Commit 635ef601 authored by Linus Walleij's avatar Linus Walleij Committed by Jonathan Cameron
Browse files

iio: Provide iio_read_channel_processed_scale() API 

Since the old iio_read_channel_processed() would
lose precision if we fall back to reading raw and
scaling, we introduce a new API that will pass in
a scale factor when reading a processed channel:
iio_read_channel_processed_scale().

Refactor iio_read_channel_processed() as a special
case with scale factor 1.

Cc: Peter Rosin <peda@axentia.se>
Cc: Chris Lesiak <chris.lesiak@licor.com>
Cc: Jonathan Cameron <jic23@kernel.org>
Cc: linux-iio@vger.kernel.org
Link: https://lore.kernel.org/linux-iio/20201224011607.1059534-1-linus.walleij@linaro.org/


Signed-off-by: default avatarLinus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20210308100219.2732156-1-linus.walleij@linaro.org


Signed-off-by: default avatarJonathan Cameron <Jonathan.Cameron@huawei.com>
parent 86073fa2

drivers/iio/inkern.c

+14 −2
Original line number Diff line number Diff line
@@ -688,7 +688,8 @@ int iio_read_channel_offset(struct iio_channel *chan, int *val, int *val2) 
}

EXPORT_SYMBOL_GPL(iio_read_channel_offset);



int iio_read_channel_processed(struct iio_channel *chan, int *val)

int iio_read_channel_processed_scale(struct iio_channel *chan, int *val,

				     unsigned int scale)

{

	int ret;
@@ -701,11 +702,15 @@ int iio_read_channel_processed(struct iio_channel *chan, int *val) 
	if (iio_channel_has_info(chan->channel, IIO_CHAN_INFO_PROCESSED)) {

		ret = iio_channel_read(chan, val, NULL,

				       IIO_CHAN_INFO_PROCESSED);

		if (ret)

			goto err_unlock;

		*val *= scale;

	} 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);

		ret = iio_convert_raw_to_processed_unlocked(chan, *val, val,

							    scale);

	}



err_unlock:
@@ -713,6 +718,13 @@ int iio_read_channel_processed(struct iio_channel *chan, int *val) 


	return ret;

}

EXPORT_SYMBOL_GPL(iio_read_channel_processed_scale);



int iio_read_channel_processed(struct iio_channel *chan, int *val)

{

	/* This is just a special case with scale factor 1 */

	return iio_read_channel_processed_scale(chan, val, 1);

}

EXPORT_SYMBOL_GPL(iio_read_channel_processed);



int iio_read_channel_scale(struct iio_channel *chan, int *val, int *val2)

include/linux/iio/consumer.h

+15 −0
Original line number Diff line number Diff line
@@ -241,6 +241,21 @@ int iio_read_channel_average_raw(struct iio_channel *chan, int *val); 
 */

int iio_read_channel_processed(struct iio_channel *chan, int *val);



/**

 * iio_read_channel_processed_scale() - read and scale a processed value

 * @chan:		The channel being queried.

 * @val:		Value read back.

 * @scale:		Scale factor to apply during the conversion

 *

 * Returns an error code or 0.

 *

 * This function will read a processed value from a channel. This will work

 * like @iio_read_channel_processed() but also scale with an additional

 * scale factor while attempting to minimize any precision loss.

 */

int iio_read_channel_processed_scale(struct iio_channel *chan, int *val,

				     unsigned int scale);



/**

 * iio_write_channel_attribute() - Write values to the device attribute.

 * @chan:	The channel being queried.