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authorIvan T. Ivanov <ivan.ivanov@linaro.org>2015-04-17 14:51:08 (GMT)
committerJonathan Cameron <jic23@kernel.org>2015-04-18 16:40:04 (GMT)
commit937125aca00e0478c4024afe58bc620a7bbe2a93 (patch)
tree7ceaa11e4a3e80d4e773b9a4a4cdf3cafc5000a9 /drivers
parentd0716b0ea4ce11a13477163c14b26e180922ba51 (diff)
downloadlinux-937125aca00e0478c4024afe58bc620a7bbe2a93.tar.xz
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')
-rw-r--r--drivers/iio/adc/qcom-spmi-vadc.c7
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 3211729..0c4618b 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)