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

[Stefan Bruens <stefan.bruens@rwth-aachen.de>]

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@rwth-aachen.de>
> 
> 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
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