From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, "Ivan T. Ivanov" , Jonathan Cameron Subject: [PATCH 4.0 031/148] iio: adc: spmi-vadc: Fix overflow in output value normalization Date: Wed, 3 Jun 2015 21:08:21 +0900 Message-Id: <20150603114206.690360184@linuxfoundation.org> In-Reply-To: <20150603114205.337615117@linuxfoundation.org> References: <20150603114205.337615117@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Sender: linux-kernel-owner@vger.kernel.org List-ID: 4.0-stable review patch. If anyone has any objections, please let me know. ------------------ From: "Ivan T. Ivanov" commit 937125aca00e0478c4024afe58bc620a7bbe2a93 upstream. 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 Signed-off-by: Jonathan Cameron Signed-off-by: Greg Kroah-Hartman --- drivers/iio/adc/qcom-spmi-vadc.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) --- a/drivers/iio/adc/qcom-spmi-vadc.c +++ b/drivers/iio/adc/qcom-spmi-vadc.c @@ -18,6 +18,7 @@ #include #include #include +#include #include #include #include @@ -471,11 +472,11 @@ static s32 vadc_calibrate(struct vadc_pr 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_pr voltage = voltage * prescale->den; - return voltage / prescale->num; + return div64_s64(voltage, prescale->num); } static int vadc_decimation_from_dt(u32 value)