i]);
> +			/* Sampling frequency cannot be lower than the minimum of 50 SPS */
> +			if (st->samp_freq_avail[len] >= 50)
> +				len++;
> +		}
>  
>  		*vals = (int *)st->samp_freq_avail;
> -		*length = ARRAY_SIZE(ad7768_clk_config);
> +		*length = len;
>  		*type = IIO_VAL_INT;
>  		return IIO_AVAIL_LIST;
>  	default:
> @@ -636,20 +824,45 @@ 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;
> +
> +	ret = iio_device_claim_direct_mode(indio_dev);
Previously we didn't claim this to set the sampling frequency.
That change looks like a potential ABI issue.  I'm fine with it
if we should always have this protected.

If you are just using it to avoid racing between setting sampling
frequency and oversampling ratio then don't use that, use a local
lock where the scope can be clearly described.

> +	if (ret)
> +		return ret;
> +
> +	ret = __ad7768_write_raw(indio_dev, chan, val, val2, info);
> +	iio_device_release_direct_mode(indio_dev);
> +
> +	return ret;
> +}

Re: [PATCH RESEND v3 16/17] iio: adc: ad7768-1: add filter type and oversampling ratio attributes

[Jonathan Santos]

On 02/16, Jonathan Cameron wrote:
> On Wed, 12 Feb 2025 15:18:59 -0300
> Jonathan Santos <Jonathan.Santos@analog.com> wrote:
> 
> > 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.
> > 
> > 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>
> As below. We should aim to 'pre bake' the value arrays for
> get_available() to avoid the potential race conditions of a consumer
> seeing a partly updated set a parameters change.
> 
> Better to see a consistent but stale one.
> 
> Jonathan
> 
> > ---
> > v3 Changes:
> > * removed unsed variables.
> > * included sinc3+rej60 filter type.
> > * oversampling_ratio moved to info_mask_shared_by_type.
> > * reordered functions to avoid foward 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 | 359 ++++++++++++++++++++++++++++++-------
> >  1 file changed, 290 insertions(+), 69 deletions(-)
> > 
> > diff --git a/drivers/iio/adc/ad7768-1.c b/drivers/iio/adc/ad7768-1.c
> > index 8aea38c154fe..18f1ea0bf66d 100644
> > --- a/drivers/iio/adc/ad7768-1.c
> > +++ b/drivers/iio/adc/ad7768-1.c
> 
> > +
> > +/* Decimation Rate range for each filter type */
> > +static const int ad7768_dec_rate_range[][3] = {
> > +	[AD7768_FILTER_SINC5] = { 8, 8, 1024 },
> > +	[AD7768_FILTER_SINC3] = { 32, 32, 163840 },
> > +	[AD7768_FILTER_WIDEBAND] = { 32, 32, 1024 },
> > +	[AD7768_FILTER_SINC3_REJ60] = { 32, 32, 163840 },
> > +};
> > +
> > +/*
> > + * The AD7768-1 supports three primary filter types:
> > + * Sinc5, Sinc3, and Wideband.
> > + * However, the filter register values can also encode
> wrap at 80 chars.
> > + * additional parameters such as decimation rates and
> > + * 60Hz rejection. This utility function separates the
> > + * filter type from these parameters.
> > + */
> 
> >  
> > -	return 0;
> > +static int ad7768_get_fil_type_attr(struct iio_dev *dev,
> > +				    const struct iio_chan_spec *chan)
> > +{
> > +	struct ad7768_state *st = iio_priv(dev);
> > +	int ret;
> > +	unsigned int mode;
> > +
> > +	ret = regmap_read(st->regmap, AD7768_REG_DIGITAL_FILTER, &mode);
> > +	if (ret)
> > +		return ret;
> > +
> > +	mode = FIELD_GET(AD7768_DIG_FIL_FIL_MSK, mode);
> > +
> > +	/*
> > +	 * From the register value, get the corresponding
> > +	 * filter type.
> 
> Very short line wrap.  Stick to 80 chars.
> 
> > +	 */
> > +	return ad7768_filter_regval_to_type[mode];
> >  }
> 
> >  
> > @@ -619,16 +798,25 @@ static int ad7768_read_avail(struct iio_dev *indio_dev,
> >  			     long info)
> >  {
> >  	struct ad7768_state *st = iio_priv(indio_dev);
> > -	int i;
> > +	int i, freq_filtered, len = 0;
> >  
> >  	switch (info) {
> > +	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
> > +		*vals = (int *)ad7768_dec_rate_range[st->filter_type];
> > +		*type = IIO_VAL_INT;
> > +		return IIO_AVAIL_RANGE;
> >  	case IIO_CHAN_INFO_SAMP_FREQ:
> > -		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);
> > +		freq_filtered = DIV_ROUND_CLOSEST(st->mclk_freq, st->oversampling_ratio);
> 
> Ah. So now it is dynamic.  This hits the previously mentioned race.
> A consumer can be holding a copy of this and acting on it whilst holding no
> locks on this device - thus it can see a mixture of values as this update
> occurs. To avoid that you need to precompute the combinations +
> store the lot in arrays.  Then this code should simply be selecting the arrays.
> A consumer holding a stale one will get a consistent (if wrong) set.
>
Yes, before the available frequencies were static, but now they depend
on the oversampling ratio. I can create a helper function to precomput
and fill this array and call it after configuring the digital filter, 
where the filter type and OSR is set.

