[PATCH v2] Add support for external reference voltage through the regulator framework

[PATCH v2] Add support for external reference voltage through the regulator framework

[Silvan Murer]

Add support for external reference voltage through the regulator framework.

Signed-off-by: Silvan Murer <silvan.murer@gmail.com>
---
Changes in v2:
	- Add 'optional properties' documentation
	- Return an error when a regulator is specified
	- Use internal reference when no regulator is specified
	- Use iio_device_register instead of devm_iio_device_register

 .../devicetree/bindings/iio/dac/ltc2632.txt        | 14 +++++
 drivers/iio/dac/ltc2632.c                          | 70 +++++++++++++++++++---
 2 files changed, 75 insertions(+), 9 deletions(-)

diff --git a/Documentation/devicetree/bindings/iio/dac/ltc2632.txt b/Documentation/devicetree/bindings/iio/dac/ltc2632.txt
index eb911e5..e0d5fea 100644
--- a/Documentation/devicetree/bindings/iio/dac/ltc2632.txt
+++ b/Documentation/devicetree/bindings/iio/dac/ltc2632.txt
@@ -12,12 +12,26 @@ Required properties:
 Property rules described in Documentation/devicetree/bindings/spi/spi-bus.txt
 apply. In particular, "reg" and "spi-max-frequency" properties must be given.
 
+Optional properties:
+	- vref-supply: Phandle to the external reference voltage supply. This should
+	  only be set if there is an external reference voltage connected to the VREF
+	  pin. If the property is not set the internal reference is used.
+
 Example:
 
+	vref: regulator-vref {
+		compatible = "regulator-fixed";
+		regulator-name = "vref-ltc2632";
+		regulator-min-microvolt = <1250000>;
+		regulator-max-microvolt = <1250000>;
+		regulator-always-on;
+	};
+
 	spi_master {
 		dac: ltc2632@0 {
 			compatible = "lltc,ltc2632-l12";
 			reg = <0>; /* CS0 */
 			spi-max-frequency = <1000000>;
+			vref-supply = <&vref>; /* optional */
 		};
 	};
diff --git a/drivers/iio/dac/ltc2632.c b/drivers/iio/dac/ltc2632.c
index d322b78..7127cf6 100644
--- a/drivers/iio/dac/ltc2632.c
+++ b/drivers/iio/dac/ltc2632.c
@@ -2,6 +2,7 @@
  * LTC2632 Digital to analog convertors spi driver
  *
  * Copyright 2017 Maxime Roussin-Bélanger
+ * expanded by Silvan Murer <silvan.murer@gmail.com>
  *
  * Licensed under the GPL-2.
  */
@@ -10,6 +11,7 @@
 #include <linux/spi/spi.h>
 #include <linux/module.h>
 #include <linux/iio/iio.h>
+#include <linux/regulator/consumer.h>
 
 #define LTC2632_DAC_CHANNELS                    2
 
@@ -28,7 +30,7 @@
 /**
  * struct ltc2632_chip_info - chip specific information
  * @channels:		channel spec for the DAC
- * @vref_mv:		reference voltage
+ * @vref_mv:		internal reference voltage
  */
 struct ltc2632_chip_info {
 	const struct iio_chan_spec *channels;
@@ -39,10 +41,14 @@ struct ltc2632_chip_info {
  * struct ltc2632_state - driver instance specific data
  * @spi_dev:			pointer to the spi_device struct
  * @powerdown_cache_mask	used to show current channel powerdown state
+ * @vref_mv			used reference voltage (internal or external)
+ * @vref_reg		regulator for the reference voltage
  */
 struct ltc2632_state {
 	struct spi_device *spi_dev;
 	unsigned int powerdown_cache_mask;
+	int vref_mv;
+	struct regulator *vref_reg;
 };
 
 enum ltc2632_supported_device_ids {
@@ -90,7 +96,7 @@ static int ltc2632_read_raw(struct iio_dev *indio_dev,
 
 	switch (m) {
 	case IIO_CHAN_INFO_SCALE:
-		*val = chip_info->vref_mv;
+		*val =  st->vref_mv;
 		*val2 = chan->scan_type.realbits;
 		return IIO_VAL_FRACTIONAL_LOG2;
 	}
@@ -247,6 +253,45 @@ static int ltc2632_probe(struct spi_device *spi)
 	chip_info = (struct ltc2632_chip_info *)
 			spi_get_device_id(spi)->driver_data;
 
