Re: [PATCH 1/2] iio: adc: Fix integration time/averaging for INA219/220

From: Stefan Bruens
Date: Mon Apr 17 2017 - 08:44:34 EST

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On Freitag, 14. April 2017 17:02:33 CEST Jonathan Cameron wrote:
> On 12/04/17 04:01, Stefan Brüns wrote:
> > INA226/230/231 has integration times per voltage channel and common
> > averaging setting for both channels, while the INA219/220 only has a
> > combined integration time/averaging setting per channel.
> > Only expose the averaging attribute for the INA226, and expose the correct
> > integration times for the INA219.
> >
> > Signed-off-by: Stefan Brüns <stefan.bruens@xxxxxxxxxxxxxx>
>
> A few bits inline.
>
> The info_mask_shared_by_dir isn't right in the driver currently.
> Those elements should be list for every channel in that direction. This
> moves where they are rather than fixing that.
>
> Please sort that mess out whilst you are here.
>
> Thanks,
>
> Jonathan
>
> > ---
> >
> > drivers/iio/adc/ina2xx-adc.c | 179
> > ++++++++++++++++++++++++++++++++++++++----- 1 file changed, 158
> > insertions(+), 21 deletions(-)
> >
> > diff --git a/drivers/iio/adc/ina2xx-adc.c b/drivers/iio/adc/ina2xx-adc.c
> > index 3263231276ca..d1678f886297 100644
> > --- a/drivers/iio/adc/ina2xx-adc.c
> > +++ b/drivers/iio/adc/ina2xx-adc.c
> > @@ -48,6 +48,7 @@
> >
> > /* settings - depend on use case */
> > #define INA219_CONFIG_DEFAULT 0x399F /* PGA=8 */
> >
> > +#define INA219_DEFAULT_IT 532
> >
> > #define INA226_CONFIG_DEFAULT 0x4327
> > #define INA226_DEFAULT_AVG 4
> > #define INA226_DEFAULT_IT 1110
> >
> > @@ -55,19 +56,24 @@
> >
> > #define INA2XX_RSHUNT_DEFAULT 10000
> >
> > /*
> >
> > - * bit mask for reading the averaging setting in the configuration
> > register + * bit masks for reading the settings in the configuration
> > register>
> > * FIXME: use regmap_fields.
>
> Either fix this or drop the fixme. It's fine to regmap fields if you
> like, but it it's not broken if it doesn't use them.

The FIXME was not added nor changed by me. I see no reason to drop it.

