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Commit 937125ac authored by Ivan T. Ivanov's avatar Ivan T. Ivanov Committed by Jonathan Cameron
Browse files

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: default avatarIvan T. Ivanov <ivan.ivanov@linaro.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarJonathan Cameron <jic23@kernel.org>
parent d0716b0e

drivers/iio/adc/qcom-spmi-vadc.c

+4 −3
Original line number Diff line number Diff line
@@ -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)