Re: [PATCH V2 2/3] iio: adc: qcom-vadc-common: add reverse scaling for PMIC5 Gen2 ADC_TM

[Jonathan Cameron <jic23@kernel.org>]

On Tue, 26 Oct 2021 21:34:34 +0530
Jishnu Prakash <quic_jprakash@quicinc.com> wrote:

> Add reverse scaling function for PMIC5 Gen2 ADC_TM, to convert
> temperature to raw ADC code, for setting thresholds for
> thermistor channels.
> 
> Signed-off-by: Jishnu Prakash <quic_jprakash@quicinc.com>
This little utility function looks fine to me.

Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

> ---
>  drivers/iio/adc/qcom-vadc-common.c       | 11 +++++++++++
>  include/linux/iio/adc/qcom-vadc-common.h |  2 ++
>  2 files changed, 13 insertions(+)
> 
> diff --git a/drivers/iio/adc/qcom-vadc-common.c b/drivers/iio/adc/qcom-vadc-common.c
> index 1472389..194d7c3 100644
> --- a/drivers/iio/adc/qcom-vadc-common.c
> +++ b/drivers/iio/adc/qcom-vadc-common.c
> @@ -677,6 +677,17 @@ u16 qcom_adc_tm5_temp_volt_scale(unsigned int prescale_ratio,
>  }
>  EXPORT_SYMBOL(qcom_adc_tm5_temp_volt_scale);
>  
> +u16 qcom_adc_tm5_gen2_temp_res_scale(int temp)
> +{
> +	int64_t resistance;
> +
> +	resistance = qcom_vadc_map_temp_voltage(adcmap7_100k,
> +		ARRAY_SIZE(adcmap7_100k), temp);
> +
> +	return div64_s64(resistance * RATIO_MAX_ADC7, resistance + R_PU_100K);
> +}
> +EXPORT_SYMBOL(qcom_adc_tm5_gen2_temp_res_scale);
> +
>  int qcom_adc5_hw_scale(enum vadc_scale_fn_type scaletype,
>  		    unsigned int prescale_ratio,
>  		    const struct adc5_data *data,
> diff --git a/include/linux/iio/adc/qcom-vadc-common.h b/include/linux/iio/adc/qcom-vadc-common.h
> index 33f60f4..598a5d2 100644
> --- a/include/linux/iio/adc/qcom-vadc-common.h
> +++ b/include/linux/iio/adc/qcom-vadc-common.h
> @@ -161,6 +161,8 @@ int qcom_adc5_hw_scale(enum vadc_scale_fn_type scaletype,
>  u16 qcom_adc_tm5_temp_volt_scale(unsigned int prescale_ratio,
>  				 u32 full_scale_code_volt, int temp);
>  
> +u16 qcom_adc_tm5_gen2_temp_res_scale(int temp);
> +
>  int qcom_adc5_prescaling_from_dt(u32 num, u32 den);
>  
>  int qcom_adc5_hw_settle_time_from_dt(u32 value, const unsigned int *hw_settle);