diff options
| author | Ivan T. Ivanov <ivan.ivanov@linaro.org> | 2015-04-17 17:51:08 +0300 |
|---|---|---|
| committer | Jonathan Cameron <jic23@kernel.org> | 2015-04-18 17:40:04 +0100 |
| commit | 937125aca00e0478c4024afe58bc620a7bbe2a93 (patch) | |
| tree | 7ceaa11e4a3e80d4e773b9a4a4cdf3cafc5000a9 /drivers/iio/adc/qcom-spmi-vadc.c | |
| parent | d0716b0ea4ce11a13477163c14b26e180922ba51 (diff) | |
iio: adc: spmi-vadc: Fix overflow in output value normalization
With 'dx' equal to 0.625V and 15 bit ADC, calculations overflow
when difference against GND is ~20% of the ADC range. Fix this.
Signed-off-by: Ivan T. Ivanov <ivan.ivanov@linaro.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
Diffstat (limited to 'drivers/iio/adc/qcom-spmi-vadc.c')
| -rw-r--r-- | drivers/iio/adc/qcom-spmi-vadc.c | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/drivers/iio/adc/qcom-spmi-vadc.c b/drivers/iio/adc/qcom-spmi-vadc.c index 3211729bcb0b..0c4618b4d515 100644 --- a/drivers/iio/adc/qcom-spmi-vadc.c +++ b/drivers/iio/adc/qcom-spmi-vadc.c @@ -18,6 +18,7 @@ #include <linux/iio/iio.h> #include <linux/interrupt.h> #include <linux/kernel.h> +#include <linux/math64.h> #include <linux/module.h> #include <linux/of.h> #include <linux/platform_device.h> @@ -471,11 +472,11 @@ static s32 vadc_calibrate(struct vadc_priv *vadc, const struct vadc_channel_prop *prop, u16 adc_code) { const struct vadc_prescale_ratio *prescale; - s32 voltage; + s64 voltage; voltage = adc_code - vadc->graph[prop->calibration].gnd; voltage *= vadc->graph[prop->calibration].dx; - voltage = voltage / vadc->graph[prop->calibration].dy; + voltage = div64_s64(voltage, vadc->graph[prop->calibration].dy); if (prop->calibration == VADC_CALIB_ABSOLUTE) voltage += vadc->graph[prop->calibration].dx; @@ -487,7 +488,7 @@ static s32 vadc_calibrate(struct vadc_priv *vadc, voltage = voltage * prescale->den; - return voltage / prescale->num; + return div64_s64(voltage, prescale->num); } static int vadc_decimation_from_dt(u32 value) |