Re: [PATCH v3 2/4] iio: adc: ad7091r5: Add scale and external VREF support

[Jonathan Cameron <jic23@kernel.org>]

On Thu, 7 Nov 2019 17:07:57 +0200
Beniamin Bia <beniamin.bia@analog.com> wrote:

> From: Paul Cercueil <paul.cercueil@analog.com>
> 
> 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@analog.com>
> Co-developed-by: Beniamin Bia <beniamin.bia@analog.com>
> Signed-off-by: Beniamin Bia <beniamin.bia@analog.com>

A suggestion inline for how to simplify the code a little by only
registering the regulator disable if we actually have a regulator.

Thanks,

Jonathan

> ---
> Changes in v3:
> -type cast from void* in remove function removed
> -error checking for devm_add_action_or_reset
> 
>  drivers/iio/adc/ad7091r-base.c | 41 ++++++++++++++++++++++++++++++++++
>  drivers/iio/adc/ad7091r-base.h |  1 +
>  drivers/iio/adc/ad7091r5.c     |  5 +++++
>  3 files changed, 47 insertions(+)
> 
> diff --git a/drivers/iio/adc/ad7091r-base.c b/drivers/iio/adc/ad7091r-base.c
> index 2ebc40dfd927..abb0d9c2ea9c 100644
> --- a/drivers/iio/adc/ad7091r-base.c
> +++ b/drivers/iio/adc/ad7091r-base.c
> @@ -11,6 +11,7 @@
>  #include <linux/interrupt.h>
>  #include <linux/module.h>
>  #include <linux/regmap.h>
> +#include <linux/regulator/consumer.h>
>  
>  #include "ad7091r-base.h"
>  
> @@ -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;
>  	struct mutex lock;
> @@ -142,6 +144,21 @@ 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;
> @@ -184,6 +201,14 @@ static irqreturn_t ad7091r_event_handler(int irq, void *private)
>  	return IRQ_HANDLED;
>  }
>  
> +static void ad7091r_remove(void *data)
> +{
> +	struct ad7091r_state *st = data;
> +
> +	if (st->reg)
> +		regulator_disable(st->reg);
> +}
> +
>  int ad7091r_probe(struct device *dev, const char *name,
>  		const struct ad7091r_chip_info *chip_info,
>  		struct regmap *map, int irq)
> @@ -217,6 +242,22 @@ 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;
> +	}
> +
> +	ret = devm_add_action_or_reset(dev, ad7091r_remove, st);
> +	if (ret)
> +		return ret;
> +
This is more complex than it needs to be...

	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;
		ret = devm_add_action_or_reset(dec, ad7091r_dis_reg, st);
		if (ret)
			return ret;
	}

with
static void ad7091r_dis_reg(void *data)
{
	struct ad7091r_state *st = data;

	regulator_disable(st->reg);
}

That way the disable is only registered if we actually have a reg
and hence we don't need to check if we do.

Also, give it a more specific name than reg.   Chances are someone
will add the main power supply control sometime in the future.


>  	/* Use command mode by default to convert only desired channels*/
>  	ret = ad7091r_set_mode(st, AD7091R_MODE_COMMAND);
>  	if (ret)
> diff --git a/drivers/iio/adc/ad7091r-base.h b/drivers/iio/adc/ad7091r-base.h
> index 5f1147735953..76b76968d071 100644
> --- a/drivers/iio/adc/ad7091r-base.h
> +++ b/drivers/iio/adc/ad7091r-base.h
> @@ -14,6 +14,7 @@ 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 f7b3326032e8..73d18ddfd2c9 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,