Re: [PATCH V1]iio: adc: spmi-vadc: Changes to support different scaling

From: Phani A, Rama Krishna
Date: Wed Oct 26 2016 - 05:27:49 EST

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Hi Sricharan,

Will incorporate the suggested changes in the next patch set.

On 25-Oct-16 6:39 PM, Sricharan wrote:

Hi Ramakrishna,

Add changes to support different scale functions to convert adc code to
physical units.

Signed-off-by: Rama Krishna Phani A <rphani@xxxxxxxxxxxxxx>
---
drivers/iio/adc/qcom-spmi-vadc.c | 319 ++++++++++++++++++++++++++++++---------
1 file changed, 249 insertions(+), 70 deletions(-)

diff --git a/drivers/iio/adc/qcom-spmi-vadc.c b/drivers/iio/adc/qcom-spmi-vadc.c
index c2babe5..e605a9d 100644
--- a/drivers/iio/adc/qcom-spmi-vadc.c
+++ b/drivers/iio/adc/qcom-spmi-vadc.c
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2012-2014, The Linux Foundation. All rights reserved.
+ * Copyright (c) 2012-2016, The Linux Foundation. All rights reserved.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 and
@@ -84,7 +84,7 @@
#define VADC_MAX_ADC_CODE 0xa800

#define VADC_ABSOLUTE_RANGE_UV 625000
-#define VADC_RATIOMETRIC_RANGE_UV 1800000
+#define VADC_RATIOMETRIC_RANGE 1800

#define VADC_DEF_PRESCALING 0 /* 1:1 */
#define VADC_DEF_DECIMATION 0 /* 512 */
@@ -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);
@@ -418,7 +496,7 @@ static int vadc_measure_ref_points(struct vadc_priv *vadc)
u16 read_1, read_2;
int ret;

- vadc->graph[VADC_CALIB_RATIOMETRIC].dx = VADC_RATIOMETRIC_RANGE_UV;
+ vadc->graph[VADC_CALIB_RATIOMETRIC].dx = VADC_RATIOMETRIC_RANGE;
vadc->graph[VADC_CALIB_ABSOLUTE].dx = VADC_ABSOLUTE_RANGE_UV;

prop = vadc_get_channel(vadc, VADC_REF_1250MV);
@@ -468,27 +546,128 @@ static int vadc_measure_ref_points(struct vadc_priv *vadc)
return ret;
}

-static s32 vadc_calibrate(struct vadc_priv *vadc,
- const struct vadc_channel_prop *prop, u16 adc_code)
+static int vadc_map_voltage_temp(const struct vadc_map_pt *pts,
+ u32 tablesize, s32 input, s64 *output)
{
- const struct vadc_prescale_ratio *prescale;
- s64 voltage;
+ 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 == 1) && (pts[i].x < input)) {

Just if (descending) instead of (descending == 1) and so on for the below as well

Will change in next patch.

+ /* table entry is less than measured*/
+ /* value and table is descending, stop */
+ break;
+ } else if ((descending == 0) &&
+ (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);
+ }

hmm, so for descending, input - pts[i -1].x is negative and
we are adding that to pts[i-1].y, is that correct ?

The formula used is to interpolate between two points using linear interpolation.

- voltage = adc_code - vadc->graph[prop->calibration].gnd;
- voltage *= vadc->graph[prop->calibration].dx;
- voltage = div64_s64(voltage, vadc->graph[prop->calibration].dy);
+ return 0;
+}

+static void vadc_scale_calib(struct vadc_priv *vadc, u16 adc_code,
+ const struct vadc_channel_prop *prop,
+ s64 *scale_voltage)
+{
+ *scale_voltage = (adc_code -
+ vadc->graph[prop->calibration].gnd);
+ *scale_voltage *= vadc->graph[prop->calibration].dx;
+ *scale_voltage = div64_s64(*scale_voltage,
+ vadc->graph[prop->calibration].dy);
if (prop->calibration == VADC_CALIB_ABSOLUTE)
- voltage += vadc->graph[prop->calibration].dx;
+ *scale_voltage +=
+ vadc->graph[prop->calibration].dx;

- if (voltage < 0)
- voltage = 0;
+ if (*scale_voltage < 0)
+ *scale_voltage = 0;
+}

- prescale = &vadc_prescale_ratios[prop->prescale];
+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, result = 0;
+ int ret;

- voltage = voltage * prescale->den;
+ switch (prop->scale_function) {

- return div64_s64(voltage, prescale->num);
+ 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);
+

This is the default case that exists today. So the code rearrange for making
the vadc_scale_calib common can be introduced in one patch and the
rest of the below new scaling functions in subsequent patches.

Will change in next patch.

