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iio: ltr501: Add light channel support

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Added support to calculate lux value from visible
and IR spectrum adc count values. Also added IIO_LIGHT
channel to enable user read the lux value directly
from device using illuminance input ABI.

Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
This commit is contained in:
Kuppuswamy Sathyanarayanan 2015-05-15 18:23:21 -07:00 committed by Jonathan Cameron
parent c24e7daf82
commit c06cee8d08
1 changed files with 51 additions and 0 deletions
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51
drivers/iio/light/ltr501.c
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@ -66,6 +66,9 @@
#define LTR501_REGMAP_NAME "ltr501_regmap"
#define LTR501_LUX_CONV(vis_coeff, vis_data, ir_coeff, ir_data) \
((vis_coeff * vis_data) - (ir_coeff * ir_data))
static const int int_time_mapping[] = {100000, 50000, 200000, 400000};
static const struct reg_field reg_field_it =
@ -298,6 +301,29 @@ static int ltr501_ps_read_samp_period(struct ltr501_data *data, int *val)
return IIO_VAL_INT;
}
/* IR and visible spectrum coeff's are given in data sheet */
static unsigned long ltr501_calculate_lux(u16 vis_data, u16 ir_data)
{
unsigned long ratio, lux;
if (vis_data == 0)
return 0;
/* multiply numerator by 100 to avoid handling ratio < 1 */
ratio = DIV_ROUND_UP(ir_data * 100, ir_data + vis_data);
if (ratio < 45)
lux = LTR501_LUX_CONV(1774, vis_data, -1105, ir_data);
else if (ratio >= 45 && ratio < 64)
lux = LTR501_LUX_CONV(3772, vis_data, 1336, ir_data);
else if (ratio >= 64 && ratio < 85)
lux = LTR501_LUX_CONV(1690, vis_data, 169, ir_data);
else
lux = 0;
return lux / 1000;
}
static int ltr501_drdy(struct ltr501_data *data, u8 drdy_mask)
{
int tries = 100;
@ -548,7 +574,14 @@ static const struct iio_event_spec ltr501_pxs_event_spec[] = {
.num_event_specs = _evsize,\
}
#define LTR501_LIGHT_CHANNEL() { \
.type = IIO_LIGHT, \
.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED), \
.scan_index = -1, \
}
static const struct iio_chan_spec ltr501_channels[] = {
LTR501_LIGHT_CHANNEL(),
LTR501_INTENSITY_CHANNEL(0, LTR501_ALS_DATA0, IIO_MOD_LIGHT_BOTH, 0,
ltr501_als_event_spec,
ARRAY_SIZE(ltr501_als_event_spec)),
@ -576,6 +609,7 @@ static const struct iio_chan_spec ltr501_channels[] = {
};
static const struct iio_chan_spec ltr301_channels[] = {
LTR501_LIGHT_CHANNEL(),
LTR501_INTENSITY_CHANNEL(0, LTR501_ALS_DATA0, IIO_MOD_LIGHT_BOTH, 0,
ltr501_als_event_spec,
ARRAY_SIZE(ltr501_als_event_spec)),
@ -596,6 +630,23 @@ static int ltr501_read_raw(struct iio_dev *indio_dev,
int ret, i;
switch (mask) {
case IIO_CHAN_INFO_PROCESSED:
if (iio_buffer_enabled(indio_dev))
return -EBUSY;
switch (chan->type) {
case IIO_LIGHT:
mutex_lock(&data->lock_als);
ret = ltr501_read_als(data, buf);
mutex_unlock(&data->lock_als);
if (ret < 0)
return ret;
*val = ltr501_calculate_lux(le16_to_cpu(buf[1]),
le16_to_cpu(buf[0]));
return IIO_VAL_INT;
default:
return -EINVAL;
}
case IIO_CHAN_INFO_RAW:
if (iio_buffer_enabled(indio_dev))
return -EBUSY;