[PATCH v2 1/3] iio: consumer.h: Fix kernel doc incosistency

[PATCH v2 1/3] iio: consumer.h: Fix kernel doc incosistency

[Lars-Peter Clausen]

For the iio_read_channel_raw and iio_read_channel_scale the kerneldoc comment
refers to an argument called "channel", while the argument is called "chan" in
the function signature. This leads to the following warnings from kerneldoc:

	Warning(include/linux/iio/consumer.h:71): No description found for parameter 'chan'
	Warning(include/linux/iio/consumer.h:71): Excess function parameter 'channel' description in 'iio_read_channel_raw'
	Warning(include/linux/iio/consumer.h:109): No description found for parameter 'chan'
	Warning(include/linux/iio/consumer.h:109): Excess function parameter 'channel' description in 'iio_read_channel_scale'

This patch fixes the warnings by naming them consistently.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
---
 include/linux/iio/consumer.h |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/linux/iio/consumer.h b/include/linux/iio/consumer.h
index 06ab4ec..62118dd 100644
--- a/include/linux/iio/consumer.h
+++ b/include/linux/iio/consumer.h
@@ -61,7 +61,7 @@ void iio_channel_release_all(struct iio_channel *chan);
 
 /**
  * iio_read_channel_raw() - read from a given channel
- * @channel:		The channel being queried.
+ * @chan:		The channel being queried.
  * @val:		Value read back.
  *
  * Note raw reads from iio channels are in adc counts and hence
@@ -82,7 +82,7 @@ int iio_get_channel_type(struct iio_channel *channel,
 
 /**
  * iio_read_channel_scale() - read the scale value for a channel
- * @channel:		The channel being queried.
+ * @chan:		The channel being queried.
  * @val:		First part of value read back.
  * @val2:		Second part of value read back.
  *
-- 
1.7.10.4

[PATCH v2 2/3] iio:inkern: Add function to read the processed value

[Lars-Peter Clausen]

Add a function to read a processed value from a channel. The function will first
attempt to read the IIO_CHAN_INFO_PROCESSED attribute. If that fails it will
read the IIO_CHAN_INFO_RAW attribute and convert the result from a raw value to
a processed value.

The patch also introduces a function to convert raw value to a processed value
and exports it, in case a user needs or wants to do the conversion by itself.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
---
Changes since v1:
	* Fix mixed up patch fragements between patch 2 and patch 3
---
 drivers/iio/inkern.c         |  114 ++++++++++++++++++++++++++++++++++++++----
 include/linux/iio/consumer.h |   38 ++++++++++++++
 include/linux/iio/iio.h      |   17 +++++++
 3 files changed, 160 insertions(+), 9 deletions(-)

diff --git a/drivers/iio/inkern.c b/drivers/iio/inkern.c
index 028c657..e53a7dd 100644
--- a/drivers/iio/inkern.c
+++ b/drivers/iio/inkern.c
@@ -229,9 +229,21 @@ void iio_channel_release_all(struct iio_channel *channels)
 }
 EXPORT_SYMBOL_GPL(iio_channel_release_all);
 
+static int iio_channel_read(struct iio_channel *chan, int *val, int *val2,
+	enum iio_chan_info_enum info)
+{
+	int unused;
+
+	if (val2 == NULL)
+		val2 = &unused;
+
+	return chan->indio_dev->info->read_raw(chan->indio_dev, chan->channel,
+						val, val2, info);
+}
+
 int iio_read_channel_raw(struct iio_channel *chan, int *val)
 {
-	int val2, ret;
+	int ret;
 
 	mutex_lock(&chan->indio_dev->info_exist_lock);
 	if (chan->indio_dev->info == NULL) {
@@ -239,10 +251,7 @@ int iio_read_channel_raw(struct iio_channel *chan, int *val)
 		goto err_unlock;
 	}
 
-	ret = chan->indio_dev->info->read_raw(chan->indio_dev,
-					      chan->channel,
-					      val, &val2,
-					      IIO_CHAN_INFO_RAW);
+	ret = iio_channel_read(chan, val, NULL, IIO_CHAN_INFO_RAW);
 err_unlock:
 	mutex_unlock(&chan->indio_dev->info_exist_lock);
 
@@ -250,6 +259,96 @@ err_unlock:
 }
 EXPORT_SYMBOL_GPL(iio_read_channel_raw);
 
