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iio: adc: Correct smb1398 scaling function

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Correct scaling function for SMB1398 to ensure
temperature is calculated accurately.

Change-Id: I7ec497ef9d1171da7a08a97730912727c583830a
Signed-off-by: Jishnu Prakash <jprakash@codeaurora.org>
[quic_collinsd@quicinc.com: changed prescale "num" and "den"
 to "numerator" and "denominator" respectively]
Signed-off-by: David Collins <quic_collinsd@quicinc.com>
This commit is contained in:
Jishnu Prakash 2020-09-02 14:25:04 +05:30 committed by David Collins
parent 2b64262524
commit 81fe95c85f
1 changed files with 20 additions and 3 deletions
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23
drivers/iio/adc/qcom-vadc-common.c
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@ -929,9 +929,26 @@ static int qcom_vadc_scale_hw_smb1398_temp(
const struct adc5_data *data,
u16 adc_code, int *result_mdec)
{
*result_mdec = qcom_vadc_scale_code_voltage_factor(adc_code * 100,
prescale, data, PMIC5_SMB1398_TEMP_SCALE_FACTOR);
*result_mdec = PMIC5_SMB1398_TEMP_CONSTANT - *result_mdec;
s64 voltage = 0, adc_vdd_ref_mv = 1875;
u64 temp;
if (adc_code > VADC5_MAX_CODE)
adc_code = 0;
/* (ADC code * vref_vadc (1.875V)) / full_scale_code */
voltage = (s64) adc_code * adc_vdd_ref_mv * 1000;
voltage = div64_s64(voltage, data->full_scale_code_volt);
if (voltage > 0) {
temp = voltage * prescale->denominator;
temp *= 100;
do_div(temp, prescale->numerator * PMIC5_SMB1398_TEMP_SCALE_FACTOR);
voltage = temp;
} else {
voltage = 0;
}
voltage = voltage - PMIC5_SMB1398_TEMP_CONSTANT;
*result_mdec = voltage;
return 0;
}