> > */
> >
> > #define INA2XX_MODE_MASK GENMASK(3, 0)
> >
> > +/* Averaging for VBus/VShunt/Power */
> >
> > #define INA226_AVG_MASK GENMASK(11, 9)
> > #define INA226_SHIFT_AVG(val) ((val) << 9)
> >
> > /* Integration time for VBus */
> >
> > +#define INA219_ITB_MASK GENMASK(10, 7)
> > +#define INA219_SHIFT_ITB(val) ((val) << 7)
> >
> > #define INA226_ITB_MASK GENMASK(8, 6)
> > #define INA226_SHIFT_ITB(val) ((val) << 6)
> >
> > /* Integration time for VShunt */
> >
> > +#define INA219_ITS_MASK GENMASK(6, 3)
> > +#define INA219_SHIFT_ITS(val) ((val) << 3)
> >
> > #define INA226_ITS_MASK GENMASK(5, 3)
> > #define INA226_SHIFT_ITS(val) ((val) << 3)
> >
> > @@ -107,6 +113,7 @@ struct ina2xx_config {
> >
> > int bus_voltage_shift;
> > int bus_voltage_lsb; /* uV */
> > int power_lsb; /* uW */
> >
> > + enum ina2xx_ids chip_id;
> >
> > };
> >
> > struct ina2xx_chip_info {
> >
> > @@ -129,6 +136,7 @@ static const struct ina2xx_config ina2xx_config[] = {
> >
> > .bus_voltage_shift = 3,
> > .bus_voltage_lsb = 4000,
> > .power_lsb = 20000,
> >
> > + .chip_id = ina219,
> >
> > },
> > [ina226] = {
> >
> > .config_default = INA226_CONFIG_DEFAULT,
> >
> > @@ -137,6 +145,7 @@ static const struct ina2xx_config ina2xx_config[] = {
> >
> > .bus_voltage_shift = 0,
> > .bus_voltage_lsb = 1250,
> > .power_lsb = 25000,
> >
> > + .chip_id = ina226,
> >
> > },
> >
> > };
> >
> > @@ -282,6 +291,66 @@ static int ina226_set_int_time_vshunt(struct
> > ina2xx_chip_info *chip,>
> > return 0;
> >
> > }
> >
> > +/* Conversion times in uS. */
> > +static const int ina219_conv_time_tab_subsample[] = { 84, 148, 276, 532
> > };
> > +static const int ina219_conv_time_tab_average[] = { 532, 1060, 2130,
> > 4260,
> > + 8510, 17020, 34050, 68100};
> > +
> > +static int ina219_lookup_int_time(unsigned int *val_us, int *bits)
> > +{
> > + if (*val_us > 68100 || *val_us < 84)
> > + return -EINVAL;
> > +
> > + if (*val_us <= 532) {
> > + *bits = find_closest(*val_us, ina219_conv_time_tab_subsample,
> > + ARRAY_SIZE(ina219_conv_time_tab_subsample));
> > + *val_us = ina219_conv_time_tab_subsample[*bits];
> > + } else {
> > + *bits = find_closest(*val_us, ina219_conv_time_tab_average,
> > + ARRAY_SIZE(ina219_conv_time_tab_average));
> > + *val_us = ina219_conv_time_tab_average[*bits];
> > + *bits |= 0x8;
> > + }
> > +
> > + return 0;
> > +}
> > +
> > +static int ina219_set_int_time_vbus(struct ina2xx_chip_info *chip,
> > + unsigned int val_us, unsigned int *config)
> > +{
> > + int bits, ret;
> > + unsigned int val_us_best = val_us;
> > +
> > + ret = ina219_lookup_int_time(&val_us_best, &bits);
> > + if (ret)
> > + return ret;
> > +
> > + chip->int_time_vbus = val_us_best;
> > +
> > + *config &= ~INA219_ITB_MASK;
> > + *config |= INA219_SHIFT_ITB(bits) & INA219_ITB_MASK;
> > +
> > + return 0;
> > +}
> > +
> > +static int ina219_set_int_time_vshunt(struct ina2xx_chip_info *chip,
> > + unsigned int val_us, unsigned int *config)
> > +{
> > + int bits, ret;
> > + unsigned int val_us_best = val_us;
> > +
> > + ret = ina219_lookup_int_time(&val_us_best, &bits);
> > + if (ret)
> > + return ret;
> > +
> > + chip->int_time_vshunt = val_us_best;
> > +
> > + *config &= ~INA219_ITS_MASK;
> > + *config |= INA219_SHIFT_ITS(bits) & INA219_ITS_MASK;
> > +
> > + return 0;
> > +}
> > +
> >
> > static int ina2xx_write_raw(struct iio_dev *indio_dev,
> >
> > struct iio_chan_spec const *chan,
> > int val, int val2, long mask)
> >
> > @@ -307,10 +376,15 @@ static int ina2xx_write_raw(struct iio_dev
> > *indio_dev,>
> > break;
> >
> > case IIO_CHAN_INFO_INT_TIME:
> > - if (chan->address == INA2XX_SHUNT_VOLTAGE)
> > + if ((chip->config->chip_id == ina226) &&
> > + (chan->address == INA2XX_SHUNT_VOLTAGE))
> >
> > ret = ina226_set_int_time_vshunt(chip, val2, &tmp);
> >
> > - else
> > + else if (chip->config->chip_id == ina226)
> >
> > ret = ina226_set_int_time_vbus(chip, val2, &tmp);
> >
> > + else if (chan->address == INA2XX_SHUNT_VOLTAGE)
> > + ret = ina219_set_int_time_vshunt(chip, val2, &tmp);
> > + else
> > + ret = ina219_set_int_time_vbus(chip, val2, &tmp);
>
> This new ordering of the if statement is convoluted and difficult to follow.
> Just use a nested if and I think it'll be easier to read.

