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Date: Thu, 14 May 2015 18:26:07 -0700
From: Kuppuswamy Sathyanarayanan
<sathyanarayanan.kuppuswamy@...ux.intel.com>
To: jic23@...nel.org, pmeerw@...erw.net
Cc: linux-iio@...r.kernel.org, srinivas.pandruvada@...ux.intel.com,
sathyanarayanan.kuppuswamy@...ux.intel.com,
linux-kernel@...r.kernel.org
Subject: [PATCH v2 1/1] iio: ltr501: Add light channel support
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@...ux.intel.com>
---
drivers/iio/light/ltr501.c | 57 ++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 57 insertions(+)
diff --git a/drivers/iio/light/ltr501.c b/drivers/iio/light/ltr501.c
index ca4bf47..449b0fd 100644
--- a/drivers/iio/light/ltr501.c
+++ b/drivers/iio/light/ltr501.c
@@ -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 +574,20 @@ 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, \
+ .scan_type = { \
+ .sign = 'u', \
+ .realbits = 16, \
+ .storagebits = 16, \
+ .endianness = IIO_CPU, \
+ }, \
+}
+
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 +615,7 @@ 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 +636,23 @@ 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;
--
1.9.1
--
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