Commit 0db5de4f authored Dec 06, 2017 by Narcisa Ana Maria Vasile Committed by Greg Kroah-Hartman Feb 03, 2018

iio: chemical: ccs811: Fix output of IIO_CONCENTRATION channels



commit 8f114acd4e1a9cfa05b70bcc4219bc88197b5c9b upstream.

in_concentration_raw should report, according to sysfs-bus-iio documentation,
a "Raw (unscaled no offset etc.) percentage reading of a substance."

Modify scale to convert from ppm/ppb to percentage:
1 ppm = 0.0001%
1 ppb = 0.0000001%

There is no offset needed to convert the ppm/ppb to percentage,
so remove offset from IIO_CONCENTRATION (IIO_MOD_CO2) channel.

Cc'd stable to reduce chance of userspace breakage in the long
run as we fix this wrong bit of ABI usage.

Signed-off-by: Narcisa Ana Maria Vasile <narcisaanamaria12@gmail.com>
Reviewed-by: Matt Ranostay <matt.ranostay@konsulko.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent e2d4cdb7

drivers/iio/chemical/ccs811.c

+3 −10

Original line number	Diff line number	Diff line
		@@ -91,7 +91,6 @@ static const struct iio_chan_spec ccs811_channels[] = {
		.channel2 = IIO_MOD_CO2,
		.modified = 1,
		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) \|
		BIT(IIO_CHAN_INFO_OFFSET) \|
		BIT(IIO_CHAN_INFO_SCALE),
		.scan_index = 0,
		.scan_type = {
		@@ -245,24 +244,18 @@ static int ccs811_read_raw(struct iio_dev *indio_dev,
		switch (chan->channel2) {
		case IIO_MOD_CO2:
		*val = 0;
		*val2 = 12834;
		*val2 = 100;
		return IIO_VAL_INT_PLUS_MICRO;
		case IIO_MOD_VOC:
		*val = 0;
		*val2 = 84246;
		return IIO_VAL_INT_PLUS_MICRO;
		*val2 = 100;
		return IIO_VAL_INT_PLUS_NANO;
		default:
		return -EINVAL;
		}
		default:
		return -EINVAL;
		}
		case IIO_CHAN_INFO_OFFSET:
		if (!(chan->type == IIO_CONCENTRATION &&
		chan->channel2 == IIO_MOD_CO2))
		return -EINVAL;
		*val = -400;
		return IIO_VAL_INT;
		default:
		return -EINVAL;
		}