+	st->vref_reg = devm_regulator_get_optional(&spi->dev, "vref");
+	if (PTR_ERR(st->vref_reg) == -ENODEV) {
+		/* use internal reference voltage */
+		st->vref_reg = NULL;
+		st->vref_mv = chip_info->vref_mv;
+
+		ret = ltc2632_spi_write(spi, LTC2632_CMD_INTERNAL_REFER,
+				0, 0, 0);
+		if (ret) {
+			dev_err(&spi->dev,
+				"Set internal reference command failed, %d\n",
+				ret);
+			return ret;
+		}
+	} else if (IS_ERR(st->vref_reg)) {
+		dev_err(&spi->dev,
+				"Error getting voltage reference regulator\n");
+			return PTR_ERR(st->vref_reg);
+	} else {
+		/* use external reference voltage */
+		ret = regulator_enable(st->vref_reg);
+		if (ret) {
+			dev_err(&spi->dev,
+				"enable reference regulator failed, %d\n",
+				ret);
+			return ret;
+		}
+		st->vref_mv = regulator_get_voltage(st->vref_reg) / 1000;
+
+		ret = ltc2632_spi_write(spi, LTC2632_CMD_EXTERNAL_REFER,
+				0, 0, 0);
+		if (ret) {
+			dev_err(&spi->dev,
+				"Set external reference command failed, %d\n",
+				ret);
+			return ret;
+		}
+	}
+
 	indio_dev->dev.parent = &spi->dev;
 	indio_dev->name = dev_of_node(&spi->dev) ? dev_of_node(&spi->dev)->name
 						 : spi_get_device_id(spi)->name;
@@ -255,14 +300,20 @@ static int ltc2632_probe(struct spi_device *spi)
 	indio_dev->channels = chip_info->channels;
 	indio_dev->num_channels = LTC2632_DAC_CHANNELS;
 
-	ret = ltc2632_spi_write(spi, LTC2632_CMD_INTERNAL_REFER, 0, 0, 0);
-	if (ret) {
-		dev_err(&spi->dev,
-			"Set internal reference command failed, %d\n", ret);
-		return ret;
-	}
+	return iio_device_register(indio_dev);
+}
+
+static int ltc2632_remove(struct spi_device *spi)
+{
+	struct iio_dev *indio_dev = spi_get_drvdata(spi);
+	struct ltc2632_state *st = iio_priv(indio_dev);
+
+	iio_device_unregister(indio_dev);
+
+	if (st->vref_reg)
+		regulator_disable(st->vref_reg);
 
-	return devm_iio_device_register(&spi->dev, indio_dev);
+	return 0;
 }
 
 static const struct spi_device_id ltc2632_id[] = {
@@ -306,6 +357,7 @@ static struct spi_driver ltc2632_driver = {
 		.of_match_table = of_match_ptr(ltc2632_of_match),
 	},
 	.probe		= ltc2632_probe,
+	.remove		= ltc2632_remove,
 	.id_table	= ltc2632_id,
 };
 module_spi_driver(ltc2632_driver);
-- 
2.7.4

Re: [PATCH v2] Add support for external reference voltage through the regulator framework

[Lars-Peter Clausen]

On 05/15/2018 10:14 PM, Silvan Murer wrote:
> Add support for external reference voltage through the regulator framework.
> 
> Signed-off-by: Silvan Murer <silvan.murer@gmail.com>

Looks good, thanks.

Reviewed-by: Lars-Peter Clausen <lars@metafoo.de>

Just two tiny whitespace issues.

[...]
>  enum ltc2632_supported_device_ids {
> @@ -90,7 +96,7 @@ static int ltc2632_read_raw(struct iio_dev *indio_dev,
>  
>  	switch (m) {
>  	case IIO_CHAN_INFO_SCALE:
> -		*val = chip_info->vref_mv;
> +		*val =  st->vref_mv;

Extra space after the '='.

>  		*val2 = chan->scan_type.realbits;
>  		return IIO_VAL_FRACTIONAL_LOG2;
>  	}
> @@ -247,6 +253,45 @@ static int ltc2632_probe(struct spi_device *spi)
>  	chip_info = (struct ltc2632_chip_info *)
>  			spi_get_device_id(spi)->driver_data;
>  
> +	st->vref_reg = devm_regulator_get_optional(&spi->dev, "vref");
> +	if (PTR_ERR(st->vref_reg) == -ENODEV) {
> +		/* use internal reference voltage */
> +		st->vref_reg = NULL;
> +		st->vref_mv = chip_info->vref_mv;
> +
> +		ret = ltc2632_spi_write(spi, LTC2632_CMD_INTERNAL_REFER,
> +				0, 0, 0);
> +		if (ret) {
> +			dev_err(&spi->dev,
> +				"Set internal reference command failed, %d\n",
> +				ret);
> +			return ret;
> +		}
> +	} else if (IS_ERR(st->vref_reg)) {
> +		dev_err(&spi->dev,
> +				"Error getting voltage reference regulator\n");
> +			return PTR_ERR(st->vref_reg);

Extra tab before the 'return'.

