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Date: Fri, 21 Oct 2016 10:17:09 +0200
From: Enric Balletbo i Serra <enric.balletbo@...labora.com>
To: linux-kernel@...r.kernel.org, linux-iio@...r.kernel.org,
jic23@...nel.org
Cc: lars@...afoo.de, gwendal@...omium.org
Subject: [PATCH] iio: light: acpi-als: Add IO_CHAN_INFO_OFFSET/SCALE to mask.
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@...labora.com>
---
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
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