For the previous static case, i call this function in the probe.
> The < 50 check makes this more complex than normal but they are still static
> choices I think as long as the input clock doesn't change.
>

I will include this in the helper function.

> > +		for (i = 0; i < ARRAY_SIZE(ad7768_mclk_div_rates); i++) {
> > +			st->samp_freq_avail[len] = DIV_ROUND_CLOSEST(freq_filtered,
> > +								     ad7768_mclk_div_rates[i]);
> > +			/* Sampling frequency cannot be lower than the minimum of 50 SPS */
> > +			if (st->samp_freq_avail[len] >= 50)
> > +				len++;
> > +		}
> >  
> >  		*vals = (int *)st->samp_freq_avail;
> > -		*length = ARRAY_SIZE(ad7768_clk_config);
> > +		*length = len;
> >  		*type = IIO_VAL_INT;
> >  		return IIO_AVAIL_LIST;
> >  	default:
> > @@ -636,20 +824,45 @@ 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;
> > +
> > +	ret = iio_device_claim_direct_mode(indio_dev);
> Previously we didn't claim this to set the sampling frequency.
> That change looks like a potential ABI issue.  I'm fine with it
> if we should always have this protected.
> 
> If you are just using it to avoid racing between setting sampling
> frequency and oversampling ratio then don't use that, use a local
> lock where the scope can be clearly described.
> 
> > +	if (ret)
> > +		return ret;
> > +
> > +	ret = __ad7768_write_raw(indio_dev, chan, val, val2, info);
> > +	iio_device_release_direct_mode(indio_dev);
> > +
> > +	return ret;
> > +}

[PATCH RESEND v3 17/17] 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.

Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com>
---
v3 Changes:
* None

v2 Changes:
* New patch in v2.

OBS: should i drop this?
---
 drivers/iio/adc/ad7768-1.c | 22 ++++++++++++++++++++--
 1 file changed, 20 insertions(+), 2 deletions(-)

diff --git a/drivers/iio/adc/ad7768-1.c b/drivers/iio/adc/ad7768-1.c
index 18f1ea0bf66d..2bf133da18c6 100644
--- a/drivers/iio/adc/ad7768-1.c
+++ b/drivers/iio/adc/ad7768-1.c
@@ -150,6 +150,17 @@ 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] = 261,
+	[AD7768_FILTER_SINC3_REJ60] = 261,
+	[AD7768_FILTER_WIDEBAND] = 433,
+};
+
 static const int ad7768_mclk_div_rates[4] = {
 	16, 8, 4, 2,
 };
@@ -229,7 +240,8 @@ 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),
+					    BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO) |
+					    BIT(IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY),
 		.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),
@@ -746,7 +758,7 @@ 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))
@@ -786,6 +798,12 @@ 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 RESEND v3 17/17] iio: adc: ad7768-1: add low pass -3dB cutoff attribute

[Jonathan Cameron]

On Wed, 12 Feb 2025 15:19:10 -0300
Jonathan Santos <Jonathan.Santos@analog.com> wrote:

> 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.
> 
> Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com>
> ---
> v3 Changes:
> * None
> 
> v2 Changes:
> * New patch in v2.
> 
> OBS: should i drop this?
I think keep it as potentially useful and is compliant with the ABI
even if a little unusual.

Jonathan