> +	} else {
> +		/* use external reference voltage */
> +		ret = regulator_enable(st->vref_reg);
> +		if (ret) {
> +			dev_err(&spi->dev,
> +				"enable reference regulator failed, %d\n",
> +				ret);
> +			return ret;
> +		}
> +		st->vref_mv = regulator_get_voltage(st->vref_reg) / 1000;
> +
> +		ret = ltc2632_spi_write(spi, LTC2632_CMD_EXTERNAL_REFER,
> +				0, 0, 0);
> +		if (ret) {
> +			dev_err(&spi->dev,
> +				"Set external reference command failed, %d\n",
> +				ret);
> +			return ret;
> +		}
> +	}
> +
[...]

Re: [PATCH v2] Add support for external reference voltage through the regulator framework

[Silvan Murer]

Hi Lars,
Thanks for your review.
Should I create a new version of this patch whithout the whitespace
issues?
Generally question: What is the next step? Do you include the reviewed
patch into the iio.git repository? And do you submit the patches to the
mainline repository?
Sorry for the basic questions, currently I try to understand the whole
flow of the patch flow :)


On Don, 2018-05-17 at 13:01 +0200, Lars-Peter Clausen wrote:
> On 05/15/2018 10:14 PM, Silvan Murer wrote:
> > 
> > Add support for external reference voltage through the regulator
> > framework.
> > 
> > Signed-off-by: Silvan Murer <silvan.murer@gmail.com>
> Looks good, thanks.
> 
> Reviewed-by: Lars-Peter Clausen <lars@metafoo.de>
> 
> Just two tiny whitespace issues.
> 
> [...]
> > 
> >  enum ltc2632_supported_device_ids {
> > @@ -90,7 +96,7 @@ static int ltc2632_read_raw(struct iio_dev
> > *indio_dev,
> >  
> >  	switch (m) {
> >  	case IIO_CHAN_INFO_SCALE:
> > -		*val = chip_info->vref_mv;
> > +		*val =  st->vref_mv;
> Extra space after the '='.
> 
> > 
> >  		*val2 = chan->scan_type.realbits;
> >  		return IIO_VAL_FRACTIONAL_LOG2;
> >  	}
> > @@ -247,6 +253,45 @@ static int ltc2632_probe(struct spi_device
> > *spi)
> >  	chip_info = (struct ltc2632_chip_info *)
> >  			spi_get_device_id(spi)->driver_data;
> >  
> > +	st->vref_reg = devm_regulator_get_optional(&spi->dev,
> > "vref");
> > +	if (PTR_ERR(st->vref_reg) == -ENODEV) {
> > +		/* use internal reference voltage */
> > +		st->vref_reg = NULL;
> > +		st->vref_mv = chip_info->vref_mv;
> > +
> > +		ret = ltc2632_spi_write(spi,
> > LTC2632_CMD_INTERNAL_REFER,
> > +				0, 0, 0);
> > +		if (ret) {
> > +			dev_err(&spi->dev,
> > +				"Set internal reference command
> > failed, %d\n",
> > +				ret);
> > +			return ret;
> > +		}
> > +	} else if (IS_ERR(st->vref_reg)) {
> > +		dev_err(&spi->dev,
> > +				"Error getting voltage reference
> > regulator\n");
> > +			return PTR_ERR(st->vref_reg);
> Extra tab before the 'return'.
> 
> > 
> > +	} else {
> > +		/* use external reference voltage */
> > +		ret = regulator_enable(st->vref_reg);
> > +		if (ret) {
> > +			dev_err(&spi->dev,
> > +				"enable reference regulator
> > failed, %d\n",
> > +				ret);
> > +			return ret;
> > +		}
> > +		st->vref_mv = regulator_get_voltage(st->vref_reg)
> > / 1000;
> > +
> > +		ret = ltc2632_spi_write(spi,
> > LTC2632_CMD_EXTERNAL_REFER,
> > +				0, 0, 0);
> > +		if (ret) {
> > +			dev_err(&spi->dev,
> > +				"Set external reference command
> > failed, %d\n",
> > +				ret);
> > +			return ret;
> > +		}
> > +	}
> > +
> [...]

