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Date: Mon, 09 Oct 2017 10:36:16 +0200
From: Maciej Purski <m.purski@...sung.com>
To: Jonathan Cameron <jic23@...nel.org>,
Stefan Brüns <stefan.bruens@...h-aachen.de>
Cc: linux-iio@...r.kernel.org,
Peter Meerwald-Stadler <pmeerw@...erw.net>,
linux-kernel@...r.kernel.org, "Andrew F . Davis" <afd@...com>,
Javier Martinez Canillas <javier@....samsung.com>,
Lars-Peter Clausen <lars@...afoo.de>,
Hartmut Knaack <knaack.h@....de>
Subject: Re: [PATCH 3/3] iio: adc: ina2xx: Allow setting Shunt Voltage PGA
gain and Bus Voltage range
On 10/08/2017 12:07 PM, Jonathan Cameron wrote:
> On Sun, 1 Oct 2017 21:48:18 +0200
> Stefan Brüns <stefan.bruens@...h-aachen.de> 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 <stefan.bruens@...h-aachen.de>
>
> 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
>
Hi,
it looks fine to me. The patches shouldn't interfere with each other.
Regards,
Maciej
>>
>> ---
>>
>> 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);
>
>
>
>
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