diff options
| author | Bryan Freed <bfreed@chromium.org> | 2012-09-05 20:55:00 +0100 |
|---|---|---|
| committer | Jonathan Cameron <jic23@kernel.org> | 2012-09-08 10:25:10 +0100 |
| commit | 932323b74e2535dbb6a1b245dfa1aa8cd2bbd8e2 (patch) | |
| tree | dd7fda9f5b49de9d7c5260b44b63af1c86348eef | |
| parent | 7b123c85bbb3fadbd02b82d77d5aee0c399b0e06 (diff) | |
iio: isl29018: Support fractional ALS scaling.iio-for-3.7c
The Industrial IO framework supports scaling ADC values by fractions,
but most drivers default to using whole numbers.
This change turns on fractional scaling in the isl29018 driver.
Signed-off-by: Bryan Freed <bfreed@chromium.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
| -rw-r--r-- | drivers/staging/iio/light/isl29018.c | 17 |
1 files changed, 15 insertions, 2 deletions
diff --git a/drivers/staging/iio/light/isl29018.c b/drivers/staging/iio/light/isl29018.c index 31d22f5591ca..6ee5567d9813 100644 --- a/drivers/staging/iio/light/isl29018.c +++ b/drivers/staging/iio/light/isl29018.c @@ -63,6 +63,7 @@ struct isl29018_chip { struct regmap *regmap; struct mutex lock; unsigned int lux_scale; + unsigned int lux_uscale; unsigned int range; unsigned int adc_bit; int prox_scheme; @@ -145,13 +146,22 @@ static int isl29018_read_sensor_input(struct isl29018_chip *chip, int mode) static int isl29018_read_lux(struct isl29018_chip *chip, int *lux) { int lux_data; + unsigned int data_x_range, lux_unshifted; lux_data = isl29018_read_sensor_input(chip, COMMMAND1_OPMODE_ALS_ONCE); if (lux_data < 0) return lux_data; - *lux = (lux_data * chip->range * chip->lux_scale) >> chip->adc_bit; + /* To support fractional scaling, separate the unshifted lux + * into two calculations: int scaling and micro-scaling. + * lux_uscale ranges from 0-999999, so about 20 bits. Split + * the /1,000,000 in two to reduce the risk of over/underflow. + */ + data_x_range = lux_data * chip->range; + lux_unshifted = data_x_range * chip->lux_scale; + lux_unshifted += data_x_range / 1000 * chip->lux_uscale / 1000; + *lux = lux_unshifted >> chip->adc_bit; return 0; } @@ -339,6 +349,8 @@ static int isl29018_write_raw(struct iio_dev *indio_dev, mutex_lock(&chip->lock); if (mask == IIO_CHAN_INFO_CALIBSCALE && chan->type == IIO_LIGHT) { chip->lux_scale = val; + /* With no write_raw_get_fmt(), val2 is a MICRO fraction. */ + chip->lux_uscale = val2; ret = 0; } mutex_unlock(&chip->lock); @@ -379,7 +391,8 @@ static int isl29018_read_raw(struct iio_dev *indio_dev, case IIO_CHAN_INFO_CALIBSCALE: if (chan->type == IIO_LIGHT) { *val = chip->lux_scale; - ret = IIO_VAL_INT; + *val2 = chip->lux_uscale; + ret = IIO_VAL_INT_PLUS_MICRO; } break; default: |