+static int iio_convert_raw_to_processed_unlocked(struct iio_channel *chan,
+	int raw, int *processed, unsigned int scale)
+{
+	int scale_type, scale_val, scale_val2, offset;
+	s64 raw64 = raw;
+	int ret;
+
+	ret = iio_channel_read(chan, &offset, NULL, IIO_CHAN_INFO_SCALE);
+	if (ret == 0)
+		raw64 += offset;
+
+	scale_type = iio_channel_read(chan, &scale_val, &scale_val2,
+					IIO_CHAN_INFO_SCALE);
+	if (scale_type < 0)
+		return scale_type;
+
+	switch (scale_type) {
+	case IIO_VAL_INT:
+		*processed = raw64 * scale_val;
+		break;
+	case IIO_VAL_INT_PLUS_MICRO:
+		if (scale_val2 < 0)
+			*processed = -raw64 * scale_val;
+		else
+			*processed = raw64 * scale_val;
+		*processed += div_s64(raw64 * (s64)scale_val2 * scale, 1000000LL);
+		break;
+	case IIO_VAL_INT_PLUS_NANO:
+		if (scale_val2 < 0)
+			*processed = -raw64 * scale_val;
+		else
+			*processed = raw64 * scale_val;
+		*processed += div_s64(raw64 * (s64)scale_val2 * scale, 1000000000LL);
+		break;
+	case IIO_VAL_FRACTIONAL:
+		*processed = div_s64(raw64 * (s64)scale_val * scale, scale_val2);
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+int iio_convert_raw_to_processed(struct iio_channel *chan, int raw,
+	int *processed, unsigned int scale)
+{
+	int ret;
+
+	mutex_lock(&chan->indio_dev->info_exist_lock);
+	if (chan->indio_dev->info == NULL) {
+		ret = -ENODEV;
+		goto err_unlock;
+	}
+
+	ret = iio_convert_raw_to_processed_unlocked(chan, raw, processed,
+							scale);
+err_unlock:
+	mutex_unlock(&chan->indio_dev->info_exist_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(iio_convert_raw_to_processed);
+
+int iio_read_channel_processed(struct iio_channel *chan, int *val)
+{
+	int ret;
+
+	mutex_lock(&chan->indio_dev->info_exist_lock);
+	if (chan->indio_dev->info == NULL) {
+		ret = -ENODEV;
+		goto err_unlock;
+	}
+
+	if (iio_channel_has_info(chan->channel, IIO_CHAN_INFO_PROCESSED)) {
+		ret = iio_channel_read(chan, val, NULL, IIO_CHAN_INFO_PROCESSED);
+	} else {
+		ret = iio_channel_read(chan, val, NULL, IIO_CHAN_INFO_RAW);
+		if (ret < 0)
+			goto err_unlock;
+		ret = iio_convert_raw_to_processed_unlocked(chan, *val, val, 1);
+	}
+
+err_unlock:
+	mutex_unlock(&chan->indio_dev->info_exist_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(iio_read_channel_processed);
+
 int iio_read_channel_scale(struct iio_channel *chan, int *val, int *val2)
 {
 	int ret;
@@ -260,10 +359,7 @@ int iio_read_channel_scale(struct iio_channel *chan, int *val, int *val2)
 		goto err_unlock;
 	}
 
-	ret = chan->indio_dev->info->read_raw(chan->indio_dev,
-					      chan->channel,
-					      val, val2,
-					      IIO_CHAN_INFO_SCALE);
+	ret = iio_channel_read(chan, val, val2, IIO_CHAN_INFO_SCALE);
 err_unlock:
 	mutex_unlock(&chan->indio_dev->info_exist_lock);
 
diff --git a/include/linux/iio/consumer.h b/include/linux/iio/consumer.h
index 62118dd..e875bcf 100644
--- a/include/linux/iio/consumer.h
+++ b/include/linux/iio/consumer.h
@@ -71,6 +71,21 @@ int iio_read_channel_raw(struct iio_channel *chan,
 			 int *val);
 
 /**
+ * iio_read_channel_processed() - read processed value from a given channel
+ * @chan:		The channel being queried.
+ * @val:		Value read back.
+ *
+ * Returns an error code or 0.
+ *
+ * This function will read a processed value from a channel. A processed value
+ * means that this value will have the correct unit and not some device internal
+ * representation. If the device does not support reporting a processed value
+ * the function will query the raw value and the channels scale and offset and
+ * do the appropriate transformation.
+ */
+int iio_read_channel_processed(struct iio_channel *chan, int *val);
+
+/**
  * iio_get_channel_type() - get the type of a channel
  * @channel:		The channel being queried.
  * @type:		The type of the channel.
@@ -93,4 +108,27 @@ int iio_get_channel_type(struct iio_channel *channel,
 int iio_read_channel_scale(struct iio_channel *chan, int *val,
 			   int *val2);
 
