The user (or an init script) may setup RShunt via sysfs after the driver was initialized, for instance based on the EEPROM contents of a modular probe. The calibration register must be set accordingly.
Signed-off-by: Marc Titinger <marc.titin...@baylibre.com> --- v2 of http://www.spinics.net/lists/linux-iio/msg23402.html: - remove unnecessary line insertions - cleanup leftover unused variable (build warning) - patch 2/2 is unchanged (see v1) --- drivers/iio/adc/ina2xx-adc.c | 39 ++++++++++++++++++++++++--------------- 1 file changed, 24 insertions(+), 15 deletions(-) diff --git a/drivers/iio/adc/ina2xx-adc.c b/drivers/iio/adc/ina2xx-adc.c index 65909d5..4e56fe3 100644 --- a/drivers/iio/adc/ina2xx-adc.c +++ b/drivers/iio/adc/ina2xx-adc.c @@ -350,6 +350,23 @@ static ssize_t ina2xx_allow_async_readout_store(struct device *dev, return len; } +/* + * Set current LSB to 1mA, shunt is in uOhms + * (equation 13 in datasheet). We hardcode a Current_LSB + * of 1.0 x10-6. The only remaining parameter is RShunt. + * There is no need to expose the CALIBRATION register + * to the user for now. But we need to reset this register + * if the user updates RShunt after driver init, e.g upon + * reading an EEPROM/Probe-type value. + */ +static int ina2xx_set_calibration(struct ina2xx_chip_info *chip) +{ + u16 regval = DIV_ROUND_CLOSEST(chip->config->calibration_factor, + chip->shunt_resistor); + + return regmap_write(chip->regmap, INA2XX_CALIBRATION, regval); +} + static int set_shunt_resistor(struct ina2xx_chip_info *chip, unsigned int val) { if (val <= 0 || val > chip->config->calibration_factor) @@ -385,6 +402,11 @@ static ssize_t ina2xx_shunt_resistor_store(struct device *dev, if (ret) return ret; + /* Update the Calibration register */ + ret = ina2xx_set_calibration(chip); + if (ret) + return ret; + return len; } @@ -602,24 +624,11 @@ static const struct iio_info ina2xx_info = { /* Initialize the configuration and calibration registers. */ static int ina2xx_init(struct ina2xx_chip_info *chip, unsigned int config) { - u16 regval; - int ret; - - ret = regmap_write(chip->regmap, INA2XX_CONFIG, config); + int ret = regmap_write(chip->regmap, INA2XX_CONFIG, config); if (ret) return ret; - /* - * Set current LSB to 1mA, shunt is in uOhms - * (equation 13 in datasheet). We hardcode a Current_LSB - * of 1.0 x10-6. The only remaining parameter is RShunt. - * There is no need to expose the CALIBRATION register - * to the user for now. - */ - regval = DIV_ROUND_CLOSEST(chip->config->calibration_factor, - chip->shunt_resistor); - - return regmap_write(chip->regmap, INA2XX_CALIBRATION, regval); + return ina2xx_set_calibration(chip); } static int ina2xx_probe(struct i2c_client *client, -- 2.5.0
