Re: [PATCH v5 3/5] iio: adc: ad7949: add support for internal vref

...
 > +

quoted

quoted

 static int ad7949_spi_probe(struct spi_device *spi)
 {
 	u32 spi_ctrl_mask = spi->controller->bits_per_word_mask;
 	struct device *dev = &spi->dev;
 	const struct ad7949_adc_spec *spec;
 	struct ad7949_adc_chip *ad7949_adc;
+	struct ad7949_channel *ad7949_chan;
+	struct fwnode_handle *child;
 	struct iio_dev *indio_dev;
+	int mode;
+	u32 tmp;
 	int ret;
+	int i;
 
 	indio_dev = devm_iio_device_alloc(dev, sizeof(*ad7949_adc));
 	if (!indio_dev) {

@@ -343,16 +383,82 @@ static int ad7949_spi_probe(struct spi_device *spi)
 		return -EINVAL;
 	}
 
-	ad7949_adc->vref = devm_regulator_get(dev, "vref");
+	/* Setup external voltage ref, buffered? */
+	ad7949_adc->vref = devm_regulator_get_optional(dev, "vrefin");
 	if (IS_ERR(ad7949_adc->vref)) {
-		dev_err(dev, "fail to request regulator\n");
-		return PTR_ERR(ad7949_adc->vref);
+		ret = PTR_ERR(ad7949_adc->vref);
+		if (ret != -ENODEV)
+			return ret;
+		/* unbuffered? */
+		ad7949_adc->vref = devm_regulator_get_optional(dev, "vref");
+		if (IS_ERR(ad7949_adc->vref)) {
+			ret = PTR_ERR(ad7949_adc->vref);
+			if (ret != -ENODEV)
+				return ret;
+			/* Internal then */
+			mode = AD7949_CFG_VAL_REF_INT_4096;
+		} else {
+			mode = AD7949_CFG_VAL_REF_EXT_TEMP;
+		}
+	} else {
+		mode = AD7949_CFG_VAL_REF_EXT_TEMP_BUF;
 	}
 
-	ret = regulator_enable(ad7949_adc->vref);
-	if (ret < 0) {
-		dev_err(dev, "fail to enable regulator\n");
-		return ret;
+	if (mode & AD7949_CFG_VAL_REF_EXTERNAL) {
+		ret = regulator_enable(ad7949_adc->vref);
+		if (ret < 0) {
+			dev_err(dev, "fail to enable regulator\n");
+			return ret;
+		}
+
+		ret = devm_add_action_or_reset(dev, ad7949_disable_reg,
+					       ad7949_adc->vref);
+		if (ret)
+			return ret;
+	}
+
+	ad7949_adc->channels = devm_kcalloc(dev, spec->num_channels,
+					    sizeof(*ad7949_adc->channels),
+					    GFP_KERNEL);
+	if (!ad7949_adc->channels) {
+		dev_err(dev, "unable to allocate ADC channels\n");
+		return -ENOMEM;
+	}
+
+	/* Initialize all channel structures */
+	for (i = 0; i < spec->num_channels; i++)
+		ad7949_adc->channels[i].refsel = mode;
+
+	/* Read channel specific information form the devicetree */
+	device_for_each_child_node(dev, child) {
+		ret = fwnode_property_read_u32(child, "reg", &i);
+		if (ret) {
+			dev_err(dev, "missing reg property in %pfw\n", child);
+			fwnode_handle_put(child);
+			return ret;
+		}
+
+		ad7949_chan = &ad7949_adc->channels[i];
+
+		ret = fwnode_property_read_u32(child, "adi,internal-ref-microvolt", &tmp);
+		if (ret < 0 && ret != -EINVAL) {
+			dev_err(dev, "invalid internal reference in %pfw\n", child);
+			fwnode_handle_put(child);
+			return ret;
+		}  

Hi Jonathan,

quoted

So if we are using external voltage, then we'd not expect this to exist.
ret != -EINVAL should deal with that. However, we then hit the following
switch
and temp isn't set to an appropriate value so we get the error.

Am I missing something?  

You're right that using an external reference, will cause this to fail.
My apologies, I've done a poor job of testing the last two revisions of
this patch. I'll do better.

Since a regulator is also required when we're using an external source,
I'll add a check for that. Something like this:

	ret = fwnode_property_read_u32(child, "adi,internal-ref-microvolt", &tmp);
	if (ret == -EINVAL && mode & AD7949_CFG_VAL_REF_EXTERNAL) {
		continue;
	} else if (ret < 0) {
		dev_err(dev, "invalid voltage reference in %pfw\n", child);
		fwnode_handle_put(child);
		return ret;
	}

Makes sense.

Given that we can now have a different scale for each channel based on
the vref source, should BIT(IIO_CHAN_INFO_SCALE) be moved to
.info_mask_separate in the channel definition?

Yes, good point.

Hopefully no one will notice the ABI change *crosses fingers*.

Jonathan

Thanks,
Liam

quoted

quoted

+
+		switch (tmp) {
+		case 2500000:
+			ad7949_chan->refsel = AD7949_CFG_VAL_REF_INT_2500;
+			break;
+		case 4096000:
+			ad7949_chan->refsel = AD7949_CFG_VAL_REF_INT_4096;
+			break;
+		default:
+			dev_err(dev, "unsupported internal voltage reference\n");
+			fwnode_handle_put(child);
+			return -EINVAL;
+		}
 	}
 
 	mutex_init(&ad7949_adc->lock);

@@ -373,7 +479,6 @@ static int ad7949_spi_probe(struct spi_device *spi)
 
 err:
 	mutex_destroy(&ad7949_adc->lock);
-	regulator_disable(ad7949_adc->vref);
 
 	return ret;
 }

@@ -385,7 +490,6 @@ static int ad7949_spi_remove(struct spi_device *spi)
 
 	iio_device_unregister(indio_dev);
 	mutex_destroy(&ad7949_adc->lock);
-	regulator_disable(ad7949_adc->vref);
 
 	return 0;
 }