Re: [PATCH v2] Add support for external reference voltage through the regulator framework

[Lars-Peter Clausen]

On 05/18/2018 11:13 AM, Silvan Murer wrote:
> Hi Lars,
> Thanks for your review.
> Should I create a new version of this patch whithout the whitespace
> issues?
> Generally question: What is the next step? Do you include the reviewed
> patch into the iio.git repository? And do you submit the patches to the
> mainline repository?
> Sorry for the basic questions, currently I try to understand the whole
> flow of the patch flow :)


Hi,

Jonathan will pick the patch up and add it to the iio.git repository, when
he finds the time and thinks the patch is good. And then the patches will
find their way to mainline.

You could ask Jonathan to fix the whitespace errors when he picks up the
patch. But it would be less work for him if you just send a version that has
the whitespace fixed (Keep by Reviewed-by tag).

- Lars

> 
> 
> On Don, 2018-05-17 at 13:01 +0200, Lars-Peter Clausen wrote:
>> On 05/15/2018 10:14 PM, Silvan Murer wrote:
>>>
>>> Add support for external reference voltage through the regulator
>>> framework.
>>>
>>> Signed-off-by: Silvan Murer <silvan.murer@gmail.com>
>> Looks good, thanks.
>>
>> Reviewed-by: Lars-Peter Clausen <lars@metafoo.de>
>>
>> Just two tiny whitespace issues.
>>
>> [...]
>>>
>>>  enum ltc2632_supported_device_ids {
>>> @@ -90,7 +96,7 @@ static int ltc2632_read_raw(struct iio_dev
>>> *indio_dev,
>>>  
>>>  	switch (m) {
>>>  	case IIO_CHAN_INFO_SCALE:
>>> -		*val = chip_info->vref_mv;
>>> +		*val =  st->vref_mv;
>> Extra space after the '='.
>>
>>>
>>>  		*val2 = chan->scan_type.realbits;
>>>  		return IIO_VAL_FRACTIONAL_LOG2;
>>>  	}
>>> @@ -247,6 +253,45 @@ static int ltc2632_probe(struct spi_device
>>> *spi)
>>>  	chip_info = (struct ltc2632_chip_info *)
>>>  			spi_get_device_id(spi)->driver_data;
>>>  
>>> +	st->vref_reg = devm_regulator_get_optional(&spi->dev,
>>> "vref");
>>> +	if (PTR_ERR(st->vref_reg) == -ENODEV) {
>>> +		/* use internal reference voltage */
>>> +		st->vref_reg = NULL;
>>> +		st->vref_mv = chip_info->vref_mv;
>>> +
>>> +		ret = ltc2632_spi_write(spi,
>>> LTC2632_CMD_INTERNAL_REFER,
>>> +				0, 0, 0);
>>> +		if (ret) {
>>> +			dev_err(&spi->dev,
>>> +				"Set internal reference command
>>> failed, %d\n",
>>> +				ret);
>>> +			return ret;
>>> +		}
>>> +	} else if (IS_ERR(st->vref_reg)) {
>>> +		dev_err(&spi->dev,
>>> +				"Error getting voltage reference
>>> regulator\n");
>>> +			return PTR_ERR(st->vref_reg);
>> Extra tab before the 'return'.
>>
>>>
>>> +	} else {
>>> +		/* use external reference voltage */
>>> +		ret = regulator_enable(st->vref_reg);
>>> +		if (ret) {
>>> +			dev_err(&spi->dev,
>>> +				"enable reference regulator
>>> failed, %d\n",
>>> +				ret);
>>> +			return ret;
>>> +		}
>>> +		st->vref_mv = regulator_get_voltage(st->vref_reg)
>>> / 1000;
>>> +
>>> +		ret = ltc2632_spi_write(spi,
>>> LTC2632_CMD_EXTERNAL_REFER,
>>> +				0, 0, 0);
>>> +		if (ret) {
>>> +			dev_err(&spi->dev,
>>> +				"Set external reference command
>>> failed, %d\n",
>>> +				ret);
>>> +			return ret;
>>> +		}
>>> +	}
>>> +
>> [...]

Re: [PATCH v2] Add support for external reference voltage through the regulator framework

[Silvan Murer]

Thank you for the additional informations.
I just submitted the fixed patch to the mailinglist.