I can change this, but the extra indentation level will force a line break to
not exceed the 78 character limit.

> > break;
> >
> > default:
> > @@ -416,10 +490,8 @@ static ssize_t ina2xx_shunt_resistor_store(struct
> > device *dev,>
> > .address = (_address), \
> > .indexed = 1, \
> > .channel = (_index), \
> >
> > - .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) \
> > - | BIT(IIO_CHAN_INFO_SCALE), \
> > - .info_mask_shared_by_dir = BIT(IIO_CHAN_INFO_SAMP_FREQ) | \
> > - BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO), \
> > + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
> > + BIT(IIO_CHAN_INFO_SCALE), \
>
> Sometimes it just feels like diff is trying to make it really hard
> to see what has changed.
>
> Firstly the new info_mask_separate is just a reformat. Fine, but not
> in this patch. Should be in it's own patch.
>
> The dropping of the shared_by_dir however makes me wonder what is going
> on. Shared_by_dir elements should be present in every single channel
> of that direction. This already isn't true in the driver and should be
> fixed to maintain consistency. This makes it worse.

Unfortunately there is no documentation how the *_shared_by_* fields have to
be used. It seems to work if a bit is only set on some channels of a group.

This patch makes is neither better nor worse. Previously, e.g.
IIO_CHAN_INFO_SAMP_FREQ was set on both the power and current channels, now it
is set on the bus and shunt voltage channels. Both variants create a single
in_sample_frequency attribute.

> > .scan_index = (_index), \
> > .scan_type = { \
> >
> > .sign = 'u', \
> >
> > @@ -433,7 +505,26 @@ static ssize_t ina2xx_shunt_resistor_store(struct
> > device *dev,>
> > * Sampling Freq is a consequence of the integration times of
> > * the Voltage channels.
> > */
> >
> > -#define INA2XX_CHAN_VOLTAGE(_index, _address) { \
> > +#define INA226_CHAN_VOLTAGE(_index, _address) { \
> > + .type = IIO_VOLTAGE, \
> > + .address = (_address), \
> > + .indexed = 1, \
> > + .channel = (_index), \
> > + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
> > + BIT(IIO_CHAN_INFO_SCALE) | \
> > + BIT(IIO_CHAN_INFO_INT_TIME), \
> > + .info_mask_shared_by_dir = BIT(IIO_CHAN_INFO_SAMP_FREQ) | \
> > + BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO), \
> > + .scan_index = (_index), \
> > + .scan_type = { \
> > + .sign = 'u', \
> > + .realbits = 16, \
> > + .storagebits = 16, \
> > + .endianness = IIO_LE, \
> > + } \
> > +}
> > +
> > +#define INA219_CHAN_VOLTAGE(_index, _address) { \
> >
> > .type = IIO_VOLTAGE, \
> > .address = (_address), \
> > .indexed = 1, \
> >
> > @@ -441,6 +532,7 @@ static ssize_t ina2xx_shunt_resistor_store(struct
> > device *dev,>
> > .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
> >
> > BIT(IIO_CHAN_INFO_SCALE) | \
> > BIT(IIO_CHAN_INFO_INT_TIME), \
> >
> > + .info_mask_shared_by_dir = BIT(IIO_CHAN_INFO_SAMP_FREQ), \
>
> This looks sort of like a bug fix. As it is just shared_by_dir it will
> apply to all input channels so should have been specified for them all in
> the first place. However, if so, the oversampling ratio should be the
> same.

