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@xxxxxxxxxx> Cc: Chris Lesiak <chris.lesiak@xxxxxxxxx> Cc: Jonathan Cameron <jic23@xxxxxxxxxx> Cc: linux-iio@xxxxxxxxxxxxxxx Link: https://lore.kernel.org/linux-iio/20201224011607.1059534-1-linus.walleij@xxxxxxxxxx/ Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx> --- ChangeLog v3->v4: - Split off as separate API-introducing patch. - Fix a goto err when scaling. - My suggestion is to apply this patch with Jonathan's ACK to the hwmon tree. --- drivers/iio/inkern.c | 16 ++++++++++++++-- include/linux/iio/consumer.h | 15 +++++++++++++++ 2 files changed, 29 insertions(+), 2 deletions(-) diff --git a/drivers/iio/inkern.c b/drivers/iio/inkern.c index db77a2d4a56b..c61fc06f98b8 100644 --- a/drivers/iio/inkern.c +++ b/drivers/iio/inkern.c @@ -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) diff --git a/include/linux/iio/consumer.h b/include/linux/iio/consumer.h index 0a90ba8fa1bb..5fa5957586cf 100644 --- a/include/linux/iio/consumer.h +++ b/include/linux/iio/consumer.h @@ -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. -- 2.29.2
