Re: [PATCH V3 2/2] iio: adc: spmi-vadc: Changes to support different scaling

[Jonathan Cameron <jic23@kernel.org>]

On 26/10/16 15:41, Rama Krishna Phani A wrote:
> Polling can also be used for End of conversion completion. Implement logic
> to choose either polling or interrupt for End of conversion completion.
Why is this change in a patch with the title above?  Should be a separate patch.

> Scaling can be done on the voltage to report adc code in physical units.
> Add changes to support different scale functions to convert adc code to
> physical units.
> 
> Signed-off-by: Rama Krishna Phani A <rphani@codeaurora.org>
> ---
>  .../devicetree/bindings/iio/adc/qcom,spmi-vadc.txt |  14 ++
>  drivers/iio/adc/qcom-spmi-vadc.c                   | 263 +++++++++++++++++----
>  2 files changed, 236 insertions(+), 41 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/iio/adc/qcom,spmi-vadc.txt b/Documentation/devicetree/bindings/iio/adc/qcom,spmi-vadc.txt
> index 0fb4613..39e31c0e 100644
> --- a/Documentation/devicetree/bindings/iio/adc/qcom,spmi-vadc.txt
> +++ b/Documentation/devicetree/bindings/iio/adc/qcom,spmi-vadc.txt
> @@ -37,6 +37,12 @@ VADC node:
>      Value type: <prop-encoded-array>
>      Definition: End of conversion interrupt.
>  
> +- qcom,vadc-poll-eoc:
> +    Usage: optional
> +    Value type: <bool>
> +    Definition: Use polling instead of interrupts for End of Conversion
> +		completion.
> +
>  Channel node properties:
>  
>  - reg:
> @@ -92,6 +98,14 @@ Channel node properties:
>              Valid values are: 1, 2, 4, 8, 16, 32, 64, 128, 256, 512
>              If property is not found, 1 sample will be used.
>  
> +- qcom,scale-function:
> +    Usage: optional
> +    Value type: <u32>
> +    Definition: Scaling function used to convert raw ADC code to
> +	units specific to a given channel. Scaled units can be
> +	microvolts, millidegC.Valid values are: 0, 1, 2, 3, 4.
> +	If property is not found, 0 scaling will be used.
> +
>  NOTE:
>  
>  Following channels, also known as reference point channels, are used for
> diff --git a/drivers/iio/adc/qcom-spmi-vadc.c b/drivers/iio/adc/qcom-spmi-vadc.c
> index ff4d549..6e521a9 100644
> --- a/drivers/iio/adc/qcom-spmi-vadc.c
> +++ b/drivers/iio/adc/qcom-spmi-vadc.c
> @@ -92,6 +92,8 @@
>  #define VADC_DEF_AVG_SAMPLES			0 /* 1 sample */
>  #define VADC_DEF_CALIB_TYPE			VADC_CALIB_ABSOLUTE
>  
> +#define VADC_DEF_SCALE_FN			SCALE_DEFAULT
> +
>  #define VADC_DECIMATION_MIN			512
>  #define VADC_DECIMATION_MAX			4096
>  
> @@ -100,9 +102,43 @@
>  
>  #define KELVINMIL_CELSIUSMIL			273150
>  
> +#define PMI_CHG_SCALE_1				-138890
> +#define PMI_CHG_SCALE_2				391750000000
> +
>  #define VADC_CHAN_MIN			VADC_USBIN
>  #define VADC_CHAN_MAX			VADC_LR_MUX3_BUF_PU1_PU2_XO_THERM
>  
> +/**
> + * enum vadc_scale_fn_type - Scaling function to convert ADC code to
> + *				physical scaled units for the channel.
> + * %SCALE_DEFAULT: Default scaling to convert raw adc code to voltage (uV).
> + * %SCALE_THERM_100K_PULLUP: Returns temperature in millidegC.
> + *				 Uses a mapping table with 100K pullup.
> + * %SCALE_PMIC_THERM: Returns result in milli degree's Centigrade.
> + * %SCALE_XOTHERM: Returns XO thermistor voltage in millidegC.
> + * %SCALE_PMI_CHG_TEMP: Conversion for PMI CHG temp
> + * %SCALE_NONE: Do not use this scaling type.
