Hi Jonathan,
On 30-Oct-16 11:05 PM, Jonathan Cameron wrote:
On 26/10/16 15:41, Rama Krishna Phani A wrote:
Logic to convert adc code to voltage is generic across all channels.
Different scaling can be done on the obtained voltage to report in physical
units. Implement separate function for generic conversion logic.
Scaling functionality can be changed per channel. Update changes to support
reporting of Raw adc code.
Pleas rewrite this description. Perhaps give examples of the changes
it makes to what is read from the various attributes?
There are several channels in the ADC of PMIC which can be used to
measure voltage, temperature, current etc., Hardware provides readings
for all channels in adc code. That adc code needs to be converted to
voltage. The logic for conversion of adc code to voltage is common for
all ADC channels(voltage, temperature and current .,etc). Once voltage
is obtained ., scaling is done on that voltage.
For Ex., Thermal SW wants to know the temperature of thermistor on PMIC
and it expects the temperature to be reported in millidegC. ADC channel
is used to read the adc code and convert it to voltage. Once the voltage
is available based on the thermistor spec that voltage is mapped to a
temperature and then that value is reported to Thermal SW.
Mapping of voltage to temperature is called scaling for that channel and
scaling function can be different per channel based on how the voltage
is reported.
I haven't immediately followed what this change is actually doing.
I 'think' the point here is to not apply the calibration to
the raw adc counts when a true raw read is requested?
When a true raw read is requested .,Scaling is not applied.
There are several unconnected looking changes in here...
Signed-off-by: Rama Krishna Phani A <rphani@xxxxxxxxxxxxxx>
---
drivers/iio/adc/qcom-spmi-vadc.c | 54 +++++++++++++++++++++-------------------
1 file changed, 28 insertions(+), 26 deletions(-)
diff --git a/drivers/iio/adc/qcom-spmi-vadc.c b/drivers/iio/adc/qcom-spmi-vadc.c
index c2babe5..ff4d549 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 */
@@ -418,7 +418,7 @@ 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);
@@ -468,21 +468,30 @@ 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 void vadc_scale_calib(struct vadc_priv *vadc, u16 adc_code,
+ const struct vadc_channel_prop *prop,
+ s64 *scale_voltage)
{
- const struct vadc_prescale_ratio *prescale;
- s64 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)
+ *scale_voltage +=
+ vadc->graph[prop->calibration].dx;
- voltage = adc_code - vadc->graph[prop->calibration].gnd;
- voltage *= vadc->graph[prop->calibration].dx;
- voltage = div64_s64(voltage, vadc->graph[prop->calibration].dy);
+ if (*scale_voltage < 0)
+ *scale_voltage = 0;
+}
- if (prop->calibration == VADC_CALIB_ABSOLUTE)
- voltage += vadc->graph[prop->calibration].dx;
+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;
- if (voltage < 0)
- voltage = 0;
+ vadc_scale_calib(vadc, adc_code, prop, &voltage);
prescale = &vadc_prescale_ratios[prop->prescale];
@@ -552,11 +561,8 @@ 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 +570,8 @@ 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;
So this is 'more raw'.
Yes., its raw value.
- case IIO_CHAN_INFO_SCALE:
- *val = 0;
- *val2 = 1000;
- return IIO_VAL_INT_PLUS_MICRO;
default:
ret = -EINVAL;
break;
@@ -616,8 +618,8 @@ struct vadc_channels {
VADC_CHAN(_dname, IIO_TEMP, 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) \
It very unusual to report both raw and processed values. Please explain
why that is needed here? It may be valid to maintain backwards compatibility
of ABI. Which would be fine. However if I read the above correctly you are
changing what comes out of reading the raw value so the ABI just changed...
With the help of IIO sysfs ., we can read the ADC channel readings
either in RAW format or in processed format. There are two separate
individual entries to read the ADC channel either in Raw format or in
processed format. Most of the clients for ADC expect the readings in
processed format.
/*
@@ -850,9 +852,9 @@ 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;
What's this change?
We can choose how we want to display our adc channel entries in sysfs.
Am using the child node name to be displayed as the sysfs entry rather
than channel number for easy interpretation.
For ex: for vcoin(coin battery voltage channel.,) with this change it
appears like below in iio adc sysfs
"in_voltage_vcoin_input"
iio_chan->info_mask_separate = vadc_chan->info_mask;
iio_chan->type = vadc_chan->type;
- iio_chan->indexed = 1;
Or for that matter this one...
reason explained above.
iio_chan->address = index++;
iio_chan++;
Thanks,
Ramakrishna
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