Hi,
On 10/18/2012 08:11 AM, Kim, Milo wrote:
> To get the battery voltage and temperature, IIO ADC functions are used.
> LP8788 ADC driver provides RAW and SCALE channel information.
> Both RAW with SCALE values are used for the ADC calculation.
> The scale is micro unit, additional conversions are required in each case.
> This patch fixes wrong ADC result.
>
> Signed-off-by: Milo(Woogyom) Kim <milo....@ti.com>
> ---
> drivers/power/lp8788-charger.c | 18 ++++++++++++++++--
> 1 file changed, 16 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/power/lp8788-charger.c b/drivers/power/lp8788-charger.c
> index 02fc9ab..3c739e6 100644
> --- a/drivers/power/lp8788-charger.c
> +++ b/drivers/power/lp8788-charger.c
> @@ -239,19 +239,26 @@ static int lp8788_get_vbatt_adc(struct lp8788_charger
> *pchg,
> unsigned int *result)
> {
> struct iio_channel *channel = pchg->chan[LP8788_VBATT];
> + int raw;
> int scaleint;
> int scalepart;
> int ret;
> + unsigned long tmp;
>
> if (!channel)
> return -EINVAL;
>
> + ret = iio_read_channel_raw(channel, &raw);
> + if (ret != IIO_VAL_INT)
> + return -EINVAL;
> +
> ret = iio_read_channel_scale(channel, &scaleint, &scalepart);
> if (ret != IIO_VAL_INT_PLUS_MICRO)
> return -EINVAL;
>
> /* unit: mV */
> - *result = (scaleint + scalepart * 1000000) / 1000;
> + tmp = raw * scaleint + div_u64(raw * scalepart, 1000000L);
> + *result = (unsigned int)tmp;
We now have a function in the IIO core which does the sampling + conversion
in one step: iio_read_channel_processed. This basically allows you to reduce
this function to
return iio_read_channel_processed(channel, result);
I'd also make the result parameter of lp8788_get_vbatt_adc signed, since
both power_supply_propval.intval and iio_read_channel_processed use a signed
int.
>
> return 0;
> }
> @@ -304,19 +311,26 @@ static int lp8788_get_battery_temperature(struct
> lp8788_charger *pchg,
> union power_supply_propval *val)
> {
> struct iio_channel *channel = pchg->chan[LP8788_BATT_TEMP];
> + int raw;
> int scaleint;
> int scalepart;
> int ret;
> + unsigned long tmp;
>
> if (!channel)
> return -EINVAL;
>
> + ret = iio_read_channel_raw(channel, &raw);
> + if (ret != IIO_VAL_INT)
> + return -EINVAL;
> +
> ret = iio_read_channel_scale(channel, &scaleint, &scalepart);
> if (ret != IIO_VAL_INT_PLUS_MICRO)
> return -EINVAL;
>
> /* unit: 0.1 'C */
> - val->intval = (scaleint + scalepart * 1000000) / 100;
> + tmp = raw * scaleint + div_u64(raw * scalepart, 1000000L);
> + val->intval = (unsigned int)tmp * 10;
>
Same here
> return 0;
> }
--
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