+ case SCALE_THERM_100K_PULLUP:
+ case SCALE_XOTHERM:
+ vadc_scale_calib(vadc, adc_code, prop, &voltage);
+
+ if (prop->calibration == VADC_CALIB_ABSOLUTE)
+ do_div(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;
+ do_div(voltage, prescale->num * 2);
+ } else {
+ voltage = 0;
+ }
+
+ voltage -= KELVINMIL_CELSIUSMIL;
+
+ return voltage;
+
+ case SCALE_PMI_CHG_TEMP:
+ vadc_scale_calib(vadc, adc_code, prop, &voltage);
+ prescale = &vadc_prescale_ratios[prop->prescale];
+ 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);
+
+ default:
+ ret = -EINVAL;
+ break;
+ }
+
+ return ret;
}

static int vadc_decimation_from_dt(u32 value)
@@ -552,11 +731,8 @@ static int vadc_read_raw(struct iio_dev *indio_dev,
if (ret)
break;

- *val = vadc_calibrate(vadc, prop, adc_code);
+ *val = vadc_scale_fn(vadc, prop, adc_code);

- /* 2mV/K, return milli Celsius */
- *val /= 2;
- *val -= KELVINMIL_CELSIUSMIL;
return IIO_VAL_INT;
case IIO_CHAN_INFO_RAW:
prop = &vadc->chan_props[chan->address];
@@ -564,12 +740,8 @@ static int vadc_read_raw(struct iio_dev *indio_dev,
if (ret)
break;

- *val = vadc_calibrate(vadc, prop, adc_code);
+ *val = (int)adc_code;
return IIO_VAL_INT;
- case IIO_CHAN_INFO_SCALE:
- *val = 0;
- *val2 = 1000;
- return IIO_VAL_INT_PLUS_MICRO;
default:
ret = -EINVAL;
break;
@@ -613,11 +785,13 @@ 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, \
- BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE), \
+ VADC_CHAN(_dname, IIO_VOLTAGE, \
+ BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_PROCESSED),\
_pre) \

For this and the below changes to VADC_CHAN_VOLT to TEMP, why is that done ?
Now both macros are setting the same flags.

For Voltage channels IIO_VOLTAGE is needed where as for Temperature channels IIO_TEMP is needed.

/*
@@ -637,12 +811,11 @@ 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)
VADC_CHAN_VOLT(VDD_VADC, 0)
-
VADC_CHAN_VOLT(P_MUX1_1_1, 0)
VADC_CHAN_VOLT(P_MUX2_1_1, 0)
VADC_CHAN_VOLT(P_MUX3_1_1, 0)
@@ -659,7 +832,6 @@ struct vadc_channels {
VADC_CHAN_VOLT(P_MUX14_1_1, 0)
VADC_CHAN_VOLT(P_MUX15_1_1, 0)
VADC_CHAN_VOLT(P_MUX16_1_1, 0)
-
VADC_CHAN_VOLT(P_MUX1_1_3, 1)
VADC_CHAN_VOLT(P_MUX2_1_3, 1)
VADC_CHAN_VOLT(P_MUX3_1_3, 1)
@@ -676,7 +848,6 @@ struct vadc_channels {
VADC_CHAN_VOLT(P_MUX14_1_3, 1)
VADC_CHAN_VOLT(P_MUX15_1_3, 1)
VADC_CHAN_VOLT(P_MUX16_1_3, 1)
-
VADC_CHAN_VOLT(LR_MUX1_BAT_THERM, 0)
VADC_CHAN_VOLT(LR_MUX2_BAT_ID, 0)
VADC_CHAN_VOLT(LR_MUX3_XO_THERM, 0)
@@ -690,42 +861,40 @@ struct vadc_channels {
VADC_CHAN_VOLT(AMUX_PU1, 0)
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_VOLT(LR_MUX1_PU2_BAT_THERM, 0)
+ VADC_CHAN_TEMP(LR_MUX3_BUF_PU1_XO_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_VOLT(LR_MUX1_PU1_PU2_BAT_THERM, 0)
+ VADC_CHAN_TEMP(LR_MUX3_BUF_PU2_XO_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,
@@ -802,6 +971,11 @@ 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;
+

Is this a new binding, in that case the documentation has to be updated for this and
probably introduce this in one first patch and more patches for the rest of the changes.

Yes ., its a new binding. Will change in next patch.

if (of_property_read_bool(node, "qcom,ratiometric"))
prop->calibration = VADC_CALIB_RATIOMETRIC;
else
@@ -850,9 +1024,9 @@ static int vadc_get_dt_data(struct vadc_priv *vadc, struct device_node *node)

iio_chan->channel = prop.channel;
iio_chan->datasheet_name = vadc_chan->datasheet_name;
+ iio_chan->extend_name = child->name;
iio_chan->info_mask_separate = vadc_chan->info_mask;
iio_chan->type = vadc_chan->type;
- iio_chan->indexed = 1;
iio_chan->address = index++;

iio_chan++;
@@ -964,16 +1138,21 @@ 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");
+

Same comment as above for introducing the new binding and the reason
for that.

Yes ., its a new binding. Will change in next patch.

+ 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);

Regards,
Sricharan

Thanks,
Ramakrishna

Next message: Paolo Valente: "[PATCH 08/14] block, bfq: preserve a low latency also with NCQ-capable drives"
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