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

[Rama Krishna Phani A <rphani-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>]

Polling can also be used for End of conversion completion. Implement logic
to choose either polling or interrupt for End of conversion completion.
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-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.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.
+ *@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");
+
+	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);
-- 
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