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patch "iio: adc: spmi-vadc: Fix overflow in output value normalization" added to staging-linus

PATCH [email protected] 1 participant 1 message May 13, 2015

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This is a note to let you know that I've just added the patch titled

iio: adc: spmi-vadc: Fix overflow in output value normalization

to my staging git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git
in the staging-linus branch.

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the next -rc kernel release.

If you have any questions about this process, please let me know.

Quoted 1 line

From 937125aca00e0478c4024afe58bc620a7bbe2a93 Mon Sep 17 00:00:00 2001

From: "Ivan T. Ivanov" <[email protected]>
Date: Fri, 17 Apr 2015 17:51:08 +0300
Subject: 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 <[email protected]>
Cc <[email protected]>
Signed-off-by Jonathan Cameron <[email protected]>
---
 drivers/iio/adc/qcom-spmi-vadc.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)
drivers/iio/adc/qcom-spmi-vadc.c +4 -3
index 3211729bcb0b..0c4618b4d515 100644
@@ -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)
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