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SubjectRe: [PATCH v2 1/3] iio: adc: ina2xx: Shift bus voltage register to mask flag bits
On Sat, 28 Oct 2017 23:12:46 +0200
Stefan Brüns <stefan.bruens@rwth-aachen.de> wrote:

> Lower bits of the INA219/220 bus voltage register are conversion
> status flags, properly shift the value.
>
> When reading via IIO buffer, the value is passed on unaltered,
> shifting is the responsibility of the user.
>
> Signed-off-by: Stefan Brüns <stefan.bruens@rwth-aachen.de>
>
I thought about sending this as a fix, but as you haven't marked
it as such and the effect is very minor I haven't done so.

Applied to the togreg branch of iio.git and pushed out as testing
for the autobuilders to play with it.

Thanks,
Jonathan
> ---
>
> Changes in v2:
> - Apply to the shunt voltage, not bus voltage register
> - Shift instead of masking the LSBs
>
> drivers/iio/adc/ina2xx-adc.c | 26 +++++++++++++++++---------
> 1 file changed, 17 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/iio/adc/ina2xx-adc.c b/drivers/iio/adc/ina2xx-adc.c
> index 3aff9556678f..84094235ff7e 100644
> --- a/drivers/iio/adc/ina2xx-adc.c
> +++ b/drivers/iio/adc/ina2xx-adc.c
> @@ -44,7 +44,6 @@
>
> #define INA226_MASK_ENABLE 0x06
> #define INA226_CVRF BIT(3)
> -#define INA219_CNVR BIT(1)
>
> #define INA2XX_MAX_REGISTERS 8
>
> @@ -79,6 +78,11 @@
> #define INA226_ITS_MASK GENMASK(5, 3)
> #define INA226_SHIFT_ITS(val) ((val) << 3)
>
> +/* INA219 Bus voltage register, low bits are flags */
> +#define INA219_OVF BIT(0)
> +#define INA219_CNVR BIT(1)
> +#define INA219_BUS_VOLTAGE_SHIFT 3
> +
> /* Cosmetic macro giving the sampling period for a full P=UxI cycle */
> #define SAMPLING_PERIOD(c) ((c->int_time_vbus + c->int_time_vshunt) \
> * c->avg)
> @@ -112,7 +116,7 @@ struct ina2xx_config {
> u16 config_default;
> int calibration_factor;
> int shunt_div;
> - int bus_voltage_shift;
> + int bus_voltage_shift; /* position of lsb */
> int bus_voltage_lsb; /* uV */
> int power_lsb; /* uW */
> enum ina2xx_ids chip_id;
> @@ -135,7 +139,7 @@ static const struct ina2xx_config ina2xx_config[] = {
> .config_default = INA219_CONFIG_DEFAULT,
> .calibration_factor = 40960000,
> .shunt_div = 100,
> - .bus_voltage_shift = 3,
> + .bus_voltage_shift = INA219_BUS_VOLTAGE_SHIFT,
> .bus_voltage_lsb = 4000,
> .power_lsb = 20000,
> .chip_id = ina219,
> @@ -170,6 +174,9 @@ static int ina2xx_read_raw(struct iio_dev *indio_dev,
> else
> *val = regval;
>
> + if (chan->address == INA2XX_BUS_VOLTAGE)
> + *val >>= chip->config->bus_voltage_shift;
> +
> return IIO_VAL_INT;
>
> case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
> @@ -203,9 +210,9 @@ static int ina2xx_read_raw(struct iio_dev *indio_dev,
> return IIO_VAL_FRACTIONAL;
>
> case INA2XX_BUS_VOLTAGE:
> - /* processed (mV) = raw*lsb (uV) / (1000 << shift) */
> + /* processed (mV) = raw * lsb (uV) / 1000 */
> *val = chip->config->bus_voltage_lsb;
> - *val2 = 1000 << chip->config->bus_voltage_shift;
> + *val2 = 1000;
> return IIO_VAL_FRACTIONAL;
>
> case INA2XX_POWER:
> @@ -532,7 +539,7 @@ static ssize_t ina2xx_shunt_resistor_store(struct device *dev,
> * Sampling Freq is a consequence of the integration times of
> * the Voltage channels.
> */
> -#define INA219_CHAN_VOLTAGE(_index, _address) { \
> +#define INA219_CHAN_VOLTAGE(_index, _address, _shift) { \
> .type = IIO_VOLTAGE, \
> .address = (_address), \
> .indexed = 1, \
> @@ -544,7 +551,8 @@ static ssize_t ina2xx_shunt_resistor_store(struct device *dev,
> .scan_index = (_index), \
> .scan_type = { \
> .sign = 'u', \
> - .realbits = 16, \
> + .shift = _shift, \
> + .realbits = 16 - _shift, \
> .storagebits = 16, \
> .endianness = IIO_LE, \
> } \
> @@ -579,8 +587,8 @@ static const struct iio_chan_spec ina226_channels[] = {
> };
>
> static const struct iio_chan_spec ina219_channels[] = {
> - INA219_CHAN_VOLTAGE(0, INA2XX_SHUNT_VOLTAGE),
> - INA219_CHAN_VOLTAGE(1, INA2XX_BUS_VOLTAGE),
> + INA219_CHAN_VOLTAGE(0, INA2XX_SHUNT_VOLTAGE, 0),
> + INA219_CHAN_VOLTAGE(1, INA2XX_BUS_VOLTAGE, INA219_BUS_VOLTAGE_SHIFT),
> INA219_CHAN(IIO_POWER, 2, INA2XX_POWER),
> INA219_CHAN(IIO_CURRENT, 3, INA2XX_CURRENT),
> IIO_CHAN_SOFT_TIMESTAMP(4),

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