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iio:inkern: Add function to read the processed value

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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>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
This commit is contained in:
Lars-Peter Clausen 2012-09-17 13:17:00 +01:00 committed by Jonathan Cameron
parent 45f010baa0
commit 48e44ce0f8
3 changed files with 164 additions and 9 deletions
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118
drivers/iio/inkern.c
View file

@ -238,9 +238,21 @@ 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) {
@ -248,10 +260,7 @@ 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);
@ -259,6 +268,100 @@ int iio_read_channel_raw(struct iio_channel *chan, int *val)
}
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;
@ -269,10 +372,7 @@ 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);

38
include/linux/iio/consumer.h
View file

@ -70,6 +70,21 @@ void iio_channel_release_all(struct iio_channel *chan);
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.
@ -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

17
include/linux/iio/iio.h
View file

@ -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 }