On Fri, Oct 21, 2016 at 1:17 AM, Enric Balletbo i Serra <enric.balletbo@xxxxxxxxxxxxx> wrote: > According the ACPI specification (Version 5.0 Errata A) [1], the data > coming from the sensor represent the ambient light illuminance reading > expressed in lux. Unfortunately ACPI interface doesn't provide a > mechanism to calibrate this value, so this raw value can be slightly > wrong. > > This patch adds IIO_CHAN_INFO_OFFSET and IIO_CHAN_INFO_SCALE attributes > to give the possibiity to the userspace to calculate a calibrated data > by doing: > > (raw_value + offset) * scale = calibrated_value (in lux) > > [1] http://www.acpi.info/DOWNLOADS/ACPI_5_Errata%20A.pdf > > Signed-off-by: Enric Balletbo i Serra <enric.balletbo@xxxxxxxxxxxxx> > --- > drivers/iio/light/acpi-als.c | 66 ++++++++++++++++++++++++++++++++++++++------ > 1 file changed, 57 insertions(+), 9 deletions(-) > > diff --git a/drivers/iio/light/acpi-als.c b/drivers/iio/light/acpi-als.c > index f0b47c5..a8093ba 100644 > --- a/drivers/iio/light/acpi-als.c > +++ b/drivers/iio/light/acpi-als.c > @@ -56,7 +56,9 @@ static const struct iio_chan_spec acpi_als_channels[] = { > }, > /* _RAW is here for backward ABI compatibility */ > .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | > - BIT(IIO_CHAN_INFO_PROCESSED), > + BIT(IIO_CHAN_INFO_PROCESSED) | > + BIT(IIO_CHAN_INFO_SCALE) | > + BIT(IIO_CHAN_INFO_OFFSET), > }, > }; > > @@ -76,6 +78,10 @@ struct acpi_als { > struct mutex lock; > > s32 evt_buffer[ACPI_ALS_EVT_BUFFER_SIZE]; > + > + int scale; > + int uscale; > + int offset; > }; > > /* > @@ -154,25 +160,64 @@ static int acpi_als_read_raw(struct iio_dev *indio_dev, > s32 temp_val; > int ret; > > - if ((mask != IIO_CHAN_INFO_PROCESSED) && (mask != IIO_CHAN_INFO_RAW)) > - return -EINVAL; > - > /* we support only illumination (_ALI) so far. */ > if (chan->type != IIO_LIGHT) > return -EINVAL; > > - ret = acpi_als_read_value(als, ACPI_ALS_ILLUMINANCE, &temp_val); > - if (ret < 0) > - return ret; > + switch (mask) { > + case IIO_CHAN_INFO_RAW: > + case IIO_CHAN_INFO_PROCESSED: It seems PROCESSED is identical to RAW. Shouldn't we remove this attribute? > + ret = acpi_als_read_value(als, ACPI_ALS_ILLUMINANCE, &temp_val); > + if (ret < 0) > + return ret; > + *val = temp_val; > + return IIO_VAL_INT; > + case IIO_CHAN_INFO_OFFSET: > + mutex_lock(&als->lock); > + *val = als->offset; > + mutex_unlock(&als->lock); > + return IIO_VAL_INT; > + case IIO_CHAN_INFO_SCALE: > + mutex_lock(&als->lock); > + *val = als->scale; > + *val2 = als->uscale; > + mutex_unlock(&als->lock); > + return IIO_VAL_INT_PLUS_MICRO; > + default: > + return -EINVAL; > + } > +} > > - *val = temp_val; > +static int acpi_als_write_raw(struct iio_dev *indio_dev, > + struct iio_chan_spec const *chan, int val, > + int val2, long mask) > +{ > + struct acpi_als *als = iio_priv(indio_dev); > + > + if (chan->type != IIO_LIGHT) > + return -EINVAL; > > - return IIO_VAL_INT; > + switch (mask) { > + case IIO_CHAN_INFO_OFFSET: > + mutex_lock(&als->lock); > + als->offset = val; > + mutex_unlock(&als->lock); > + return 0; > + case IIO_CHAN_INFO_SCALE: > + mutex_lock(&als->lock); > + als->scale = val; > + als->uscale = val2; > + mutex_unlock(&als->lock); > + return 0; > + default: > + return -EINVAL; > + } > } > > static const struct iio_info acpi_als_info = { > .driver_module = THIS_MODULE, > .read_raw = acpi_als_read_raw, > + .write_raw = acpi_als_write_raw, > }; > > static int acpi_als_add(struct acpi_device *device) > @@ -189,6 +234,9 @@ static int acpi_als_add(struct acpi_device *device) > > device->driver_data = indio_dev; > als->device = device; > + als->scale = 1; > + als->uscale = 0; > + als->offset = 0; > mutex_init(&als->lock); > > indio_dev->name = ACPI_ALS_DEVICE_NAME; > -- > 2.1.0 > -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