No. TI226 has one oversampling ("averaging" in the DS) setting applying to all
channels. TI219 has no explicit averaging.

Apparently, on the TI226, all 4 channels (current, power, bus voltage, shunt)
should have the IIO_CHAN_INFO_SAMP_FREQ and IIO_CHAN_INFO_OVERSAMPLING bits
set in the info_mask_shared_by_dir, while the TI219 should have set only the
IIO_CHAN_INFO_SAMP_FREQ bit.

> > .scan_index = (_index), \
> > .scan_type = { \
> >
> > .sign = 'u', \
> >
> > @@ -450,9 +542,18 @@ static ssize_t ina2xx_shunt_resistor_store(struct
> > device *dev,>
> > } \
> >
> > }
> >
> > -static const struct iio_chan_spec ina2xx_channels[] = {
> > - INA2XX_CHAN_VOLTAGE(0, INA2XX_SHUNT_VOLTAGE),
> > - INA2XX_CHAN_VOLTAGE(1, INA2XX_BUS_VOLTAGE),
> > +
> > +static const struct iio_chan_spec ina226_channels[] = {
> > + INA226_CHAN_VOLTAGE(0, INA2XX_SHUNT_VOLTAGE),
> > + INA226_CHAN_VOLTAGE(1, INA2XX_BUS_VOLTAGE),
> > + INA2XX_CHAN(IIO_POWER, 2, INA2XX_POWER),
> > + INA2XX_CHAN(IIO_CURRENT, 3, INA2XX_CURRENT),
> > + IIO_CHAN_SOFT_TIMESTAMP(4),
> > +};
> > +
> > +static const struct iio_chan_spec ina219_channels[] = {
> > + INA219_CHAN_VOLTAGE(0, INA2XX_SHUNT_VOLTAGE),
> > + INA219_CHAN_VOLTAGE(1, INA2XX_BUS_VOLTAGE),
> >
> > INA2XX_CHAN(IIO_POWER, 2, INA2XX_POWER),
> > INA2XX_CHAN(IIO_CURRENT, 3, INA2XX_CURRENT),
> > IIO_CHAN_SOFT_TIMESTAMP(4),
> >
> > @@ -589,7 +690,14 @@ static int ina2xx_debug_reg(struct iio_dev
> > *indio_dev,
> >
> > }
> >
> >
> > /* Possible integration times for vshunt and vbus */
> >
> > -static IIO_CONST_ATTR_INT_TIME_AVAIL("0.000140 0.000204 0.000332 0.000588
> > 0.001100 0.002116 0.004156 0.008244"); +static
> > IIO_CONST_ATTR_NAMED(ina219_integration_time_available,
> > + integration_time_available,
> > + "0.000084 0.000148 0.000276 0.000532 0.001060 0.002130
0.004260
> > 0.008510 0.017020 0.034050 0.068100"); +
> > +static IIO_CONST_ATTR_NAMED(ina226_integration_time_available,
> > + integration_time_available,
> > + "0.000140 0.000204 0.000332 0.000588 0.001100 0.002116
0.004156
> > 0.008244"); +
> >
> > static IIO_DEVICE_ATTR(in_allow_async_readout, S_IRUGO | S_IWUSR,
> >
> > ina2xx_allow_async_readout_show,
> >
> > @@ -599,20 +707,39 @@ static IIO_DEVICE_ATTR(in_shunt_resistor, S_IRUGO |
> > S_IWUSR,>
> > ina2xx_shunt_resistor_show,
> > ina2xx_shunt_resistor_store, 0);
> >
> > -static struct attribute *ina2xx_attributes[] = {
> > +static struct attribute *ina219_attributes[] = {
> > + &iio_dev_attr_in_allow_async_readout.dev_attr.attr,
> > + &iio_const_attr_ina219_integration_time_available.dev_attr.attr,
> > + &iio_dev_attr_in_shunt_resistor.dev_attr.attr,
> > + NULL,
> > +};
> > +
> > +static struct attribute *ina226_attributes[] = {
> >
