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Commit b4ac3015 authored by Jishnu Prakash's avatar Jishnu Prakash
Browse files

iio: adc: Correct smb1398 scaling function 



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

Change-Id: I7ec497ef9d1171da7a08a97730912727c583830a
Signed-off-by: default avatarJishnu Prakash <jprakash@codeaurora.org>
parent 9eaefd97

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

+20 −3
Original line number Diff line number Diff line
@@ -909,9 +909,26 @@ 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->den;

		temp *= 100;

		do_div(temp, prescale->num * PMIC5_SMB1398_TEMP_SCALE_FACTOR);

		voltage = temp;

	} else {

		voltage = 0;

	}



	voltage = voltage - PMIC5_SMB1398_TEMP_CONSTANT;

	*result_mdec = voltage;



	return 0;

}