> + */
> +enum vadc_scale_fn_type {
> +	SCALE_DEFAULT = 0,
> +	SCALE_THERM_100K_PULLUP,
> +	SCALE_PMIC_THERM,
> +	SCALE_XOTHERM,
> +	SCALE_PMI_CHG_TEMP,
> +	SCALE_NONE,
> +};
> +
> +/**
> + * struct vadc_map_pt - Map the graph representation for ADC channel
> + * @x: Represent the ADC digitized code.
> + * @y: Represent the physical data which can be temperature, voltage,
> + *     resistance.
> + */
> +struct vadc_map_pt {
> +	s32 x;
> +	s32 y;
> +};
> +
>  /*
>   * VADC_CALIB_ABSOLUTE: uses the 625mV and 1.25V as reference channels.
>   * VADC_CALIB_RATIOMETRIC: uses the reference voltage (1.8V) and GND for
> @@ -148,6 +184,9 @@ struct vadc_prescale_ratio {
>   *	start of conversion.
>   * @avg_samples: ability to provide single result from the ADC
>   *	that is an average of multiple measurements.
Make sure your indentation matches the rest of the comment..
> + *@scale_function: Represents the scaling function to convert voltage
> + *	physical units desired by the client for the channel.
> + *	Referenced from enum vadc_scale_fn_type.
>   */
>  struct vadc_channel_prop {
>  	unsigned int channel;
> @@ -156,6 +195,7 @@ struct vadc_channel_prop {
>  	unsigned int prescale;
>  	unsigned int hw_settle_time;
>  	unsigned int avg_samples;
> +	unsigned int scale_function;
>  };
>  
>  /**
> @@ -197,6 +237,44 @@ struct vadc_priv {
>  	{.num =  1, .den = 10}
>  };
>  
> +/* Voltage to temperature */
> +static const struct vadc_map_pt adcmap_100k_104ef_104fb[] = {
> +	{1758,	-40},
> +	{1742,	-35},
> +	{1719,	-30},
> +	{1691,	-25},
> +	{1654,	-20},
> +	{1608,	-15},
> +	{1551,	-10},
> +	{1483,	-5},
> +	{1404,	0},
> +	{1315,	5},
> +	{1218,	10},
> +	{1114,	15},
> +	{1007,	20},
> +	{900,	25},
> +	{795,	30},
> +	{696,	35},
> +	{605,	40},
> +	{522,	45},
> +	{448,	50},
> +	{383,	55},
> +	{327,	60},
> +	{278,	65},
> +	{237,	70},
> +	{202,	75},
> +	{172,	80},
> +	{146,	85},
> +	{125,	90},
> +	{107,	95},
> +	{92,	100},
> +	{79,	105},
> +	{68,	110},
> +	{59,	115},
> +	{51,	120},
> +	{44,	125}
> +};
> +
>  static int vadc_read(struct vadc_priv *vadc, u16 offset, u8 *data)
>  {
>  	return regmap_bulk_read(vadc->regmap, vadc->base + offset, data, 1);
> @@ -468,6 +546,51 @@ static int vadc_measure_ref_points(struct vadc_priv *vadc)
>  	return ret;
>  }
>  
> +static int vadc_map_voltage_temp(const struct vadc_map_pt *pts,
> +				 u32 tablesize, s32 input, s64 *output)
> +{
> +	bool descending = 1;
> +	u32 i = 0;
> +
> +	if (!pts)
> +		return -EINVAL;
> +
> +	/* Check if table is descending or ascending */
> +	if (tablesize > 1) {
> +		if (pts[0].x < pts[1].x)
> +			descending = 0;