+/**
+ * iio_convert_raw_to_processed() - Converts a raw value to a processed value
+ * @chan:		The channel being queried
+ * @raw:		The raw IIO to convert
+ * @processed:		The result of the conversion
+ * @scale:		Scale factor to apply during the conversion
+ *
+ * Returns an error code or 0.
+ *
+ * This function converts a raw value to processed value for a specific channel.
+ * A raw value is the device internal representation of a sample and the value
+ * returned by iio_read_channel_raw, so the unit of that value is device
+ * depended. A processed value on the other hand is value has a normed unit
+ * according with the IIO specification.
+ *
+ * The scale factor allows to increase the precession of the returned value. For
+ * a scale factor of 1 the function will return the result in the normal IIO
+ * unit for the channel type. E.g. millivolt for voltage channels, if you want
+ * nanovolts instead pass 1000 as the scale factor.
+ */
+int iio_convert_raw_to_processed(struct iio_channel *chan, int raw,
+	int *processed, unsigned int scale);
+
 #endif
diff --git a/include/linux/iio/iio.h b/include/linux/iio/iio.h
index 30affa5..c0ae76a 100644
--- a/include/linux/iio/iio.h
+++ b/include/linux/iio/iio.h
@@ -40,6 +40,8 @@ enum iio_chan_info_enum {
 
 #define IIO_CHAN_INFO_SHARED_BIT(type) BIT(type*2)
 #define IIO_CHAN_INFO_SEPARATE_BIT(type) BIT(type*2 + 1)
+#define IIO_CHAN_INFO_BITS(type) (IIO_CHAN_INFO_SHARED_BIT(type) | \
+				    IIO_CHAN_INFO_SEPARATE_BIT(type))
 
 #define IIO_CHAN_INFO_RAW_SEPARATE_BIT			\
 	IIO_CHAN_INFO_SEPARATE_BIT(IIO_CHAN_INFO_RAW)
@@ -261,6 +263,21 @@ struct iio_chan_spec {
 	unsigned		differential:1;
 };
 
+
+/**
+ * iio_channel_has_info() - Checks whether a channel supports a info attribute
+ * @chan: The channel to be queried
+ * @type: Type of the info attribute to be checked
+ *
+ * Returns true if the channels supports reporting values for the given info
+ * attribute type, false otherwise.
+ */
+static inline bool iio_channel_has_info(const struct iio_chan_spec *chan,
+	enum iio_chan_info_enum type)
+{
+	return chan->info_mask & IIO_CHAN_INFO_BITS(type);
+}
+
 #define IIO_ST(si, rb, sb, sh)						\
 	{ .sign = si, .realbits = rb, .storagebits = sb, .shift = sh }
 
-- 
1.7.10.4

Re: [PATCH v2 2/3] iio:inkern: Add function to read the processed value

[Jonathan Cameron]

On 09/17/2012 01:17 PM, Lars-Peter Clausen wrote:
> Add a function to read a processed value from a channel. The function will first
> attempt to read the IIO_CHAN_INFO_PROCESSED attribute. If that fails it will
> read the IIO_CHAN_INFO_RAW attribute and convert the result from a raw value to
> a processed value.
>
> The patch also introduces a function to convert raw value to a processed value
> and exports it, in case a user needs or wants to do the conversion by itself.
>
Another patch with a couple of overly long lines where readibility is not hurt
by breaking them. Hence I have done so when merging.
Please do fix the trivial stuff from checkpatch.

Otherwise a good series and all merged to togreg branch.

> Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
> ---
> Changes since v1:
> 	* Fix mixed up patch fragements between patch 2 and patch 3
> ---
>  drivers/iio/inkern.c         |  114 ++++++++++++++++++++++++++++++++++++++----
>  include/linux/iio/consumer.h |   38 ++++++++++++++
>  include/linux/iio/iio.h      |   17 +++++++
>  3 files changed, 160 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/iio/inkern.c b/drivers/iio/inkern.c
> index 028c657..e53a7dd 100644
> --- a/drivers/iio/inkern.c
> +++ b/drivers/iio/inkern.c
> @@ -229,9 +229,21 @@ void iio_channel_release_all(struct iio_channel *channels)
>  }
>  EXPORT_SYMBOL_GPL(iio_channel_release_all);
>
> +static int iio_channel_read(struct iio_channel *chan, int *val, int *val2,
> +	enum iio_chan_info_enum info)
> +{
> +	int unused;
> +
> +	if (val2 == NULL)
> +		val2 = &unused;
> +
> +	return chan->indio_dev->info->read_raw(chan->indio_dev, chan->channel,
> +						val, val2, info);
> +}
> +
>  int iio_read_channel_raw(struct iio_channel *chan, int *val)
>  {
> -	int val2, ret;
> +	int ret;
>
>  	mutex_lock(&chan->indio_dev->info_exist_lock);
>  	if (chan->indio_dev->info == NULL) {
> @@ -239,10 +251,7 @@ int iio_read_channel_raw(struct iio_channel *chan, int *val)
>  		goto err_unlock;
>  	}
>
> -	ret = chan->indio_dev->info->read_raw(chan->indio_dev,
> -					      chan->channel,
> -					      val, &val2,
> -					      IIO_CHAN_INFO_RAW);
> +	ret = iio_channel_read(chan, val, NULL, IIO_CHAN_INFO_RAW);
>  err_unlock:
>  	mutex_unlock(&chan->indio_dev->info_exist_lock);
>
> @@ -250,6 +259,96 @@ err_unlock:
>  }
>  EXPORT_SYMBOL_GPL(iio_read_channel_raw);
>
> +static int iio_convert_raw_to_processed_unlocked(struct iio_channel *chan,
> +	int raw, int *processed, unsigned int scale)
> +{
> +	int scale_type, scale_val, scale_val2, offset;
> +	s64 raw64 = raw;
> +	int ret;
> +
> +	ret = iio_channel_read(chan, &offset, NULL, IIO_CHAN_INFO_SCALE);
> +	if (ret == 0)
> +		raw64 += offset;
> +
> +	scale_type = iio_channel_read(chan, &scale_val, &scale_val2,
> +					IIO_CHAN_INFO_SCALE);
> +	if (scale_type < 0)
> +		return scale_type;
> +
> +	switch (scale_type) {
> +	case IIO_VAL_INT:
> +		*processed = raw64 * scale_val;
> +		break;
> +	case IIO_VAL_INT_PLUS_MICRO:
> +		if (scale_val2 < 0)
> +			*processed = -raw64 * scale_val;
> +		else
> +			*processed = raw64 * scale_val;
> +		*processed += div_s64(raw64 * (s64)scale_val2 * scale, 1000000LL);
> +		break;
> +	case IIO_VAL_INT_PLUS_NANO:
> +		if (scale_val2 < 0)
> +			*processed = -raw64 * scale_val;
> +		else
> +			*processed = raw64 * scale_val;
> +		*processed += div_s64(raw64 * (s64)scale_val2 * scale, 1000000000LL);
> +		break;
> +	case IIO_VAL_FRACTIONAL:
> +		*processed = div_s64(raw64 * (s64)scale_val * scale, scale_val2);
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +
> +	return 0;
> +}
> +
> +int iio_convert_raw_to_processed(struct iio_channel *chan, int raw,
> +	int *processed, unsigned int scale)
> +{
> +	int ret;
> +
> +	mutex_lock(&chan->indio_dev->info_exist_lock);
> +	if (chan->indio_dev->info == NULL) {
> +		ret = -ENODEV;
> +		goto err_unlock;
> +	}
> +
> +	ret = iio_convert_raw_to_processed_unlocked(chan, raw, processed,
> +							scale);
> +err_unlock:
> +	mutex_unlock(&chan->indio_dev->info_exist_lock);
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(iio_convert_raw_to_processed);
> +
> +int iio_read_channel_processed(struct iio_channel *chan, int *val)
> +{
> +	int ret;
> +
> +	mutex_lock(&chan->indio_dev->info_exist_lock);
> +	if (chan->indio_dev->info == NULL) {
> +		ret = -ENODEV;
> +		goto err_unlock;
> +	}
> +
> +	if (iio_channel_has_info(chan->channel, IIO_CHAN_INFO_PROCESSED)) {
> +		ret = iio_channel_read(chan, val, NULL, IIO_CHAN_INFO_PROCESSED);
> +	} else {
> +		ret = iio_channel_read(chan, val, NULL, IIO_CHAN_INFO_RAW);
> +		if (ret < 0)
> +			goto err_unlock;
> +		ret = iio_convert_raw_to_processed_unlocked(chan, *val, val, 1);
> +	}
> +
> +err_unlock:
> +	mutex_unlock(&chan->indio_dev->info_exist_lock);
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(iio_read_channel_processed);
