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 <[email protected]> --- 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: + 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