> > &iio_dev_attr_in_allow_async_readout.dev_attr.attr,
> >
> > - &iio_const_attr_integration_time_available.dev_attr.attr,
> > + &iio_const_attr_ina226_integration_time_available.dev_attr.attr,
> >
> > &iio_dev_attr_in_shunt_resistor.dev_attr.attr,
> > NULL,
> >
> > };
> >
> > -static const struct attribute_group ina2xx_attribute_group = {
> > - .attrs = ina2xx_attributes,
> > +static const struct attribute_group ina219_attribute_group = {
> > + .attrs = ina219_attributes,
> >
> > };
> >
> > -static const struct iio_info ina2xx_info = {
> > +static const struct attribute_group ina226_attribute_group = {
> > + .attrs = ina226_attributes,
> > +};
> > +
> > +static const struct iio_info ina219_info = {
> >
> > .driver_module = THIS_MODULE,
> >
> > - .attrs = &ina2xx_attribute_group,
> > + .attrs = &ina219_attribute_group,
> > + .read_raw = ina2xx_read_raw,
> > + .write_raw = ina2xx_write_raw,
> > + .debugfs_reg_access = ina2xx_debug_reg,
> > +};
> > +
> > +static const struct iio_info ina226_info = {
> > + .driver_module = THIS_MODULE,
> > + .attrs = &ina226_attribute_group,
> >
> > .read_raw = ina2xx_read_raw,
> > .write_raw = ina2xx_write_raw,
> > .debugfs_reg_access = ina2xx_debug_reg,
> >
> > @@ -678,6 +805,10 @@ static int ina2xx_probe(struct i2c_client *client,
> >
> > ina226_set_average(chip, INA226_DEFAULT_AVG, &val);
> > ina226_set_int_time_vbus(chip, INA226_DEFAULT_IT, &val);
> > ina226_set_int_time_vshunt(chip, INA226_DEFAULT_IT, &val);
> >
> > + } else {
> > + chip->avg = 1;
> > + ina219_set_int_time_vbus(chip, INA219_DEFAULT_IT, &val);
> > + ina219_set_int_time_vshunt(chip, INA219_DEFAULT_IT, &val);
> >
> > }
> >
> > ret = ina2xx_init(chip, val);
> >
> > @@ -689,10 +820,16 @@ static int ina2xx_probe(struct i2c_client *client,
> >
> > indio_dev->modes = INDIO_DIRECT_MODE | INDIO_BUFFER_SOFTWARE;
> > indio_dev->dev.parent = &client->dev;
> > indio_dev->dev.of_node = client->dev.of_node;
> >
> > - indio_dev->channels = ina2xx_channels;
> > - indio_dev->num_channels = ARRAY_SIZE(ina2xx_channels);
> > + if (id->driver_data == ina226) {
> > + indio_dev->channels = ina226_channels;
> > + indio_dev->num_channels = ARRAY_SIZE(ina226_channels);
> > + indio_dev->info = &ina226_info;
> > + } else {
> > + indio_dev->channels = ina219_channels;
> > + indio_dev->num_channels = ARRAY_SIZE(ina219_channels);
> > + indio_dev->info = &ina219_info;
> > + }
> >
> > indio_dev->name = id->name;
> >
> > - indio_dev->info = &ina2xx_info;
> >
> > indio_dev->setup_ops = &ina2xx_setup_ops;
> >
> > buffer = devm_iio_kfifo_allocate(&indio_dev->dev);

--
Stefan Brüns / Bergstraße 21 / 52062 Aachen
home: +49 241 53809034 mobile: +49 151 50412019
work: +49 2405 49936-424

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