> +
>  int iio_read_channel_scale(struct iio_channel *chan, int *val, int *val2)
>  {
>  	int ret;
> @@ -260,10 +359,7 @@ int iio_read_channel_scale(struct iio_channel *chan, int *val, int *val2)
>  		goto err_unlock;
>  	}
>
> -	ret = chan->indio_dev->info->read_raw(chan->indio_dev,
> -					      chan->channel,
> -					      val, val2,
> -					      IIO_CHAN_INFO_SCALE);
> +	ret = iio_channel_read(chan, val, val2, IIO_CHAN_INFO_SCALE);
>  err_unlock:
>  	mutex_unlock(&chan->indio_dev->info_exist_lock);
>
> diff --git a/include/linux/iio/consumer.h b/include/linux/iio/consumer.h
> index 62118dd..e875bcf 100644
> --- a/include/linux/iio/consumer.h
> +++ b/include/linux/iio/consumer.h
> @@ -71,6 +71,21 @@ int iio_read_channel_raw(struct iio_channel *chan,
>  			 int *val);
>
>  /**
> + * iio_read_channel_processed() - read processed value from a given channel
> + * @chan:		The channel being queried.
> + * @val:		Value read back.
> + *
> + * Returns an error code or 0.
> + *
> + * This function will read a processed value from a channel. A processed value
> + * means that this value will have the correct unit and not some device internal
> + * representation. If the device does not support reporting a processed value
> + * the function will query the raw value and the channels scale and offset and
> + * do the appropriate transformation.
> + */
> +int iio_read_channel_processed(struct iio_channel *chan, int *val);
> +
> +/**
>   * iio_get_channel_type() - get the type of a channel
>   * @channel:		The channel being queried.
>   * @type:		The type of the channel.
> @@ -93,4 +108,27 @@ int iio_get_channel_type(struct iio_channel *channel,
>  int iio_read_channel_scale(struct iio_channel *chan, int *val,
>  			   int *val2);
>
> +/**
> + * iio_convert_raw_to_processed() - Converts a raw value to a processed value
> + * @chan:		The channel being queried
> + * @raw:		The raw IIO to convert
> + * @processed:		The result of the conversion
> + * @scale:		Scale factor to apply during the conversion
> + *
> + * Returns an error code or 0.
> + *
> + * This function converts a raw value to processed value for a specific channel.
> + * A raw value is the device internal representation of a sample and the value
> + * returned by iio_read_channel_raw, so the unit of that value is device
> + * depended. A processed value on the other hand is value has a normed unit
> + * according with the IIO specification.
> + *
> + * The scale factor allows to increase the precession of the returned value. For
> + * a scale factor of 1 the function will return the result in the normal IIO
> + * unit for the channel type. E.g. millivolt for voltage channels, if you want
> + * nanovolts instead pass 1000 as the scale factor.
> + */
> +int iio_convert_raw_to_processed(struct iio_channel *chan, int raw,
> +	int *processed, unsigned int scale);
> +
>  #endif
> diff --git a/include/linux/iio/iio.h b/include/linux/iio/iio.h
> index 30affa5..c0ae76a 100644
> --- a/include/linux/iio/iio.h
> +++ b/include/linux/iio/iio.h
> @@ -40,6 +40,8 @@ enum iio_chan_info_enum {
>
>  #define IIO_CHAN_INFO_SHARED_BIT(type) BIT(type*2)
>  #define IIO_CHAN_INFO_SEPARATE_BIT(type) BIT(type*2 + 1)
> +#define IIO_CHAN_INFO_BITS(type) (IIO_CHAN_INFO_SHARED_BIT(type) | \
> +				    IIO_CHAN_INFO_SEPARATE_BIT(type))
>
>  #define IIO_CHAN_INFO_RAW_SEPARATE_BIT			\
>  	IIO_CHAN_INFO_SEPARATE_BIT(IIO_CHAN_INFO_RAW)
> @@ -261,6 +263,21 @@ struct iio_chan_spec {
>  	unsigned		differential:1;
>  };
>
> +
> +/**
> + * iio_channel_has_info() - Checks whether a channel supports a info attribute
> + * @chan: The channel to be queried
> + * @type: Type of the info attribute to be checked
> + *
> + * Returns true if the channels supports reporting values for the given info
> + * attribute type, false otherwise.
> + */
> +static inline bool iio_channel_has_info(const struct iio_chan_spec *chan,
> +	enum iio_chan_info_enum type)
> +{
> +	return chan->info_mask & IIO_CHAN_INFO_BITS(type);
> +}
> +
>  #define IIO_ST(si, rb, sb, sh)						\
>  	{ .sign = si, .realbits = rb, .storagebits = sb, .shift = sh }
>
>

