On 11/15/2012 01:15 PM, Lars-Peter Clausen wrote:
> The temperature scale and offset depend on the reference voltage, the current
> formula used in the driver assumes a 2.5V reference. This patch modifies the
> code to report the unprocessed value for the temperature channel "raw" property
> and to provide proper "scale" and "offset" properties which depend on the
> selected reference voltage.
added to togreg branch of iio.git. Thanks.
>
> Signed-off-by: Lars-Peter Clausen <lars@xxxxxxxxxx>
> ---
> drivers/staging/iio/adc/ad7298_core.c | 51 ++++++++++++++++-------------------
> 1 file changed, 23 insertions(+), 28 deletions(-)
>
> diff --git a/drivers/staging/iio/adc/ad7298_core.c b/drivers/staging/iio/adc/ad7298_core.c
> index 6dd696f..b74b76f 100644
> --- a/drivers/staging/iio/adc/ad7298_core.c
> +++ b/drivers/staging/iio/adc/ad7298_core.c
> @@ -45,7 +45,8 @@ static const struct iio_chan_spec ad7298_channels[] = {
> .indexed = 1,
> .channel = 0,
> .info_mask = IIO_CHAN_INFO_RAW_SEPARATE_BIT |
> - IIO_CHAN_INFO_SCALE_SEPARATE_BIT,
> + IIO_CHAN_INFO_SCALE_SEPARATE_BIT |
> + IIO_CHAN_INFO_OFFSET_SEPARATE_BIT,
> .address = AD7298_CH_TEMP,
> .scan_index = -1,
> .scan_type = {
> @@ -80,7 +81,7 @@ static int ad7298_scan_direct(struct ad7298_state *st, unsigned ch)
>
> static int ad7298_scan_temp(struct ad7298_state *st, int *val)
> {
> - int tmp, ret;
> + int ret;
> __be16 buf;
>
> buf = cpu_to_be16(AD7298_WRITE | AD7298_TSENSE |
> @@ -102,24 +103,24 @@ static int ad7298_scan_temp(struct ad7298_state *st, int *val)
> if (ret)
> return ret;
>
> - tmp = be16_to_cpu(buf) & RES_MASK(AD7298_BITS);
> + *val = sign_extend32(be16_to_cpu(buf), 11);
>
> - /*
> - * One LSB of the ADC corresponds to 0.25 deg C.
> - * The temperature reading is in 12-bit twos complement format
> - */
> + return 0;
> +}
> +
> +static int ad7298_get_ref_voltage(struct ad7298_state *st)
> +{
> + int vref;
>
> - if (tmp & (1 << (AD7298_BITS - 1))) {
> - tmp = (4096 - tmp) * 250;
> - tmp -= (2 * tmp);
> + if (st->ext_ref) {
> + vref = regulator_get_voltage(st->reg);
> + if (vref < 0)
> + return vref;
>
> + return vref / 1000;
> } else {
> - tmp *= 250; /* temperature in milli degrees Celsius */
> + return AD7298_INTREF_mV;
> }
> -
> - *val = tmp;
> -
> - return 0;
> }
>
> static int ad7298_read_raw(struct iio_dev *indio_dev,
> @@ -130,7 +131,6 @@ static int ad7298_read_raw(struct iio_dev *indio_dev,
> {
> int ret;
> struct ad7298_state *st = iio_priv(indio_dev);
> - int scale_mv;
>
> switch (m) {
> case IIO_CHAN_INFO_RAW:
> @@ -155,24 +155,19 @@ static int ad7298_read_raw(struct iio_dev *indio_dev,
> case IIO_CHAN_INFO_SCALE:
> switch (chan->type) {
> case IIO_VOLTAGE:
> - if (st->ext_ref) {
> - scale_mv = regulator_get_voltage(st->reg);
> - if (scale_mv < 0)
> - return scale_mv;
> - scale_mv /= 1000;
> - } else {
> - scale_mv = AD7298_INTREF_mV;
> - }
> - *val = scale_mv;
> + *val = ad7298_get_ref_voltage(st);
> *val2 = chan->scan_type.realbits;
> return IIO_VAL_FRACTIONAL_LOG2;
> case IIO_TEMP:
> - *val = 1;
> - *val2 = 0;
> - return IIO_VAL_INT_PLUS_MICRO;
> + *val = ad7298_get_ref_voltage(st);
> + *val2 = 10;
> + return IIO_VAL_FRACTIONAL;
> default:
> return -EINVAL;
> }
> + case IIO_CHAN_INFO_OFFSET:
> + *val = 1093 - 2732500 / ad7298_get_ref_voltage(st);
> + return IIO_VAL_INT;
> }
> return -EINVAL;
> }
>
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