> +	}
> +
> +	while (i < tablesize) {
> +		if ((descending) && (pts[i].x < input)) {
> +			/* table entry is less than measured*/
> +			 /* value and table is descending, stop */
> +			break;
> +		} else if ((!descending) &&
> +				(pts[i].x > input)) {
> +			/* table entry is greater than measured*/
> +			/*value and table is ascending, stop */
> +			break;
> +		}
> +		i++;
> +	}
> +
> +	if (i == 0) {
> +		*output = pts[0].y;
> +	} else if (i == tablesize) {
> +		*output = pts[tablesize - 1].y;
> +	} else {
> +		/* result is between search_index and search_index-1 */
> +		/* interpolate linearly */
> +		*output = (((s32)((pts[i].y - pts[i - 1].y) *
> +			(input - pts[i - 1].x)) /
> +			(pts[i].x - pts[i - 1].x)) +
> +			pts[i - 1].y);
> +	}
> +
> +	return 0;
> +}
> +
>  static void vadc_scale_calib(struct vadc_priv *vadc, u16 adc_code,
>  			     const struct vadc_channel_prop *prop,
>  			     s64 *scale_voltage)
> @@ -489,15 +612,61 @@ static s64 vadc_scale_fn(struct vadc_priv *vadc,
>  			 const struct vadc_channel_prop *prop, u16 adc_code)
>  {
>  	const struct vadc_prescale_ratio *prescale;
> -	s64 voltage = 0;
> +	s64 voltage = 0, result = 0;
> +	int ret;
> +
> +	switch (prop->scale_function) {
> +	case SCALE_DEFAULT:
> +		vadc_scale_calib(vadc, adc_code, prop, &voltage);
> +
> +		prescale = &vadc_prescale_ratios[prop->prescale];
> +		voltage = voltage * prescale->den;
> +		return div64_s64(voltage, prescale->num);
> +
> +	case SCALE_THERM_100K_PULLUP:
> +	case SCALE_XOTHERM:
> +		vadc_scale_calib(vadc, adc_code, prop, &voltage);
> +
> +		if (prop->calibration == VADC_CALIB_ABSOLUTE)
> +			voltage /= 1000;
> +
> +		vadc_map_voltage_temp(adcmap_100k_104ef_104fb,
> +				      ARRAY_SIZE(adcmap_100k_104ef_104fb),
> +				      voltage, &result);
> +		result *= 1000;
> +		return result;
> +
> +	case SCALE_PMIC_THERM:
> +		vadc_scale_calib(vadc, adc_code, prop, &voltage);
> +
> +		if (voltage > 0) {
> +			prescale = &vadc_prescale_ratios[prop->prescale];
> +			voltage = voltage * prescale->den;
> +			voltage /= (prescale->num * 2);
> +		} else {
> +			voltage = 0;
> +		}
> +
> +		voltage -= KELVINMIL_CELSIUSMIL;
>  
> -	vadc_scale_calib(vadc, adc_code, prop, &voltage);
> +		return voltage;
>  
> -	prescale = &vadc_prescale_ratios[prop->prescale];
> +	case SCALE_PMI_CHG_TEMP:
> +		vadc_scale_calib(vadc, adc_code, prop, &voltage);
> +		prescale = &vadc_prescale_ratios[prop->prescale];
> +		voltage = voltage * prescale->den;
>  
> -	voltage = voltage * prescale->den;
> +		voltage = div64_s64(voltage, prescale->num);
> +		voltage = ((PMI_CHG_SCALE_1) * (voltage * 2));