Re: [PATCH v2 2/3] iio:inkern: Add function to read the processed value

[Lars-Peter Clausen]

On 09/17/2012 10:55 PM, Jonathan Cameron wrote:
> On 09/17/2012 01:17 PM, Lars-Peter Clausen wrote:
>> Add a function to read a processed value from a channel. The function will first
>> attempt to read the IIO_CHAN_INFO_PROCESSED attribute. If that fails it will
>> read the IIO_CHAN_INFO_RAW attribute and convert the result from a raw value to
>> a processed value.
>>
>> The patch also introduces a function to convert raw value to a processed value
>> and exports it, in case a user needs or wants to do the conversion by itself.
>>
> Another patch with a couple of overly long lines where readibility is not hurt
> by breaking them. Hence I have done so when merging.
> Please do fix the trivial stuff from checkpatch.

I tend to ignore the 80 line limit warnings from checkpatch on purpose if
the line is only 81 or 82 characters long and breaking it would introduce a
new line continuation.

> 
> Otherwise a good series and all merged to togreg branch.
> 

Thanks.

>> Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
>> ---
>> Changes since v1:
>> 	* Fix mixed up patch fragements between patch 2 and patch 3
>> ---
>>  drivers/iio/inkern.c         |  114 ++++++++++++++++++++++++++++++++++++++----
>>  include/linux/iio/consumer.h |   38 ++++++++++++++
>>  include/linux/iio/iio.h      |   17 +++++++
>>  3 files changed, 160 insertions(+), 9 deletions(-)
>>
>> diff --git a/drivers/iio/inkern.c b/drivers/iio/inkern.c
>> index 028c657..e53a7dd 100644
>> --- a/drivers/iio/inkern.c
>> +++ b/drivers/iio/inkern.c
>> @@ -229,9 +229,21 @@ void iio_channel_release_all(struct iio_channel *channels)
>>  }
>>  EXPORT_SYMBOL_GPL(iio_channel_release_all);
>>
>> +static int iio_channel_read(struct iio_channel *chan, int *val, int *val2,
>> +	enum iio_chan_info_enum info)
>> +{
>> +	int unused;
>> +
>> +	if (val2 == NULL)
>> +		val2 = &unused;
>> +
>> +	return chan->indio_dev->info->read_raw(chan->indio_dev, chan->channel,
>> +						val, val2, info);
>> +}
>> +
>>  int iio_read_channel_raw(struct iio_channel *chan, int *val)
>>  {
>> -	int val2, ret;
>> +	int ret;
>>
>>  	mutex_lock(&chan->indio_dev->info_exist_lock);
>>  	if (chan->indio_dev->info == NULL) {
>> @@ -239,10 +251,7 @@ int iio_read_channel_raw(struct iio_channel *chan, int *val)
>>  		goto err_unlock;
>>  	}
>>
>> -	ret = chan->indio_dev->info->read_raw(chan->indio_dev,
>> -					      chan->channel,
>> -					      val, &val2,
>> -					      IIO_CHAN_INFO_RAW);
>> +	ret = iio_channel_read(chan, val, NULL, IIO_CHAN_INFO_RAW);
>>  err_unlock:
>>  	mutex_unlock(&chan->indio_dev->info_exist_lock);
>>
>> @@ -250,6 +259,96 @@ err_unlock:
>>  }
>>  EXPORT_SYMBOL_GPL(iio_read_channel_raw);
>>
>> +static int iio_convert_raw_to_processed_unlocked(struct iio_channel *chan,
>> +	int raw, int *processed, unsigned int scale)
>> +{
>> +	int scale_type, scale_val, scale_val2, offset;
>> +	s64 raw64 = raw;
>> +	int ret;
>> +
>> +	ret = iio_channel_read(chan, &offset, NULL, IIO_CHAN_INFO_SCALE);
>> +	if (ret == 0)
>> +		raw64 += offset;
>> +
>> +	scale_type = iio_channel_read(chan, &scale_val, &scale_val2,
>> +					IIO_CHAN_INFO_SCALE);
>> +	if (scale_type < 0)
>> +		return scale_type;
>> +
>> +	switch (scale_type) {
>> +	case IIO_VAL_INT:
>> +		*processed = raw64 * scale_val;
>> +		break;
>> +	case IIO_VAL_INT_PLUS_MICRO:
>> +		if (scale_val2 < 0)
>> +			*processed = -raw64 * scale_val;
>> +		else
>> +			*processed = raw64 * scale_val;
>> +		*processed += div_s64(raw64 * (s64)scale_val2 * scale, 1000000LL);
>> +		break;
>> +	case IIO_VAL_INT_PLUS_NANO:
>> +		if (scale_val2 < 0)
>> +			*processed = -raw64 * scale_val;
>> +		else
>> +			*processed = raw64 * scale_val;
>> +		*processed += div_s64(raw64 * (s64)scale_val2 * scale, 1000000000LL);
>> +		break;
>> +	case IIO_VAL_FRACTIONAL:
>> +		*processed = div_s64(raw64 * (s64)scale_val * scale, scale_val2);
>> +		break;
>> +	default:
>> +		return -EINVAL;
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +int iio_convert_raw_to_processed(struct iio_channel *chan, int raw,
>> +	int *processed, unsigned int scale)
>> +{
>> +	int ret;
>> +
>> +	mutex_lock(&chan->indio_dev->info_exist_lock);
>> +	if (chan->indio_dev->info == NULL) {
>> +		ret = -ENODEV;
>> +		goto err_unlock;
>> +	}
>> +
>> +	ret = iio_convert_raw_to_processed_unlocked(chan, raw, processed,
>> +							scale);
>> +err_unlock:
>> +	mutex_unlock(&chan->indio_dev->info_exist_lock);
>> +
>> +	return ret;
>> +}
>> +EXPORT_SYMBOL_GPL(iio_convert_raw_to_processed);
>> +
>> +int iio_read_channel_processed(struct iio_channel *chan, int *val)
>> +{
>> +	int ret;
>> +
>> +	mutex_lock(&chan->indio_dev->info_exist_lock);
>> +	if (chan->indio_dev->info == NULL) {
>> +		ret = -ENODEV;
>> +		goto err_unlock;
>> +	}
>> +
