On Sun, 1 Oct 2017 21:48:18 +0200 Stefan Brüns <[email protected]> wrote:
> Reducing shunt and bus voltage range improves the accuracy, so allow > altering the default settings. > > Both settings are exposed as gain values. While for the shunt voltage > this is straightforward, the bus range settings of 32V (default) and 16V > are mapped to gain values of 1 resp. 2, to provide a uniform API to > userspace. > > As the gain settings are incorporated into the raw values by the sensor > itself, adjusting of the scale attributes is not necessary. > > Signed-off-by: Stefan Brüns <[email protected]> cc'd Maciej Purski who is working to improve the current calibration elements - I'd like you both to review each others patches if possible as the ABI is getting complex in here! I think what you have here won't interfere with Maciej's work, but would like you two to confirm that. Note that patch set probably needs a revision as I've suggested a rather different approach. Thanks, Jonathan > > --- > > drivers/iio/adc/ina2xx-adc.c | 111 > +++++++++++++++++++++++++++++++++++++++++-- > 1 file changed, 108 insertions(+), 3 deletions(-) > > diff --git a/drivers/iio/adc/ina2xx-adc.c b/drivers/iio/adc/ina2xx-adc.c > index 1930f853e8c5..7e9ce43ad15d 100644 > --- a/drivers/iio/adc/ina2xx-adc.c > +++ b/drivers/iio/adc/ina2xx-adc.c > @@ -48,8 +48,10 @@ > #define INA2XX_MAX_REGISTERS 8 > > /* settings - depend on use case */ > -#define INA219_CONFIG_DEFAULT 0x399F /* PGA=8 */ > +#define INA219_CONFIG_DEFAULT 0x399F /* PGA=1/8, BRNG=32V */ > #define INA219_DEFAULT_IT 532 > +#define INA219_DEFAULT_BRNG 1 /* 32V */ > +#define INA219_DEFAULT_PGA 125 /* 1000/8 */ > #define INA226_CONFIG_DEFAULT 0x4327 > #define INA226_DEFAULT_AVG 4 > #define INA226_DEFAULT_IT 1110 > @@ -62,6 +64,14 @@ > */ > #define INA2XX_MODE_MASK GENMASK(3, 0) > > +/* Gain for VShunt: 1/8 (default), 1/4, 1/2, 1 */ > +#define INA219_PGA_MASK GENMASK(12, 11) > +#define INA219_SHIFT_PGA(val) ((val) << 11) > + > +/* VBus range: 32V (default), 16V */ > +#define INA219_BRNG_MASK BIT(13) > +#define INA219_SHIFT_BRNG(val) ((val) << 13) > + > /* Averaging for VBus/VShunt/Power */ > #define INA226_AVG_MASK GENMASK(11, 9) > #define INA226_SHIFT_AVG(val) ((val) << 9) > @@ -131,6 +141,8 @@ struct ina2xx_chip_info { > int avg; > int int_time_vbus; /* Bus voltage integration time uS */ > int int_time_vshunt; /* Shunt voltage integration time uS */ > + int range_vbus; /* Bus voltage maximum in V */ > + int pga_gain_vshunt; /* Shunt voltage PGA gain */ > bool allow_async_readout; > }; > > @@ -227,6 +239,18 @@ static int ina2xx_read_raw(struct iio_dev *indio_dev, > *val = 1; > return IIO_VAL_INT; > } > + > + case IIO_CHAN_INFO_HARDWAREGAIN: > + switch (chan->address) { > + case INA2XX_SHUNT_VOLTAGE: > + *val = chip->pga_gain_vshunt; > + *val2 = 1000; > + return IIO_VAL_FRACTIONAL; > + > + case INA2XX_BUS_VOLTAGE: > + *val = chip->range_vbus == 32 ? 1 : 2; > + return IIO_VAL_INT; > + } > } > > return -EINVAL; > @@ -361,6 +385,74 @@ static int ina219_set_int_time_vshunt(struct > ina2xx_chip_info *chip, > return 0; > } > > +static const int ina219_vbus_range_tab[] = { 1, 2 }; > +static int ina219_set_vbus_range_denom(struct ina2xx_chip_info *chip, > + unsigned int range, > + unsigned int *config) > +{ > + if (range == 1) > + chip->range_vbus = 32; > + else if (range == 2) > + chip->range_vbus = 16; > + else > + return -EINVAL; > + > + *config &= ~INA219_BRNG_MASK; > + *config |= INA219_SHIFT_BRNG(range == 1 ? 