Re: [PATCH] staging:iio:lpc32xx_adc: Add scale/offset support

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On 08/11/12 09:31, Roland Stigge wrote:
Hi Alban,

thanks for the patch. I can confirm that it compiles and runs fine, but
maybe someone else can comment on the IIO part.

Why not do this with regulators?  That would give a more flexible
system and all that stuff is already well supported (if fixed voltages
are supplied then used fixed regulators).
Some nitpicking below.

On 07/11/12 17:44, Alban Bedel wrote:
Signed-off-by: Alban Bedel <alban.bedel@xxxxxxxxxxxxxxxxx>
---
  .../bindings/staging/iio/adc/lpc32xx-adc.txt       |    6 ++++
  drivers/staging/iio/adc/lpc32xx_adc.c              |   30 +++++++++++++++++++-
  2 files changed, 35 insertions(+), 1 deletions(-)

diff --git a/Documentation/devicetree/bindings/staging/iio/adc/lpc32xx-adc.txt b/Documentation/devicetree/bindings/staging/iio/adc/lpc32xx-adc.txt
index b3629d3..515c128 100644
--- a/Documentation/devicetree/bindings/staging/iio/adc/lpc32xx-adc.txt
+++ b/Documentation/devicetree/bindings/staging/iio/adc/lpc32xx-adc.txt
@@ -6,6 +6,11 @@ Required properties:
    region.
  - interrupts: The ADC interrupt

+Optional properties:
+- reference-voltages: the 3 reference voltages value (in mV) to use
+  for scaling. If not given or 0 a scaling factor of 1 is used.
+- offsets: the 3 offsets to add to the raw value before scaling.
+
  Example:

  	adc@40048000 {
@@ -13,4 +18,5 @@ Example:
  		reg = <0x40048000 0x1000>;
  		interrupt-parent = <&mic>;
  		interrupts = <39 0>;
+		reference-voltages = <5000>, <3300>, <1200>;
  	};
diff --git a/drivers/staging/iio/adc/lpc32xx_adc.c b/drivers/staging/iio/adc/lpc32xx_adc.c
index 10c5962..aaa23ac 100644
--- a/drivers/staging/iio/adc/lpc32xx_adc.c
+++ b/drivers/staging/iio/adc/lpc32xx_adc.c
@@ -64,6 +64,8 @@ struct lpc32xx_adc_info {
  	struct completion completion;

  	u32 value;
+	u32 ref_voltage[3];
+	u32 offset[3];
  };

  static int lpc32xx_read_raw(struct iio_dev *indio_dev,
@@ -91,6 +93,26 @@ static int lpc32xx_read_raw(struct iio_dev *indio_dev,
  		return IIO_VAL_INT;
  	}

+	if (mask == IIO_CHAN_INFO_SCALE) {
+		if (info->ref_voltage[chan->channel]) {
+			unsigned factor;
+			factor = div_u64((u64)info->ref_voltage[chan->channel] *
+					 (u64)1000000,
+					 ADC_VALUE_MASK);
+			*val = factor / 1000000;
+			*val2 = factor % 1000000;
+			return IIO_VAL_INT_PLUS_MICRO;
+		} else {
+			*val = 1;
+			return IIO_VAL_INT;
+		}
+	}
+
+	if (mask == IIO_CHAN_INFO_OFFSET) {
+		*val = info->offset[chan->channel];
+		return IIO_VAL_INT;
+	}
+
  	return -EINVAL;
  }

@@ -103,7 +125,9 @@ static const struct iio_info lpc32xx_adc_iio_info = {
  	.type = IIO_VOLTAGE,				\
  	.indexed = 1,					\
  	.channel = _index,				\
-	.info_mask = IIO_CHAN_INFO_RAW_SEPARATE_BIT,	\
+	.info_mask = IIO_CHAN_INFO_RAW_SEPARATE_BIT |	\
+	             IIO_CHAN_INFO_SCALE_SEPARATE_BIT |	\
+	             IIO_CHAN_INFO_OFFSET_SEPARATE_BIT,	\

Shouldn't here be tabs instead of spaces? You can check with
scripts/checkpatch.pl

  	.address = AD_IN * _index,			\
  	.scan_index = _index,				\
  }
@@ -149,6 +173,10 @@ static int __devinit lpc32xx_adc_probe(struct platform_device *pdev)
  	}

  	info = iio_priv(iodev);
+	of_property_read_u32_array(pdev->dev.of_node, "reference-voltages",
+				   info->ref_voltage, ARRAY_SIZE(info->ref_voltage));

Considering that there is one line break already, maybe there should be
another one for keeping line length.

+	of_property_read_u32_array(pdev->dev.of_node, "offsets",
+				   info->offset, ARRAY_SIZE(info->offset));

  	info->adc_base = ioremap(res->start, resource_size(res));
  	if (!info->adc_base) {

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