>> +	if (iio_channel_has_info(chan->channel, IIO_CHAN_INFO_PROCESSED)) {
>> +		ret = iio_channel_read(chan, val, NULL, IIO_CHAN_INFO_PROCESSED);
>> +	} else {
>> +		ret = iio_channel_read(chan, val, NULL, IIO_CHAN_INFO_RAW);
>> +		if (ret < 0)
>> +			goto err_unlock;
>> +		ret = iio_convert_raw_to_processed_unlocked(chan, *val, val, 1);
>> +	}
>> +
>> +err_unlock:
>> +	mutex_unlock(&chan->indio_dev->info_exist_lock);
>> +
>> +	return ret;
>> +}
>> +EXPORT_SYMBOL_GPL(iio_read_channel_processed);
>> +
>>  int iio_read_channel_scale(struct iio_channel *chan, int *val, int *val2)
>>  {
>>  	int ret;
>> @@ -260,10 +359,7 @@ int iio_read_channel_scale(struct iio_channel *chan, int *val, int *val2)
>>  		goto err_unlock;
>>  	}
>>
>> -	ret = chan->indio_dev->info->read_raw(chan->indio_dev,
>> -					      chan->channel,
>> -					      val, val2,
>> -					      IIO_CHAN_INFO_SCALE);
>> +	ret = iio_channel_read(chan, val, val2, IIO_CHAN_INFO_SCALE);
>>  err_unlock:
>>  	mutex_unlock(&chan->indio_dev->info_exist_lock);
>>
>> diff --git a/include/linux/iio/consumer.h b/include/linux/iio/consumer.h
>> index 62118dd..e875bcf 100644
>> --- a/include/linux/iio/consumer.h
>> +++ b/include/linux/iio/consumer.h
>> @@ -71,6 +71,21 @@ int iio_read_channel_raw(struct iio_channel *chan,
>>  			 int *val);
>>
>>  /**
>> + * iio_read_channel_processed() - read processed value from a given channel
>> + * @chan:		The channel being queried.
>> + * @val:		Value read back.
>> + *
>> + * Returns an error code or 0.
>> + *
>> + * This function will read a processed value from a channel. A processed value
>> + * means that this value will have the correct unit and not some device internal
>> + * representation. If the device does not support reporting a processed value
>> + * the function will query the raw value and the channels scale and offset and
>> + * do the appropriate transformation.
>> + */
>> +int iio_read_channel_processed(struct iio_channel *chan, int *val);
>> +
>> +/**
>>   * iio_get_channel_type() - get the type of a channel
>>   * @channel:		The channel being queried.
>>   * @type:		The type of the channel.
>> @@ -93,4 +108,27 @@ int iio_get_channel_type(struct iio_channel *channel,
>>  int iio_read_channel_scale(struct iio_channel *chan, int *val,
>>  			   int *val2);
>>
>> +/**
>> + * iio_convert_raw_to_processed() - Converts a raw value to a processed value
>> + * @chan:		The channel being queried
>> + * @raw:		The raw IIO to convert
>> + * @processed:		The result of the conversion
>> + * @scale:		Scale factor to apply during the conversion
>> + *
>> + * Returns an error code or 0.
>> + *
>> + * This function converts a raw value to processed value for a specific channel.
>> + * A raw value is the device internal representation of a sample and the value
>> + * returned by iio_read_channel_raw, so the unit of that value is device
>> + * depended. A processed value on the other hand is value has a normed unit
>> + * according with the IIO specification.
>> + *
>> + * The scale factor allows to increase the precession of the returned value. For
>> + * a scale factor of 1 the function will return the result in the normal IIO
>> + * unit for the channel type. E.g. millivolt for voltage channels, if you want
>> + * nanovolts instead pass 1000 as the scale factor.
>> + */
>> +int iio_convert_raw_to_processed(struct iio_channel *chan, int raw,
>> +	int *processed, unsigned int scale);
>> +
>>  #endif
>> diff --git a/include/linux/iio/iio.h b/include/linux/iio/iio.h
>> index 30affa5..c0ae76a 100644
>> --- a/include/linux/iio/iio.h
>> +++ b/include/linux/iio/iio.h
>> @@ -40,6 +40,8 @@ enum iio_chan_info_enum {
>>
>>  #define IIO_CHAN_INFO_SHARED_BIT(type) BIT(type*2)
>>  #define IIO_CHAN_INFO_SEPARATE_BIT(type) BIT(type*2 + 1)
>> +#define IIO_CHAN_INFO_BITS(type) (IIO_CHAN_INFO_SHARED_BIT(type) | \
>> +				    IIO_CHAN_INFO_SEPARATE_BIT(type))
>>
>>  #define IIO_CHAN_INFO_RAW_SEPARATE_BIT			\
>>  	IIO_CHAN_INFO_SEPARATE_BIT(IIO_CHAN_INFO_RAW)
>> @@ -261,6 +263,21 @@ struct iio_chan_spec {
>>  	unsigned		differential:1;
>>  };
>>
>> +
>> +/**
>> + * iio_channel_has_info() - Checks whether a channel supports a info attribute
>> + * @chan: The channel to be queried
>> + * @type: Type of the info attribute to be checked
>> + *
>> + * Returns true if the channels supports reporting values for the given info
>> + * attribute type, false otherwise.
>> + */
>> +static inline bool iio_channel_has_info(const struct iio_chan_spec *chan,
>> +	enum iio_chan_info_enum type)
>> +{
>> +	return chan->info_mask & IIO_CHAN_INFO_BITS(type);
>> +}
>> +
>>  #define IIO_ST(si, rb, sb, sh)						\
>>  	{ .sign = si, .realbits = rb, .storagebits = sb, .shift = sh }
>>
>>
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[PATCH v2 3/3] staging:iio:hwmon bridge: Use iio_read_channel_processed