> +		voltage = (voltage + PMI_CHG_SCALE_2);
> +		return div64_s64(voltage, 1000000);
>  
> -	return div64_s64(voltage, prescale->num);
> +	default:
> +		ret = -EINVAL;
> +		break;
> +	}
> +
> +	return ret;
>  }
>  
>  static int vadc_decimation_from_dt(u32 value)
> @@ -615,7 +784,9 @@ struct vadc_channels {
>  	},								\
>  
>  #define VADC_CHAN_TEMP(_dname, _pre)					\
> -	VADC_CHAN(_dname, IIO_TEMP, BIT(IIO_CHAN_INFO_PROCESSED), _pre)	\
> +	VADC_CHAN(_dname, IIO_TEMP,	\
> +		BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_PROCESSED), \
> +		_pre)	\
>  
>  #define VADC_CHAN_VOLT(_dname, _pre)					\
>  	VADC_CHAN(_dname, IIO_VOLTAGE,				\
> @@ -639,7 +810,7 @@ struct vadc_channels {
>  	VADC_CHAN_TEMP(DIE_TEMP, 0)
>  	VADC_CHAN_VOLT(REF_625MV, 0)
>  	VADC_CHAN_VOLT(REF_1250MV, 0)
> -	VADC_CHAN_VOLT(CHG_TEMP, 0)
> +	VADC_CHAN_TEMP(CHG_TEMP, 0)
>  	VADC_CHAN_VOLT(SPARE1, 0)
>  	VADC_CHAN_VOLT(SPARE2, 0)
>  	VADC_CHAN_VOLT(GND_REF, 0)
> @@ -693,41 +864,41 @@ struct vadc_channels {
>  	VADC_CHAN_VOLT(AMUX_PU2, 0)
>  	VADC_CHAN_VOLT(LR_MUX3_BUF_XO_THERM, 0)
>  
> -	VADC_CHAN_VOLT(LR_MUX1_PU1_BAT_THERM, 0)
> +	VADC_CHAN_TEMP(LR_MUX1_PU1_BAT_THERM, 0)
>  	VADC_CHAN_VOLT(LR_MUX2_PU1_BAT_ID, 0)
> -	VADC_CHAN_VOLT(LR_MUX3_PU1_XO_THERM, 0)
> -	VADC_CHAN_VOLT(LR_MUX4_PU1_AMUX_THM1, 0)
> -	VADC_CHAN_VOLT(LR_MUX5_PU1_AMUX_THM2, 0)
> -	VADC_CHAN_VOLT(LR_MUX6_PU1_AMUX_THM3, 0)
> +	VADC_CHAN_TEMP(LR_MUX3_PU1_XO_THERM, 0)
> +	VADC_CHAN_TEMP(LR_MUX4_PU1_AMUX_THM1, 0)
> +	VADC_CHAN_TEMP(LR_MUX5_PU1_AMUX_THM2, 0)
> +	VADC_CHAN_TEMP(LR_MUX6_PU1_AMUX_THM3, 0)
>  	VADC_CHAN_VOLT(LR_MUX7_PU1_AMUX_HW_ID, 0)
> -	VADC_CHAN_VOLT(LR_MUX8_PU1_AMUX_THM4, 0)
> -	VADC_CHAN_VOLT(LR_MUX9_PU1_AMUX_THM5, 0)
> +	VADC_CHAN_TEMP(LR_MUX8_PU1_AMUX_THM4, 0)
> +	VADC_CHAN_TEMP(LR_MUX9_PU1_AMUX_THM5, 0)
>  	VADC_CHAN_VOLT(LR_MUX10_PU1_AMUX_USB_ID, 0)
> -	VADC_CHAN_VOLT(LR_MUX3_BUF_PU1_XO_THERM, 0)
> +	VADC_CHAN_TEMP(LR_MUX3_BUF_PU1_XO_THERM, 0)
>  
> -	VADC_CHAN_VOLT(LR_MUX1_PU2_BAT_THERM, 0)
> +	VADC_CHAN_TEMP(LR_MUX1_PU2_BAT_THERM, 0)
>  	VADC_CHAN_VOLT(LR_MUX2_PU2_BAT_ID, 0)
> -	VADC_CHAN_VOLT(LR_MUX3_PU2_XO_THERM, 0)
> -	VADC_CHAN_VOLT(LR_MUX4_PU2_AMUX_THM1, 0)
> -	VADC_CHAN_VOLT(LR_MUX5_PU2_AMUX_THM2, 0)
> -	VADC_CHAN_VOLT(LR_MUX6_PU2_AMUX_THM3, 0)
> +	VADC_CHAN_TEMP(LR_MUX3_PU2_XO_THERM, 0)
> +	VADC_CHAN_TEMP(LR_MUX4_PU2_AMUX_THM1, 0)
> +	VADC_CHAN_TEMP(LR_MUX5_PU2_AMUX_THM2, 0)
> +	VADC_CHAN_TEMP(LR_MUX6_PU2_AMUX_THM3, 0)
>  	VADC_CHAN_VOLT(LR_MUX7_PU2_AMUX_HW_ID, 0)
> -	VADC_CHAN_VOLT(LR_MUX8_PU2_AMUX_THM4, 0)
> -	VADC_CHAN_VOLT(LR_MUX9_PU2_AMUX_THM5, 0)
> +	VADC_CHAN_TEMP(LR_MUX8_PU2_AMUX_THM4, 0)