On Fre, 2018-05-18 at 11:59 +0200, Lars-Peter Clausen wrote:
> On 05/18/2018 11:13 AM, Silvan Murer wrote:
> > 
> > Hi Lars,
> > Thanks for your review.
> > Should I create a new version of this patch whithout the whitespace
> > issues?
> > Generally question: What is the next step? Do you include the
> > reviewed
> > patch into the iio.git repository? And do you submit the patches to
> > the
> > mainline repository?
> > Sorry for the basic questions, currently I try to understand the
> > whole
> > flow of the patch flow :)
> 
> Hi,
> 
> Jonathan will pick the patch up and add it to the iio.git repository,
> when
> he finds the time and thinks the patch is good. And then the patches
> will
> find their way to mainline.
> 
> You could ask Jonathan to fix the whitespace errors when he picks up
> the
> patch. But it would be less work for him if you just send a version
> that has
> the whitespace fixed (Keep by Reviewed-by tag).
> 
> - Lars
> 
> > 
> > 
> > 
> > On Don, 2018-05-17 at 13:01 +0200, Lars-Peter Clausen wrote:
> > > 
> > > On 05/15/2018 10:14 PM, Silvan Murer wrote:
> > > > 
> > > > 
> > > > Add support for external reference voltage through the
> > > > regulator
> > > > framework.
> > > > 
> > > > Signed-off-by: Silvan Murer <silvan.murer@gmail.com>
> > > Looks good, thanks.
> > > 
> > > Reviewed-by: Lars-Peter Clausen <lars@metafoo.de>
> > > 
> > > Just two tiny whitespace issues.
> > > 
> > > [...]
> > > > 
> > > > 
> > > >  enum ltc2632_supported_device_ids {
> > > > @@ -90,7 +96,7 @@ static int ltc2632_read_raw(struct iio_dev
> > > > *indio_dev,
> > > >  
> > > >  	switch (m) {
> > > >  	case IIO_CHAN_INFO_SCALE:
> > > > -		*val = chip_info->vref_mv;
> > > > +		*val =  st->vref_mv;
> > > Extra space after the '='.
> > > 
> > > > 
> > > > 
> > > >  		*val2 = chan->scan_type.realbits;
> > > >  		return IIO_VAL_FRACTIONAL_LOG2;
> > > >  	}
> > > > @@ -247,6 +253,45 @@ static int ltc2632_probe(struct spi_device
> > > > *spi)
> > > >  	chip_info = (struct ltc2632_chip_info *)
> > > >  			spi_get_device_id(spi)->driver_data;
> > > >  
> > > > +	st->vref_reg = devm_regulator_get_optional(&spi->dev,
> > > > "vref");
> > > > +	if (PTR_ERR(st->vref_reg) == -ENODEV) {
> > > > +		/* use internal reference voltage */
> > > > +		st->vref_reg = NULL;
> > > > +		st->vref_mv = chip_info->vref_mv;
> > > > +
> > > > +		ret = ltc2632_spi_write(spi,
> > > > LTC2632_CMD_INTERNAL_REFER,
> > > > +				0, 0, 0);
> > > > +		if (ret) {
> > > > +			dev_err(&spi->dev,
> > > > +				"Set internal reference
> > > > command
> > > > failed, %d\n",
> > > > +				ret);
> > > > +			return ret;
> > > > +		}
> > > > +	} else if (IS_ERR(st->vref_reg)) {
> > > > +		dev_err(&spi->dev,
> > > > +				"Error getting voltage
> > > > reference
> > > > regulator\n");
> > > > +			return PTR_ERR(st->vref_reg);
> > > Extra tab before the 'return'.
> > > 
> > > > 
> > > > 
> > > > +	} else {
> > > > +		/* use external reference voltage */
> > > > +		ret = regulator_enable(st->vref_reg);
> > > > +		if (ret) {
> > > > +			dev_err(&spi->dev,
> > > > +				"enable reference regulator
> > > > failed, %d\n",
> > > > +				ret);
> > > > +			return ret;
> > > > +		}
> > > > +		st->vref_mv = regulator_get_voltage(st-
> > > > >vref_reg)
> > > > / 1000;
> > > > +
> > > > +		ret = ltc2632_spi_write(spi,
> > > > LTC2632_CMD_EXTERNAL_REFER,
> > > > +				0, 0, 0);
> > > > +		if (ret) {
> > > > +			dev_err(&spi->dev,
> > > > +				"Set external reference
> > > > command
> > > > failed, %d\n",
> > > > +				ret);
> > > > +			return ret;
> > > > +		}
> > > > +	}
> > > > +
> > > [...]