[Lars-Peter Clausen]

Use the iio_read_channel_processed function to read the sample value in the
proper unit instead of using iio_read_channel_raw and iio_read_channel_scale and
doing the unit conversion manually.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
---
Changes since v1:
	* Fix mixed up patch fragements between patch 2 and patch 3
---
 drivers/staging/iio/iio_hwmon.c |   33 +++++----------------------------
 1 file changed, 5 insertions(+), 28 deletions(-)

diff --git a/drivers/staging/iio/iio_hwmon.c b/drivers/staging/iio/iio_hwmon.c
index 69d4a3b..5d49122 100644
--- a/drivers/staging/iio/iio_hwmon.c
+++ b/drivers/staging/iio/iio_hwmon.c
@@ -42,40 +42,17 @@ static ssize_t iio_hwmon_read_val(struct device *dev,
 				  struct device_attribute *attr,
 				  char *buf)
 {
-	long result;
-	int val, ret, scaleint, scalepart;
+	int result;
+	int ret;
 	struct sensor_device_attribute *sattr = to_sensor_dev_attr(attr);
 	struct iio_hwmon_state *state = dev_get_drvdata(dev);
 
-	/*
-	 * No locking between this pair, so theoretically possible
-	 * the scale has changed.
-	 */
-	ret = iio_read_channel_raw(&state->channels[sattr->index],
-				      &val);
+	ret = iio_read_channel_processed(&state->channels[sattr->index],
+					&result);
 	if (ret < 0)
 		return ret;
 
-	ret = iio_read_channel_scale(&state->channels[sattr->index],
-					&scaleint, &scalepart);
-	if (ret < 0)
-		return ret;
-	switch (ret) {
-	case IIO_VAL_INT:
-		result = val * scaleint;
-		break;
-	case IIO_VAL_INT_PLUS_MICRO:
-		result = (s64)val * (s64)scaleint +
-			div_s64((s64)val * (s64)scalepart, 1000000LL);
-		break;
-	case IIO_VAL_INT_PLUS_NANO:
-		result = (s64)val * (s64)scaleint +
-			div_s64((s64)val * (s64)scalepart, 1000000000LL);
-		break;
-	default:
-		return -EINVAL;
-	}
-	return sprintf(buf, "%ld\n", result);
+	return sprintf(buf, "%d\n", result);
 }
 
 static void iio_hwmon_free_attrs(struct iio_hwmon_state *st)
-- 
1.7.10.4