[PATCH v2 1/2] iio: adc: ad799x: Implement selecting external reference voltage input on AD7991, AD7995 and AD7999.

[PATCH v2 1/2] iio: adc: ad799x: Implement selecting external reference voltage input on AD7991, AD7995 and AD7999.

[Florian Boor]

Make use of the AD7991_REF_SEL bit and support using the external
reference voltage if 'vref-supply' is present.

Signed-off-by: Florian Boor <florian.boor@kernelconcepts.de>
---

Changes in v2:
- Check if a provided external vref regulator is provided.
- Drop unused setting
- Add ad79xx documentation (second patch)

 drivers/iio/adc/ad799x.c | 21 +++++++++++++++++++--
 1 file changed, 19 insertions(+), 2 deletions(-)

diff --git a/drivers/iio/adc/ad799x.c b/drivers/iio/adc/ad799x.c
index 18bf8386d50a..2ff926a4e9b3 100644
--- a/drivers/iio/adc/ad799x.c
+++ b/drivers/iio/adc/ad799x.c
@@ -770,6 +770,8 @@ static int ad799x_probe(struct i2c_client *client,
 				   const struct i2c_device_id *id)
 {
 	int ret;
+	int extra_config = 0;
+	bool vref_external = true;
 	struct ad799x_state *st;
 	struct iio_dev *indio_dev;
 	const struct ad799x_chip_info *chip_info =
@@ -797,7 +799,15 @@ static int ad799x_probe(struct i2c_client *client,
 	ret = regulator_enable(st->reg);
 	if (ret)
 		return ret;
-	st->vref = devm_regulator_get(&client->dev, "vref");
+		
+	/* check if an external reference is supplied */
+	st->vref = devm_regulator_get_optional(&client->dev, "vref");
+
+	if (PTR_ERR(st->vref) == -ENODEV) {
+		vref_external = false;
+		/* get dummy */
+		st->vref = devm_regulator_get(&client->dev, "vref");
+	}
 	if (IS_ERR(st->vref)) {
 		ret = PTR_ERR(st->vref);
 		goto error_disable_reg;
@@ -806,6 +816,13 @@ static int ad799x_probe(struct i2c_client *client,
 	if (ret)
 		goto error_disable_reg;
 
+	/* use external reference voltage, optional if regulator present */
+	if (vref_external && 
+	   ((st->id == ad7991) || (st->id == ad7995) || (st->id == ad7999))) {
+		dev_info(&client->dev, "Using external reference voltage\n");
+		extra_config |= AD7991_REF_SEL;
+	}
+
 	st->client = client;
 
 	indio_dev->name = id->name;
@@ -815,7 +832,7 @@ static int ad799x_probe(struct i2c_client *client,
 	indio_dev->channels = st->chip_config->channel;
 	indio_dev->num_channels = chip_info->num_channels;
 
-	ret = ad799x_update_config(st, st->chip_config->default_config);
+	ret = ad799x_update_config(st, st->chip_config->default_config | extra_config);
 	if (ret)
 		goto error_disable_vref;
 
-- 
2.30.2

[PATCH v2 2/2] dt-binding: iio: Add documentation for AD799x driver

[Florian Boor]

New documentation for AD799x series of I²C ADC ICs.

Signed-off-by: Florian Boor <florian.boor@kernelconcepts.de>
---
 .../bindings/iio/adc/adi,ad799x.yaml          | 61 +++++++++++++++++++
 1 file changed, 61 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/adc/adi,ad799x.yaml

diff --git a/Documentation/devicetree/bindings/iio/adc/adi,ad799x.yaml b/Documentation/devicetree/bindings/iio/adc/adi,ad799x.yaml
new file mode 100644
index 000000000000..90b3b01482fe
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/adc/adi,ad799x.yaml
@@ -0,0 +1,61 @@
+# SPDX-License-Identifier: GPL-2.0
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/adc/adi,ad799x.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Analog Devices AD7991, AD7992, AD7993, AD7994, AD7995, AD7997, AD7998,
+       AD7999 and similar analog to digital converters
+
+maintainers:
+  - Michael Hennerich, Analog Devices Inc. <Michael.Hennerich@analog.com>
+
+description: |
+  Specifications on the converters can be found at:
+    AD7991, AD7995, AD7999:
+      https://www.analog.com/media/en/technical-documentation/data-sheets/AD7991_7995_7999.pdf
+    AD7992:
+      https://www.analog.com/media/en/technical-documentation/data-sheets/AD7992.pdf
+    AD7993, AD7994:
+      https://www.analog.com/media/en/technical-documentation/data-sheets/AD7993_7994.pdf
+    AD7997, AD7998:
+      https://www.analog.com/media/en/technical-documentation/data-sheets/AD7997_7998.pdf
+
+properties:
+  compatible:
+    enum:
+      - adi,ad7991
+      - adi,ad7992
+      - adi,ad7993
+      - adi,ad7994
+      - adi,ad7995
+      - adi,ad7997
+      - adi,ad7998
+      - adi,ad7999
+
+  reg:
+    maxItems: 1
+
+  vcc-supply:
+    description:
+      ADC power supply
+
+  vref-supply:
+    description:
+      ADC reference voltage supply, optional for AD7991, AD7995 and AD7999
+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+        adc1: ad7991@28 {
+                reg = <0x28>;
+                compatible = "adi,ad7991";
+                vcc-supply = <&vcc_3v3>;
+                vref-supply = <&adc_vref>;
+        };
+...
-- 
2.30.2

