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>

diff --git a/drivers/iio/chemical/ccs811.c b/drivers/iio/chemical/ccs811.c
index 840a6cb..8cfac6d 100644 (file)
--- a/drivers/iio/chemical/ccs811.c
+++ b/drivers/iio/chemical/ccs811.c
@@ -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;
        }