> +	VADC_CHAN_TEMP(LR_MUX9_PU2_AMUX_THM5, 0)
>  	VADC_CHAN_VOLT(LR_MUX10_PU2_AMUX_USB_ID, 0)
> -	VADC_CHAN_VOLT(LR_MUX3_BUF_PU2_XO_THERM, 0)
> +	VADC_CHAN_TEMP(LR_MUX3_BUF_PU2_XO_THERM, 0)
>  
> -	VADC_CHAN_VOLT(LR_MUX1_PU1_PU2_BAT_THERM, 0)
> +	VADC_CHAN_TEMP(LR_MUX1_PU1_PU2_BAT_THERM, 0)
>  	VADC_CHAN_VOLT(LR_MUX2_PU1_PU2_BAT_ID, 0)
> -	VADC_CHAN_VOLT(LR_MUX3_PU1_PU2_XO_THERM, 0)
> -	VADC_CHAN_VOLT(LR_MUX4_PU1_PU2_AMUX_THM1, 0)
> -	VADC_CHAN_VOLT(LR_MUX5_PU1_PU2_AMUX_THM2, 0)
> -	VADC_CHAN_VOLT(LR_MUX6_PU1_PU2_AMUX_THM3, 0)
> +	VADC_CHAN_TEMP(LR_MUX3_PU1_PU2_XO_THERM, 0)
> +	VADC_CHAN_TEMP(LR_MUX4_PU1_PU2_AMUX_THM1, 0)
> +	VADC_CHAN_TEMP(LR_MUX5_PU1_PU2_AMUX_THM2, 0)
> +	VADC_CHAN_TEMP(LR_MUX6_PU1_PU2_AMUX_THM3, 0)
>  	VADC_CHAN_VOLT(LR_MUX7_PU1_PU2_AMUX_HW_ID, 0)
> -	VADC_CHAN_VOLT(LR_MUX8_PU1_PU2_AMUX_THM4, 0)
> -	VADC_CHAN_VOLT(LR_MUX9_PU1_PU2_AMUX_THM5, 0)
> +	VADC_CHAN_TEMP(LR_MUX8_PU1_PU2_AMUX_THM4, 0)
> +	VADC_CHAN_TEMP(LR_MUX9_PU1_PU2_AMUX_THM5, 0)
>  	VADC_CHAN_VOLT(LR_MUX10_PU1_PU2_AMUX_USB_ID, 0)
> -	VADC_CHAN_VOLT(LR_MUX3_BUF_PU1_PU2_XO_THERM, 0)
> +	VADC_CHAN_TEMP(LR_MUX3_BUF_PU1_PU2_XO_THERM, 0)
>  };
>  
>  static int vadc_get_dt_channel_data(struct device *dev,
> @@ -804,6 +975,11 @@ static int vadc_get_dt_channel_data(struct device *dev,
>  		prop->avg_samples = VADC_DEF_AVG_SAMPLES;
>  	}
>  
> +	ret = of_property_read_u32(node, "qcom,scale-function",
> +				   &prop->scale_function);
> +	if (ret)
> +		prop->scale_function = SCALE_DEFAULT;
> +
>  	if (of_property_read_bool(node, "qcom,ratiometric"))
>  		prop->calibration = VADC_CALIB_RATIOMETRIC;
>  	else
> @@ -966,16 +1142,21 @@ static int vadc_probe(struct platform_device *pdev)
>  	if (ret)
>  		return ret;
>  
> -	irq_eoc = platform_get_irq(pdev, 0);
> -	if (irq_eoc < 0) {
> -		if (irq_eoc == -EPROBE_DEFER || irq_eoc == -EINVAL)
> -			return irq_eoc;
> -		vadc->poll_eoc = true;
> -	} else {
> -		ret = devm_request_irq(dev, irq_eoc, vadc_isr, 0,
> -				       "spmi-vadc", vadc);
> -		if (ret)
> -			return ret;
> +	vadc->poll_eoc = of_property_read_bool(node,
> +						"qcom,vadc-poll-eoc");
Should definitely be done on availability of the IRQ rather than a separate
device tree element.
> +
> +	if (!vadc->poll_eoc) {
> +		irq_eoc = platform_get_irq(pdev, 0);
> +		if (irq_eoc < 0) {
> +			if (irq_eoc == -EPROBE_DEFER || irq_eoc == -EINVAL)
> +				return irq_eoc;
> +			vadc->poll_eoc = true;
> +		} else {
> +			ret = devm_request_irq(dev, irq_eoc, vadc_isr, 0,
> +					       "spmi-vadc", vadc);
> +			if (ret)
> +				return ret;
> +		}
>  	}
>  
>  	ret = vadc_reset(vadc);
>