Re: [PATCH v2 2/2] dt-binding: iio: Add documentation for AD799x driver

[Jonathan Cameron]

On Wed,  8 Sep 2021 17:25:25 +0200
Florian Boor <florian.boor@kernelconcepts.de> wrote:

> New documentation for AD799x series of I²C ADC ICs.

interrupts?

Otherwise seems to match what the driver support.

Thanks,

Jonathan

> 
> Signed-off-by: Florian Boor <florian.boor@kernelconcepts.de>
> ---
>  .../bindings/iio/adc/adi,ad799x.yaml          | 61 +++++++++++++++++++
>  1 file changed, 61 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/iio/adc/adi,ad799x.yaml
> 
> diff --git a/Documentation/devicetree/bindings/iio/adc/adi,ad799x.yaml b/Documentation/devicetree/bindings/iio/adc/adi,ad799x.yaml
> new file mode 100644
> index 000000000000..90b3b01482fe
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/adc/adi,ad799x.yaml
> @@ -0,0 +1,61 @@
> +# SPDX-License-Identifier: GPL-2.0
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/iio/adc/adi,ad799x.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Analog Devices AD7991, AD7992, AD7993, AD7994, AD7995, AD7997, AD7998,
> +       AD7999 and similar analog to digital converters
> +
> +maintainers:
> +  - Michael Hennerich, Analog Devices Inc. <Michael.Hennerich@analog.com>
> +
> +description: |
> +  Specifications on the converters can be found at:
> +    AD7991, AD7995, AD7999:
> +      https://www.analog.com/media/en/technical-documentation/data-sheets/AD7991_7995_7999.pdf
> +    AD7992:
> +      https://www.analog.com/media/en/technical-documentation/data-sheets/AD7992.pdf
> +    AD7993, AD7994:
> +      https://www.analog.com/media/en/technical-documentation/data-sheets/AD7993_7994.pdf
> +    AD7997, AD7998:
> +      https://www.analog.com/media/en/technical-documentation/data-sheets/AD7997_7998.pdf
> +
> +properties:
> +  compatible:
> +    enum:
> +      - adi,ad7991
> +      - adi,ad7992
> +      - adi,ad7993
> +      - adi,ad7994
> +      - adi,ad7995
> +      - adi,ad7997
> +      - adi,ad7998
> +      - adi,ad7999
> +
> +  reg:
> +    maxItems: 1
> +
> +  vcc-supply:
> +    description:
> +      ADC power supply
> +
> +  vref-supply:
> +    description:
> +      ADC reference voltage supply, optional for AD7991, AD7995 and AD7999
> +
> +required:
> +  - compatible
> +  - reg
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +        adc1: ad7991@28 {
> +                reg = <0x28>;
> +                compatible = "adi,ad7991";
> +                vcc-supply = <&vcc_3v3>;
> +                vref-supply = <&adc_vref>;
> +        };
> +...

Re: [PATCH v2 1/2] iio: adc: ad799x: Implement selecting external reference voltage input on AD7991, AD7995 and AD7999.

[Jonathan Cameron]

On Wed,  8 Sep 2021 17:25:24 +0200
Florian Boor <florian.boor@kernelconcepts.de> wrote:

> Make use of the AD7991_REF_SEL bit and support using the external
> reference voltage if 'vref-supply' is present.
> 
> Signed-off-by: Florian Boor <florian.boor@kernelconcepts.de>

Hi Florian,

> ---
> 
> Changes in v2:
> - Check if a provided external vref regulator is provided.
> - Drop unused setting
> - Add ad79xx documentation (second patch)
> 
>  drivers/iio/adc/ad799x.c | 21 +++++++++++++++++++--
>  1 file changed, 19 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iio/adc/ad799x.c b/drivers/iio/adc/ad799x.c
> index 18bf8386d50a..2ff926a4e9b3 100644
> --- a/drivers/iio/adc/ad799x.c
> +++ b/drivers/iio/adc/ad799x.c
> @@ -770,6 +770,8 @@ static int ad799x_probe(struct i2c_client *client,
>  				   const struct i2c_device_id *id)
>  {
>  	int ret;
> +	int extra_config = 0;
> +	bool vref_external = true;
>  	struct ad799x_state *st;
>  	struct iio_dev *indio_dev;
>  	const struct ad799x_chip_info *chip_info =
> @@ -797,7 +799,15 @@ static int ad799x_probe(struct i2c_client *client,
>  	ret = regulator_enable(st->reg);
>  	if (ret)
>  		return ret;
> -	st->vref = devm_regulator_get(&client->dev, "vref");
> +		
> +	/* check if an external reference is supplied */
> +	st->vref = devm_regulator_get_optional(&client->dev, "vref");
> +
> +	if (PTR_ERR(st->vref) == -ENODEV) {
> +		vref_external = false;
> +		/* get dummy */
> +		st->vref = devm_regulator_get(&client->dev, "vref");

Why?  Instead of doing this add if (st->vref) around the regulator
enable and disable.  We don't want to pretend there is a regulator when
there isn't one connected and we are using VDD as the reference.

