Re: [PATCH 2/4] iio: adc: ad7091r5: Add scale and external VREF support

[Jonathan Cameron]

On Mon, 21 Oct 2019 20:06:06 +0300
Beniamin Bia <beniamin.bia@xxxxxxxxxx> wrote:

> From: Paul Cercueil <paul.cercueil@xxxxxxxxxx>
> 
> The scale can now be obtained with the "in_voltage_scale" file.
> By default, the scale returned corresponds to the internal VREF of 2.5V.
> 
> It is possible to use an external VREF (through the REFIN/REFOUT pin of
> the chip), by passing a regulator to the driver. The scale will then be
> calculated according to the voltage reported by the regulator.
> 
> Signed-off-by: Paul Cercueil <paul.cercueil@xxxxxxxxxx>
> Co-developed-by: Beniamin Bia <beniamin.bia@xxxxxxxxxx>
> Signed-off-by: Beniamin Bia <beniamin.bia@xxxxxxxxxx>
My only comment on this one is that you could use devm_add_action_or_reset
to deal with the regulator clean up.

> ---
>  drivers/iio/adc/ad7091r-base.c | 42 +++++++++++++++++++++++++++++++++-
>  drivers/iio/adc/ad7091r-base.h |  1 +
>  drivers/iio/adc/ad7091r5.c     |  5 ++++
>  3 files changed, 47 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/iio/adc/ad7091r-base.c b/drivers/iio/adc/ad7091r-base.c
> index 140413329754..d416f0912531 100644
> --- a/drivers/iio/adc/ad7091r-base.c
> +++ b/drivers/iio/adc/ad7091r-base.c
> @@ -14,6 +14,7 @@
>  #include <linux/interrupt.h>
>  #include <linux/module.h>
>  #include <linux/regmap.h>
> +#include <linux/regulator/consumer.h>
>  
>  #define AD7091R_REG_RESULT  0
>  #define AD7091R_REG_CHANNEL 1
> @@ -42,6 +43,7 @@ enum ad7091r_mode {
>  struct ad7091r_state {
>  	struct device *dev;
>  	struct regmap *map;
> +	struct regulator *reg;
>  	const struct ad7091r_chip_info *chip_info;
>  	enum ad7091r_mode mode;
>  };
> @@ -139,6 +141,21 @@ static int ad7091r_read_raw(struct iio_dev *iio_dev,
>  		ret = IIO_VAL_INT;
>  		break;
>  
> +	case IIO_CHAN_INFO_SCALE:
> +		if (st->reg) {
> +			ret = regulator_get_voltage(st->reg);
> +			if (ret < 0)
> +				goto unlock;
> +
> +			*val = ret / 1000;
> +		} else {
> +			*val = st->chip_info->vref_mV;
> +		}
> +
> +		*val2 = chan->scan_type.realbits;
> +		ret = IIO_VAL_FRACTIONAL_LOG2;
> +		break;
> +
>  	default:
>  		ret = -EINVAL;
>  		break;
> @@ -215,6 +232,18 @@ int ad7091r_probe(struct device *dev, const char *name,
>  			return ret;
>  	}
>  
> +	st->reg = devm_regulator_get_optional(dev, "vref");
> +	if (IS_ERR(st->reg)) {
> +		if (PTR_ERR(st->reg) == EPROBE_DEFER)
> +			return -EPROBE_DEFER;
> +
> +		st->reg = NULL;
> +	} else {
> +		ret = regulator_enable(st->reg);
> +		if (ret)
> +			return ret;

I would use devm_add_action_or_reset with appropriate wrapper
around disabling the regulator. That will get rid of the
need to manually deal with errors or remove path.

> +	}
> +
>  	/* Use command mode by default */
>  	ret = ad7091r_set_mode(st, AD7091R_MODE_COMMAND);
>  	if (ret < 0)
> @@ -222,18 +251,29 @@ int ad7091r_probe(struct device *dev, const char *name,
>  
>  	ret = iio_device_register(iio_dev);
>  	if (ret)
> -		return ret;
> +		goto err_disable_reg;
>  
>  	dev_dbg(dev, "Probed\n");
>  	return 0;
> +
> +err_disable_reg:
> +	if (st->reg)
> +		regulator_disable(st->reg);
> +
> +	return ret;
>  }
>  EXPORT_SYMBOL_GPL(ad7091r_probe);
>  
>  int ad7091r_remove(struct device *dev)
>  {
>  	struct iio_dev *iio_dev = dev_get_drvdata(dev);
> +	struct ad7091r_state *st = iio_priv(iio_dev);
>  
>  	iio_device_unregister(iio_dev);
> +
> +	if (st->reg)
> +		regulator_disable(st->reg);
> +
>  	return 0;
>  }
>  EXPORT_SYMBOL_GPL(ad7091r_remove);
> diff --git a/drivers/iio/adc/ad7091r-base.h b/drivers/iio/adc/ad7091r-base.h
> index 7a29f86ea82b..cec4fb75fecc 100644
> --- a/drivers/iio/adc/ad7091r-base.h
> +++ b/drivers/iio/adc/ad7091r-base.h
> @@ -18,6 +18,7 @@ struct ad7091r_state;
>  struct ad7091r_chip_info {
>  	unsigned int num_channels;
>  	const struct iio_chan_spec *channels;
> +	unsigned int vref_mV;
>  };
>  
>  extern const struct regmap_config ad7091r_regmap_config;
> diff --git a/drivers/iio/adc/ad7091r5.c b/drivers/iio/adc/ad7091r5.c
> index 1ba838c58c31..65bcd8bb692a 100644
> --- a/drivers/iio/adc/ad7091r5.c
> +++ b/drivers/iio/adc/ad7091r5.c
> @@ -35,10 +35,13 @@ static const struct iio_event_spec ad7091r5_events[] = {
>  #define AD7091R_CHANNEL(idx, bits, ev, num_ev) { \
>  	.type = IIO_VOLTAGE, \
>  	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
> +	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
>  	.indexed = 1, \
>  	.channel = idx, \
>  	.event_spec = ev, \
>  	.num_event_specs = num_ev, \
> +	.scan_type.storagebits = 16, \
> +	.scan_type.realbits = bits, \
>  }
>  static const struct iio_chan_spec ad7091r5_channels_irq[] = {
>  	AD7091R_CHANNEL(0, 12, ad7091r5_events, ARRAY_SIZE(ad7091r5_events)),
> @@ -58,11 +61,13 @@ static const struct iio_chan_spec ad7091r5_channels_noirq[] = {
>  static const struct ad7091r_chip_info ad7091r5_chip_info_irq = {
>  	.channels = ad7091r5_channels_irq,
>  	.num_channels = ARRAY_SIZE(ad7091r5_channels_irq),
> +	.vref_mV = 2500,
>  };
>  
>  static const struct ad7091r_chip_info ad7091r5_chip_info_noirq = {
>  	.channels = ad7091r5_channels_noirq,
>  	.num_channels = ARRAY_SIZE(ad7091r5_channels_noirq),
> +	.vref_mV = 2500,
>  };
>  
>  static int ad7091r5_i2c_probe(struct i2c_client *i2c,