1 : 0) & INA219_BRNG_MASK; > + > + return 0; > +} > + > +static const int ina219_vshunt_gain_tab[] = { 125, 250, 500, 1000 }; > +static const int ina219_vshunt_gain_frac[] = { > + 125, 1000, 250, 1000, 500, 1000, 1000, 1000 }; > + > +static int ina219_set_vshunt_pga_gain(struct ina2xx_chip_info *chip, > + unsigned int gain, > + unsigned int *config) > +{ > + int bits; > + > + if (gain < 125 || gain > 1000) > + return -EINVAL; > + > + bits = find_closest(gain, ina219_vshunt_gain_tab, > + ARRAY_SIZE(ina219_vshunt_gain_tab)); > + > + chip->pga_gain_vshunt = ina219_vshunt_gain_tab[bits]; > + bits = 3 - bits; > + > + *config &= ~INA219_PGA_MASK; > + *config |= INA219_SHIFT_PGA(bits) & INA219_PGA_MASK; > + > + return 0; > +} > + > +static int ina2xx_read_avail(struct iio_dev *indio_dev, > + struct iio_chan_spec const *chan, > + const int **vals, int *type, int *length, > + long mask) > +{ > + switch (mask) { > + case IIO_CHAN_INFO_HARDWAREGAIN: > + switch (chan->address) { > + case INA2XX_SHUNT_VOLTAGE: > + *type = IIO_VAL_FRACTIONAL; > + *length = sizeof(ina219_vshunt_gain_frac) / sizeof(int); > + *vals = ina219_vshunt_gain_frac; > + return IIO_AVAIL_LIST; > + > + case INA2XX_BUS_VOLTAGE: > + *type = IIO_VAL_INT; > + *length = sizeof(ina219_vbus_range_tab) / sizeof(int); > + *vals = ina219_vbus_range_tab; > + return IIO_AVAIL_LIST; > + } > + } > + > + return -EINVAL; > +} > + > static int ina2xx_write_raw(struct iio_dev *indio_dev, > struct iio_chan_spec const *chan, > int val, int val2, long mask) > @@ -403,6 +495,14 @@ static int ina2xx_write_raw(struct iio_dev *indio_dev, > } > break; > > + case IIO_CHAN_INFO_HARDWAREGAIN: > + if (chan->address == INA2XX_SHUNT_VOLTAGE) > + ret = ina219_set_vshunt_pga_gain(chip, val * 1000000 + > + val2, &tmp); > + else > + ret = ina219_set_vbus_range_denom(chip, val, &tmp); > + break; > + > default: > ret = -EINVAL; > } > @@ -547,7 +647,10 @@ static ssize_t ina2xx_shunt_resistor_store(struct device > *dev, > .channel = (_index), \ > .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \ > BIT(IIO_CHAN_INFO_SCALE) | \ > - BIT(IIO_CHAN_INFO_INT_TIME), \ > + BIT(IIO_CHAN_INFO_INT_TIME) | \ > + BIT(IIO_CHAN_INFO_HARDWAREGAIN), \ > + .info_mask_separate_available = \ > + BIT(IIO_CHAN_INFO_HARDWAREGAIN), \ > .info_mask_shared_by_dir = BIT(IIO_CHAN_INFO_SAMP_FREQ), \ > .scan_index = (_index), \ > .scan_type = { \ > @@ -758,7 +861,6 @@ 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, > ina2xx_allow_async_readout_store, 0); > @@ -793,6 +895,7 @@ static const struct iio_info ina219_info = { > .driver_module = THIS_MODULE, > .attrs = &ina219_attribute_group, > .read_raw = ina2xx_read_raw, > + .read_avail = ina2xx_read_avail, > .write_raw = ina2xx_write_raw, > .debugfs_reg_access = ina2xx_debug_reg, > }; > @@ -874,6 +977,8 @@ static int ina2xx_probe(struct i2c_client *client, > chip->avg = 1; > ina219_set_int_time_vbus(chip, INA219_DEFAULT_IT, &val); > ina219_set_int_time_vshunt(chip, INA219_DEFAULT_IT, &val); > + ina219_set_vbus_range_denom(chip, INA219_DEFAULT_BRNG, &val); > + ina219_set_vshunt_pga_gain(chip, INA219_DEFAULT_PGA, &val); > } > > ret = ina2xx_init(chip, val);