If we are in that mode, we need to change which regulator is read in
read_raw()


> +	}
>  	if (IS_ERR(st->vref)) {
>  		ret = PTR_ERR(st->vref);
>  		goto error_disable_reg;
> @@ -806,6 +816,13 @@ static int ad799x_probe(struct i2c_client *client,
>  	if (ret)
>  		goto error_disable_reg;
>  
> +	/* use external reference voltage, optional if regulator present */
> +	if (vref_external && 
> +	   ((st->id == ad7991) || (st->id == ad7995) || (st->id == ad7999))) {
> +		dev_info(&client->dev, "Using external reference voltage\n");
> +		extra_config |= AD7991_REF_SEL;
> +	}
> +
>  	st->client = client;
>  
>  	indio_dev->name = id->name;
> @@ -815,7 +832,7 @@ static int ad799x_probe(struct i2c_client *client,
>  	indio_dev->channels = st->chip_config->channel;
>  	indio_dev->num_channels = chip_info->num_channels;
>  
> -	ret = ad799x_update_config(st, st->chip_config->default_config);
> +	ret = ad799x_update_config(st, st->chip_config->default_config | extra_config);
>  	if (ret)
>  		goto error_disable_vref;
>  

Re: [PATCH v2 1/2] iio: adc: ad799x: Implement selecting external reference voltage input on AD7991, AD7995 and AD7999.

[Florian Boor]

Hi Jonathan,

On 11.09.21 18:43, Jonathan Cameron wrote:
> On Wed,  8 Sep 2021 17:25:24 +0200
> Florian Boor <florian.boor@kernelconcepts.de> wrote:
> 
>> Make use of the AD7991_REF_SEL bit and support using the external
>> reference voltage if 'vref-supply' is present.
>>
>> Signed-off-by: Florian Boor <florian.boor@kernelconcepts.de>
> 
> Hi Florian,
> 
>> ---
>>
>> Changes in v2:
>> - Check if a provided external vref regulator is provided.
>> - Drop unused setting
>> - Add ad79xx documentation (second patch)
>>
>>  drivers/iio/adc/ad799x.c | 21 +++++++++++++++++++--
>>  1 file changed, 19 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/iio/adc/ad799x.c b/drivers/iio/adc/ad799x.c
>> index 18bf8386d50a..2ff926a4e9b3 100644
>> --- a/drivers/iio/adc/ad799x.c
>> +++ b/drivers/iio/adc/ad799x.c
>> @@ -770,6 +770,8 @@ static int ad799x_probe(struct i2c_client *client,
>>  				   const struct i2c_device_id *id)
>>  {
>>  	int ret;
>> +	int extra_config = 0;
>> +	bool vref_external = true;
>>  	struct ad799x_state *st;
>>  	struct iio_dev *indio_dev;
>>  	const struct ad799x_chip_info *chip_info =
>> @@ -797,7 +799,15 @@ static int ad799x_probe(struct i2c_client *client,
>>  	ret = regulator_enable(st->reg);
>>  	if (ret)
>>  		return ret;
>> -	st->vref = devm_regulator_get(&client->dev, "vref");
>> +		
>> +	/* check if an external reference is supplied */
>> +	st->vref = devm_regulator_get_optional(&client->dev, "vref");
>> +
>> +	if (PTR_ERR(st->vref) == -ENODEV) {
>> +		vref_external = false;
>> +		/* get dummy */
>> +		st->vref = devm_regulator_get(&client->dev, "vref");
> 
> Why?  Instead of doing this add if (st->vref) around the regulator
> enable and disable.  We don't want to pretend there is a regulator when
> there isn't one connected and we are using VDD as the reference.
> 
> If we are in that mode, we need to change which regulator is read in
> read_raw()

I have to admit I wondered about how this is handled as well. My idea was not to
change it at this point and improve this later in a separate patch.
But I see the point - I'll add this change as well.

Greetings

Florian

-- 
The dream of yesterday                  Florian Boor
is the hope of today                    Tel: +49(0) 271-338857-15
and the reality of tomorrow.		Fax: +49(0) 271-338857-29
[Robert Hutchings Goddard, 1904]        florian.boor@kernelconcepts.de
                                        http://www.kernelconcepts.de/en

kernel concepts GmbH
Hauptstraße 16
57074 Siegen
Deutschland
Geschäftsführer: Ole Reinhardt
HR Siegen, HR B 9613